UNIVERSITY OF CALIFORNIA
AT LOS ANGELES
CONTRIBUTIONS TO A SCIENCE
OF
NEMATOLOGY
By
N.'A. fcOBB
914 - 1935
CONTRIBUTIONS TO A SCIENCE OF NEMATOLOGY
Contents
Page
I. Antarctic Marine Free-Living Nematodes of the
Shackleton Expedition 1
II. North American Free-Living Fresh-Water Nema-
todes Z5
III. The Asymmetry of the Nematode Bunonema in-
equale, n. sp 101
IV. Selachinema, a New Nematode Genus with Remark-
able Mandibles 113
V. Notes on Nemas 117
VI. The Mononchs, a Genus of Free-Living Predatory
Nematodes 129
VII. Filter-Bed Nemas: Nematodes of the Slow Sand
Filter-Beds of American Cities 189
VIII. The Orders and Classes of Nemas 213
IX. One Hundred New Nemas
(Type Species of 100 New Genera) 217
X. Howardula benigna, a Nemic Parasite of the
Cucumber -Bee tie 345
XI. Marionella ' 353
XII. Greeffiella 359
XIII. An Amendation of Hoplolaimus Daday 1905 nee
auctores 363
XIV. Notes on Paratylenchus, a Genus of Nemas . . . 367
XV. Biological Relationships of the Mathematical
Series 1, 2, 4, etc 371
XVI. Nemic Spermatogenesis 375
XVII. The Screw Nemas, Parasites of Codfish, Haddock
and Other Fishes 388
XVIII. Ungella secta n. gen. n. sp., a Nemic Parasite
of the Burmese Oligochaete (Earthworm) .... 394
XIX. A New Species of the Nemic Genus Syringolaimus. 398
XX. The Chromatropism of Mermis subnigrescens . . . 403
XXI. Survey of Nemas in Marine Beach Sand 411
XXII. The Ambulatory Tubes and Other Features of the
Nema Draconema cephalatum 413
XXIII. Observations on the Morphology and Physiology
of Nemas 419
XXIV. The Demanian Vessels in Nemas of the Genus
Oncholaimus 423
XXV. Metoncholaimus pristiurus (Zur Strassen). . . . 439
XXVI. A Key to the Genera of Free-Living Nemas . . . 451
87184
ANTARCTIC MARINE
FREE-LIVING NEMATODES
OF THE
SHACKLETON EXPEDITION
Contributions to a Science of Nematology
I
BY
N. A. COBB
(With fifty illustrations in the text)
BALTIMORE
WILLIAMS & WILKINS CO.
1914
To Shackleton
And his Men,
Who to bring these stranger forms
Braved the ice and cold
Of the Southern Main,
This tribute from a comber of milder shores.
ANTARCTIC MARINE
FREE-LIVIXG NEMATODES
OF THE
SHACKLETON EXPEDITION
BY N. A. COBB
CONTRIBUTIONS TO A SCIENCE OF NEMATOLOGY l
Nematodes are so frequent in the Shackleton collections as to prove
the seabottoms of the farthest south to swarm with these little beings.
Hundreds of them, male, female and young, were taken from a mere
thimbleful of the dredgings. The same tale comes from stations wide
apart. Countless myriads find sustenance in these cold dark depths,
and must in their turn be devoured by larger forms, until the series
culminates in herds of seal and schools of whale. "All that in them is,"
takes on added meaning!
Whence do these nematodes derive their sustenance? The stomachs
of a number of the species contain diatoms with such regularity as to
leave no doubt that these microscopic plants constitute a main food
supply. The undigested frustules of the diatoms are voided and go to
make up the permanent sea floor, so that the interesting little creatures
whose portraits follow, or at least a part of them, assist in building
what some future epoch may disclose as dry land formations of diato-
maceous earth as remarkable as those of the United States or those
of Tripoli. Some of the other species appear to be predacious, though
none belong to the truly carnivorous group of the Enoplidae. No doubt
the greater part of the species are vegetarian.
These antarctic species are on the whole somewhat smaller than those
of warmer seas, but one of them, that mentioned last, is a veritable
1 N ematology a contraction of Nematodology. The founding of this branch
of science, on a par with Entomology for example, is fully justified by the fact
that the Nematodes constitute such a distinct and highly characteristic group of
organisms, containing an enormous number of species readily susceptible of
division into definite Orders, some of which are of great economic importance.
ANTARCTIC MARINE
giant of its kind. Seven tropical Monhysteras taken at random from
the writer's collections prove to average hardly 50 per cent longer
than the average of the seven polar Monhysteras here described.
There is little evidence that these polar species are less fecund than
those found elsewhere. It is hardly conceivable that the body tem-
perature of the marine polar species is higher than that of the water
in which they live, namely, near the freezing point of fresh water, and
yet, in spite of the freezing temperature, and the long polar night,
nematode protoplasm seems to glide on through its mitosis dance to
much the same purpose as if bathed in equatorial light and ensconced
in the warm pools of tropical reefs.
Through long residence and much travel in Pacific regions the writer
has had unusual opportunity to become acquainted with their charac-
teristics, and having at
times paid particular
attention to the marine
nematodes of these re-
gions (map), is able
from personal observa-
tion to say concerning
the nematodes Lieu-
tenant Shackleton's
expedition brought
from the far South, that
in nothing are they
more remarkable than
in the striking resem-
blance they bear to
forms found in the
warmer parts of the
water hemisphere.
Their nearest known
relatives are found in
Xew Zealand and the
islands off the coast of
the south end of South
America. Nearly all of
the Shackleton species belong to known genera, and the two new
genera are nearly related to genera already known, Aplectus to the known
Plectus and Austronema to the known Monhystera.
Fig. 1. Marks indicate about twenty of the
author's Xematode Stations Xorth American, Asi-
atic, Australasian and Oceanic at the great ma-
jority of which he has made personal examinations,
and with the nematode fauna of which the Shackle-
ton nematode collections are compared.
FREE-LIVING NEMATODES 5
The spermatogenesis of Terschellingia polaris, n. sp. presents some
very interesting features which are noted in connection with the de-
scription. Kecently it has been suggested that of the two kinds of
spermatozoa Boveri and Schleip have shown to exist in the males of
the free-living generation of Khabdias bufonis, 2 one kind, supposedly
that producing males, becomes functionless, thus accounting for the
succeeding generation consisting solely of "parthenogenetic females,"
found in frogs' lungs. The spermatozoa of Ascaris equorum 3 and (?)
Cystidicola farionis f have been shown also to be of two sorts. In all
these cases the two kinds of spermatozoa are very similar to each other,
so much so that the differences were long overlooked by keen observers.
In Terschellingia polaris the differences in the male generative cells are
of an extremely striking character, and seem to lend countenance to
the earlier suggestion of the writer, that spermatocytes may in their
reduction division produce polar bodies or their true homologues, abor-
tive spermatozoa. We realize now that there has been too large a
degree of assumption in taking it for granted that all four of the sper-
matozoa quartette are equivalent simply because they are similar in
form and size. A careful examination of their structure is revealing
important differences.
Very possibly it is a comparatively minor phenomenon that the polar
bodies of eggs remain attached to their larger functional companion
cell. Taking this view, three of the four companion-spermatozoa may,
without violence, be regarded as homologues of the "polar bodies."
Whether they are functional or not is a matter that may be considered
quite apart from their history or structure. Generally speaking we
know little or nothing about their relative "potency." That all, or any
definite fraction of them are functional is more or less pure supposition.
What we know is that some of them are functional perhaps all, per-
haps not.
Though these things are thus far outside our field of experience, they
constitute problems that seem certain soon to be attacked from the
experimental side, by following the history of specific members of the
spermatid quartette; and one object of this note is to call attention to
the fact that the free-living nematodes offer an attractive field for such
work.
2 Rhabdias bufonis (Schrank 1788) S. and H. 1905 = " Rhabditis nigrovenosa."
3 A scan's equorum Goeze 1782 = "A scan's megalocephala."
4 (?) Cystidicola farionis Fischer 1798 = " A ncry acanthus cystidicola."
6 ANTARCTIC MARINE
Incidentally there is raised the very interesting question whether
Terschellingia polaris may not be the free-living form of a dimorphic
species having a parasitic stage in some higher antarctic form. It is
the writer's impression, based on a very considerable amount of obser-
vation, that numerous free-living nematode forms, marine as well as
land and fresh water, belong to such dimorphic species.
The following diagram illustrates the nature of the formula used in
the tabulation of the various necessary measurements :
Fig. 2. Diagram of the descriptive decimal formula used for nematodes ; 6, 7,
8, 10, 6 are the transverse measurements, while 7, 14, 28, 50, 88 are the correspond-
ing longitudinal measurements. The formula in this case is :
7. 14. 28. 50. 88.
T! 8. 10. 6.
The unit of measurement is the hundredth part of the length of the
body, whatever that may be. The measurements become, therefore,
percentages of the length. The absolute length is given in millimeters
as a final non-paired term.
The measurements are taken with the animal viewed in profile; the
first are taken at the base of the pharynx, the second at the nerve-ring,
the third at the cardiac constriction or end of the neck, the fourth at
the vulva in females and at the middle (3/) in males, the fifth at the
anus. The formulae represent the average of several specimens.
When the specimens were received from Mr. James Murray, the
biologist of the Shackleton Expedition, they were in formalin. They
were next treated with cold concentrated solution of mercuric chloride,
then stained with Mayer's acid carmine and finally examined in balsam.
It is W 7 ell to bear these facts in mind in reading the measurements, as
both the relative and absolute measurements vary somewhat with
various methods of fixation and preservation. The number of speci-
mens and their state of preservation is noted at the end of each de-
scription, and from the data a rough guess may often be made as to
the abundance of the species and the relative frequency of the sexes.
By the use of suggestive conventional signs the formulae are made
to convey considerable additional information. Thus the formula on p.
7 indicates that the cuticle is traversed by rather coarse transverse striae, 5
* Formula line of short dashes. See table, p. 7.
FREE-LIVING NEMATODES
85.
~ 2 .
-H
T.T
which are resolvable into rows of dot-like markings 6 modified on the lat-
eral fields, 7 where there are distinct wings to the cuticle, 8 one on each side
of the lateral lines. The N \
excretory pore is located
near the lips, 9 and the
tail end is armed with ph
iii! i sp
caudal glands and a spin-
neret. 10 The oesophagus has a posterior or cardiac bulb two-thirds as
wide as the base of the neck. 11 The two ovaries are symmetrically ar-
ranged, reflexed, and occupy 19 per cent of the length of the body. 12
And, similarly, the male internal sexual organ is single and outstretched,
and occupies 56 per cent of the length of the body.
Among the dredgings at Ross Island were three containing nematodes
which furnished material for this report. These three were marked:
(1) "Bay, Cape Royds, in 10 to 20 fathoms of water, May 81, 1908;" (2)
"Cape Royds, in 25 to 50 fathoms of water, July, 1908;" (3) "Bay,
in 13 fathoms of water, April 30, 1908." These are referred to in the
following descriptions as, (1), Bay, Cape Royds; (2), Cape Royds;
and (3), Bay.
Terminology relating to Striation of Cuticle.
Tern
250
500
Bather fine
750
Fine
" 1000
Very fine
" 1500 or more
None
The camera lucida sketches are all made to the same scale, namely,
a magnification of 750 diameters, except in the case of Thoracostoma,
which was drawn at 400 diameters. The sketches may be relied upon
as accurate. Information in the keys is not repeated elsewhere.
8 Dots above and below the line between the second and third terms.
7 Modified dots outside those just mentioned in 6.
8 Lines above and below the formula line between the second and third terms.
9 Oblique line near the pharyngeal terms of the formula.
10 Angular mark at right-hand end of formula.
11 Underscoring the third diametral measurement, thus indicating the presence
of a bulb. Length of mark indicates the size of the bulb.
12 Curved marks before and after 47, and 19 used as an exponent figure.
NOTE : Absence of any particular mark indicates the absence of that particu-
lar feature so far as at present known.
ANTARCTIC MARINE
KEY BASS!) OH CHARACTERS NOT EMPHASISED ELSEKHEf
25 New Species and
2 New Genera
-f- Terschellingia polaris 5
meridiana 14
edentata 16
Austronema spirurun 8
. -n- Monhystera
.-F. -f Monhystera
pilosa
unifonais
frigida
TAIL CONOID, THEN CYLINDROID,AT LEAST IN FEMALES
Posterior(cardiac)oesophageal bulb present
"Bulb oblate :...
Bulb pyrifora
Musculature of bulb broken into 2 parts ;
striae resolvable into elongate markings
Wings (interrupted striae) inconspicuous 'f Chronadora
Wings pronounced -n 'f Spilophora
Musculature of bulb unbroken; striae resolve
into dotlike markings, at least on head
Striae difficult of resolution Spira septentrionalis 1
Striae easy to resolve
Cardiac bulb three-fourths as wide as neck ._-':' Spilophora antarctica 17
Cardiac bulb one-half as wide as neck _--'f Aplectus antarcticus '3
Posterior(cardiac)oesophageal bulb none
Anphids almost invisible transverse slits ::ia subsirailis -2
Anphids circular, usually 'easy to see
Pharynx Plectoid, long, resembling oesophagus .. -
Pharynx short, often small
Intestinal cells clearly reticulated Sabateria antarctica 4
Intestinal cells not clearly reticulated
Oesoph. trifle larger fn. behind nerveri
Oesophagus plain
Renette distinctly developed
Somatic setae as long as body is wide
Somatic setae none or inconspicuous .
Renette inconspicuous or none
Chromatin bodies, 1 in front of each anph'd-n -f Monhystera
Chromatin bodies n'r.acphids none or faint
Contour crenate.esp. vejitral side of tail ----f Monhystera
Contour entire -f Monhys. septentrionalis
TAIL CONOID, NO PART CYLINDROID
Po3terior(cardiac)oesophageal bulb present
Bulb elongated, not clearly subdivided; renette
cell probably ellipsoidal -?.--:"- La xus septentrionalis
Bulb pyriform, musculature broken into unequal
parts; renette cell elongated
Contour on ventral side of nale tail serrate .-?. 'f Spilophora
Contour entire
Benette cell 1/^wide as long ;Phar. bulb faint .-71 Chroiadora
Renette cell ^ " " " " pronounced-:- 'f 1 Euchr. septentrionalis 19
Posterior bulb none!12,13), or a sere swelling
Striae of minute BO re or less elongate elenents
Dorsal tooth with no minute dental opponents .-;?. 'f Euchrorcad. antarctica 20
Dorsal " with 1 (22) or 2 (21) Subn. " "
Tail regular, terminus about Vg wide as base . 'f' Euchronad. denticulata 21
Tarl suddenly narrowed on Vent. side n'r.anus -n 'f' Euchrosadora neridiana
Striae appear impossible of further resolution
Lips strong, chi tinous,acute,conoid,eversible . Axonolaimrs polaris
Lips not acute, nobile but not eversible
Cardiac region conspicuously non-staining n-f Monhystera meridiana
Cardiac region of average nature
Unicellular lateral glands and pores absent _-j Monnystera antarctica 13
Unicellular lateral glands and pores present---'!' Thoracosio-a polare 25
polaris 10
11
23
serrata 18
polaiis 15
22 .
2-1
12
FREE-LIVING NEMATODES
KEY. BASED ON MALE CHARACTERS
19 New Species and
2 New Genera
PRE-ANAL SUPPLEMENTARY ORGANS PRESENT
Suppl. organs IQ.submedian, in 2 rows of 5 each . . -m-f Thoracostona polare 25
Supplementary organs in a single ventral row
Organs 3(or 1 i n Anticoma ),f a i n t in Sp .serrata
Fora tubular, 1/5 as wide as long
Length 2 / bod y Diam.jjust in front of spicula, -
Length % " " ;Ant.Org. 1 tail-L'gth.f rin.anus -
Form companulate.very minute, deep as wide ....
Organs 7,equidistant > faint in Sp.edentata
Form cup-like, as deep as body'wall is thick
Cardiac bulb present
Cardiac bulb reduced to a faint swelling ..
Form papilloid.row 3 body-widths long
PRE-ANAL SUPPLEMENTARY ORGANS ABSENT
Accessory pieces to spicula absent or faint
Spicula suddenly hookshaped at proxinal end .
Spicula of usual form, cephalated by expans
Fora arcuate, proximae ventral to body axi
Anticoma .subsiiilis 2
-m-f Aplectus antarcticus 3
-m 'f Spilophora serrata is
-m Chromadora polaris 15
-n T Euchromad. antarctica 20
-n 'f Spilophora edentata ie
-m-f Austroneraa spirurum Q
Form somewhat L-shaped,Prox. dorsal to B'dy
Accessory piece or pieces to spicula presen
Apophysis to accessory piece bending backw rd
Proximal ends of spicula not cephalated
Proximal ends of spicula cephalated
Cephalated by constriction
Cephalated by more or less expansion
Form more or less L-shaped
Structure rather robust
Structure frail
Form nearly straight, or arcuate
Spicula nearly straight
Spicula arcuate
L'gth 2V% times anal body diameter
L'gth l 1 /^ - not very slender
Apophysis to accessory pieces absent
Spicula cephalated by contraction
Spicula cephalated by expansion
Cephalum set off by a constriction
Cephalum not set off by a constriction
-a t' Spilophora antarctica 17
-m-f Monhystera raeridiana 12
-n -f- Terschellingia polaris 5
-ra-f Monhystera antarctica 13
-a f Monhystera polaris 10
-n -f Monhystera frigida 9
-m- Monhystera
pilosa 7
-m-f Monhystera uniforuis Q
-m f- Laxus septentrionalis 23
-;- ':' Euchromadora meridiana 22
-H 'f 1 Euchr. septentrionalis 19
-m 'f Spilophora antarctica^
KEY TO SIGNS
'f', ovaries 2, symmetrical .reflexed. -^-.testes 2, one extending each way.
-f-, " 2 " outstretched. - n , " 2, one only outstretched .
-f , ovary 1 .outstretched forward, -n .testis 1, outstretched forward.
Abbreviations
Ib , lip or lipregion
on , pnaryngeal tooth
am , anphid
Ic , locule of cuirasse
pp , labial papillae
ph , pharynx
oe , oesophagus
st , cephalic setae
sp , spinneret
ep , excretory pore
pc , cordifora piece
10 ANTARCTIC MARINE
DESCRIPTIONS OF THE SPECIES
CHARACTERS COMMON TO ALL THE SPECIES
Disregarding Thoracostoma, which is exceptional in the large size
of the caudal glands, the possession of eye-spots, of distinct dermal pores
and of oesophageal glands, and also in the possession of relatively very
strong spicula with a compound framework, it may be said that the
following characters are common to all the species here described:
There is no median oesophageal bulb, and no pre-rectum. The tail
is of approximately the same form in both sexes, and in all cases is sup-
plied with a rather simple spinneret, and with caudal glands the lat-
ter confined to the tail. The eggs, so far as known, are smooth and
comparatively thin-shelled, and are deposited before segmentation
begins.
All known males have equal spicula of simple framework, and all
are without bursa. There are no eye-spots. The cuticle is colorless,
or nearly so, is without distinct pores, and is destitute of longitudinal
striae except obscure indications in Spilophora serrata and Chromadora
meridiana, where the secondary elements of the cuticle arrange them-
selves also to a certain extent in longitudinal lines.
The renette, when present, has its cell behind the cardiac constriction,
except in Anticoma. Glands in the interior of the oesophagus have
been seen only in Thoracostoma, and possibly, though these latter are
of another character, in Monhystera frigida and polaris. The intestinal
granules give rise to a tessellation only in Anticoma and Laxus. The
spicula are arcuate, except in some Monhysteras; and cephalated except
in Anticoma, Terschellingia and Euchromadora antarctica. There are
no male papillae except in Anticoma and Monhystera antarctica. Male
supplementary organs occur only in Anticoma, Chromodora polaris, Eu-
chromadora antarctica, Aplectus, Thoracostoma, and in Spilophora ser-
rata and edentata. The musculature of the oesophagus is fine except in
Thoracostoma and Monhystera polaris, frigida and pilosa, though it is
somewhat coarse in the bulb of Laxus.
If the reader will add these characters to those given under each
species heading, and will utilize in a similar way the common charac-
ters given in the keys and generic descriptions, he will find himself in
possession of a very detailed description of each species, covering a
number of new and interesting anatomical features.
FREE-LIVING NEMATODES U
SPIRA, Bastian, 1865 13
1. Spira septentrionalis, n. sp. The striae, invisible except near the head are
resolvable into rather irregular dots. The three lips are without papillae. The
i 7.4 10.6 Y 92.3 neck is cylindroid posteriorly,
s ' i"g ' "2 is j 7' 1-4nm ' convex-conoid anteriorly. The
amphids, seen thus far only in
dorso-ventral view, have a central elevation, probably appear-
ing as a "fleck" in the surface view, and are about half as wide
as the corresponding diameter of the head. The oesophagus
is half as wide as the neck, and ends in a rather obscure bulb containing an in-
distinct valve, two-thirds as wide as itself. No distinct cardia was seen. The
intestine, separated from the oesophagus by a collum about half as wide as the
neck, becomes at once three-fourths as wide as the body; it is but a few cells in
girth, and the cells contain few or no granules. The rectum is conspicuous, the
posterior lip of the anus prominently elevated. From the anus the tail tapers
for two-thirds of its length, then becomes cylindroid to the swollen terminus,
which is one-fifth as wide as the base. The caudal glands were not clearly seen,
but are apparently arranged in a loose tandem in the anterior third of the tail!
The female reproductive organs are probably double and reflexed.
Habitat; remarks. Cape Royds. Described from a single somewhat shrunken
specimen.
ANTICOMA, Bastian, 1865
2. Anticoma subsimilis, n. sp. The thin cuticle is almost invisibly striated.
On each lateral line there is a row of five somewhat curved cervical setae,
r ' 26 si 8 each having a length equal to one-
r- ' '' :.. i.5mm. fourth the corresponding width
of the neck. These two rows
begin at a distance from the anterior end equal to nearly three
times the width of the head, and have a length equal to the corre-
sponding diameter of the neck. The cuticle becomes thicker at
the lips, which bear a circlet of six papillae. The oesophagus is cylindroid in
the anterior part, but becomes conoid posteriorly. The mobility of the lips is
proved by the nature of the ingested food. Seen dorso-ventrally the pharynx
appears more nearly cylindroid than when seen laterally. Seen laterally it
tapers so that finally it is one-fifth as wide as the corresponding part of the head.
The lining is rather thin, but refractive. The cardia, one-half as wide as the
neck, is conoid with a short cylindroid extension. The rather thick-walled in-
testine, separated from the oesophagus by a collum three-fifths as wide as the
neck, becomes at once three-fourths as wide as the body, and is about six cells
in girth. The intestinal cells contain numerous small, uniform, distinct granules.
The posterior lip of the anus is elevated. The caudal glands are packed together
13 The abbreviations used in lettering the sketches, which represent the ante-
rior and posterior extremities respectively, are explained near the foot of page 9.
As a rule the information given in the sketches is not repeated elsewhere. As
far as possible the sketches are derived from typical specimens.
12 ANTARCTIC MARINE
in the anterior two-fifths of the tail. The elongated renette-cell, two and one-
half times as long as the body-diameter, and one-fourth as wide a? long, lies a
little in front of the cardia, and is not re flexed. The excretory pore is somewhat
behind the pharynx. Distinct nerve-cells, more numerous behind the ring, are
arranged (at least in front of the ring), in six longitudinal groups. The cylin-
drical part of the tail is about one-tenth as wide as the base.
The slender, uniform, but rather strong spicula, as wide as the narrowest part
of the tail, are twice as long as the anal body-diameter, and lie with their proxi-
mal ends dorsal to the body axis. The proximal eighth of each spiculum is sep-
arately more or less arcuate, so that one may speak of a curved cephalum or
proximal end. Two separate accessory pieces, rather frail, bent at the distal
end, one-sixth as long as the spicula and parallel to them, form a rather close
collar round the distal ends of the spicula. On each side of the b'ody there are
four equidistant, ventro-submedian, pre-anal, papilla-like setae, one-sixth as
long as the body-diameter, extending in a row from near the anus to near the sup-
plementary organ. There are about three ventro-submedian post-anal setae on
each side of the middle part of the tail.
Habitat; remarks. Cape Royds; Bay, Cape Royds. One adult and several
immature somewhat shrunken specimens. This species differs from A. similis in
having five pectoral hairs, longer setae, a sub-cyliridroid pharynx, and an
oesophagus without expansion behind the nerve-ring
APLECTUS, new genus
Species of this newly proposed genus have the general form of Plectus, but have
the phar3iix less definitely developed, and the renette-cell farther back and not
reflexed. They differ also in having nearly obsolete lips, and a nearly cylindroid
oesophagus whose small cardiac bulb is without a three-fold striated valve. The
spinneret also differs from that of Plectus, as shown in the sketch. The male
supplementary organs in the two genera also differ materially. These facts
together with the marine habitat and the relative abundance of the males of
Apleclus, appear to make necessary a separate genus for the reception of this
antarctic species. The following is the type species.
3. Aplectus antarcticus, n.g., n. sp. The rather thin cuticle is traversed by
about 700 duplex striae, which give the contour an obscurely doubly crenate
appearance. Two wings, separated
! 12 : e - 2I> . . . '. 51 ' . . . 87 : , e,, b y a distance about equal to the width
y^jj .8 2.2~^ 2.3, 2.4 1.9 ' O f an annule, begin near the middle
** -Q . : si of the neck and end near the middle
H/ '....:. -r;r..: ' > .6mn. of the tail. Cervical setae, similar
to the cephalic setae, occur one or two
on each lateral line; and on the male tail there are setae, one-third to one-eighth as
long as the body is wide. The lips are very small and difficult to observe. The
pharynx, very inconspicuous and hard to distinguish, is probably double, the
narrow, tubular, anterior part extending to a little behind the amphids, the pos-
terior part, which closely resembles the oesophagus, extending nearly halfway
to the nerve-ring where there is a break in the musculature. In the lateral view
there are seen close behind the cephalic setae, under the cuticle, very minute
FREE-LIVING NEMATODES 13
bodies that stain, of which those most clearly seen were the dorsal and ventral
ones. Probably there is a circlet of these bodies. Just behind these stained
bodies, that is, a little behind the setae, there is an appearance as if of a small
quadrate cavity, one-third as wide as the head. This is not a cavity, however.
Its posterior limits are a trifle more than a head-width from the anterior end.
The amphids are variable in size and form,. being considerably larger and slightly
more elongated in the male. The posterior border appears interrupted. The
slender cylindroid oesophagus, is probably very obscurely Rhabditoid, and ends
posteriorly in an obscurely rhomboidal to pyriform bulb or swelling, three-fifths
to two-thirds as wide as the neck. The cylindroid cardia, one-fourth as wide as
the body, and twice as long as wide, is really a modified part of the intestine, and
is composed of small strongly staining cells. The thick walled intestine, sepa-
rated from the oesophagus by a collum one-fourth to two-fifths as wide as the
neck, is few, probably four, cells in girth. These cells contain numerous, indis-
tinct, rather fine and uniform granules.
The tail, tapering from the anus, is cylindroid in the posterior two-fifths and
ends in an almost imperceptibly swollen apiculate terminus one-third to one-half
as wide as the base. The caudal glands are arranged in loose tandem in the an-
terior half of the tail; their ampullae are distinct and no wider than the ducts,
but stain more strongly. The elongated renette-cell, which is difficult to observe,
is as long as the body is wide, and one-fifth as wide as long, and occurs at a dis-
tance behind the neck equal to eight times the width of the body. The very
slender duct, invisible except where stained, empties through a pore apparently
opposite the nerve-ring. The nerve-ring surrounds the oesophagus rather squarely
and is accompanied by somewhat distinct nerve-cells rather definitely grouped.
From the inconspicuous, small continuous vulva the small vagina leads inward
halfway across the body to the straight uteri. The rather elongated eggs are
two to two and one-half times as long as the body is wide, and fully one-third as
wide as long. The broad ovaries, cylindroid, but tapering near the extremities,
reach three-fourths of the way back to the vulva, and contain about twelve ova, ar-
ranged rather irregularly. The spermatozoa in the uterus are of such a size that
it would take at least seven or eight side by side to equal the body-diameter.
The arcuate, rather strong, sub-slender, sub-acute spicula, one and one-fourth
times as long as the anal body-diameter, are slightly cephalated by expansion,
the cephalum being set off by a broad shallow constriction, and lie with their
proximae dorsal to the body-axis. There are two rather strong, sub-slender,
slightly bent accessory pieces, parallel to the spicula then bending away, the
applied part being one-fourth as long as the spicula. The receding part is arcuate
in the same direction as the spicula, and from its end there passes a strand of
muscle to the ventral body-wall behind the anus. The ejaculatory duct is one-
fourth, the vas deferens and cylindroid testes one-half as wide as the body. The
blunt blind ends of the testes are two-thirds of the neck's length from the cardia
and one and one-half times the tail's length from the anus, respectively.
The protrudable, sub-equidistant supplementary organs are separated by a
distance equal to nearly one and one-fourth times the body-diameter, and the
posterior one is located at a distance in front of the anus equal to twice the anal
body diameter. They are rather straight but have the distal third bent ven-
trally, and the distal end flattened and pulled out posteriorly into a spur, or
14 ANTARCTIC MARINE
toe, which always remains outside the body. The entire profile contour is
like that of a high boot with its leg bent backward. The projecting part is twice
as long as the diameter of the tube, and is roughened at the end with ten or
twelve exceedingly minute striae or warts. The proximal ends of the organs are
rounded and not cephalated.
Habitat ; remarks. Bay, Cape Royds. About fourteen females and six males,
in good condition. The sketch is that of a female.
SABATIERTA, de Rouville, 1903
4. Sabatieria antarctica, n. sp. Striae about 800, resolvable with great dif-
ficulty into dot-like markings. There are no lips. The tubular pharynx, ex-
9.3.17.7 Y as. tending to opposite, the posterior
2"."5 ' 2.6 zTs 2". 4 ' 9na ' borders of the amphids, as shown
by a slight accentuation of the
lining, is surrounded by an almost imperceptible, slightly unsym-
metrical pharyngeal bulb three-fourths as wide as the head. At
the somewhat oblique nerve-ring the oesophagus has a diameter
equal to one-third the width of the corresponding part of the neck, but swells
posteriorly to two-thirds the width of the base of the neck. The rather cylin-
droid cardia is one-third as wide as the neck, and one and one-half times as long
as wide. The thick-walled intestine, separated from the oesophagus by a collum
two-thirds as wide as the body-diameter, soon becomes three-fourths as wide as
the body and is about two cells in girth. From the elevated posterior lip of the
anus the rather prominent rectum extends inward and forward a distance equal
to the anal body-diameter. From the anus the tail tapers for three-fourths of
its length, then becomes cylindroid to the slightly swollen terminus. The caudal
glands are probably small and near the anus.
Habitat; remarks. Cape Royds. Described from a single young specimen
in fair condition.
TERSCHELLINGIA, de Man, 1888
5. Terschellingia polaris, n. sp. The cuticle is traversed by about 700 striae,
plainly visible near the extremities only. Narrow double wings, having a width
about equal to that of two an- 33
nules of the cuticle, begin near ' : 8 . . . 9 : 9 : 15 : 5 .T 44 :. . . 84 : 9 , 73cra
the middle of the neck. The _ : - 3.2 3.6 4. 2.5
central raised body, or "fleck,"
of the amphid stains about as
strongly as the nuclei else-
where in the body. Very minute, inconspicuous papillae, probably six in number,
occur on the confluent lips. The vestibule is very minutely longitudinally stri-
ated. About halfway to the amphids there is a break in the musculature of the
oesophagus; the pharynx probably extends to this point. The conoid neck con-
tains a cylindroid oesophagus which, near the nerve-ring, is one-third as wide as
the neck, but ends in a bulb five-sixths as wide as the base of the neck. The
lining of the oesophagus is distinct, its most prominent optical expression being
a single refractive line. The cardiac valve causes a slight, simple modification
in the lining, one-eighth as wide as the bulb. The more or less thick-walled in-
FREE-LIVIXG XEMATODES 15
testine is separated from the oesophagus by a cardiac collum one-sixth as wide
as the neck, and soon becomes two-thirds as wide as the body. The first few
cells of the intestine, at the cardiac region, are very small, with relatively large
nuclei that stain strongly. The intestine is separated from the rectum by a
pyloric collum one-fourth as wide as the corresponding portion of the body.
From the anus, whose posterior lip is elevated, the chitinized rectum leads in-
ward and forward a distance equal to the length of the anal body-diameter. The
granules of the intestinal cells are small and scarce.
The tail tapers from the anus and ends in a slightly swollen terminus. A few
small, stiff, cylindroid, blunt caudal setae are to be seen, mostly about one-fourth
as long as the terminus is wide. The broadly saccate caudal glands, arranged in
a loose tandem in the anterior fourth of the tail, empty through distinct ducts
and elongated, narrow ampullae. What appears to.be an irregularly ellipsoidal
renette-cell is located at a distance behind the neck equal to the width of the body;
it is half as long as the body is wide, and three-fourths as wide as long. The
nerve-ring, which surrounds the oesophagus more or less obliquely, is accompa-
nied by distinct nerve-cells definitely grouped, both in front of it and behind, and
extending backward to near the cardiac bulb. From the small and inconspicuous,
but more or less elevated vulva, the conoid, non-chitinized vagina leads inward
at right angles to the ventral surface two-fifths the way across the body. The
eggs have a length nearly one and three-fourths times that of the body-diameter,
appear about half as wide as long, and have been seen in the uterus one at a time.
The medium sized, more or less tapering ovaries contain fifteen to twenty develop-
ing ova, for the most part flattened and arranged single file.
The more or less slender, sub-acute, uniform, slightly yellowish spicula have
a simple and rather strong framework, and are one and one-fourth times as long
as the anal body-diameter. The proximal ends appear to lie opposite the body
axis. The triangular, blunt accessory pieces have a simple and rather frail frame-
work; the part applied to the spicula is one-fourth as long as they, while the ta-
pering apophyses lie a little backward and end opposite the body-axis. The ejac-
ulatory duct is one-fourth, and the testis one-half, as wide as the body. The
comparatively few (about a dozen) primary spermatocytes occur in the testis
in single file, then come three pairs double file these latter relatively huge.
That is to say, the primary soermatocytes increase much in size and then divide
transversely into very unequal parts, a small distal part and a large proximal
part, and these two unequal parts divide almost simultaneously in the longitudi-
nal direction. Thus there appear four cells arranged in two pairs side by side, a
small strongly staining pair with inconspicuous nuclei, and a large pair which
do not stain except in their relatively small nuclei which show about seven small
more or less globular chromosomes. These two divisions represent the usual
reduction divisions, and give rise to spermatozoa of very different size and ap-
pearance. The phenomenon is reminiscent of the formation of the polar bodies.
In some specimens the smaller cells, those that in their appearance remind one
of polar bodies, appear as if divided a second time, but there is uncertainty about
this. It is the writer's intention to prepare a separate report on this species
and its spermatogenesis.
Habitat; remarks. Cape Royds; Bay, Cape Royds. Numerous specimens,
mostly somewhat shrunken.
16 ANTARCTIC MARINE
AUSTRONEMA, new genus
The single species for which this new genus is proposed has many of the char-
acters of Monhystera, but differs in so many important respects as to call for
separate classification. The principal differences of generic value are the pos-
session by Austronema of an oesophagus altered in the posterior half, a well
developed ventral gland, special lateral cells, hamate spicula without acces-
sory pieces, and glandular (?) organs associated with the spicula. Other minor
differences exist, such as the occurrence of the special group of setae near the
middle of the tail. The following is the type species.
6. Austronema spirurum, n. g., n. sp. The cuticle is traversed by exceedingly
minute transverse striae. The lips are confluent. The conoid neck contains a
cylindroid oesophagi!?, whose di-
ameter measured near the nerve-
J 4 ring is one-half as great as that of
87 3 the corresponding portion of the
2'; 2"* ' 8nn ' neck, but which finally becomes
two-thirds as wide as the base of
the neck. There is a break in the musculature of the oesophagus just behind
the nerve-ring, and behind this break the refractive nature of the lining is some-
what different, and, moreover, in many of the preserved specimens the diameter
of the oesophagus from this point onward is suddenly somewhat greater. There
is a conoid to cylindroid cardia about one-half as wide as the base of the neck.
The very thick-walled intestine, two to four cells in girth, becomes at once three-
fourths as wide as the body. For a short distance behind the cardiac collum,
namely, for a distance about equal to two-thirds the body width, the tissues of
the intestine do not stain. The lining of the intestine is refractive and distinct,
so that the almost imperceptibly zigzagged lumen can be readilv followed. The
intestine is separated from the oesophagus by a collum two-fifths as wide as tKe
base of the neck. The size of the numerous, yellowish, uniform granules contained
in the intestinal cells varies in the different parts of the intestine; they are much
coarser posteriorly than anteriorly. From the anus, the posterior lip of which
is elevated, the chitinized rectum extends inward and forward a distance equal
to the anal body diameter.
The tail tapers in such a manner that at the middle its diameter is about half
as great as at the base. Its terminus is about one-fifth as wide as its base. The
ellipsoidal caudal glands are arranged in a loose tandem in the anterior third of
the tail. Very short, stiff, inconspicuous, ventrally submedian caudal setae
occur on each side of the tail, two on the anterior half of the tail, and three near
the middle and close together and finally, one or two on the cylindroid, narrow,
posterior half. The pyriform to ellipsoidal granular renette-cell is located at a
distance behind the base of the neck equal to one and one-half body-diameters.
It is one and one-half times as long as the body is wide, and one-third as wide as
long, and presses the intestine considerably to one side. It does not appear to
have any companion cell. The medium sized nerve-ring surrounds the oesopha-
gus somewhat squarely, and is accompanied by distinct nerve-cells extending
well back toward the base of the neck. From the rather small, but rather con-
FREE-LIVING NEMATODES 17
spicuous, elevated vulva, the well developed, tubular, muscular vagina extends
inward and obliquely forward. It is about twice as long as the corresponding
body-diameter, and about two-thirds as long as the uterus. The eggs are about
as long as the body is wide, and three-fourths as wide as long, and have been seen
two or three at a time in the uterus. The ovary is of medium size, and tapers so as
to become narrow. It contains many ova, arranged single file somewhat irreg-
ularly so near the uterus.
The slender, more or less uniform spicula taper from the middle toward the
proximal ends, and present the striking peculiarity of being strongly curved at
the distal extremity, forming a hook across which there is a thin, transparent
membrane. They are one and three-fourths times as long as the anal body-diam-
eter, and are so arranged that their proximal ends appear as if lying to the dorsal
side of the body axis. Their yellowish framework is rather strong, and the proxi-
mal two-thirds may sometimes be seen to be nearly straight. At the extreme end
the spicula have a very minute recurved apiculum or point. Two (?) pairs of
ellipsoidal granular unicellular glands (?) occur some distance in front of the
spicula. This species has the head of a Monhystera but differs, in having the
oesophagus altered in the posterior half, a well developed ventral gland, special
lateral cells, hamate spicula without accessory pieces, and the tail with a group
of small setae near the middle.
Habitat; remarks. Cape Royds. The five females and five males examined
were in fair condition.
MONHYSTERA, Bastian, 1865
The following are characters common to all the species of Monhystera here
described.
Cervical and somatic setae none or scattered and short, except in M. pilosa. Neck
conoid, but cylindroid in the posterior half in M. pilosa, and M. meridiana. Tail
tapering from the anus or a little in front of it. Oesophagus somewhat cylindroid
without swellings of any kind, for the most part about half as wide as the nec'k,
but finally three-fifths to three-fourths as wide as the base of the neck. Cardia
present, except in M. frigida, hemispherical to cylindroid, and one-fourth to one-
half as wide as the base of the neck. Intestine separated from the oesophagus by
a collum one-third to one-half as wide as the neck, becoming almost at once about
three-fourths as wide as the body, its walls thick and two to four cells in girth,
and the lining usually so refractive that the lumen is a rather distinct feature.
Granules of the intestinal cells numerous, fine and uniform. Rectum of about
the same length as the anal body diameter. Caudal setae none or inconspicuous
except in M. pilosa. Lateral fields one-third, more rarely one-half, as wide as the
body. Renette unknown except in M. pilosa and M. uniformis. Nerve-ring of
medium width, surrounding the oesophagus rather squarely, the nerve cells in its
vicinity usually rather diffusely arranged. Vulva small or of medium size and in
these species not very conspicuously elevated except in M. uniformis. Vagina one
to two times as long as the body is wide, and extending inward and forward.
7. Monhystera pilosa, n. sp. Striae about 1700. There are numerous long, very
slender, flexible cervical and somatic setae, often arranged in pairs, one member of
IS
ANTARCTIC MARINE
the pair in front
of the other, on
the sub-median
lines. There are
probably three
lips, bearing six
minute setose
papillae ar-
ranged in a sin-
gle circlet. The
lining of the oe-
sophagus is very
' distinct, and the
musculature
rather coarse. The granules of the intestine are yellowish brown. Toward the
posterior extremity, for some distance in front of the anus, there is a strong
development of lateral cells, which do not appear to exist elsewhere in the
body. These cells extend forward toward the middle of the body, and have been
traced no farther. Their size, which is variable, is such that two or three occur
side by side in the lateral fields. The tail is cylindroid in its posterior three-
fifths, with a width there one-eighth as great as that of its base, and has a slightly
swollen terminus. The caudal ducts, of which two were seen, are narrow and
distinct. From the excretory pore at the end of the third fifth of the neck
there leads inward a very narrow duct whose length is nearly equal to the thick-
ness of the cuticle. The duct leading thence back to the renette cell is, however,
of considerable width about one-fourth as wide as the oesophagus and is read-
ily traced back to a point opposite the anterior part of the intestine, where the
renette cell pushes the intestine to one side. The spicula are uniform, with a
width near the distal extremity one-sixth as great as the corresponding body
width. The single accessory piece, parallel to and close to the distal thirds of the
spicula, has an apophysis tapering to an obscure and slightly recurved point. This
apophysis lies at right angles to the spicula, and then curves forward a little. The
ejaculatory duct is one-third as wide as the body, the vas deferens considerably
wider. The blind end of the anterior, larger testis is disposed in one or two coils.
Habitat; remarks. Bay, Cape Royds. The single specimen examined was in
good condition.
8. Monhystera uniformis, n. sp. Apparently there are three very obscure con-
fluent lips. The amphids when seen in the dorso- ventral view seem to be well
chitinized, and appear deepest in the
anterior part, where they are one
fifth as deep as the head is wide. The
cardia is twice as long as wide. The
cylindroid part of the tail is one-third
to one-fourth as wide as the base.
Broadly saccate caudal glands are
found in the anterior half of the tail. At a distance behind the neck equal to three
to four body-widths there is an ellipsodial renette cell with a large nucleus. This
gland-cell is one and one-half times as long as the body is wide and half as wide as
long. The location of the excretory pore has not been made out with certainty;
13.2 20. -83'
.9 12.8 20. -M
FREE-LIVING NEMATODES 19
possibly it is just behind the nerve-ring. The small, weak, tubular, non-chitinized
vagina leads into a uterus which is five times as long as the body is wide. The
eggs are about four times as long as the body is wide, and one-fifth as wide as
long. The medium sized cylindroid ovary contains about twenty-five ova,
arranged somewhat irregularly. The tail of the male is like that of his mate
except that it is conoid nearly to the terminus. The very slender uniform spicula
are two and one-half times as long as the anal body diameter. Their frame-
work is simple, and the proximal ends lie somewhat dorsal to the body axis. The
single accessory piece is frail, its framework simple; the applied part being one
eighth as long as the spicula, the blunt, backward pointing apophysis being one-
fifth as long as the anal body diameter and having its proximal end opposite the
body axis. The ejaculatory duct is one-third, the testis two thirds, as wide as the
body.
Habitat; remarks. Cape Royds. Six females and three males, in fairly good
condition.
9. Monhystera f rigida, n. sp. About 1400 striae give to the margin a crenate con-
tour. The very inconspicuous lips are probably three in number. The amphids
appear circular, but are really reg- < ^ , 36
ular spirals of one and one-half lb "~"/|P " 3 9 ' 7 18>1 ' B?
winds, having a raised transverse
ridge extending part way across.
A deeply staining nucleus, of the
same size and character as the
nuclei of the nerve cells near the ring, occurs immediately in front of each amphid.
In the posterior end of the oesophagus there are two, possibly three, elongated,
granular gland-cells, quite as long as the body is wide. The rectum is prominent.
The vagina is small and weak. The eggs are about four times as long as the body
is wide. The rather narrow, cylindroid ovary contains twenty or more ova, arrang-
ed mostly in single file. The uniform slender, frail, sub-acute spicula are one and
one-half times as long as the anal body diameter and lie with their proximae op-
posite the body axis. The very inconspicuous, very slender and frail acces-
sory piece is bent so that the applied part is one-third to one-fourth as long as the
spicula, while the uniform backward bending part is one-fifth as long as the anal
body diameter. Its proximal end lies to the ventral side of the body axis. The
ejaculatory duct is one-third, the testis two-thirds, as wide as the body.
Habitat ; remarks. Cape Royds. The single female and the two males examined
were in fair condition.
10. Monhystera polaris, n. sp. The 600 striae give to the margin a minutely
crenate contour, most plainly to be seen just behind the anus. The three double,
more or less distinct lips
^ j 4i are fairly developed. Two
'-> i BO innervated papillae occur
! K5 2 ' 5 2 ' 6 3 ' 4 2>1 on each of the lips, six
I i. 11. 21. -M- 84. papillae in all. The am-
an w/?^-V'/,/ i.V^2.~5 2.V~ 2.V~ 2.7 Illma1 ' phids are sunken, but
usually show a well stain-
ed projecting margin two-
thirds as wide as the amphid. A little in front of each amphid is a single some-
what spherical nucleus, one-fourth as wide as the oesophagus, containing granules,
20 ANTARCTIC MARINE
as do the ganglion cells near the nerve-ring. These two neuclei probably indicate
the presence of two nerve cells. They are best seen in the dorso-ventral view. The
refractive elements of the lining of the oesophagus, especially in certain aspects
of the head, appear to extend into. the pharynx in a peculiar way, as shown in the
sketch. The rectum is more or less prominent, and in the male the anus is raised.
The tail tapers in such a manner that at the middle it is one-third as wide as at
the anus. Its terminus is slightly swollen. Caudal setae appear on the base of the
tail.
The vagina extends inward nearly at right angles to the body wall, about half
way across the body. The uterus, three to four times as long as the body is wide,
contains spermatozoa one fifth as wide as the body. The posterior, rudimentary
branch of the uterus, nearly twice, as long as the width of the body, also contains
spermatozoa. The eggs are nearly twice as long as the body is wide, and one-third
as wide as long. The broad tapering ovary contains about twenty ova arranged
single file, and as many more packed irregularly in the distal fourth.
The brownish, rather slender, uniform, acute spicula are one and one-third
times as long as the anal body diameter. The framework of the spicula is more or
less strong, and the proximal ends lie opposite or a little dorsal to the body axis.
The single, rather straight and rather frail accessory piece is of a simple character,
and has a backward pointing apophysis one-sixth as long as the anal body diame-
ter. The male presents the peculiarity of possessing two testes, an uncommon
thing in Monhystera. They are rather wide and of unequal size, the anterior,
more or less cylindroid one being considerably the wider. The blind end of one
testis is at the cardia, that of the other about one tail-length in front of the anus.
Habitat; remarks. Cape Royds; Bay, Cape Royds; Bay. Seven females and
six males, somewhat shrunken. The specimens from the various localities differ
slightly in (1) the size and form of the cephalic setae, (2) the length and width of
the spicula, (3) the prominence of the amphids, (4) the prominence of the striae
on the tail. Diatoms and other unicellular organisms were seen in the intestine.
11. Monhystera septentrionalis, n. sp. The lips are confluent. The lining of
the oesophagus is rather prominent, and one-fifth as wide as the oesophagus itself.
33 The small and inconspicuous, some-
- u ' y ~ E6 83- .5mm. what ellipsoidal caudal glands are
1-9 arranged in a loose tandem in the
anterior half of the tail. The anus is continuous. The conoid,
rather muscular vagina is one and one-half times as long as the body
diameter. The eggs are elongated, twice as long as the body is
wide, and less than half as wide as long. About thirty ova occur in single file in
the gently tapering ovary.
Habitat; remarks. Bay, Cape Royds. Seven good female specimens. The
amphids are often a little farther back than illustrated.
12. Monhystera meridiana, n. sp. The striae, about 1000 in number, are respon-
sible for a somewhat crenate contour, more noticeable near the tail. The strongly
developed cardiac region, set
off by a constriction on each
side, is as wide as the intestine,
and forms a small but distinct
segment of the alimentary
canal. The vulva is elevated.
Eggs twice as long as the body
FREE-LIVING NEMATODES 21
is wide, and one-third as wide as long, occur in the straight uterus. Toward its
blind end the narrow, tapering ovary is one-fourth as wide as the body. The tail
of the male is conoid in such a fashion that at a distance from the anus equal to
four times the anal body diameter it has a width equal to one-fourth the anal
body width; thence it tapers very gradually to the terminus, whose width is con-
siderably less than that of the spicula. The slender, uniform, acute spicula are
one and three-fourths times as long as the anal body diameter. Theejaculatory
duct and vas deferens are one-fourth as wide as the body. Apparently there are
two tapering testes, but the end of the posterior one was not definitely seen; it
appeared, however, to be eight to twelve body widths in front of the anus.
Spermatocytes occur in single file near the end of the anterior testicle.
Habitat; remarks. Bay, Cape Royds. One female and three males in a
somewhat shrunken state.
13. Monhystera antarctica, n. sp. The cephalic setae are very minute and diffi-
cult to see. Six excessively minute forward pointing papillae occur, one on each
lip. Apparently the pharynx is tra-
versed near its middle by a trans-
verse ridge, and this is the reason I ^&\ !- 2 2.7 2.9 3.7
why it appears in optical section
as if armed with two teeth. From
the anus, the posterior lip of which
is elevated, the rather prominent, chitinized rectum leads inward. Anal glands
are present. The rather large and conspicuous nuclei of the intestinal cells are
arranged about a body-width apart. The terminus of the tail is one-fourth as
wide as the base. The broadly saccate caudal glands, of which two are larger than
the third, are arranged in close tandem in the anterior half of the tail; their
ampullae are distinct. The lateral fields are one-half as wide as the body. At a
distance behind the base of the neck equal to four times the width of the body
there is frequently to be seen in the female a large cell, one-half as wide as the
body, with a prominent nucleus. This cell occurs in females only. Though its
connections have not been definitely made out, it sometimes seems to empty
through a pore a little in its rear. The straight uterus, five to six times as long
as the body is wide, contains elongated eggs, as long as the bodj r diameter, and
half as wide as long. The cylindroid ovary contains ova arranged in double file-
irregularly so toward the blind end.
The tail of the male is a little stouter than that of his mate. The rather frail,
slender, uniform, sub-acute spicula, one and one-half to one and three-fourths
times as long as the anal body-diameter, lie with their proximae dorsal to the body
axis. The single accessory piece, parallel to the distal third of the spicula, and
then bending back in a thumb-shaped apophysis, lies with its proximal end oppo-
site the body axis. On the tail there are very faint inconspicuous setose papillae
one ventro-submedian on each side, at the end of the anterior fourth, and two or
three sub-ventral just behind the middle of the tail. The ejaculatory duct is one-
fourth to one-third, the vas deferens and tapering testis one-half, as wide as the
body.
Habitat ; remarks. Bay, Cape Royds. Numerous slightly shrunken specimens.
22 ANTARCTIC MARINE
CHROMADORA, Bastian, 1865
14. Chromadora meridiana, n. sp. Among the secondary elements into which
the 600 transverse striae are resolvable there are two longitudinal rows that stand
Ut al ^ the latfiral fields a
'.6 8.8^13.8 '46 86.
.V~3.~3 r r~3Y~5~~~?~2 > ' 9ia ' little more prominently than
the others. Outside these, on
on'' : : * B * either side, is another row almost imperceptibly emphasized.
S P " "-"" The annules are retrorse posteriorly, and the reverse anteriorly,
the change taking place opposite the vulva on the female. The few very short
cervical and somatic setae to be seen scattered here and there are one-half to one-
third as long as the body is wide, though a few nearer the head are considerably
longer than the cephalic setae. There appear to be twelve subdistinct lips, each
bearing a single papilla. The conoid neck contains a cylindroid oesophagus,
which, measured at the nerve-ring, is one-third as wide as the corresponding
portion of the neck. The oesophagus ends posteriorly in a bulb three-fourths as
wide as the base of the neck, containing an inconspicuous elongated valve one-
third as wide as itself. The musculature of the bulb is broken into two very
unequal parts. There is no cardia. The wall of the intestine varies from thick
to somewhat thin, and is six to eight cells in girth. The intestine becomes at once
about three-fourths as wide as the body. Its lumen is distinct, and about one-
fourth as wide as itself. The rather numerous granules to be seen in the cells of
the intestines are uniform and small. From the anus, which is depressed, the
chitinized rectum leads inward and forward a distance equal to the length of the
anal body-diameter.
The arcuate tail tapers from in front of the anus, but is usually cylindroid in the
posterior fifth, and has a terminus one-sixth as wide as its base. The broadly sac-
cate caudal glands are packed together in the anterior fourth of the tail, and empty
through distinct narrow ducts. The length of the few, scattered, straight caudal
setae is about equal to the width of two annules of the cuticle. The lateral fields
are one-third as wide as the body. The granular renette cell, which is somewhat
longer than the body is wide, and one fourth as wide as long, is located at a distance
from the base of the neck equal to the width of the body, and empties by means of
a slender duct, through the excretory pore located at the lips. It has a smaller
companion cell in its rear. The nerve-ring surrounds the oesophagus somewhat
squarely. The cells in its vicinity are distinct in character, and many of them have
narrow connections directed forward. From the obscurely depressed somewhat
conspicuous vulva, the small tubular vagina leads inward at right angles to the
ventral surface one-third the distance across the body. The eggs are about as
long as the body is wide, and usually about three-fourths as wide as long, and have
been seen in the uterus one to three at a time. The spermatozoa seen in the females
are one-eighth as wide as the body. The tapering ovaries reach about three-
fourths the distance back to the vulva, and contain each about fifteen mostly dis-
coid ova, arranged more or less single file.
Habitat; remarks. Bay, Cape Royds. Five females in fair condition.
15. Chromadora polaris, n. sp. This species closely resembles Chromadora me-
ridiana from the same region, but differs in having narrower dimensions, more
FREE-LIVING NEMATODES 23
slender oesophagus, bulb and intestine, a / eo
more strictly conoid tail, and a somewhat .'-- -'-> i. r .a
thinner cuticule, the striations of which are
even less modified on the lateral fields. There are about four hundred and fifty
transverse striae. The cuticle is hardly perceptibly modified on the lateral fields
in the anterior half of the body, but in the posterior half, especially opposite the
copulatory muscles, there is a distinct modification, which at its widest part is
nearly twice as wide as one of the corresponding striae. The modification be-
comes less pronounced behind the anus, and disappears near the terminus. The
renette cell occurs at a distance behind the neck equal to twice the diameter of
the body.
The stoutish, somewhat tapering, rather blunt, yellowish spicula are one and
one-fourth times as long as the anal body diameter, and at their widest point one-
sixth as wide as the body. They are almost imperceptibly cephalated by expan-
sion and lie with their proximae a little ventral to the body axis. The frame has
a median piece from near the middle onward. The two arcuate, slender, rather
strong accessory pieces are three-fifths as long as the spicula and lie parallel to
them. The seven chitinized supplementary organs, separated from each other
by a distance equal to the diameter of one of the organs, occupy a space about
equal to one and one-half times the body diameter, the posterior one occurring
about opposite the proximal ends of the spicula. These organs are very much like
those of Chromadora minor. The ejaculatory duct and vas deferens are one-
fourth, the broad cylindroid testis one-half as wide as the body. Copulatory
muscles extend forward somewhat beyond the supplementary organs.
Habitat; remarks. Bay, Cape Royds. Two good specimens, both v male.
SPILOPHORA, Bastian, 1865
The following are characters common to all the species of Spilophora here
described.
Cuticle with two lateral wings, beginning near the head and ending on the tail.
Neck conoid. Tail tapering from somewhat in front of the anus. The lips are
small and often indistinct, but when decipherable can usually be seen to be twelve
in number, each with a single forward-pointing papilla. Throughout most of its
length the oesophagus is more or less cylindroid, but ends posteriorly in a pyriform
bulb two-thirds to four-fifths as wide as the base of the neck, and containing a
fusiform valve (sometimes obscure) one-fourth to one-half as wide as itself. There
is no distinct cardia. The intestine is separated from the oesophagus by a distinct
broad constriction about one-third as wide as the corresponding part of the body.
The more or less prominent chitinized rectum, about as long as the anal body diam-
eter, leads inward and forward. The caudal setae are small and scattered. The
nerve-ring is of medium size and surrounds the oesophagus rather squarely, and is
accompanied by distinct nerve cells. The vulva is more or less elevated and con-
spicuous and from it the vagina leads inward at right angles to the ventral surface
about half way across the body. So far as known the eggs are ellipsoidal. The
rather slender, blunt spicula are about one and one-fourth times as long as the
anal body diameter. The arcuate accessory piece is parallel to, and half to
three-fourths as long as, the spicula. The testis is relatively wide.
24 ANTARCTIC MARINE
16. Spilophora edentata, n. sp. Striae about 600, producing a crenate contour,
interrupted by the two lateral wings which are so formed as to appear somewhat
like the keel and ribs of a
boat. Four sub-cephalic
setae occur opposite the base
Pi 7rT : - \-f ^-J^Lzk. 1 ^ 7 ---* 5 . 6 -- 8 !'- f the phar > rnx - There are
gp .J^:j--.-Y i.~6~~3.2~r 3^3 3.~3 ~ 2 .e 1<anp f e w subme dian somatic
setae, each about one-third
as long as the body is wide. There appears to be no distinct dorsal pharyngeal
tooth, but possibly an exceedingly minute more or less ventral one, unless indeed
this appearance be due to the optical effect of one of the striae that exist separately
in the posterior part of the pharynx. The masculature of the bulb is broken into
two very unequal parts. The rather thin-walled intestine becomes at once two-
thirds as wide as the body and is about six cells in girth. The cells contain numer-
ous very small, uniform colorless granules. The cylindrical part of the tail of the
female is about one-fourth as wide as the base. The broadly saccate caudal glands
are arranged in a loose tandem in the anterior half of the tail, and are connected
with the spinneret by distinct but very narrow ducts with no clearly visible am-
pullae. The lateral fields, one-third as wide as the body, contain small scattered
nuclei, as well as others less numerous and twice as large. The granular ellipsoidal
renette cell, which presses the intestine to one side, a little behind the neck, is
about half as long as the body is wide, and one half as wide as long. The duct is
hardly half as wide as one of the annules, and the ampulla, opposite the base of
the pharynx is almost invisible. The excretory pore is at the lips. The nerve cells
are arranged in rather indistinct groups, better seen behind the ring.
The male tail appears to be more nearly conoid throughout, and has a spinneret
only about one-eighth as wide as its base. The tapering spicula in their widest
part are one-sixth as wide as the corresponding part of the body, and are cephal-
ated by a very inconspicupous constriction. The accessory pieces are slender and
rather frail. The testis is about half as wide as the body. Rather distinct, well
spaced, oblique copulatory muscles are present in front of the anus for a distance
equal to one and one-half tail-lengths. Apparently pairs of male glands, emptying
into the cloaca, are present as in Euchromadora and Chromadora, but the details
remain unknown.
Habitat; remarks. Bay, Cape Royds. A single female and four males, all in
fair condition.
17. Spilophora antarctica, n. sp. Striae about 400, producing a somewhat
crenate contour, and interrupted by two lateral wings separated by a distance
equal to one-fifth the body dia-
44 ? 4 77. meter. Cervical setae occur at
3.2 2. ' 5na> least near the head. The cardiac
56 valve is simple in structure. The
"*" 8 : > .SDD. relatively somewhat thick-walled
3-3 2 ' 6 intestine soon becomes two-thirds
as wide as the body, and is about
two cells in girth, these latter containing scattered, rather uniform, colorless
granules. The posterior lip of the anus is more or less elevated. The cylindroid
part of the tail is one-fifth as wide as the base, or somewhat less. The renette cell
FREE-LIVING NEMATODES 25
has not been clearly seen, but the intestine is pushed to one side as if a small one
were present, a little behind the neck. The nerve-cells extend past the base of
the neck, especially on the ventral side. The eggs occur one at a time in either
uterus. The rather broad, tapering ovaries, which extend two-thirds of the way
back to the vulva, contain few ova, arranged single file. The testis is one-half to
three-fifths as wide as the body.
Habitat; remarks. Cape Royds; Bay, Cape Royds. Six females and three
males, in a somewhat shrunken state.
18. Spilophora serrata, n. sp. Striae about 500, interrupted by the lateral
wings, which occupy a space equal to one-fourth the body diameter. The second-
ary elements of the cuticle j, ^
appear as dots on the head, pp ; ^0J!^\\ ?/u i-_ E _ : Ji'J_'_ 4 i' ^l*. 5 ,
and produce a punctate lffi '."'-|^v-' - 1>5 2>6 ; 2 ^1 3 - 4 2 - 5
appearance there. Four l'.-f^\ j K 1P . 8 .i7.i - H E9 86.
rather irregular pairs of sub- sp 'jjlJE&Jfj l ~ E 2 V : ~ J V ~ 3 ~7 iT ' 9 "'
cephalic setae, like the ceph-
alic setae, but shorter, mated one in front of the other, occur at a distance from
the lips equal to twice the width of the head. There are few cervical setae. The
vestibule of the pharynx is longitudinally striated. This is one of the few
species of Spilophora in which the amphids can be plainly seen. The rather thick-
walled intestine soon becomes three-fourths as wide as the body, and is ten to
twelve cells in girth, the cells containing numerous uniform, colorless granules
nearly equal in diameter to the width of one of the annules of the cuticle. The
posterior lip of the anus is elevated. The terminus of the tail is about one-sixth
as wide as its base. The two broadly saccate caudal glands are arranged in close
tandem opposite the anus and in the anterior fourth of the tail. Their ampullae
are not distinct. The third caudal gland (?), just behind the anus, is a strongly
staining cell, with a duct, or connection, that reaches to near the terminus. The
non-granular renette cell, one body-width behind the neck, twice as long as the
body is wide, has a small companion-cell in its rear. The excretory pore is probab-
ly near the lips. Opposite the renette cell there are two, and probably three,
ellipsoidal cells in each lateral field, each cell being one-third as long as the body
is wide, and one-third as wide as long. These cells constitute two pairs, or three.
The eggs are about one and one-half times as long as the body is wide, and two
thirds as wide as long, and occur in the uteri one at a time. Each of the medium
sized, tapering ovaries reaches half way back to the vulva, and contains about
fifteen ova arranged single file.
The strong, rather uniform, colorless spicula are cephalated by a constriction
and are obliquely truncated at the distal end, where there are two or three exceed-
ingly minute teeth. The subslender, rather strong and simple accessory pieces
recede a little from the spicula. Of the slightly elevated, somewhat protrudable
supplementary organs, whose width is about equal to that of two annules, the
hindermost is near the anus. They are farther apart anteriorly, the distance
between the first and second equaling one-third of the body width, that between
the second and third, one and one-half times the body width. The ejaculatory
duct is one-third as wide as the body the vas deferens and testis one-half. At
least one pair of glands of the kind seen in the males of Euchromadora occurs nearly
twice as far in front of the anus as the terminus is behind it; each gland-cell is
26 ANTARCTIC MARINE
/
fusiform, one-half as long as the body is wide, and one-half as wide as long. Both
of the males examined had a ventral swelling near the center of the tail, as long as
the corresponding body diameter.
Habitat ; remarks. Bay, Cape Royds. The two females and two males studied
were in good condition.
EUCHROMADORA, De Man, 1886
The following are characters common to all the species of Euchromadora here
described.
The neck is more or less cylindroid in the posterior part, but usually slightly
conoid anteriorly. The tail tapers from in front of the anus, and has no terminal
swelling. Cervical setae none or small and scattered, except in E. septentrionalis,
somatic setae none or very inconspicuous. Caudal setae none or inconspicuous,
except in E. denticulata. Each of the six lips is double, so that there appear to
be twelve more or less alike. These are usually distinct when the mouth is open,
but so folded together when the mouth is closed as to become less distinct, and to
impart to the then narrow vestibule a longitudinally striated appearance. Labial
papillae twelve, in a single circlet, forming the apices of the lobes of the lips. The
pharyngeal region of the oesophagus is swollen, so as to form a faint pharyngeal
"bulb," rather obscurely pyriform or elongated in form. The oesophagus is cylin-
droid in the anterior half, and conoid or perhaps clavate in the posterior part,
but is without a true cardiac bulb except in E. septentrionalis. Oesophageal
lining distinct, often increased posteriorly. There is no distinct cardia. The
rather thin walled intestine becomes almost at once three-fifths to three-
fourths as wide as the body and is from six to nine cells in girth. It is separated
from the oesophagus by a distinct collum one-fifth to one-third as wide as the
corresponding part of the body. The chitinous rectum, as long as the anal body
diameter, leads inward and forward from the more or less elevated anus. The
caudal glands are found in the anterior fourth of the tail (and in E. meridiana also
a short distance in front of anus), and empty through ducts devoid of ampullae,
except in the case of E. denticulata. The lateral fields are about one-third as wide
as the body. The elongated, granular renette cell, one to two body-widths behind
the neck, has one or two smaller companion cells in its rear. The medium sized
nerve-ring surrounds the oesophagus rather squarely. From the somewhat ele-
vated but rather inconspicuous vulva the vagina leads inward at right angles to
the ventral surface about halfway across the body. The reflexed, tapering ovaries
reach half to two-thirds the way back to the vulva, and contain a dozen or more de-
veloping ova, arranged more or less irregularly, especially toward the blind end.
The more or less slender spicula are sub-acute, and accompanied by arcuate
parallel accessory pieces half as long as themselves. The single testis is cylindroid
and about half as wide as the body.
19. Euchromadora septentrionalis, n. sp. The 600 striae, very difficult to see
except at the extremities, are resolvable into minute elongated elements, which
are interrupted by very narrow
and inconspicuous lateral
3.2 2.3 ' wings, beginning near the head
55 and ceasing near the end of the
1. 6 10.4_,_16.6 -M 88.
, y 2 y. y y s - 3 y .. tail. Two sub-cephalic setae,
nearly as long as the cephalic
FREE-LIVING NEMATODES 27
setae, occur one in front of the other on each sub-median line, at a distance from
the head end equal to one and one-fourth times the head width. The cervical
setae, more numerous on the anterior part of the neck/ are sometimes longer than
the cephalic setae. The lips, otherwise typical, have successive rings of elements
surrounding the interior of the vestibule. The oesophagus is one-third as wide as
the neck, but swells posteriorly into a true cardiac bulb, containing a fusiform
valve one-third as wide as itself. The intestinal granules are scarce and colorless.
The elongated caudal glands are arranged in a close tandem, and have distinct
ducts. The renette cell, three times as long as the body is wide, empties through
a very inconspicuous pore at the base of the lips. Strongly staining, elongated,
distinctly granular bodies are found in the lateral fields behind the neck. They
are one-half as long as the body is wide, and two-thirds as wide as long, and they
occur as rightsand lefts, i. e. are paired. The first pair is one body-width behind
the neck, and the successive pairs, continuing to the anus, are separated from
each other by a distance three times as great as the radius of the body.
The tail of the male is a little stouter than that of his mate. The uniform,
slender, frail spicula are as long as the anal body diameter, and one-twelfth as
wide as long. There are two strong grooved accessory pieces, twice as wide as
the spicula, bearing excessively minute teeth at their blunt distal ends. There
are at least five unicellular clavate glands on the dorsal side, extending in front
of the anus for a distance equal to the length of the tail. First, anteriorly there
is a pair, then a second pair, then apparently a single one, all with slender ducts
They were not very well seen, and this enumeration may not be exact.
Habitat; remarks. Cape Royds; Bay, Cape Royds. Numerous specimens,
somewhat shrunken.
20. Euchromadora antarctica, n. sp. The cuticle is traversed by about 550
transverse striae, resolvable into dots near the head, and into basketwork-like
markings on the neck and else-
where. These striae are of such
a size as to give rise to an
obscurely crenate contour line.
There is a simple, very obscure
cardiac valve, one-third as
wide as the base of the oesophagus. The cells of the intestine contain numerous
rather small, colorless, uniform granules. The ellipsoidal caudal glands are ar-
ranged in a loose tandem, and empty through very narrow ducts. The renette
cell is about as long as the body is wide, and one-third as wide as long, and presses
the intestine somewhat to one side. The nerve-cells around the oesophagus are
of a distinct character, but are scattered so as to exhibit no very systematic
arrangement. The prolate to ellipsoidal eggs are considerably longer than the
body is wide, and three-fourths as wide as long. They have been seen in the
uterus one at a time. The tapering ovaries contain upwards of a dozen ova.
The slender, uniform spicula have a more or less frail framework, and are about
twice as long as the anal body-diameter. They are not cephalated, but the proxi-
mal parts are somewhat wider. This wider part lies a little to the ventral side
of the body-axis, that is, it appears to do so when the animal is viewed in profile.
The single, slender accessory piece has a framework that is more or less frail,
and has its proximal end opposite the body-axis. The supplementary organs are
28 ANTARCTIC MARINE
spread along a distance about equal to five or six body-diameters, the distance
between the adjacent organs being about equal to the radius of the body. These
organs. are of such a nature that when the body is stretched out they hardly dis-
turb the ventral contour, but when the tail end is incurved, as is often the case,
they become slightly raised, so that the altitude is about equal to one-half the
width of one of the annules of the cuticle. In this contracted condition of the
ventral surface of the body the distance between the organs is about equal to
their own diameter. The ejaculatory duct is one-fourth, the vas deferens three-
fourths, and the testis two-fifths as wide as the corresponding portions of the
body. The testis is cylindroid. Rather distinct, oblique copulatory muscles
are found coextensive with the supplementary organs.
Habitat; remarks. Cape Royds; Bay, Cape Royds. Numerous specimens,
somewhat shrunken.
21. Euchromadora denticulata, n. sp. Striae about 400, resolvable into bas-
ketwork-like markings of a rather obscure character on the anterior part of the
neck. The lips are sub-
2.4 14.' 26. 53 Y 83. distinct. At the nerve-
~I.~2~~ir4~~I.~7~~3.~V ring the oesophagus has
a diameter equal to two-
fifths the corresponding diameter of the neck, but swells
posteriorly to three-fourths the corresponding diameter.
In the posterior swelling the lining is somewhat expanded.
The dimly seen pyloric collum is one-third as wide as the body. Intestinal
granules are scarce. The ellipsoidal caudal glands occur in a close tandem
opposite the anus and in the anterior fourth of the rather massive tail. The
caudal setae, six ventro-submedian, and six dorso-submedian, are slender, stiff,
somewhat cylindroid, sub-acute, and one-sixth as long as the anal body-width.
The renette-cell, two-thirds as long as the body is wide and one-third as wide as
long, empties through a pore opposite the nerve-ring. In both the specimens
examined there appears a slender seta-like appendage (?) at the mouth of the
excretory pore. The female reproductive organs are double and symmetrical,
and probably reflexed.
Habitat; remarks. Cape Royds. Two females, in fair condition.
22. Euchromadora meridiana, n. sp. The cuticle is much like that of Euchro-
madora vulgaris, (Bast.) de Man. 400 striae, retrorse posteriorly and the reverse
anteriorly, make the con- 33
tour obscurely crenate. PP " \l^V~ JL_ 6 J_ 4 ^- 1 _i: l
The oesophagus, cylin-
droid anteriorly, conoid < . - <
posteriorly, has several ...... 8 . 4
breaks in its muscula-
ture, the most prominent being at the beginning of the final fifth of the neck.
The numerous intestinal granules are small, uniform, and indistinct. The rather
ellipsoidal caudal glands are arranged in an open tandem. Immediately behind
the anus the tail has a diameter equal to three-fourths the anal body-diameter;
thence onward it tapers but very slightly to the middle, where it begins to taper
more rapidly to the terminus which is one-third as wide as the anal body-diameter.
The lateral fields are somewhat distinctly cellular. The renette-cell, which pushes
FREE-LIVING NEMATODES 29
the intestine to one side, is twice as long as the body is wide, one-fourth to one-
fifth as wide as long. Just behind the nerve-ring there is a large ampulla as
long as the body is wide, and one-third as wide as long. In all the specimens
examined there appears a slender seta-like appendage at the mouth of the excre-
tory pore somewhat longer than the cuticle is thick. The ovaries are broad.
The male tail is like that of the female, but more uniformly tapering, with
less of a diminution just behind the anus. The strongly arcuate, sub-slender,
rather strong and tapering spicula, somewhat cephalated at the tapered distal
ends, are one and two-thirds times as long as the anal body-diameter, and lie
with their proximae slightly ventral to the body-axis. There are two, more or
less separate accessory pieces, each in two parts, one behind the spicula; the
other in front or alongside, the front part being like a reduced spiculum. The
ejaculatory duct is one-fifth, the vas deferens one-half as wide as the body.
Habitat; remarks. Cape Royds; Bay. About a dozen somewhat shrunken
specimens, the two sexes occurring in about equal numbers.
LAXUS, Cobb, 1894
23. Laxus septentrionalis, n. sp. There are upwards of 1000 plain, transverse
striae so small as to be difficult of resolution. The three subdistinct, more or
less bluntly conoid lips
are united by a mem-
brane, and form a circlet
around the mouth, very
difficult to see, except
when the mouth is open.
Only when the mouth is open can the connecting membrane be seen. It is prob-
able that the pharynx contains an obscure dorsal tooth. The structure which
gives rise to this supposition is of fair size, and thinly covered w y ith chitin. The
cylindroid to conoid neck contains a cylindroid oesophagus, which, measured
near the nerve-ring, is one-half as wide as the corresponding portion of the neck.
Though the amphids appear circular, they are in reality spiroidal. The pharynx
is situated in the midst of an almost imperceptible elongated pharyngeal swell-
ing, two-thirds as wide as the head. The thick walled intestine, six cells in girth,
soon becomes five-sixths as wide as the body. It has a distinct lumen, and is
separated from the oesophagus by a collum hardly one-third as wide as the base
of the neck. For a distance about equal to the length of the body-diameter the
cells of the intestine are comparatively free from granules. Thereafter they are
uniformly packed with yellowish granules having a width a little greater than
that of one of the striae of the cuticle. From the continuous anus the prominent,
chitinized rectum extends inward and forward a distance three-fourths as great
as the length of the anal body-diameter.
The tail tapers froni the anus to a terminus one-third as wide as its base. Ap-
parently the ellipsoidal caudal glands are packed together somewhat behind the
middle of the tail. Their ampullae, near the terminus, are more or less distinct.
The lateral fields, which are one-third as wide as the body, are margined by re-
fractive lines, at least in balsam specimens. The renette has not been clearly
seen, but is supposed to be located at a distance behind the neck equal to the
30 ANTARCTIC MARINE
radius of the body, and to be about one-half as long as the body is wide, and one-
half as wide as long. It empties by means of a short duct, and a rather struc-
tureless ampulla half as wide as the oesophagus, through the excretory pore near
the nerve-ring. The vulva is more or less continuous, and rather inconspicuous.
The elongated eggs are one and one-half times as long as the body is wide, and
one-third as wide as the body. They have conspicuous nuclei. Of the narrow
ovaries the posterior one is only one-third to one-half as long as the anterior,
which contains twenty developing ova, arranged single file, while the posterior
one contains only about fifteen.
The slender, uniform spicula have a more or less frail framework. The single
accessory piece, also more or less frail, presents,a stoutish, uniform, blunt apoph-
ysis one-half as long as the anal body-diameter, arranged at right angles to the
part which is applied to the spicula. This latter is one-third as long as the spic-
ula. The vas deferens is one-third, the tapering testes about one-half as wide as
the body. These latter, however, finally become very narrow. The blind end
of the posterior testis lies in front of the anus a distance about equal to six times
the length of the tail.
Habitat; remarks. Bay, Cape Royds; Bay. Four females and two males,
slightly shrunken.
AXOXOLAIMUS, de Man, 1889
24. Axonolaimus polaris, n. sp. The striae of the thin cuticle are very difficult
to resolve and are best seen on and near the tail. One is left in doubt as to whether
4 9 7 3 Y 94.7 the COnt Ur is P lain > or Vei T mi '
' '", i-7r.n. nutely crenate. Apparently there
are six subcephalic setae, each
half as long as the diameter of the head measured at the labial
CP \ ' \ constriction. Though there are no somatic setae there are a
few scattered setae on the neck, generally somewhat shorter
than the subcephalic setae. The conoid neck contains a conoid oesophagus,
whose diameter near the nerve-ring is two-fifths as great as that of the corre-
sponding part of the neck, and which finally becomes two-thirds as wide as the
base of the neck. There is no distinct cardia. The thick walled intestine is
two to three cells in girth, and becomes at once three-fourths as wide as the
body, being separated from the oesophagus by a collum three-fifths as wide as
the base of the neck. On account of the food contained in it the lumen of the
intestine is distinct. The intestinal cells contain very fine, scattered, colorless
granules in the middle of which the nucleus appears as a distinct feature in
stained specimens. From the raised anus the chitinized rectum extends inward
and forward a distance equal to the anal body-diameter. The tail tapers from
the anus, bears very minute hairs near the end, and contains broadly saccate
caudal glands packed in its anterior third. The nerve-ring surrounds the oesoph-
agus squarely, is of medium size, and is accompanied by obscure nerve-cells,
which are not very distinctly grouped.
Habitat; remarks. Bay, Cape Royds. Single young specimen, in fair con-
dition. In the sketch the lips are shown partly everted.
FREE-LIVING NEMATODES 31
THORACOSTOMA, Marion, 1870
25. Thoracostoma polare, n. sp. The thick yellow cuticle is traversed by mi-
nute, transverse striae difficult of resolution, and in its deeper layers, at least
near the head, by fine ^_ J V ^ 38
oblique striae crossing each lfc -1^ V\ : - - 8 - 14< t<5 ' "' ?
other at an angle of about pc .--/t--r*f' ^ \ ' 4 1- " 3 1-5 ' 8
forty-five degrees. Subce- \*-'ffij$M\ .2 4.9 12. _ M - 69 99.4
phahc setae, like the ce- \^r^\\\j/^ \ .4 i'g i';' 3 ' i'T '^ i9.a
phalic in form and size, oc-
cur in groups of three or four together, near the border of the "cuirasse," and a
little farther back. Similar cervical setae occur on the anterior part of the neck
singly and separated by a distance one-fourth to one-third as great as the diame-
ter of the neck measured at the middle. The remaining cervical setae as well as
the somatic setae are reduced to papillae. All these setae are arranged in more
or less irregular lateral and submedian lines. The head is furnished with a chiti-
nous, faintly yellowish "cuirasse," extending back to opposite the base of the
pharynx, and divided longitudinally into six lobes by as many sutures. Each
of these lobes is perforated near the posterior margin by two oblique, irregular
locules, each a little more than half as long as the amphids are wide. The three
amalgamated lips are nearly obsolete. Six forward pointing, inconspicuous, in-
nervated papillae form a single circlet on the front of the head. The simple,
rather narrow, more or less irregularly pyramidal, well chitinized pharynx is as
long as the head is wide, and is somewhat narrowed posteriorly, where the two
ventrally submedian oesophageal glands empty into it. The third oesophageal
gland, ventral in position, empties into the lumen of the oesophagus a little more
than halfway back to the eye-spots. When shut the pharynx rather closely
resembles the lumen of the oesophagus, which possesses a well developed chiti-
nous lining. The only armature of the pharynx is the dorsal, labial, two-lobed
cordiform piece of chitin just at the mouth opening, arranged much as described
by Dr. de Man for Thoracostoma antarcticum, v. Linst. Two faint refractive lines
close together lead backward from the posterior part of each amphid. The two
rather widely separated eye-spots are located at a distance from the anterior
extremity equal to four times the width of the head, and are one-sixth as wide
as the corresponding part of the neck, and about as long as wide. These are
somewhat heart shaped, and are composed of compactly arranged brownish
granules. There are obscure indications of a refractive body, or "lens," in the
hollowed out front part of each eye-spot. The conoid oesophagus is about half
as wide as the neck, and presents a faint, elongated pharyngeal swelling. The
cylindroid cardia is one-fifth to one-fourth as wide as the base of the neck. The
thick-walled intestine, separated from the oesophagus by a collum one-third as
wide as the base of the neck, becomes at once three-fifths as wide as the body,
and is about six cells in girth. The intestinal cells contain numerous uniform,
colorless granules. The posterior lip of the anus is slightly elevated.
The hemispherical-conoid to convex-conoid tail tapers from the anus and
ends in a very broad, bluntly rounded terminus. The spinneret is a very slightly
depressed pore with a suggestion of yellowish color, arranged a little unsymmetri-
cally, so that it empties somewhat toward the ventral side, and not axially. It
32 AXTARCTIC MARINE
is unarmed, though a little in front of it there are a very few papilla-like setae.
The three more or less elongated saccate caudal glands extend in a loose tandem
in front of the anus a distance five times as great as the corresponding body-
diameter. Their distinct and somewhat tortuous ducts widen to three separate
ampullae so as to fill the middle of the tail. The vulva is slightly depressed and
is rather inconspicuous. The vagina extends inward at right angles to the ven-
tral surface about halfway across the body. Both before and behind the vulva
there are well developed unicellular glands. Each of the two straight uteri is
about seven times as long as the body is wide, and contains a row of five or six
eggs in the specimens examined. The rather thick-shelled eggs are three-fourths
as long as the body is wide, and nearly as wide as long. Owing to their pressure
on each other the eggs take on a more or less rectangular contour. The broad ova-
ries reach two-thirds the way back to the vulva, and contain scores of discoid
ova, arranged more or less in single file.
The anus of the male is broadly elevated. The tail of the male has a compli-
cated sexual armature. Near the anus on the anterior fourth of the tail there
are six stout, stiff, conoid, somewhat blunt, ventrally submedian setae on each
side, the longest of which, those nearest the anus, are nearly as long as the cuti-
cle is thick, and the smallest of which, the hindermost, are very small. The pre-
anal setae are arranged in ventrally submedian rows, of which the individual
setae are much nearer together posteriorly than anteriorly. Between the anus
and the single ventral median supplementary organ there are ten of these setae;
between the latter and the posterior member of the ventrally submedian rows
of supplementary organs there are two of these setae; between the ultimate and
the penultimate members of the submedian series there are also two. Thence
forward between any two members of the submedian series there is but a single
seta. In all, therefore, there are about seventeen of these setae on each submedi-
an line in front of the anus. In addition there are two very inconspicuous, papil-
loid, tapering, acute, lateral setae near the terminus. The lateral fields, one-third
to two-fifths as wide as the body, are composed of several rows of cells among
which are placed glandular, saccate cells, of two or three times as great diameter,
connected with the exterior by means of pores in the cuticle. The relative num-
ber and position of these glandular cells may be judged to a certain extent from
the fact that in the female near the vulva three of these large saccate cells are
separated from each other by spaces about equal to their own diameter. These
cells are entirely similar to those described by Jaegerskiold, de Man, and other
authors, who have made observations on species of Thoracostoma. The distinct
cells connected with the more or less broad and oblique nerve-ring are arranged
into rather distinct groups and are a prominent feature of the middle half of the
neck.
The stout, blunt, yellowish spicula, cephalated by a very slight constriction,
are arcuate in the distal half, and are one and three-fourths times as long as the
anal body-diameter. At the widest part, a little in front of the middle, they
are about one-fourth as wide as the corresponding part of the body. From the
widest part they taper gradually to the distal ends, but taper more suddenly
toward the proximal ends, which lie opposite the body-axis and have a width
when viewed in profile about twice as great as the thickness of the adjacent cuti-
cle on the dorsal side of the body. The difference between the anterior and pos-
FREE-LIVING NEMATODES 33
terior parts of the spicula is greater than in Thoracostoma setosum, Linst. The
strong, chitinous framework is strengthened by a middle piece in the distal three-
fifths. The two separate, strong, rather stout accessory pieces are bent a very
little, and are half as long as the spicula. They are of somewhat irregular width,
but appear when seen in profile about twice as wide as the dorsal cuticle is thick.
They lie parallel to the spicula, but their cephalated proximal ends, a little wider
than those of the spicula, are bent away a little and lie somewhat to the dorsal side
of the body-axis.
The elevated, mammiform supplementary organs, about one-sixth as wide
as the body and half as high as wide, are arranged in ventrally submedian rows
one and two-thirds times as long as the body is wide, the posterior members being
located a distance in front of the anus equal to one and two-thirds times the length
of the spicula. They are a little farther apart posteriorly than anteriorly, the
longest space being about equal to the length of the radius of the body as seen
in profile at the corresponding part. In addition to these two rows of five organs
each there is a single ventral organ a little in front of the middle of the spiciila,
similar in size and form to the others, but manifestly of a different structure.
Sometimes there is an appearance as if a rudimentary sixth ventrally submedian
organ is present in front of the fifth. Oblique copulatory muscles are arranged
close together coextensive with the supplementary organs. The ejaculatory
duct is about one-fifth as wide as the corresponding part of the body.
Habitat; remarks. Bay, Cape Royds; Cape Royds. Three females and two
males, in good condition.
February, 1914.
NORTH AMERICAN
FREE-LIVING FRESH-WATER
NEMATODES
CONTRIBUTIONS TO A SCIENCE OF NEMATOLOGY
II
BY N. A. COBB
(With eighty illustrations)
INTRODUCTION.
The little creatures described in these pages belong to a very
important but as yet comparatively little known class of animal
organisms, the nematodes.
Something more than a mere reconnaissance leads to the con-
clusion that over nine-tenths of the nematode species still remain
unknown, a greater disproportion between the known and the un-
known than exists in almost any other class of organisms.
Nematodes are distributed far and wide in inconceivable num-
bers, and without doubt constitute a group in the animal kingdom
comparable with insects both in number of species and economic
importance. They vary in length from one two-hundredth of an inch
to several feet, though the great majority are less than half an inch
long. They differ from most other slender, wormlike forms in
their lack of locomotive appendages, the outer surface, except for
the presence of setae, is usually quite smooth. Being more or less
cylindrical in form, they are often called "round-worms." They
live free in the soil, in fresh and salt water, and are found parasitic
in a great variety of animals and plants.
NEMATODES AS CAUSES OF DISEASE
The parasitic species often cause fatal diseases of plants and
of animals, including mankind. The dreaded hookworm is a nema-
tode. So is that scourge of the tropics, the guinea worm. Trichina,*
"Trichinella spiralis.
Reprinted from Trans. American Microscopical Society. Vol. XXXIII, April, 1914.
36 NORTH AMERICAN
costing civilized nations hundreds of thousands of dollars yearly
for the inspection of pork, is a nematode. If trichina,-infested or
measly pork be eaten by human beings, the result is a serious, often-
times fatal, sickness, called trichinosis, epidemics of which have
claimed victims by the hundred. Nematodes have recently been
suspected, with good show of reason, of being carriers of cancer.
So the list of serious human nematode diseases might be increased
until practically half a hundred had been enumerated.
No less serious are the nematode diseases of plants and of
the lower animals. The common gall-worm has been found infest-
ing the roots of several hundred different species of plants, among
them most of our cultivated crops, and causes a'n annual loss
amounting to millions of dollars. There is another nematode that
has at times completely checked the growing of sugar beets in cer-
tain regions. The list of serious plant diseases of this character
could easily be increased to scores. The same is true of animals.
Every domestic, doubtless every wild, species has a number of
specific nematode parasites sapping its vitality.
WONDERFUL VARIETY OF HABITAT.
Not the least interesting thing about nematodes is the astound-
ing variety of their habitats. They occur in arid deserts and at the
bottoms of lakes and rivers, in the waters of hot springs and in
polar seas where the temperature is constantly below the freezing
point of pure water. They were thawed out alive from Antarctic
ice in the far south by members of the Shackelton expedition. They
occur at enormous depths in Alpine lakes and in the ocean. As
parasites of fishes they traverse the seas ; as parasites of birds they
float across continents and over high mountain ranges. Their eggs
and larvae, invariably of microscopic size, are carried from place to
place by an exceedingly great variety of agencies. Almost any vis-
ible thing that moves is capable of transporting nematode eggs or
larvae. Sometimes the eggs and larvae are so resistant to dryness
that if converted to dust they revive when moistened. This
revival of mummified nematodes may take place after as long a
period as a quarter of a century.
Nematodes are found in queer places. The wildest imagina-
tion could hardly outpicture the facts. One species is found prac-
FREE-LIVING FRESH-WATER NEMATODES 37
tically only in the vermiform appendix of man; another has its
adult form only, in the seeds of wheat. A third form occurs in
the felt mats on which the Germans are accustomed to set their
mugs of beer, and has been found in no other habitat. On the feet
of birds and insects the eggs, larvae, and adults of certain nema-
todes are carried to the tops of the tallest trees. The sour sap is-
suing from the wounds of a tree, often many feet above the ground,
not infrequently contains nematodes that are specific to the wounds
of that particular kind of tree. The tap water of even well-con-
ducted cities often contains nematodes.
Nematodes are inconceivably abundant. A thimbleful of mud
from the bottom of the ocean may contain hundreds of specimens.
The number of nematodes in the top six inches of an acre of ordi-
nary arable soil amounts to thousands of millions. Statistical cal-
culations relative to the number of nematodes in a single acre of
soil near San Antonio, Texas, U. S. A., disclosed that if they could
start in a procession for Washington, D. C., two thousand miles
away, each close on the tail of the one in front, the head of the
procession would reach Washington before the rear had left San
Antonio. As nematodes are usually very prolific, a single female
sometimes producing thousands of eggs, the number of eggs vastly
exceeds that of the adults".
We must therefore conceive of nematodes and their eggs as
being carried by the wind, and by flying birds and running animals ;
as floating from place to place in nearly all the waters of the earth ;
and as shipped from point to point throughout the civilized world
in vehicles of traffic.
There are beneficial nematodes, though knowledge of this phase
of the subject is in its earliest infancy. Some nematodes feed ex-
clusively on their injurious brethren. Others devour baneful micro-
organisms. Their adaptations and relationships appear to be sim-
ilar to those of insects.
NORTH AMERICAN FRESH-WATER SPECIES.
The nematodes here described are the main portion of those
found during a rather casual search for aquatic species that would
serve as the basis of a special chapter in a zoological textbook de-
voted to fresh water organisms. The object of the textbook was
287184
38 NORTH AMERICAN
to characterize each known genus by describing and illustrating a
typical species.
When the work on the nematode chapter was begun there was
hardly a single adequately described North American species, so
that the initial task was one of pure discovery. This was followed
by the work of research and definition, and this finally by that of
selection and presentation of typical species in a manner suitable
to a college textbook.
The famous Philadelphian, Dr. Joseph Leidy, appears to be
the only naturalist who had previously attempted to describe any of
our fresh water nematodes, and even he did but little. I have at-
tempted to rehabilitate his Anguilhda longa, which, as Bastian sur-
mised, belongs to the more modern genus Trilobus. I have had to
assume that the variety Leidy had before him was that most com-
mon in the ditches, brooks and rivers of the Chesapeake region,
and have given to this form the name Trilobus longus (Leidy)
Bastian.
All the other species proved to be new, some of them repre-
sentatives of new genera. Most of the new genera have already
been described in my contribution to the Proceedings of the Wash-
ington Academy of Sciences, October, 1913.
An aquatic species as here defined is any species inhabiting
either fresh water, or non-brackish swampy soil below the water
table ; hence a species that will not drown in fresh water ; a species
fitted to utilize oxygen dissolved in fresh water.
Including those of the present article, the fresh water North
American species so far described are as follows :
Achromadora minima Cyatholaimus truncatus
Actinolaimus radiatus Diplogaster fictor, Bastian
Alaimus simplex Dolichodorus heterocephalus
Anonchus monhystera Dorylaimus fecundus
Aphanolaimus minor Ethmolaimus americanus
Aphanolaimus spirurus Iota octangulare
Bastiana exilis Ironus americanus
Cephalobus setosus Mesomermis virginiana
Cephalobus subelongatus Microlaimus fluviatilis
Chronogaster gracilis Monhystera sentiens
Cryptonchus nudus Mononchus similis
FREE-LIVING FRESH-WATER NEMATODES
39
Oncholaimus punctatus Spilophora canadensis
Plectus tubifer Teratocephalus cornutus
Prismatolaimus stenurus Trilobus longus (Leidy), Ba'stian
Rhabditis punctatus Tripyla lata
Rhabdolaimus minor Tylcnchus symmetricus
There has been little time or opportunity to search specially for
these fresh water forms, and the fact that it has been possible in so
short a time to assemble so many genera and species is proof of
the enormous abundance and multifarious nature of these organ-
isms. No doubt there is a horde of species awaiting discovery in
North American waters.
THE NEMATODE FORMULA.
The following diagram illustrates the nature of the formula
used in the tabulation of the various necessary measurements :
=?#;
Fig. 1. Diagram of the descriptive decimal formula used for nematodes; 6, 7, 8, 10,
6 are the transverse measurements, while 7, 14, 28, 50, 88 are the corresponding longi-
tudinal measurements. The formula in this case is:
7. 14. 28. SO. 88.
6. 7. 8. 10. 6.
The unit of measurement is the hundreth part of the length
of the body, whatever that may be. The measurements become,
therefore, percentages of the length. The absolute length is given
in millimeters as a final non-paired term. This decimal method of
presenting the measurements is the most compact and convenient
method, and is being used more and more year by year.
The measurements are taken with the animal viewed in profile ;
the first are taken at the base of the pharynx, the second at the
nerve-ring, the third at the cardiac constriction or end of the neck,
the fourth at the vulva in females and at the middle (M) in males,
the fifth at the anus. The formulae represent the average of sev-
eral specimens whenever possible.
There are several methods of securing the measurements, one
of the most convenient being the preparation of a camera lucida
"skeleton" to scale, consisting of a line following the body axis
4O NORTH AMERICAN
from one end to the other, and diametral lines at the base of the
pharynx, the nerve-ring, the end of the neck, at the vulva in fe-
males and at the middle in males, and finally at the anus. This
skeleton is then measured with a metric scale and map measure,
and the percentages divided out with the aid of a slide rule.
IOTA, Cobb, 1913.
Fig. 1, Plate II.
57
14. 21. 25. -85 Q2.
1. Iota octangulare, n.sp. .4 mm.
II. 12. 12. 9. 6.
Along the longitudinal fields the striae are so modified as to give the
worm somewhat the appearance of being covered by eight rows of relatively
large scales arranged in pairs. Six small, simple, flattish lips surround the
vestibule. The lips are supplied with six small, innervated papillae. These
lie in the midst of a plate-shaped disk, the first annule. There are no recog-
nized traces of amphids, but the recessive nature of the second annule is
suggestive, and it is possible that this peculiarity of the second annule is in
some way connected with the amphids. There are no eye-spots. The narrow
vestibule leads to the equally narrow pharynx, which consists essentially of
a muscular tube closely surrounding the spear. This latter is of relatively
very large size, and strictly Tylenchoid in structure. Its length is about
equivalent to the first twelve annules of the cuticle. It is divisible into two
parts : a long cylindrical hollow shaft tapering to a point near its apex, and
having a length about equivalent to the first nine annules ; behind this shaft
a basal portion or "hilt," which in its distal part has a structure like that
of the shaft, but with a slightly greater diameter. This hilt terminates in a
threefold, flattish bulb about one-fourth as wide as the corresponding por-
tion of the neck. The lumen of the spear is continuous with that of the
oesophagus. This latter consists mainly of a narrow, chitinous tube, which
is usually somewhat coiled when the spear is at rest. That portion of the
oesophagus containing the hilt of the spear and the coiled oesophageal tube
just mentioned constitutes a somewhat obscure elongated "bulb." This bulb,
however, is not the morphological equivalent of the bulb usually seen in the
oesophagus of Tylenchus and Aphelenchus, as it has no radial muscles, and
contains no valvular apparatus. The remaining short portion of the oesopha-
gus is tubular and narrow, though it swells slightly at the terminus, where it is
about one-eighth to one-ninth as wide as the base of the neck. The ex-
cretory pore empties through the exterior margin of the nineteenth annule,
or thereabouts. It may be distinctly seen when the worm is viewed from
the ventral side, and less distinctly seen in profile.
Habitat: Dismal Swamp, Va. Flemming solution to glycerine.
FREE-LIVING FRESH-WATER NEMATODES 41
RHABDOLAIMUS, de Man, 1880.
Fig. 2, Plate II.
28
2. Rhabdolaimus minor, n.sp. 4 ' 6 * 5 ' ^ <5I> 77 ' 5 2 8 mm
2.4 37 3-8 4- 2.
The thin layers of the transparent, naked, colorless cuticle appear to be
destitute of any but very fine transverse striations, most clearly visible near the
head. The conoid neck ends in a rounded head which is not set off in any
way. There are no cephalic setae. Careful focussing appears to indicate on
the outer margin of the head the presence of almost invisible papilla-like or-
gans which may perhaps be representatives of cephalic setae. There are no
lips. The amphids are located at a distance from the anterior extremity
about three times as great as the width of the lip-region, and a little more
than twice as great as the width of the head near where they occur. Seen
in dorso-ventral view they have the appearance of obscure openings from
which there leads inward and backward slight refractive elements which
soon become indefinite. Immediately behind the mouth opening there is at
least one obscure refractive element of small size, apparently very much as
figured by Dr. de Man in his description of the type species. The tubular
pharynx is long and slender, extending backward for a considerable distance
behind the amphids. Its total length is probably a little less than one-third
the distance to the nerve-ring, though the limits are not definite in the speci-
mens so far examined. The oesophagus is at first about three-fourths as
wide as the head and continues to have this diameter, or a slightly greater
diameter, until near the end, where it expands to form the pyriform cardiac
bulb which contains an obscure valvular apparatus. This bulb is three-
fourths as wide as the base of the neck. The lining of the oesophagus may
be faintly seen throughout its length. The rather thin-walled intestine which
is separated from the oesophagus by a slight constriction becomes at once
three-fourths as wide as the body. It appears to be composed of cells of
such size that probably only four to six are required to build a circumfer-
ence. From the nearly continuous anus, the rectum, which is somewhat
longer than the anal body diameter, extends inward and forward. The tail
begins to taper from a little in front of the anus and tapers regularly to
the terminus which is armed with a striking, elongated, unarmed, slightly
tapering, acute spinneret. Where the tail joins the spinneret the diameter is
about one-fifth as great as at the anus. There is a sudden and very slight
diminution of diameter of the terminus where it joins the spinneret. From
the inconspicuous vulva, the vagina leads inward and forward. The sym-
metrically reflexed ovaries reach about half way back to the vulva. The
thin-shelled, smooth eggs are relatively large and elongated and have
been seen in the uterus one at a time. They are about four to five
times as long as the body is wide and about one-fifth as wide as long.
They appear to be deposited before segmentation begins.
Habitat: Mud, Beach pool, Pine Point, Douglas Lake, Michigan.
Sublimate to balsam.
42 NORTH AMERICAN
DIPLOGASTER, Max Schultz, 1857.
Fig. 3, Plate II.
35
1.3 10.7 13.8 '51' 88.1
3. Diplogaster fictor, Bastian 1.5 mm.
1.3 1.4 1.4 1.7 1.4
The thin layers of the transparent, colorless, practically naked cuticle
are traversed by exceedingly fine transverse striae, resolvable with high
powers under favorable conditions, which become considerably coarser to-
ward the head, where they are resolvable into rows of refractive dots ar-
ranged in longitudinal, as well as transverse lines. A short distance behind
the head the longitudinal rows arrange themselves in pairs. These pairs
indicate the locus of about twenty-four cuticular ribs or wings, which extend
from the middle of the neck to near the anus. On the tail these ribs again
resolve themselves into double rows of dots, and gradually disappear as the
tail grows narrower. Very little is to be seen of them behind the middle
of the tail. The cylindroid neck ends in a somewhat rounded head, which
bears near its outer margin a circlet of six somewhat forward-pointing,
tapering cephalic setae, each about one-third as long as the head is wide.
There is one of these setae on each submedian line and one on each lateral
line. Just in front of the base of each lateral seta a minute obscure pore or
papilla was observed, which did not appear to exist in connection with the
other setae. The amphids, though only faintly visible, are of relatively
large size. Their form is partly indicated by a lateral area on which the
punctations of the cuticle are absent. This is a somewhat elliptical area
placed transversely on the side of the head, with its long axis at right angles
to the lateral line. Its length is equal to half that of the correspond-
ing diameter of the head. Its anterior contour is more definite than the
posterior, although it is only by the most caerful focusing that the defintie
line of contour can be distinguished. Through the middle of the area, how-
ever, there is quite a distinct arcuate line, with its convex side toward the
lips. When seen dorso-ventrally the amphids have the appearance of
distinct oblique openings, leading inward and backward. When the mouth
is opened and the lips recurved the amphids are moved forward somewhat
and the transverse line mentioned becomes more strongly curved and forms
a semi-circumference. The circular mouth opening is very finely striated on
the inner surface of the lip region. These striae begin on the inner face of
the lips near where the cuticular wall of the pharynx first appears. They
extend backward nearly to the base of the pharynx and end in-
definitely. In front of this finely longitudinally striated area the transverse
marginal portion of the lips is more coarsely divided into fourteen
parts. The lips are capable of being opened, so that the oral aperture
is two-thirds as wide as the head. Under such circumstances it is seen
that the lip region is flower-like in form with fourteen recurved seg-
ments, the distal tapering portion of each of which is plain and
FREE-LIVING FRESH-WATER NEMATODES 43
transparent, while the basal portion is traversed longitudinally by four min-
ute, refractive, somewhat beaded longitudinal striae. The pharynx is about
as deep as it is wide, and in its widest part is a little more than half as wide
as the front of the head. It is well filled at the base with the two cres-
cent-shaped, pointed, pharyngeal teeth. These extend inward and
then forward, their points being close to the body axis. The front contours
of the teeth are incurved, and at one point on their front surface they are
exceedingly finely striated. Each of these teeth occupies about one-fourth
of the width of the head; measured in the longitudinal direction its ex-
treme limits are less than when measured transversely. The entire length of
the pharynx is probably somewhat greater than the width of the head,
though it joins the lumen of the oesophagus in such an indefinite way
that it is sometimes rather difficult to say where the pharynx ceases and the
true oesophagus begins. The portion of the oesophagus surrounding the
pharynx is, however, distinctly, though slightly, swollen, so that it is proper
to speak of an elongated pharyngeal bulb. Just at the base of the phraynx
this bulb is two-thirds as wide as the corresponding portion of the head. At
a point two or three body diameters farther back it is only about half as
wide as the corresponding portion of the neck; thence onward it expands
a very little. Near the middle of the neck the oesophagus expands to form
the elongated muscular median bulb, which is three-fourths as wide as the
middle of the neck. Here the lining is more strongly developed, and occupies
about one-fourth of the optical longitudinal section, while the lining of the
preceding portion of the oesophagus occupies not more than one-fifth to one-
sixth of the diameter. Behind the median bulb the oesophagus is less strongly
developed. The lining is much less conspicuous and the radial muscular fibers
are less abundant. At first this posterior portion of the oesophagus is only
about one-fourth as wide as the middle of the neck. It expands gradually
until near the end, then more rapidly so as to form an elongated-
clavate swelling, three-fourths as wide as the base of the neck. The lining
of this portion of the oesophagus is a distinct feature, but is by no means so
strongly developed as that of the preceding portions of the eosophagus.
There is a well developed flattish cardia, half as wide as the base of the
neck. The intestine, which is separated from the oesophagus by a distinct
constriction, becomes at once about three-fourths as wide as the body. Its
cells contain scattered, nearly colorless granules of variable size, the largest
of which have a diameter nearly equal to the distance between two of the
adjacent longitudinal striations. From the slightly depressed anus the rec-
tum, which is about one and one-half times as long as the anal body diam-
eter, extends inward and forward. The tail is conoid from the anus and
tapers rather regularly to the extremely fine, hair-like terminus. There are
no caudal glands.
From the rather prominently elevated vulva the chitinized vagina leads
inward at right angles to the ventral surface half way across the body, where
it joins the two symmetrically-placed uteri. The reflexed ovaries reach
44 NORTH AMERICAN
about half way back to the vulva and contain six to ten developing ova ar-
ranged single file. The thin-shelled eggs, which are deposited before
segmentation begins, are fully twice as long as the body is wide and
about one-third as wide as long, and occur in the uteri one at a time.
Full-grown ova are ellipsoidal, and about one and one-half times as long
as the body is wide and about half as wide as long.
55
.9 12.3 15.5 -M 86.6
i.o mm.
i.i 1.4 1.4 1.5 1.6
The tail of the male is like that of his mate in form. There are no sup-
plementary organs in front of the anus. The special male papillae charac-
teristic of this genus are located as follows : A single tapering, ventrally
submedian papilla a little in front of the proximal ends of the spicula, and
slightly farther back a lateral pre-anal papilla; a ventrally submedian papilla
as far behind the anus as that first described is in front of it ; a lateral papilla
twice as far behind the anus as that just described ; a ventrally submedian
papilla as far behind that just described as the latter is behind the previous
post-anal papilla; between the two ventrally submedian papillae just de-
scribed a group of minute subventral papillae ; near the middle of the tail,
on the slender part, two sublateral papillae. Most of these papillae are
slender, tapering, and one-third to one-half as long as the anal body diame-
ter. The two equal, yellowish, arcuate, acute spicula are about one and one-
fourth times as long as the anal body diameter. They taper pretty regu-
larly from near the proximal ends, where they are one-fourth as wide as
the corresponding portion of the body. The proximal ends diminish sud-
denly in diameter, and are then cephalated by expansion. Each expansion is
a rather strongly refractive, more or less bulbous piece of chitin. The acces-
sory piece is arcuate and about one-third as long as the spicula. It is par-
allel to and applied closely to the spicula. Its framework consists of two
distinct, nearly parallel parts. The ejaculatory duct is about one-fourth as
wide as the body. The blind end of the single outstretched testicle lies a
little farther behind the base of the neck than this latter is behind the an-
terior extremity.
Habitat: Spring. Washington Country Club, Chevy Chase, Md.
Sublimate to balsam.
PRISMATOLAIMUS, de Man, 1880.
Fig. 4, Plate III.
14
4. Prismatolaimus sternus, n.sp. i.i mm.
1.2 1.5 1.9 1.9 1.5
The moderately thin layers of the transparent, colorless cuticle are tra-
versed by about 550 transverse striae, resolvable with high powers into
rows of minute elements. There are no longitudinal striations. Scattered on
FREE-LIVING FRESH-WATER NEMATODES 45
the neck and body there are a few hairs arranged at right angles to the
surface. These generally have a length equal to the width of two to three
annules of the cuticle. The cylindroid neck ends in a somewhat truncated
head, which is not set off in any way. On the outer margin of the head at
the base of the lips there is a circlet of ten widely spreading, straight, taper-
ing cephalic setae, two of somewhat unequal size on each submedian line,
and one on each lateral line. The longest of these setae are a little more
than half as long as the head is wide. For two-thirds of their length they
are finger-shaped; the remaining third is a much narrower bristle. The
very thin lips are arched over the prismoid pharynx, which is nearly as deep
as the head is wide, and about three-fifths as wide as the head. It attains
its full width immediately behind the lips, and continues to have the same
width to the end, so that the bottom of the pharynx, though not even, ex-
tends across the base of the head approximately at right angles to the body
axis. Where the lumen of the oesophagus joins the pharynx there is, how-
ever, a slight backward extension of the pharyngeal cavity. There are no
eye-spots. The amphids occur in the form of somewhat elongated trans-
verse markings placed transversely on the neck somewhat farther behind
the base of the pharynx than this latter is behind the anterior extremity.
Each amphid has a length about one-third as great as the corresponding
width of the neck, and is about half as wide as long. Behind each amphid,
at a distance equal to the width of two to three annules of the cuticle, there
is a short seta. The oesophagus receives the base of the pharynx, and is
at once nearly three-fourths as wide as the head. It narrows very slightly
in diameter as it passes backward, so that where it passes through the nerve-
ring it is about two-thirds as wide as the neck. It continues to have prac-
tically the same diameter to near the end, where it is two-thirds as wide as
the base of the neck. Immediately in front of the intestine there is a small
segment of the oesophagus which is set off by a constriction. This
portion is somewhat spheroidal in form. The lining of the oesophagus is a
distinct feature throughout its length, and comes into view in the optical
section as a single refractive line. This line is nowhere materially altered.
There is no distinct cardia, unless the above mentioned spheroidal segment
of the oesophagus may be so considered. The rather thick walled intestine,
which is set off from the oesophagus by a distinct constriction, becomes at
once about two-thirds as wide as the body, and is composed of cells of such
a size that probably about four are required to build a circumference. These
cells contain numerous granules of rather uniform size, which are not dis-
posed so as to give rise to a tessellation. From the somewhat continuous
anus the rectum, which is about as long as the anal body diameter, extends
inward and forward. The tail end begins to taper from some distance in
front of the anus, and tapers regularly thereafter throughout the anterior
portion of the tail. The posterior portion tapers very slightly, and has a
diameter one to two times as great as the width of one of the annules of
the cuticle, measured near the anus. Though the terminus has considerable
46 NORTH AMERICAN
width there is no spinneret. The lateral fields are about one-third as wide
as the body. The nerve-ring surrounds the oesophagus somewhat squarely.
On the dorsal side, a little behind the cardiac constriction there is a body
which presses the intestine a little to one side, which may perhaps be the
renette cell. This body has a length as great as the corresponding body di-
ameter, and is about one-fourth to one-third as wide as long. The vulva is
somewhat elevated, and from it the vagina extends inward at right angles to
the ventral surface about one-third the distance across the body. There are
two symmetrically disposed, reflexed ovaries, the blind ends of which lie
near the vulva, the position depending to a considerable extent upon the de-
velopment of the much elongated eggs. The ovaries are moved backward
and forward to a certain extent in accordance with the stage of develop-
ment of the eggs. The eggs, which have been seen in the uteri one at a time,
are much elongated four or five times as long as the body is wide
and about one-fifth as wide as long. They appear to be deposited before
segmentation begins.
Habitat: Roadside pool, Douglas Lake, Michigan. Sublimate to
balsam.
SPILOPHORA, Bastian, 1865.
Fig. 5, Plate III.
5. Spilophora canadensis, n.sp.
The thin, transparent layers of the colorless, practically naked cuticle
are traversed by 750 transverse striae, resolvable with high powers into
rows of dots, which at the lateral wings are so modified as to give rise to
two distinct longitudinal rows of dots of larger size. Along the middle of
the body one of these rows is more pronounced than the other. Opposite
the base of the neck the distance between these two longitudinal rows is
about four times as great as the distance between two of the dot-like ele-
ments. There are no eye-spots, nor have any distinct traces of amphids been
seen. If the latter are present they must be very inconspicuous. The lips are
so small that it is very difficult to count them, but there appear to be twelve,
each one obscurely conical. There are no very marked subdivisions between
these lips, so that the shallow cyathiform anterior portion of the pharynx,
(a, Fig. 5) which is about half as wide as the head and about one-third to
one-half as deep as wide, is not prominently striated radially as is some-
times the case in this and related genera. From the slightly depressed vulva,
the vagina leads inward at right angles to the ventral surface about half way
across the body, where it joins the two symmetrically-placed uteri. The re-
flexed ovaries reach fully half way back to the vulva, at least in young speci-
mens such as have been examined, and contain a dozen to twenty developing
ova arranged in more or less double file. The eggs appear to be elongated,
somewhat longer than the body is wide and about one-third as wide as long.
It is possible, however, that there is some error here as the description is
FREE-LIVING FRESH-WATER NEMATODES 47
derived from a single specimen in which these features are rather obscure.
The reversal in the striations of the cuticle is plainly to be seen in the re-
gion of the vulva, and its location is indicated by a slight rise in the contour.
This slight elevation extends also to the subcuticle.
60
.5 8.3 14.8 -M 88.4
.7 mm.
2. 4.3 4.7 5. 3.2
The wing markings on the anterior part of the tail are pronounced,
but on the posterior part much less so. A little in front of the
anus they are as pronounced as they are at the base of the
neck, and both are equally visible, and the structure not infrequently re-
sembles that of a ladder with the rungs placed close together, just as it does
on the neck. The lateral fields appear to be about one-third as wide as the
body. Near the middle of the body may plainly be seen the location where
the cuticle reverses its structure. Although the striations are minute they
present the same character as in species where the striations are coarse, and,
upon careful examination, can be seen to be retrorse in opposite directions
on the two halves of the body.
Habitat : Fresh water ponds, Cape Breton Island, Dominion of Canada.
MICROLAIMUS, de Man, 1880.
Fig. 6, Plate III.
27
6. Microlaimus fluviatilis, n.sp. *- 6 8 -5 *5-5 V 85. mm
1-9 3-5 4-3 47 2.6
The thin layers of the transparent, colorless, naked cuticle are traversed
by exceedingly fine transverse striae, which are resolvable with great diffi-
culty into rows of dots, and are not modified on the lateral fields. The
conoid neck ends in a rounded head set off by an almost imperceptible con-
striction. On the outer margin of the head there is a circlet of four sub-
median, slightly tapering cephalic setae, each about one-third as long as the
head is wide. The vestibule is considerably shorter than any of the cephalic
setae, and is longitudinally striated, indicating, no doubt, that the lips can
be opened outward in receiving food. These longitudinal striations of the
vestibule are too minute to be counted, but there are apparently about twelve.
The circular amphids are about one-fourth as wide as the corresponding
portion of the head, and are located at a distance from the anterior ex-
tremity equal to one and one-half times the diameter of the front of the
head. There are no eye-spots. The limits of the pharynx are indicated by
a slight constriction in the oesophagus. The base of the pharynx is some-
what more than halfway back to the amphids. The general form of the
pharynx is cylindroid or prismoid. It is armed with minute and very in-
conspicuous, somewhat inward pointing and apparently not very regular
teeth or projections. The most conspicuous of these projections are two just
behind the base of the lips, one dorsal and the other apparently ventral, and
48 NORTH AMERICAN
a third at the base of the pharynx on the dorsal side. The oesophagus be-
gins as a tube about half as wide as the corresponding portion of the neck,
and continues to have this diameter until it swells to form the pyriform
cardiac bulb, which is about three-fourths as wide as the base of the neck,
and contains a distinct chitinized threefold, rather simple, valvular apparatus,
occupying two-fifths of the diameter as seen in longitudinal section. The
musculature of the bulb is divided into three sections, a small anterior sec-
tion, a middle and a posterior section. Of these two latter the posterior is
slightly the smaller. The lining of the oesophagus is a fairly distinct feature
throughout its length. There is no very distinct cardia. The intestine joins
the middle of the posterior surface of the cardiac bulb, and is there one-
fourth as wide as the base of the neck. It soon expands so as to become
about two-thirds as wide as the body. It is rather thick walled, and is com-
posed of rather thick cells which are of such a size that about four are re-
quired to build a circumference. These cells contain minute granules. From
the anus the rectum, which is considerably longer than the anal body diam-
eter, extends inward and forward. The tail is conoid, and tapers from the
anus toward the terminus, which is conoid and has a diameter one-third as
great as that of the base of the tail, and bears a blunt convex-conoid unarmed
spinneret. The rather small caudal glands appear to be located in the an-
terior third of the tail. The lateral fields have not been seen. From the
inconspicuous vulva the vagina leads inward at right angles to the ventral
surface to the single or double uterus, which when single extends forward.
There sometimes appears to be a small posterior rudimentary branch to the
sexual organs, which is about equal in length to the corresponding body
diameter. The reflexed ovary reaches about halfway back to the vulva,
and contains about half a dozen or more ova arranged somewhat irregu-
larly. The eggs appear in the uterus one at a time. They are smooth, some-
what thin-shelled, and are about twice as long as the body is wide, and about
one-third as wide as long. They appear to be deposited before segmentation
begins. Specimens with one ovary, and those with two, appear to be about
equally numerous ; as no other difference has been detected, they are in-
cluded for the present under the same name and description. The renette
cell is an elongated cell located a short distance behind the base of the neck.
It is fully as long as the body is wide, and about one-fourth as wide as the
body. The excretory pore appears to be located opposite the nerve-ring.
The nerve-ring surrounds the oesophagus somewhat squarely.
Habitat: Maple River, Michigan. Sublimate to balsam.
TRIPYLA, Bastian, 1865.
Fig. 7, Plate III.
49,
--,.,, LI 6.8 19.6 '54' 83.5
7. Tnpyla lata, n.sp. 2.4 mm.
2.3 3-1 3-5 4- 3-2
The thick layers of the transparent, colorless, naked cuticle are apparently
traversed by about 250 transverse striae, which are not further re-
FREE-LIVING FRESH-WATER NF.MATODES 49
solvable. In the lumen of the pharynx at a point removed from the
anterior extremity a distance a little greater than the radius of the
head, there is a minute inward-pointing dorsal tooth, having a length
about equal to the width of one of the annules of the cuticle. This
and other matters prove that the pharynx, although not readily dis-
tinguished, extends backward a distance about equal to the width of
the head. In some specimens it is possible to see a distinct transverse
fold in the lining of the oesophageal tube. This is located at a dis-
tance from the anterior extremity about equal to the corresponding
diameter of the head, and undoubtedly indicates the posterior lim-
its of the pharynx. It is possible that the tooth just mentioned may be con-
nected with internal glandular structures in the oesophagus, as the interior
of the dorsal segment of the oesophagus at this point is usually more or
less different in structure from the other portions and does not seem to be
made up entirely of muscular fibers. The oesophagus is separated from the
intestine by a flattish, pseudo-bulb. The bulb is separated from the oesopha-
gus on one side and the intestine on the other by deep and distinct constric-
tions. In the anterior constriction there are at least two granular, elongated
cells of considerable size. The nerve-ring surrounds the oesophagus rather
squarely. Nothing definite is known concerning the renette or the excretory
pore. From the inconspicuous vulva, the vagina leads inward at right
angles to the ventral surface fully half way across the body, where it joins
the two symmetrically-placed uteri. The reflexed ovaries reach about half
way back to the vulva, and contain a dozen to twenty developing ova ar-
ranged somewhat irregularly. Both in front of and behind the vulva there
are unicellular glands, having a diameter about one-sixth as great as that
of the body.
50
.7 6.8 19.3 -M- 82.8
2.4 mm.
2.1 3.2 3.9 4.8 4.1
The tail of the male is like that of the female except that the anus
is slightly raised. In front of the anus there is a ventral row of about
twenty innervated supplementary organs, reaching to near the head.
The distance between two consecutive organs is about equal to the ra-
dius of the body. Each of these appears to consist of a nerve-ending
which penetrates the cuticle and forms a papilla, around which there is
an almost imperceptible elevation having a width about equal to two of
the annules of the cuticle. The visibility of this small organ is quite as
much due to the alteration in the body wall and subcuticle as to that in
the cuticle. There are no supplementary setae or papillae either in
front of the anus or behind it. The two equal, slightly arcuate, uni-
formly tapering, acute spicula are about one and one-fourth times as
long as the anal body diameter. Their proximal ends are not cephal-
ated, though the wall of the cuticle is very slightly thickened at that
point. The spicula taper regularly from the proximal ends to the rather
50 NORTH AMERICAN
truncated points. There are obscure accessory pieces lying close to the
surface of the spicula and forming a double groove in which these lat-
ter slide. The ejaculatory duct, though narrow at first, soon becomes
nearly half as wide as the body. There are two slender, outstretched
testicles extending in opposite directions from near the middle of the
body. The anterior one has its blind end about as far behind the base
of the neck as the nerve-ring is in front of it.
Habitat : Alpine lakes, Bald Mountain, Colorado. Formalin to glycerine.
TERATOCEPHALUS, de Man, 1876.
Fig. 8, Plate IV.
ii
8. Teratocephalus cornutus, n.sp. : : '- : .8 mm.
i.i i.o 1.8 1.9 i.i
The thin, transparent layers of the colorless naked cuticle are traversed
by about 1500 transverse striae, resolvable into rows of minute dots, which
are modified on the lateral fields. These modifications have been seen in
all parts of the body, and near the tail consist of two to three irregular
longitudinal rows of enlarged dots. The posterior portion of the neck ta-
pers but little. The anterior portion becomes convex-conoid toward the head,
which bears a lip region more or less set off by a constriction opposite the
base of the spreading cephalic setae, which are four in number and
submedian in position. Each seta is a little more than half as long as the
head. These are connected with a refractive six-ribbed chitinous dome-like
framework, which extends back to opposite the middle of the pharynx. The
ribs start at the lip region, extend backward, and then join each other oppo-
site the base of the vestibule. The chitinous refractive elements at this latter
region form a rather distinctly crenate contour around the head. No
other setae than the cephalic setae have been seen in any part of the body.
The lips appear to be rather thin, and are arched together over the
unarmed pharynx, which is somewhat elongated and about half as wide
as the base of the head. While it is somewhat irregular in form it
is approximately prismoidal or cylindroid and nearly as deep as the
head is wide. Its walls are not very strongly chitinized, but more
strongly so anteriorly than posteriorly. The oesophagus receives the
base of the pharynx, and soon becomes half as wide as the base
of the head. In the anterior portion of the oesophagus, a short distance ,
behind the pharynx are three slightly arcuate, refractive elements, corre-
sponding somewhat in curvature with the contour of the front end
of the oesophagus. These resemble to a certain extent the refractive ele-
ments in the posterior chamber of the pharynx of Plectus. In the present
species they are about as long as the pharynx, and are separated a dis-
tance about equal to one body width. They are a little wider and more
plainly visible anteriorly than posteriorly. The obscure amphids, as
FREE-LIVING FRESH-WATER NEMATODES 51
far behind the base of the pharynx as this latter is behind the anterior
extremity, are one third as wide as the corresponding part of the head,
and consist of obscure spirals of one wind. There are no eye-spots.
The oesophagus begins as a tube about half as wide as the correspond-
ing portion of the head, but expands very slightly as it passes back-
ward, so that at the middle it is about two-thirds as wide as the
middle of the neck. Behind this point it diminishes. There is a
break in the musculature somewhat similar to that occurring in Cephalobus.
At the break, which occurs at the beginning of the fourth fifth, the
oesophagus is somewhat narrow, about half as wide as the corre-
sponding portion of the neck. It finally expands to form the ellipsoidal
cardiac bulb, which has a relatively large, chitinous, striated, complicated,
three-fold valvular apparatus half as wide as itself. There is a truncate-
conoid cardia about one-third as wide as the base of the neck. The lining
of the oesophagus is a fairly distinct feature. The thick-walled intestine,
which is separated from the oesophagus by a constriction, soon becomes two-
thirds as wide as the body. It is composed of cells of such a size that four
are required to build a circumference. The walls of these cells are refrac-
tive, so that the cells are readily distinguished from each other, though there
is no distinct tessellation. These cells contain minute very uniform granules.
The lining of the intestine is refractive, so that the lumen is distinctly to be
seen. From the rather inconspicuous anus the rectum, which is about as
long as the anal body diameter, extends inward and forward. The internal
sexual organs are double and symmetrically reflexed. The tail is conoid
from the anus to the subacute terminus. This species is related to those
described by Dr. de Man under the name of Teratocephalus. It is doubtful
whether these forms will not have to be subdivided at some future time,
after the accumulation of the necessary data.
Habitat: Maple River, Michigan. Sublimate to balsam.
ALAIMUS, de Man, 1880.
Fig. 9, Plate IV.
.2 ii. 19- 35- 92.
9. Alaimus simplex, n.sp.
.3 .8 .9 i.i -6
The thin, transparent layers of the colorless, naked cuticle would ordi-
narily be described as destitute of striations. Very minute striations may
be observed in the subcuticle at the extremities, when the specimens are ex-
amined under favorable conditions with the highest powers. There are
obscure traces of lateral wings. The conoid neck ends in a rounded head
not set off in any way. There are no distinct lips, and only the faintest
possible indications of labial papillae. These are so obscure that it has been
found impossible to enumerate them. There is no pharynx and the mouth
opening is exceedingly minute. No amphids or eye-spots have been seen.
52 NORTH AMERICAN
The oesophagus begins at the lip region as a tube two-thirds as wide as the
head, and expands gradually and rather regularly to the end, where it has
a diameter three-fourths as great as that of the neck. A short distance be-
hind the head end, a distance six times as great as the diameter of the head,
there is a slight alteration in the structure of the oesophagus the significance
of which remains doubtful. The lining of the oesohpagus is not a very dis-
tinct feature. There is a very obscure, small cardia. The intestine, which
is separated from the oesophagus by a constriction, becomes at once about
two-thirds to three-fourths as wide as the body. At first its cells contain
but few scattered granules, but soon they are characterized by the presence
in them of loosely scattered yellowish-brown granules of variable size, the
largest of which have a diameter nearly one-eighth as great as that of the
body itself, and the smallest of which are very much smaller. These are
not arranged so as to give rise to any distinct tessellation. Toward the end
of the intestine the granules again become less abundant and smaller, so
that for some distance in front of the rectum there is only here and there
a granule. From the depressed and conspicuous anus the chitinized rec-
tum, which is a little longer than the anal body diameter, extends inward
and forward. There is no distinct pre-rectum. The tail end begins to taper
from a long distance in front of the anus, but tapers very gradually to
behind the anus. Thence onward it is inclined to be arcuate and tapers
regularly to near the terminus. Near the end it tapers more rapidly than
elsewhere, and finally comes to an almost acute point at the terminus. A
short distance in front of the terminus, however, the diameter is about half
as great as it is at the anus. There does not appear to be any spinneret, and
therefore, of course, caudal glands are absent. The lateral fields appear to
be about one-third as wide as the body. Nothing is known concerning the
excretory pore. From the slightly elevated vulva the vagina leads inward
nearly at right angles to the surface more than halfway across the body,
where it joins the single uterus, which extends backward. The ovary is
reflexed, and the blind end is about halfway back to the vulva. The eggs
occur in the uterus one or two at a time, and are very much elongated. They
are about six times as long as the body is wide, and about one-eighth as wide
as long, and are covered by a distinct, smooth shell. They are apparently
deposited before segmentation begins. The spermatozoa appear to be elon-
gated-ellipsoidal, and a little more pointed at one end than at the other. They
have a length one-fifth that of the body diameter.
68
2 . 3 mm.
3 -6 .7 .9 .7
The tail of the male is like that of the female in form and size, but
the anus is somewhat elevated. In front of the anus there appears to be a
ventral row of very obscure, broad, flattish supplementary organs. Perhaps
these ought to be described as locations of nerve endings rather than
as distinct organs. Their number remains doubtful, but there are about
FREE-LIVING FRESH-WATER NEMATODES 53
three or four occupying a distance equal to half the length of the tail.
The two equal, straight spicula are rather obscure. Their length is no
greater than the length of the anal body diameter. Oblique copulatory
muscles are seen in the vicinity of the spicula, and there is a refrac-
tive element passing backward from the accessory piece toward the
ventral side of the tail near the anus, which may be muscular, or
possibly chitinous and serving for the attachment of muscles. The
ejaculatory duct is about one-third as wide as the body, the vas def-
erens somewhat wider. Whether there are two testes or only one has
not been determined. There is a broad, rounded, blunt end of a
testis located as far behind the base of the neck as this latter is behind
the anterior extremity.
Habitat: Big Lake, Fla. Bouin solution to glycerine.
PLECTUS, Bastian, 1865.
Fig. 10, Plate IV.
35
2. 10.7 IQ. '49' 92.6
10. Plectus tubifer, n.sp. .74 mm.
2.1 34 3-5 3-2 2.3
The skin is of medium thickness, colorless, and traversed transversely
by fine, plain striae. The striae are of such a size that about twenty of them
occupy a space equivalent to the body diameter. There are no hairs on* the
surface of the body, but throughout the length of the body, more particularly
on the submedian lines, may be seen very faint markings in the cuticle, which
indicate the location of four rows of pores connecting with interior organs.
Immediately behind the lateral organs one sees the first of the series of pores
located in the lateral line. This first pore, though much smaller than the
lateral organs, is yet somewhat larger than the succeeding ones, which grad-
ually spread out to form two submedian rows. The total number of these
pores on one side (of the male) is about one hundred; that is, there are about
two hundred in all. The six low, rounded lips are rather massive, and are
arched together over the pharynx. These lips appear to be armed with
chitinous processes on the inner surface, these processes surrounding a short
napiform vestibule leading to the pharynx proper. If any labial papillae are
present they are exceedingly minute ; what appear to be traces of papillae
may occasionally be seen. The lateral organs are well forward, being lo-
cated only slightly behind the cephalic setae. They present transversely
elongated contour markings open on the posterior margin. The lateral fields
appear to attain a considerable width and two chitinous, lateral markings
close together with a third between them, appear to indicate the existence of
a wing on each side of the body.
54 NORTH AMERICAN
54
1.9 10.1 19.2 '-M 91.5
79 mm
2. 3-1 34 3-6 3-3
2.4 10. 19.5 '-M 93.
3-2 3-3
possessed four supplementary organs, the additional one being some little
distance in front of the others, which were arranged as illustrated.
Sometimes there are only two of these organs, one smaller than the other.
The cuticle of the ventral surface is slightly thickened and elevated where
it is pierced by these tubular organs, which appear in some instances to be
slightly exserted. Apart from these preanal supplementary organs, there
are ventrally submedian papillae on the tail ; one pair near the middle, an-
other pair half way between these and the anus, and a third pair part way
from that first mentioned to the terminus. There is a fourth pair indistinctly
to be seen just behind the anus; these are closer together than the members
of the other pairs. Furthermore there are one or two very small pairs near
the terminus, but perhaps these may partake more of the nature of hairs
than of papillae. Just in front of the anus there is a single ventral almost
setose papilla. There occur in front of the anus at least two pairs of ven-
trally submedian papillae. These are located one just in front of the pos-
terior supplementary organ and the other just behind it. Most of these
features are not easy to decipher, very careful observation being necessary to
enumerate the papillae as above. There are two testicles, one anterior to
the other, the anterior being outstretched and extending forward, the pos-
terior being reflexed near its middle, so that its blind end lies somewhere
near the junction of the two. The anterior one of this pair is connected
with the seminal vesicle by a tubular portion, which lies alongside the re-
flexed posterior member.
Habitat: Arlington, Va. Flemming solution to glycerine.
DORYLAIMUS, Dujardin, 1845.
Fig. 12, Plate V.
43
11. Dorylaimus fecundus, n.sp. : '- 3.4 mm.
.5 i.i 1.6 1.9 1.2
The thin layers of the transparent, colorless, naked cuticle are traversed
by exceedingly fine, plain, transverse striations resolvable with the highest
powers of the microscope under favorable conditions. Longitudinal striations
are visible throughout the length of the body. The presence of amphids is
indicated by a transverse marking immediately behind the lip region, and
somewhat in front of the guiding ring of the spear. The anterior contour
of each organ is a transverse line about three-fifths as long as the corre-
sponding portion of the head is wide. Extending backward from this are
lateral contours which approach each other slightly and end indefinitely. The
FREE-LIVING FRESH-WATER NEMATODES 55
oesophagus begins as a tube about half as wide as the corresponding portion
of the neck, and continues to have this diameter until near the middle of
the neck, where it first begins to expand. A little behind the middle of the
neck it expands rather suddenly, so that the remainder of the organ is about
two-thirds as wide as the base of the neck. There is a much elongated
conoid cardia nearly as long as the body is wide. The intestine, which be-
comes at once three-fourths as wide as the body, is separated from the
oesophagus by a distinct though slight constriction. The cells forming the
intestine are of such a size that about four or five are required to build a
circumference. They contain granules of variable size, the larger of which
have a diameter equal to the thickness of the outer transparent cuticle, and
the smaller a diameter only about one-fourth as great as that of the larger.
These granules are so arranged as to give rise to a very obscure tesselation.
The pre-rectum is about three to four times as long as the corresponding
body diameter, and is separated from the intestine by a difference in struc-
ture, the granules contained in its cells being smaller, and not darkening un-
der the influence of osmic acid, as do those of the intestine. Nothing is
known concerning the salivary glands or the renette. The longitudinal fields
are well developed, being about half as wide as the body. The nerve-ring
surrounds the oesophagus somewhat obliquely. Each of the two elongated
uteri may contain three to five eggs at a time. These, as they appear in the
uteri, are elongated, finely granular, rather thin-shelled, and about one and
one-half times as long as the body is wide, and about half as wide as long.
The shells are flexible, so that owing to the pressure of one egg on another
in the uterus the surfaces are often indented.
3-5 mm.
.6 1.2 1.4 1.4 1.4
In addition to the ventral row of supplementary male organs shown in
the illustration, there are two rows of ventrally submedian, innervated papil-
lae, arranged in a somewhat equidistant manner. Where these reach the
surface of the body they give rise to almost imperceptible elevations which,
however, are of a different character from those at the ends of the ventral
organ shown in p, Fig. 12. In other words, these papillae are more nearly the
homologues of the ordinary tactile hairs or papillae so common on the sur-
face of nematode worms. These submedian papillae are located at a
distance from each other equal to about two-thirds the body diameter.
They are very nearly coextensive with the oblique copulatory muscles.
Habitat: Algae, Potomac River, Washington, D. C, 1911. Flem-
ming solution to glycerine.
56 NORTH AMERICAN
IRONUS, Bastian, 1865.
Fig. 13, Plate V.
30
12. Ironus americanus, n.sp. : : 2.3 mm.
1.6 2.3 2.7 2.9 1.3
The moderately thin layers of the transparent, colorless, naked cuticle
appear to be destitute of striations. There are three somewhat conoid lips,
which when open, give to the head a somewhat truncated appearance, when
folded a somewhat rounded appearance. Each lip bears internally a slightly
arcuate, conical tooth, whose altitude is somewhat greater than the width
of its base. When the mouth is so opened that the apices of these refractive
teeth are about on a level with the anterior extremity their bases lie a little
in front of the bases of the cephalic setae. The apices of these teeth are
slightly blunt and they have a slight outward curvature. The walls of the
pharynx are strongly refractive, and have about the same thickness as the
walls of the cuticle. The chitin of the walls of the pharynx, however, is
more refractive than that of the cuticle. In this respect it resembles the
chitin of which the teeth are composed. Except for the teeth at the mouth
opening the pharynx is unarmed, but presents on the dorsal side about half
way between the head and its posterior extremity three or four exceedingly
minute projections with corresponding depressions. The oesophagus begins
near the base of the pharynx, at least it is at this point that the radial struc-
ture becomes pronounced. At first it is about two-thirds as wide as the cor-
responding portion of the neck. It enlarges a little and very gradually, so that
finally it is about half as wide as the base of the neck. The lining of the
oesophagus is an exceedingly distinct feature throughout its length. It gen-
erally has the appearance of three refractive lines occupying a space nearly
one-fourth as wide as the oesophagus itself. There is a large cylindroid
or hemispherical cardia, one-third as wide as the base of the neck. The in-
testine, which is separated from the oesophagus by a deep, narrow and dis-
tinct constriction, becomes at once about three-fifths as wide as the body.
Its cells contain scattered granules of variable size, the largest of which have
a diameter nearly equal to the width of the refractive portion of the lining of
the oesophagus, and the smallest of which have a diameter not more than
one-tenth as great. The body wall is thick, generally occupying about three-
fifths of the diameter of the body. The lateral fields are a little more than
one-third as wide as the body. Nothing is known concerning the renette
or the excretory pore. There is no spinneret. The tail, nevertheless, con-
tains small cells near the anus which bear a certain resemblance to the ordi-
nary caudal glands. From the slightly elevated vulva, the vagina leads in-
ward at right angles to the ventral surface half way across the body where
it joins the two symmetrically-placed uteri. The reflexed ovaries reach
three-fourths the distance back to the vulva, at least in specimens which do
not contain eggs. The ovaries contain about a dozen ova arranged for the
FREE-LIVING FRESH-WATER NEMATODES 57
most part single file. Nothing very definite is known concerning the form
and size of the eggs, but from the size of the apparently matured ova it is
assumed that the eggs are considerably elongated, perhaps two to two and
one-half times as long as the body is wide, and if so, it is unlikely that
more than one is contained in the uterus at a time.
Habitat: Deer Bottom, Pikes Peak region, Colorado. Formalin to
glycerine.
ONCHOLAIMUS, Dujardin, 1845.
Fig. 14, Plate V.
13. Oncholaimus punctatus, n.sp.
The rather thin., transparent, colorless layers of the naked cuticle appear
to be destitute of striations. It is rather difficult to observe the cuticle on
account of the presence in it of numerous dot-like elements, which near the
head are arranged in longitudinal groups, of which the widest is the lateral
group. The longitudinal arrangement of the granules, is continuous through-
out the body, but it is most marked on the lateral fields where there is a
definite band of them, having a width about two-fifths as great as the width
of the body. Each margin of this band is made up of a distinct longitudinal
row of granules arranged single file. The neck is slightly conoid, becoming
slightly convex-conoid toward the rounded head, which is not set off in any
way, or at most by an exceedingly obscure, broad constriction opposite the
pharynx. The six lips are distinct and well developed and have a distinct,
somewhat chitinous framework. They are arched together over the pharynx
in such a way as to produce a dome-like effect, the very thin and movable
flaps at the ends of the lips meeting together at the middle of the front of
the head. Opposite the middle of the amphids there is a transverse marking
or line which extends around the middle of the head. It is characterized by
staining somewhat more strongly with carmine than the other portions of
the cuticle. There are no eye-spots. The oesophagus begins at the base of
the pharynx with a diameter three-fourths as great as that of the base of the
head, and it continues to have this diameter until some distance behind the
nerve-ring. It then begins to expand gradually, so that finally it is about
three-fourths to four-fifths as wide as the base of the neck. The lining is a
distinct feature throughout the length of the oesophagus. There is a dis-
tinct conoid cardia, whose base is about half as wide as the corresponding
portion of the body. The intestine, which is separated from the oesophagus
by a deep and distinct constriction, appears to have rather thin walls and to
be composed of cells of such a size that probably six or more would be re-
quired to build a circumference. These cells contain numerous granules of
rather uniform size.
The lateral fields are about two-fifths as wide as the body. The loca-
tion of the ventral gland has not been made out. The excretory pore is lo-
58 NORTH AMERICAN
cated just behind the base of the pharynx. The duct which leads to it seems
to be destitute of an ampulla.
40
1.9 10.2 21.4 -M- 92.
_ - 2.1 mm.
1.2 2.2 2.8 2.5 1.8
In front of the anus there is a series of about fifty pairs of oblique
copulatory muscles, whose presence is indicated by the oblique groups of
granules in the cuticle. The ejaculatory duct is about one-third as wide as
the body. The blind end of the anterior testicle is about twice as far behind
the base of the neck as this latter is behind the anterior extremity.
Habitat : Fresh water ponds, Cape Breton Island, Dominion of Canada.
Sublimate to balsam.
DOLICHODORUS, n.g.
Fig. 16, Plate VI.
58
14. Dolichodorus heterocephalus, n.sp.' 3 (34) 7 '* 9 '* ' 52 ' 97 ' 2 3. mm.
.6 (i.i) 1.6 1.7 2.1 1.2
The thin layers of the transparent, naked, colorless cuticle are traversed
by transverse striae resolvable with high powers under favorable conditions
into rows of exceedingly minute, somewhat irregular elements. This reso-
lution is not at all difficult in specimens which are moulting. Under these
conditions scales of the outer cuticle sometimes survive, readily resolvable
into refractive transverse markings between which are the small elements
mentioned. Ordinarily at first glance, the cuticle appears to be merely re-
solvable into transverse striae which are somewhat roughened on the edges
of the dividing lines. The conoid neck ends in a head which has a very
prominent lip-region set off by a very prominent and deep constriction. The
front of the head is rounded, and the constriction separating the lip-region
from the remainder of the head is of such a nature that the contour of the
lip-region, when seen in optical longitudinal section is somewhat elliptical, so
that the lip-region has the form of an ellipsoid of rotation. The depth of
this figure is about equal to half its width. No papillae have been seen on
the lips, but minute papillae might readily be present without having been
observed. No traces of amphids have been seen. There are no eye-spots.
The vestibule is exceedingly narrow and closely surrounds the apex of the
very slender narrow spear. This latter extends nearly half-way to the an-
terior border of the median bulb and is long and slender like that of
Trichodorus. The oesophagus at the base of the spear is a tube about one-
third as wide as the corresponding portion of the neck, and continues to have
this diameter until it expands suddenly to form the elongated median bulb,
which is three-fourths as wide as the corresponding portion of the neck and
fully twice as long as wide and is armed internally with a conspicuous, ellip-
soidal, rather simple valvular apparatus nearly half as wide as itself. When
FREE-LIVING FRESH-WATER NEMATODES 59
seen in optical longitudinal section the bulb is a little wider posteriorly than
anteriorly, so that its sides are not parallel, but approach each other a trifle
as they pass forward. The bulb ends more abruptly posteriorly than an-
teriorly, and is continued by a narrow section of the oesophagus only one-
eighth as wide as the corresponding portion of the neck and about as long
as the corresponding portion of the neck is wide. This is succeeded by a
broadly clavate swelling which does not have any distinct chitinous lining,
and is of granular structure, rather than muscular. This swelling is about
two-thirds as wide as the base of the neck. The lining of the oesophagus
is a fairly distinct feature in all parts in front of the posterior swelling.
The intestine joins the middle of the rounded surface of the posterior oeso-
phageal swelling and is at this point only one-tenth to one-eighth as wide
as the corresponding portion of the body, but soon expands to be two-fifths
as wide as the body. It is, therefore, relatively narrow. On the other hand,
the body walls are correspondingly thick. Nothing is known concerning
the renette cell. It is probable that there is an excretory pore located near
the nerve-ring.
60
.3 (2.3) 7.9 10.9 -M 99.3
2.4 mm.
.4 ( .8) 1.2 1.4 1.7 1.8
The tail of the male is conoid and extends beyond the anus a distance
hardly as great as the length of the anal body diameter. It seems likely that
the tail is also flattish. When seen dorso-ventrally it appears to be about one-
half as long as the spicula, and ends in a dentate terminus one-third as
wide as the base of the tail. The cuticle of the tail is very thick, and at
first sight seems rather closely to resemble the structure of the two bursal
flaps. The distinctly two-parted bursa springs from opposite the middle of
the spicula and extends backward and is completely furcated at a point
about opposite the base of the tail. The flaps extend backward beyond the
terminus of the tail and give to the posterior extremity somewhat the appear-
ance of ending in three thin transparent, colorless flaps, one of which is
soon seen to be the true caudal extension. The flaps of the bursa are striated
in much the same manner as the cuticle, and the margins of the flaps are
distinctly thickened. No distinct ribs have been seen in the two broad
backward pointing flaps of the bursa. The two equal, rather strongly built,
tapering spicula have a length about one and one-half times as great as that
of the diameter measured opposite their proximal ends. They are accom-
panied by a rather simple accessory piece one-half as long as themselves,
judging from its appearance when seen dorso-ventrally. The proximal ends
of the spicula can hardly be said to be cephalated, but they are obliquely
trancated and wider than elsewhere. When seen dorso-ventrally this width
appears to be one-fourth as great as that of the corresponding portion of
the body. No special setae are present and no special papillae have been
seen. The single outstretched testicle extends forward and has its blind
end located about three to four times as far behind the base of the neck
60 NORTH AMERICAN
as this latter is behind the anterior extremity. Near its blind end its diam-
eter is about one-half as great as that of the body. The spermatozoa art
small and numerous and it appears that the reduction divisions take place in
a short segment of the testis not far from the blind end.
Habitat: Freshwater, Douglas Lake, Michigan. Silver Spring, Florida.
Female, Flemming solution to glycerine; from Florida. Male, from Michi-
gan, sublimate to balsam.
CYATHOLAIMUS, Bastian, 1865.
Fig. 17, Plate VI.
26.
15. Cyatholaimus truncatus, n.sp. : : 1.6 mm.
1.8 2. 2.1 3.3 2.1
The moderately thick layers of the transparent, colorless, naked cuticle
are traversed by about fifteen hundred transverse striae, resolvable into
transverse rows of distinct dots, which are not very materially modified in
the lateral fields. The slightly conoid neck ends in a truncated head, whose
lip region is set off by an almost imperceptible expansion. The cuticle be-
comes somewhat thicker toward the head, and the dotlike markings more
distinct and refractive. Beginning near the head and ending near the spin-
neret there are circular markings arranged in somewhat irregular rows
along the lateral fields. The longitudinal distance between these markings
near the middle of the body is a little greater than the radius of the body,
and the diameter of the circles is somewhat greater than the width of one
of the annules, sometimes twice as great. These markings are not all of the
same size, some being nearly twice as large as others.* The lip region is
twelve-parted, and there are twelve longitudinal chitinous structures sur-
rounding the vestibule. These no doubt indicate the infolding of the lips
when closed. Probably the best conception of the lip region is expressed by
saying that there are six lips, each two-parted, but that the divisions are all
very similar to each other. On the front of the lips there are six forward
pointing innervated papillae arranged in the usual position. Along the outer
margin of the head there are ten acute, tapering, cephalic setae, two lateral,
and four submedian pairs. The longest of these setae are about equal to
the radius of the head. According to the position of the lips these setae
vary in attitude. They may be folded together on the front of the head so
as to be in the position of the spokes of a wheel, but they may point
forward when the mouth is partly open, and are in a somewhat spreading
position when the mouth is wide open. The pharynx is on the whole con-
oid, and about three-fourths as deep as the head is wide. Springing from a
little behind its middle is a strong, conical, acute, forward pointing dorsal
tooth, the ventral contour of which lies approximately in the axis of the
*The two most pronounced rows are nearly opposite the edges of the lateral fields,
but there is an irregular median row.
FREE-LIVING FRESH-WATER NEMATODES 6l
head. Surrounding the pharynx the muscles are somewhat more powerful
than in the oesophagus immediately behind, so that there is a very faint
pharyngeal bulb. The oesophagus is at first about two-thirds as wide as
the corresponding portion of the neck, but gradually enlarges after passing
through the nerve-ring, so that finally it is two-thirds as wide as the base
of the neck. The lining of the oesophagus is a distinct feature throughout
its length. There is no very distinct cardia. There are no eye-spots. The
amphids, which are about one-third as wide as the head, are spirals of about
two and one-half winds, and are placed opposite the apex of the dorsal
tooth. The intestine, which is separated from the oesophagus by a distinct
constriction, is at first one-half to two-thirds as wide as the body, but in the
greater part of its length is about two-thirds as wide as the body. It is
thick walled, and is composed of cells of such a size that comparatively few
are required to build a circumference, probably about six. The cells con-
tain rather numerous, conspicuous, brownish granules of variable size, the
largest of which have a diameter about equal to double the width of one
of the annules of the cuticle, the smallest of which are very much smaller.
These granules are arranged irregularly, and can hardly be said to suggest
any tessellation. From the broad, raised anus the rectum, which is refractive
and nearly as long as the anal body diameter, extends inward and forward.
The tail is conoid to the subacute conoid spinneret, which has a diameter
about one-eighth to one-tenth as great as that of the base of the tail. There
do not appear to be any caudal setae. The lateral fields appear to be fully
one-third as wide as the body. The nerve-ring surrounds the oesophagus
somewhat obliquely. The excretory pore appears to be situated at a distance
from the anterior extremity about two and one-half times as great as the
width of the head. The renette cell appears to be small and located some
distance behind the base of the neck. From the elevated vulva the vagina
leads inward at right angles to the ventral surface about half way across
the body, where it joins the two-parted uterus. The reflexed, tapering
ovaries reach about two-thirds the way back to the vulva, and contain a
dozen or more developing ova arranged somewhat irregularly, especially
toward the blind end. The rather thin shelled ovate to ellipsoidal eggs are
a little longer than the body is wide, and about two-thirds as wide as long.
They have been seen to occur in each uterus one at a time, and are appar-
ently deposited before segmentation begins.
59-
1.7 6.6 15. -M 91.
_ I 1.6 mm.
1.6 2.2 2.3 2.3 2.6
The tail of the male is like that of the female in form and size, but the
anus is more prominently elevated. There is a row of four small pre-anal,
ventral, tubular, protrudable supplementary organs. The final one of these
is opposite the middle of the spicula ; the penultimate nearly opposite the
proximal ends of the spicula. The foremost is about three times as far
from the anus as the penultimate. From this it will be seen that the organs
62 NORTH AMERICAN
are slightly more nearly approximated to each other posteriorly. These
organs are not conspicuous features, and scarcely disturb the ventral con-
tour. It is possible that each is connected with a unicellular glandular struc-
ture nearby. The two equal, tapering, somewhat arcuate spicula are one and
one-third times as long as the anal body diameter. Their proximal ends
are cephalated by expansion. The accessory pieces alongside are four-fifths
as long as the spicula, and somewhat broader than the spicula. In their
widest part they are one-sixth as wide as the corresponding portion of the
body. They are of rather uniform width throughout. There is a slight
constriction near each end, and the distal extremity appears to be very
minutely dentate. The spicula are about half as wide as the accessory pieces.
The ejaculatory duct is two-thirds as wide as the corresponding portion of
the body, as is also the testis. The blind end is as far behind the base of
the neck as this latter is behind the anterior extremity.
Habitat: Silver Springs, Fla. Flemming solution to glycerine.
ETHMOLAIMUS, de Man, 1880.
Fig. 19, Plate VII.
27
16. Ethmolaimus americanus, n.sp. '- - : .6 mm.
2.4 3.4 3.9 5.6 2.1
The thin, transparent layers of the practically naked cuticle are tra-
versed by very fine transverse striae, resolvable with high powers into rows
of closely set dots, which are not modified on the lateral fields. Near the
head the dots are a little coarser than elsewhere on the anterior portion of
the body. On the tail the dots are much farther apart and, though really
arranged in transverse rows, at first glance appear to be scattered irreg-
ularly. The conoid neck ends in a somewhat truncated head, which bears
on its outer margin a circlet of four slender, spreading submedian cephalic
setae, each about half as long as the head is wide. There appear to be
twelve minute papillae in the lip region, which when folded together forms
a rather small, cyathiform cavity, in the midst of which stands the thumb-
shaped, forward-pointing dorsal tooth. This tooth is attached to a dis-
tinctly thickened rib of chitin, which extends from the lip region back to the
base of the pharynx, and is thicker anteriorly than it is posteriorly. This
thickened dorsal rib causes the pharynx to appear somewhat more strongly
built on the dorsal side than on the ventral side. The tooth tapers slightly
to a blunt point, and has a length about one-fourth as great as the width of
the front of the head. Behind it the pharynx is somewhat prismoid and
approximately one-fifth as wide as the head. It ends abruptly at the base.
The pharynx is surrounded by a pharyngeal bulb, the musculature of which
is set off distinctly from that of the oesophagus, in addition to which there is
a constriction between the bulb and the oesophagus. The somewhat obscure,
slender, apparently spiral amphids consist of about one and one-half winds.
They are located opposite the posterior portion of the pharynx, and are one-
FREE-LIVING FRESH-WATER NEMATODES 63
third as wide as the corresponding portion of the head. There are no eye-
spots. The oesophagus begins as a tube three-fifths as wide as the base of the
head, and it continues to have this diameter until it expands rather sud-
denly to form a somewhat ellipsoidal or obscurely pyriform cardiac bulb,
which is four-fifths as wide as the base of the neck, and contains an obscure,
elongated, relatively narrow valvular apparatus. The lining of the oeso-
phagus is a distinct feature throughout its length. There is no very dis-
tinct cardia, but the preliminary cells of the intestine are different from those
which immediately follow. The rather thick-walled intestine is separated
from the oesophagus by a deep and distinct constriction, and becomes at
once about half as wide as the body. Thereafter it widens out gradually so
as to become three-fourths as wide as the body. It is composed of cells of
such a size that probably about six to eight are required to build a circum-
ference. The cells contain granules of variable size, the largest of which have
a diameter half as great as that o'f the terminus of the tail. From the rather
inconspicuous but slightly depressed anus the rectum, which is about as
long as the anal body diameter, extends inward and forward. The body be-
gins to taper slightly from some distance in front of the anus, but tapers
more rapidly behind the anus in such fashion that at the beginning of the
posterior fifth the diameter is about one-sixth as great as at the anus ; thence
onward the tail is cylindroid, and ends in a tubular spinneret, less than half
as wide as the terminus. The spinneret tapers slightly to a blunt point, and
is armed at its base with one or more setae as long as itself. The caudal
glands appear to be located in the base of the tail. The lateral fields are
well-developed and fully one-third as wide as the body. The renette cell
appears to be located a short distance behind the cardiac bulb. The position
of the excretory pore is unknown, possibly it is at the base of the lips.
The nerve-ring surrounds the oesophagus somewhat obliquely. From the
elevated, rather broad vulva the vagina leads inward at right angles to the
ventral surface fully half way across the body, where it joins the sym-
metrically-placed uteri. The reflexed ovaries reach as far back as the vulva,
at least in specimens in which the uteri contain no eggs. The fully de-
veloped ova are nearly twice as long as the body is wide and about one-
third as wide as long. The form, size and number of the eggs remains un-
determined, but it seems probable that they occur in the uteri one at a time.
Habitat: Spring, Washington Country Club, Ctu.y Chase, Md.
Sublimate to balsam.
MONHYSTERA, Bastian, 1865.
Fig. 20, Plate VII.
62.
.6 8.7 22. -72. 88.
17. Monhystera sentiens, n.sp. i.o mm.
1.0 3- 1 4-3 4-8 3-1
The thin, transparent layers of the colorless cuticle are traversed by
about eight hundred transverse striae, resolvable with difficulty into rows of
64 NORTH AMERICAN
somewhat dotlike elements. These striae are more readily visible toward
the extremities, especially the posterior extremity. The conoid neck becomes
convex-conoid toward the head, which is somewhat rounded. Throughout
the body there are rather numerous, long, slender somatic setae having a
length equal to the radius of the body. These setae are a little longer toward
the extremities than they are near the middle of the body. On the outer
margin of the head, a trifle in front of the base of the pharynx, there are
ten spreading, tapering cephalic setae, one on each lateral line, and two of
somewhat unequal size on each submedian line. The longest of these setae
are more than half as long as the head is wide. A little more than twice as
far back as the amphids there is a rather definite circlet of cervical or sub-
cephalic setae arranged in submedian positions. The lips appear to be three
in number, and are longitudinally striated or fluted. The thin flap-like, stri-
ated portions are capable of assuming a revolute position. The basal por-
tion of the lip region is considerably thicker than the flaps, and is arched
over the margin of the pharynx. This latter is wide and shallow. Just
beneath the lips it is two-thirds as wide as the front of the head. It closes
together rapidly, so that its base is located at a distance from the anterior
extremity about equal to the radius of the head. In other words, the pos-
terior portion of the pharynx is about half way back to the amphids. These
latter are circular, and one-third to one-fourth as wide as the correspond-
ing portion of the head. Their distance from the anterior extremity is about
equal to half the width of the front of the head. A short distance in front
of each amphid there is a granular nucleus, which closely resembles the
nerve cells that are found in the neck, and seems doubtless to be the nucleus
of the nerve cell which is connected in some way with the function of the
amphids. The oesophagus reaches to the base of the lips, and into it is set
the posterior portion of the pharynx. At first the oesophagus is only two-
thirds as wide as the base of the head. It continues to have this diameter, or
a little more, until after it passes through the nerve-ring. Thence onward it
gradually increases so that finally it is about two-thirds as wide as the base
of the neck. The lining of the oesophagus is a fairly distinct feature. The
intestine, which is separated from the oesophagus by a distinct constriction,
is composed of cells of such a size that probably six to eight are required to
build a circumference. The anterior portion of the intestine is somewhat
bulbous in form, and is separated from the oesophagus on the one side and
the true intestine on the other, by a pair of constrictions. This portion may
be looked upon as a strongly developed cardia. The intestine is moderately
thick walled, and ends posteriorly in a short, wide rectum, hardly as long as
the anal body diameter. The posterior extremity of the female begins to
taper from near the vulva, and continues to taper at about the same rate
behind the tail as in front of it. The tail itself is conoid in the anterior four-
fifths, and cylindroid in the posterior fifth. The terminus is hardly swollen,
and is about one-sixth as wide as the base of the tail. The spinneret is
rounded and bears a couple of submedian setae twice as long as its own
FREE-LIVING FRESH-WATER NEMATODES 65
diameter. The three caudal glands are located in the anterior third of
the tail. The lateral fields vary in width in different parts of the body.
A little in front of the anus they are about two-fifths as wide as the corre-
sponding portion of the body, and contain rather numerous scattered nuclei
of such a size that about eight would be required to reach across the field.
Farther forward the field is narrower, about one-fourth as wide as the
middle of the body. Anteriorly it is wider, about one-third as wide as the
base of the neck. Nothing is known concerning the renette. The nerve-
ring surrounds the oesophagus somewhat obliquely a little in front of the
middle of the neck. From the elevated and rather large and conspicuous
vulva the vagina leads inward at right angles nearly half way across the
body, where it joins the single uterus, which extends forward, and is of
such a size as to contain apparently but one egg at a time. The ovary, which
at first is three-fourths as wide as the body, extends forward and tapers
gradually, so that at the blind end, considerably in front of the cardia and
a short distance behind the nerve-ring, it is one-fourth as wide as the corre-
sponding portion of the body. It sometimes happens that the blind end of
the ovary is disposed in a single coil. The rather thick shelled eggs are as
long as the body is wide, and about three-fourths as wide as long, and appear
to be deposited before segmentation begins. The small spermatozoa found in
the uterus are of such a size that at least ten placed side by side would be
required to span the diameter of one of the eggs. There is a very small,
posterior rudimentary branch to the uterus, which extends backward from
the vulva a distance about equal to two-thirds the radius of the body.
Around the vulva are four distinct, unicellular vaginal glands.
7i-
.7 9.4 22. -M- 87.
1.5 mm.
1.6 2.9 3.5 4-2 3-3
The tail of the male resembles that of the female in form and size.
As in the females, the three caudal glands are found in the anterior third
of the tail, and do not extend materially farther forward than the anus.
The two equal, L-shaped, slender, slightly tapering brownish spicula are a
little longer than the anal body diameter. The anterior three-fifths lie nearly
parallel to the body axis, while the posterior two-fifths are arranged nearly
at right angles to the body axis. The distal extremities of the spicula are
slightly widened. At their widest part, namely near the proximal ends, the
spicula are about one-eighth as wide as the corresponding portion of the
body. They are very slightly narrower distally than proximally, where they
are barely cephalated by expansion. The accessory piece is not strongly
developed. The main portion of it lies parallel to the distal two-fifths of the
spicula, and is connected with the dorsal surface of the body by means of
muscles. The ejaculatory duct is one-half as wide as the corresponding
portion of the body. There are two outstretched testes. The blind end of
the anterior testis is located a short ' distance behind the nerve-ring, while
the blind end of the posterior testis is located about as far in front of the
66 NORTH AMERICAN
anus as the terminus is behind it. The testes are broad and some parts appear
to fill up the main portion of the body cavity.
Habitat: Sand bar off Plummer's Island, Potomac River. Subli-
mate to balsam.
ONCHOLAIMELLUS, de Man, 1886.
Fig. 21, Plate VII.
53
o 85 18 -M- QI
18. Oncholaimellus heterurus, n.sp. 1.2 mm.
.8 1.5 1.8 1.8 1.4
The moderately thick layers of the transparent, naked, colorless cuticle
seem to be destitute of markings of any kind. If there are any striations
they must be exceedingly minute. The conoid neck becomes a little convex-
conoid toward the head, which is subtruncated, and has a lip region almost
imperceptibly expanded. There are ten long, curved, tapering, cephalic
setae, located a trifle in front of the middle of the pharynx, two lateral, and
eight submedian. The members of the submedian pairs are placed one in
front of the other, the hinder members being only about two-thirds as long
as the forward members. It is the forward members that are in the same
circlet with the lateral setae. These latter are about as long as the longest
submedian setae. The bases of the lips are nearly as thick as the wall of
the head, but they gradually become quite thin, though the flaps are not so
marked as they usually are in Oncholaimus. There are six lips, and each
bears on its anterior surface, near the margin of the head, a somewhat out-
ward pointing, minute, innervated papilla, which does not very markedly in-
terfere with the contour of the front of the head. The somewhat cylindroid
pharynx is about twice as long as the front of the head is wide, and the
average diameter of the cavity is a little more than one-third of its length.
At the middle the pharynx is about half as wide as the corresponding por-
tion of the head. Its walls are fairly well chitinized, and appear to be des-
titute of onchi. The description is derived from a single specimen, in which
the mouth is filled with detritus, and it is possible that very minute teeth
might have escaped observation, but this does not seem at all probable.
The bottom of the pharynx where it is set on the end of the oesophagus, is
in the shape of a broad, shallow, hollow cone. At a distance from the
anterior extremity twice as great as the length of the pharynx the amphids
are seen. These are somewhat elongated, roughly ovate in contour, and
more distinctly marked anteriorly than posteriorly. The anterior border is
a curved, chitinous structure about one-third as wide as the corresponding
portion of the head. Slightly behind the anterior border the amphid has its
greatest diameter. It is about as long as the corresponding radius of the
head, and is extended backward by an apparently tubular structure, which
soon becomes indefinite. Viewed dorso-ventrally the amphids appear like
rather deep invaginations of the cuticle, and each occupies fully half of the
FREE-LIVING FRESH-WATER NEMATODES 67
corresponding radius of the neck, and opposite them the oesophagus is a
trifle narrower than it is either in front of or behind them. The oeso-
phagus, which at first is about half as wide as the base of the head, con-
tinues to have approximately the same diameter until after it passes through
the nerve-ring, which is somewhat in front of the middle of the neck. Be-
hind the nerve-ring the oesophagus becomes somewhat wider, and is finally
about two-thirds as wide as the base of the neck. The lining of the oeso-
phagus is a fairly distinct feature. The intestine, which becomes at once
nearly three-fourths as wide as the body, is set off from the oesophagus by
a distinct constriction. There does not appear to be any well developed car-
dia. The cells composing the intestine contain scattered granules, which
give rise to a very obscure tessellation, and also contain doubly refractive
granules, which, however are not spherical in form, though their diameter
in different directions is not very variable. The tail of the male tapers rap-
idly from the anus, so that at the end of the anterior fourth it has a
diameter but little greater than that of the terminal spinneret. Near the an-
terior end of the cylindrical part there occur a pair of subventral arcuate,
tapering setae, which are about as long as the corresponding diameter of
the tail. In front of these there is a ventrally submedian pair of papillae,
and also there is a dorsally submedian pair a little in front of these latter.
The spinneret is of a simple character, and has the terminus almost imper-
ceptibly swollen. There do not appear to be any setae on the spinneret.
A trifle in front of the proximal ends of the spicula there springs from a
ventrally submedian lines a somewhat weakly developed bursa, which extends
slightly beyond the body contour, but only does this in front of the anus.
It recedes into the cuticle at a point slightly in front of the caudal setae.
This bursa does not have any ribs and is not striated in any way. The two
equal, elongated, rather uniform, slightly cephalated spicula are a little
more than twice as long as the anal body diameter, and in their anterior
halves are nearly straight. In their posterior halves they are slightly
arcuate. At the point where they attain their greatest width they are about
one-fourth as wide as the corresponding portion of the body. Seen dorso-
ventrally they are somewhat narrower and straighter than when seen in
profile. The accessory piece appears to be compounded of a number of
small chitinous elements, the whole structure being a little less than one-
third as long as the spicula. It is not very strongly developed, and is not a
very conspicuous feature. The ejaculatory duct is about half as wide as the
corresponding portion of the body. There are two testes outstretched in
opposite directions. The blind end of the anterior testis is about as far be-
hind the base of the neck as this latter is behind the anterior extremity.
The posterior testis is smaller, but just how much smaller is unknown, as
its blind end could not be located in the single specimen examined. Little or
nothing is known concerning the lateral fields and the renette.
Habitat: Fresh water pond, near Ocala, Fla. Bouin solution to
glycerine.
68 NORTH AMERICAN
Note : There is some doubt as to whether this species should be as-
signed to the genus Oncholaimellus for the following reasons: There are
no pharyngeal teeth. The amphid varies somewhat from that of the type
species. The spicula are of equal size, whereas in the type species orie of the
spicula is only half as long as the other.
CEPHALOBUS.. Bastian, 1865.
Fig. 22, Plate VIII.
5i.
1 8 15 23 '61 04
19. Cephalobus sub-elongatus, n.sp. .6 mm.
1.6 3. 3-6 4-3 2.1
The thin, transparent, colorless layers of the naked cuticle are traversed
by about seven hundred plain, transverse striae, resolvable with high powers
without very much difficulty. The conoid neck becomes convex-conoid to-
ward the obscurely lobed head, which is rounded in front, and is set off by
an almost imperceptible, broad, exceedingly shallow constriction. There are
no cephalic setae, and no eye-spots ; no amphids have been seen. There are
three rather distinct, bluntly conoid lips, which are rounded in front, each
of which apparently has two inconspicuous innervated papillae. The open
vestibule leads to a conoid pharynx, which is about one and one-half times
as long as the lip region is wide, and tapers from front to back in a com-
paratively uniform way. Between the lips it has a width about one-third as
great as that of the lip region. The posterior half of the pharynx rests in
the anterior end of the oesophagus, which enlarges very perceptibly, so that
a little behind the base of the pharynx it is more than half as wide as the
corresponding portion of the head. It continues to have relatively much
the same width until near the middle, where it is about three-fifths as wide
as the middle of the neck. There it suddenly diminishes in size so as to be
only one-fourth to one-fifth as wide as the corresponding portion of the
neck. Passing through the nerve-ring with this narrow diameter it finally
enlarges to form an ellipsoidal cardiac bulb about two-thirds as wide as the
base of the neck, containing a rather distinct triplex but not very complex
valvular apparatus of the form usually seen in this genus. There is no very
definite cardia. The intestine, which is separated from the oesophagus by
a rather broad and shallow constriction, is at first only half as wide as the
corresponding portion of the body. It soon becomes thicker walled, and
enlarges so as to be three-fourths as wide as the corresponding portion of
the body. It is composed of cells of such a size that probably only about
two are required to build a circumference. The contents of the cells are not
distributed so as to give rise to anything distinct in the way of tessellation.
The posterior lip of the anus is very slightly elevated. From the anus the
rectum, which is somewhat longer than the anal body diameter, leads inward
and forward. The rectum is separated from the intestine by a rather dis-
tinct constriction. The tail is at first convex-conoid, the convexity existing
FREE-LIVING FRESH-WATER NEMATODES 69
almost entirely on the dorsal surface. Through the middle third the tail
tapers much more rapidly than elsewhere, so that at the beginning of the
posterior fourth it has a diameter no more than one-fifth as great as at the
anus. Thence onward it is conoid to the acute terminus. There is no spin-
neret. Very little is known concerning the lateral fields, but at the middle
of the body they appear to be one-third as wide as the corresponding portion
of the body. There do not appear to be any distinct wings. The excretory
pore is located opposite the nerve-ring. This latter surrounds the oesophagus
obliquely, and is accompanied by nerve cells, of which the greater number
are behind the nerve-ring and in front of the cardiac bulb. From the mas-
sive elevated vulva the rather strongly chitinized, slightly colored vagina
leads inward at right angles to the ventral surface nearly half way across
the body, where it joins the single uterus, which extends forward. In speci-
mens which do not yet contain fully developed eggs, and in which the uterus
is occupied by spermatozoa, the flexure in the sexual apparatus occurs about
half way between the vulva and the base of the neck. The ovary extends
straight backward, and finally tapers to a blunt end a short distance in front
of the anus. At the rear end the ovary is one-half as wide as the corre-
sponding portion of the body. The ova appear to be arranged more or less
single file in the greater part of the ovary, whose walls contain distinct
nuclei of relatively large size. These nuclei are of such a size that about
six to eight placed side by side would reach across the body, and are re-
moved from each other in a longitudinal direction a distance equal to about
two-thirds of the body diameter. None of these cells could be seen in that
portion of the sexual tube in front of the vulva, and it is surmised that the
cells composing the ovarian tube are markedly different in their character
from those composing the tube between the ovary and the uterus and those
composing the wall of the uterus. The spermatozoa have been seen packed in
the uterus somewhat like a roll of coin, though each one is thinner at the
margins than at the center where the nucleus exists. The spermatozoa are
of such a size that the uterus may contain about two dozen, arranged single
file.
Habitat : Moss, Bog. W. End of Douglas Lake, Mich. This species close-
ly resembles C. elongatus de Man, and possibly may prove to be the same. At
present, judging from a single specimen it appears to differ in the following
points: (i) The tail of the female is of different form, since that of elongatus
is nearly conical ; (2) No wings have been seen on sub-elongatus, while they
appear to be a marked feature of elongatus; (3) There is no expansion of
the lip region in elongatus as in sub-elongatus; (4) The vulva in sub-elon-
gatus is far more massive; (5) the pharynx in elongatus is more elongated,
and longer as compared with the length of the head; (6) oesophagus is
relatively slenderer in elongatus. Sublimate to balsam.
2.5 15. 31.6 Y 94.
20. Cephalobus setosus, n.sp. -7 mm-
The moderately thick layers of the naked, transparent, colorless cuticle
are traversed by 425 transverse striae, which are not further resolvable.
70 NORTH AMERICAN
The striae are more or less interrupted on the lateral fields by two wings,
or by a single wing indicated by two longitudinal lines. The width of the
wing near the middle of the body is about equivalent to the width of four
of the annules of the cuticle. Toward the tail end the width of the inter-
rupted space is about equivalent to the width of three of the annules, and
near the middle of the neck the width is also about equivalent to that of
three of the corresponding annules. Through the middle of the lateral space
on which the annules are interrupted there passes a longitudinal refractive
line. The posterior portion of the neck is cylindroid; the anterior half
conoid to the head, which is not set off in any way. The lips are arranged
in two series: an outer series of six two-parted lips, and an inner series of
three obscurely two-parted projecting flaps, each armed at the anterior
rounded corners with short, arcuate, tapering, acute, forward-pointing
bristles. Each of the two parts of the six outer lips or appendages is con-
oid and acute, and the spaces separating them are much narrower than those
separating the lips themselves. At the base of each of the lateral two-parted
lips there is a transverse mark, which may possibly be the outer expression
of the amphid. This marking is very minute and about four times as wide
as it is long, and is placed transversely on the base of the lip, iust in front
of the foremost cervical annule. It spans about one-sixth of the width of the
head at this point. The three inner appendages, which may more properly
be termed the lips, are about as long as they are wide, and seem to be flex-
ible. They rather closely surround the mouth opening. Each is half as
wide again at its free extremity as it is at the base, and the total length is
about equal to one-fourth of the diameter of the front of the head. The
setae with which these lips or flaps are armed are about two-thirds as long
as the flaps themselves. The rather obscure, narrow, cylindroid pharynx
is about as long as the base of the head is wide, and its lumen is hardly
wider than the thickness of the cuticle. The oesophagus surrounds the
pharynx, but is narrower in this region than it is immediately behind the
pharynx. Behind the pharynx it commences as a tube about three-fifths as
wide as the base of the head, and continues to have about the same diameter
until after it passes through the nerve-ring. It does increase a trifle in
diameter, however, so that at the nerve-ring it is about one-half as wide as
the corresponding portion of the neck. Some distance behind the nerve-ring,
namely, at a distance about equal to one and one-half diameters of the neck,
there is a slight break in the musculature of the oesophagus. Behind this
break the oesophagus begins to taper very gradually and continues to de-
crease in diameter until it finally expands to form the somewhat ellipsoidal or
pyriform cardiac bulb, which is about two-thirds as wide as the base of the
neck, and contains a distinct, rather simple, triple, chitinized valvular appa-
ratus. That portion of the oesophagus immediately in front of the cardiac
bulb has a diameter about one-fourth as great as that of the corresponding
portion of the neck. The lining of the oesophagus can be seen throughout its
length, and is a fairly distinct feature. The intestine which at first is thin-
FREE-LIVING FRESH-WATER NEMATODES /I
walled is separated from the oesophagus by a distinct and deep constriction,
and becomes at once about three-fourths as wide as the body. The anterior
portion of the intestine is characterized by the presence of a considerable cav-
ity, which, however, soon narrows, and, as the internal wall of the intestine
is rather strongly refractive, the narrow, sinuous lumen is a very conspicuous
feature. From the rather conspicuous depressed anus the rectum, which is
rather strongly chitinized and somewhat longer than the anal body diameter,
extends inward and forward. The tail is somewhat concave conoid from
the anus to the very acute terminus. There are no caudal glands. The lat-
eral fields appear to be about one-third as wide as the body. The nerve-
ring surrounds the oesophagus somewhat squarely. The excretory pore
appears to be located near the nerve-ring. The nature of the internal sexual
organs remains uncertain, but the vulva is evidently located near the middle
of the body. The description is derived from an immature specimen.
Habitat: Cranberry bog, Arlington Farm, Virginia. Flemming so-
lution to glycerine.
BASTIANA, de Man, 1876.
Fig. 23, Plate VIII.
.2 8. 18. 58. 89.
21. Bastiana exihs, n.sp. - 1.4 mm.
5 -8 i. i. 5 i.i
The moderately thick layers of the transparent, colorless, naked cuticle
are traversed by about eight hundred forty transverse striae, which do not
appear to be further resolvable. These striae exist in the outer as well as
inner cuticle, so that the entire contour of the body is crenate. Rather con-
spicuous lateral wings are present, the optical expression of which is two
distinctly refractive longitudinal lines opposite the lateral fields, separated
from each other by a distance somewhat greater than the width of one of
the annules of the cuticle. The gradually tapering conoid neck ends in a
somewhat truncate head, which is not set off in any way, and which bears
a circlet of at least six cephalic setae, of which four submedian are the
longer, and somewhat longer than the head is wide. Possibly each of these
latter is accompanied by a shorter seta, thus making ten in all. Apparently
labial papillae are present, but they have not been sufficiently clearly seen
to permit of enumeration. There is no distinct pharynx. The amphids, lo-
cated as in B. gracilis deMan, are somewhat in the form of the end of a
shepherd's crook. They are perhaps to be regarded as broad spiral bands of
about one turn. So regarded, the band may be conceived to begin on the
ventral side where its end is rounded and its contour distinct, pass forward,
and then curve backward and end indefinitely at a point somewhat in the
rear of the beginning. The amphids are half to two-thirds as wide as the
corresponding portion of the neck, and somewhat longer than wide. There
are no eye-spots. The oesophagus begins as a tube fully two-thirds as wide
as the head. It gradually increases in diameter as it passes backward, and at
72 NORTH AMERICAN
its posterior extremity is three-fourths as wide as the base of the neck.
There is no definite cardia. The lining of the oesophagus is indistinct. The
intestine, which is separated from the oesophagus by an obscure constriction,
becomes at once three-fourths as wide as the body, is rather thick walled,
and its cells contain rather uniform, colorless granules, not arranged in any
definite manner. From the rather raised anus the conspicuous rectum, which
is twice as long as the anal body diameter, extends inward and forward.
The tail is conoid, but tapers more rapidly near the acute terminus. A short
distance in front of the terminus it is nearly half as wide as at the base.
Nothing is known concerning the renette. The lateral fields have not been
distinctly seen, but they appear to be about one-third as wide as the body.
Nothing definite is known concerning the internal sexual organs, as the speci-
mens examined were not fully developed.
60.
.4 6. IQ. -M- 92.
- 1.4 mm.
.5 1.2 1.4 2. 1.2
The tail of the male is like that of the female in form and size,
except that the anus is more prominently raised. In front of the anus
and extending forward to the base of the neck there is a ventral row of
ninety supplementary organs. These are of small size, and each ap-
pears when seen in profile to be a slight conical, innervated elevation
having an altitude about one-third as great as the width of its base.
These organs are removed from each other a distance on an average
about equal to the radius of the body or a little more. They are some-
what nearer together posteriorly than anteriorly. Near the base of the
neck the distance between two adjacent organs is about equal to the
body diameter. The two equal, tapering, acute, nearly straight spicula
are about one and one-third times as long as the anal body diameter.
They are slightly cephalated by expansion, the cephalum occupying
about one-third of the length. At the widest part, namely in the cephala,
the spicula are one-fourth to one-third as wide as the corresponding
portion of the body. They do not appear to have any accessory pieces.
The spicula appear, when seen in profile, to be arranged at an angle
of forty-five degrees to the body axis. Beginning at the anus and ex-
tending obliquely backward there is a strand of muscle which is at-
tached to the dorsal side of the body. The two testes are outstretched
in opposite directions. The blind end of the anterior testis is about as
far behind the base of the neck as the nerve-ring is in front of it, while
the blind end of the posterior testis is about twice as far in front of
the anus as this latter is in front of the terminus.
Habitat: Fresh water, Tynne Station, Fla. Bouin solution to gly-
cerine.
FREE-LIVING FRESH-WATER NEMATODES 73
APHANOLAIMUS, de Man, 1880.
Fig. 25, Plate VIII.
43-
.5 8.8 20. '50.' 88.
22. Aphanolaimus spinferus, n.sp. - 1.5 mm
.7 1.5 2.1 3.1 1.9
The thin, transparent layers of the colorless, naked cuticle are traversed
by about one thousand transverse striae, which do not appear to be further
resolvable, or at any rate are resolvable with difficulty. The cuticle is also
traversed by longitudinal striations, manifestly due to subcuticular struc-
tures, the submedian fields and the attachment of the muscle cells. The
contour of the body is minutely crenate. There is .a distinct wing extending
throughout the length of the body, whose presence is indicated by two re-
fractive lines occupying a space hardly greater than the width of one of the
annules of the cuticle. On being carefully examined these lines show traces
of the striations of the cuticle. The conoid neck ends in a somewhat rounded
head, whose lip region is set off by a minute constriction just in front of
the amphids. The contour of the front of the head is rounded, or, like
that of a very flat truncated cone. In the midst of the truncation there is
an exceedingly minute depression, the mouth pore. There does not appear
to be any very distinct pharynx, but the lining of the oesophagus is slightly
altered in the region of the head back as far as the posterior margins of the
amphids. It is not unlikely that this represents a distinct, though rudi-
mentary pharynx. The species, however, would naturally at first sight be
classed as being without a pharynx. The oesophagus begins as a tube about
half as wide as the base of the head, and expands very gradually until after
it passes through the nerve-ring. At the nerve-ring its width is about one-
third that of the corresponding portion of the neck. Behind the nerve-ring
the oesophagus begins to expand a little more rapidly, though still slowly.
When it reaches the end of the neck it is half as wide as the base of the
neck. For a distance equal to one body diameter, however, it decreases in
size, so that where it joins the intestine it is very narrow, only about one-
fifth as wide as the corresponding body diameter. Nevertheless, there ap-
pears to be a distinct, though exceedingly minute cardia. The lining of the
oesophagus is a fairly distinct feature throughout its length. The intestine,
which is at first thin-walled, gradually becomes half as wide as the body, and
is composed of cells of such a size that only two or three are required to
build a circumference. For the most part the wall of the intestine is moder-
ately thick. From the very slightly raised, rather inconspicuous anus the
slender rectum, which is about one and one-half times as long as the anal
body diameter, extends inward and forward. It is separated from the in-
testine by a very distinct and deep constriction. Near the middle the lateral
fields are about one-third as wide as the body. The ventral gland is a rather
elongated, saccate cell a little longer than the base of the neck is wide,
and about one-third as wide as long. It contains a large spherical nucleus,
74 NORTH AMERICAN
with a large, fairly distinct nucleolus. There extend backward from
this cell two finger-shaped, submedian extensions nearly as long as the cell
itself. Notwithstanding the distinctness of the organ and appendages the
position of the excretory pore remains to be discovered. The tail tapers
from in front of the anus in such fashion that at the beginning of the
final fourth it has a diameter about one-fourth as great as at the anus.
Thence onward the tail is cylindroid to the terminus, which bears a trun-
cated, conical, unarmed spinneret. The three caudal glands are minute,
close together, opposite to and a little behind the anus. From the slightly
depressed vulva the chitinized vagina leads inward at right angles to the
ventral surface half way across the body, where it joins the two symmetrical-
ly placed uteri. The reflexed ovaries reach about one-third the distance
back to the vulva and contain a few developing ova arranged single file.
The species is viviparous. Two embryos and a developing egg have been
seen in each uterus at the same time. The eggs are somewhat elongated,
about as long as the body is wide, and a little less than half as wide as they
are long.
64
.2 10. I4.(?) M 82.
1.5 mm.
.7 i.i 2. 2.4 1.9
The tail of the male is like that of the female in form and size. In
front of the anus there is a ventral series of seven tubular, protrudable, sup-
plementary organs, occupying a space nearly equal to the length of the tail.
The hindermost is opposite the proximal ends of the spicula. Each of these
organs is about half as long as the body is wide, has its proximal end slightly
cephalated by expansion, and its distal end slightly curved. The circular
apertures through which the organs are protruded disturb the ventral con-
tour distinctly, each of them occupying a space about equal to the width of
four annules of the cuticle. There are no special setae or papillae either in
front of the anus or behind it. The two equal, uniform, slender, very
strongly arcuate spicula are about one and one-half times as long as the
anal body diameter, and their proximal ends are cephalated by expansion.
The proximal ends lie nearly opposite the body axis. There is a simple ac-
cessory piece, applied for a short distance to the distal ends of the spicula,
having a backward pointing process two-thirds as long as the anal body
diameter.
Habitat: Potomac River, Washington, D. C. Sublimate to balsam.
3i
23. Aphanolaimus minor, n.sp. * .6 mm.
8 3-3 3-9 4-7 2.6
The moderately thin, transparent layers of the colorless, naked cuticle
are traversed by fine transverse striae, resolvable with moderate powers,
and not modified on the lateral fields. The presence of wings is indicated
by two lines extending from near the middle of the neck well onto the tail.
FREE-LIVING FRESH- WATER NEMATODES 75
These occupy a space a little more than the width of one of the annules of
the cuticle, but sometimes one of these lines is more prominent than the
other. The conoid neck ends in a rounded head, which is not set off in any
way. There are no cephalic setae. There does not appear to be any distinct
pharynx. The lining of the oesophagus is slightly modified back twice as
far as the posterior margins of the amphids, and very likely this portion of
the tube may be regarded as a narrow rudimentary pharynx. Twice as far
from the anterior extremity as the base .of this supposed pharynx the
oesophagus is distinctly interrupted by a break in the musculature, although
there is no change in size, and just behind this break there are three distinct,
elongated nuclei, one in each segment of the oesophagus. These appear-
ances are reminiscent of the arrangement in Plectus, to which Aphanolaimus
is doubtless related. There do not appear to be any distinct lips, though
possibly there may be three exceedingly minute, well amalgamated, flattish
ones. Although at first glance the amphids appear to be circular, they are
really spiral in form. They are about one-fifth as wide as the corresponding
portion of the neck. Their distance from the anterior extremity is about
equal to the diameter of the head; or in other words, their centers are re-
moved from the anterior extremity a distance about twice as great as their
diameter. The amphids appear to be slightly larger in the male than in the
female. There are no eye-spots. The oesophagus begins at the base of the
above described pharynx, as a tube about half as wide as the corresponding
portion of the neck. It widens very gradually, so that where it passes
through the nerve-ring it is nearly one-third as wide as the corresponding
portion of the neck. At the middle, nearly opposite the nerve-ring, there
is an almost imperceptible increase in diameter, indicative of a deteriorated
median swelling. Finally, it expands into the narrowly pyriform cardiac
swelling destitute of any distinct valvular apparatus. This swelling is half
to two-thirds as wide as the base of the neck. The lining of the oesophagus
is a distinct feature throughout its length. There is no distinct cardia. The
intestine, which is at first only one-fifth as wide as the base of the neck,
joins the middle of the posterior surface of the cardiac swelling. It is
moderately thick-walled, and gradually becomes about two-thirds as wide as
the body. It appears to be made up of cells of such a size that few, prob-
ably two or three, or possibly four, are required to build a circumference.
The body tapers gradually from a long distance in front of the anus. This
latter is very slightly raised, more particularly on the anterior margin. From
it the rectum, which is about as long as the anal body diameter, extends in-
ward and forward. The tail is conoid in the anterior three-fourths. The
posterior fourth is cylindrical and has a diameter nearly one-third as great
as that of the base of the tail. It ends in a rounded, unarmed spinneret, bear-
ing an apiculum. The lateral fields appear to be about one-third as wide as
the body. The nerve-ring surrounds the oesophagus somewhat obliquely.
There appears to be a small renette cell opposite the anterior portion of
tire intestine, but the position of the excretory pore has not been discovered.
76 NORTH AMERICAN
From the inconspicuous vulva the vagina leads inward at right angles to the
ventral surface about half way across the body, where it joins the two sym-
metrically-placed uteri. The reflexed ovaries reach about half way back
to the vulva and contain half a dozen or more developing ova arranged
somewhat irregularly. The thin-shelled, ellipsoidal eggs are about as long
as the body is wide and about three-fifths as wide as long. They have been
seen in the uterus one at a time, and apparently are deposited before seg-
mentation begins.
3. 15. 23. -M- 85.
.5 mm.
1.8 3.4 3.8 4-2 34
The tail of the male is conoid in the anterior three-fourths in such
fashion that the beginning of the final fourth has a diameter of about one-
eighth that of the base of the tail ; thence onward the tail is nearly cylin-
drical or expands slightly, and ends in a rounded terminus bearing an api-
culum forming an unarmed spinneret. The caudal glands are located in the
base of the tail. In front of the anus in the male there is a ventral row of
eight or nine protrudable. obscurely S-shaped, yellowish supplementary or-
gans. These appear to be of rather uniform size and are equally spaced.
Their length is somewhat greater than that of the radius of the body, and
they are placed at an angle of about thirty degrees to the body axis. They
are of rather uniform diameter throughout their length, but taper a little
toward the blunt distal extremity, and are obscurely cephalated at the
proximal ends. The distal extremity of the hindermost of these organs is
located nearly opposite the proximal ends of the spicula. The entire distance
occupied by the series is about one and one-half times as great as the length
of the tail. The two equal, tapering, strongly arcuate, brownish yellow spicula
are about one and one-half times as long as the anal body diameter. Their
proximal ends are cephalated by expansion, and extending from the proximal
ends toward the distal extremities there are straight, refractive lines indicat-
ing possibly that there is more to the framework of the spicula than appears
at first glance. The spicula curve inward and backward to near the dorsal
side of the tail, and then pass forward so that their proximal extremities lie
opposite the body axis. The spicula are accompanied by a rather straight,
slender, slightly tapering, blunt accessory piece applied to their distal fifths.
From this point the accessory piece extends inward and backward at an
angle of sixty degrees, and ends a little to the dorsal side of the
body axis. At their widest part, just behind the cephala, the spicula
have a width about one-fifth as great as that of the corresponding portion of
the body. A little behind the middle of the tail there are two ventrally sub-
median setae, about half as long as the corresponding diameter of the tail.
The ejaculatory duct is about one-third as wide as the body. There are two
testicles, one extending forward and the other backward. The blind end of
the anterior testicle is a little farther behind the base of the neck than the
FREE-LIVING FRESH-WATER NEMATODES 77
nerve-ring is in front of it. The blind end of the posterior testicle lies just
in front of the anterior supplementary organ.
Habitat: Mud, Potomac River. Sublimate to balsam.
TYLENCHUS, Bastian, 1865.
60
24. Tylenchus symmetries, n.sp. 2 -7 108 17. -49- 90.2 mm
i-4 2.8 3.3 3.8 2.7
The moderately thick layers of the transparent, colorless, naked cuticle
are traversed by fine plain transverse striae, which are not further resolvable.
There are two wings on the lateral fields, removed from each other a dis-
tance about equal to one-fourth to one-fifth the body diameter. The space
between these wings is very faintly marked with longitudinal lines, of which
two near the middle are more prominent than the others. The wings them-
selves bear traces of transverse striation. These wings begin near the
middle of the neck and end on the tail. The conoid neck becomes convex-
conoid toward the somewhat rounded head, which is not set off, or at least
only by an almost imperceptible constriction a short distance behind the lip
region. There are no distinct lips. What appear to be the faintest possible
traces of papillae may be seen on the lips, but these do not disturb the rounded
contour of the head. Were it not for the innervations it would be prac-
tically impossible to see them. The pharynx is tubular and just wide enough
to make a passage for the spear. This latter is slender, nearly one and one-
half times as long as the base of the head, and has a three-bulbed base about
one-fifth to one-fourth as wide as the corresponding portion of the head.
Near the middle the spear is closely surrounded by a rather inconspicuous
guiding-ring or cylinder, about one-fourth as long as the spear. At its
widest part, namely, in the proximal half, the diameter of the spear is less
than the width of two of the adjacent annules of the cuticle. The oesophagus
begins as a tube about one-third as wide as the base of the head, and con-
tinues to have this diameter until it expands to form the ellipsoidal or pro-
late median bulb. This latter is about three-fifths to two-thirds as wide as
the middle of the neck, and contains a distinct ellipsoidal valvular apparatus
about one-fifth as wide as the bulb itself. Behind the median bulb the
oesophagus is smaller than elsewhere. For a distance equal to twice the
width of the neck it has a width only about one-eighth to one-sixth
as great as that of the corresponding portion of the neck. There-
after, it expands to form the elongated-pyriform non-muscular cardiac swell-
ing, which is half as wide as the base of the neck, and contains a rather
conspicuous nucleus. The lining of the oesophagus is a fairly distinct feature
in its anterior part; but posteriorly it is much less distinct, and is very diffi-
cult to observe in the cardiac swelling. The intestine, which is separated
from the oesophagus by an indistinct constriction, becomes at once fully two-
thirds as wide as the body. Its cells are packed with large granules of some-
what variable size, the largest of which have a diameter about one-eighth as
great as that of the body, the smallest being considerably smaller. These
78 NORTH AMERICAN
granules are so prominent as to obscure the cellular structure of the in-
testine. From the very slightly elevated and rather inconspicuous anus the
rectum, which is hardly as long as the anal body diameter, extends inward
and forward. The tail is conoid to the terminus, where it rather suddenly
tapers much more rapidly to a very acute point. This rapidly tapering por-
tion has a length about equal to one-fourth the anal body diameter, and the
diameter at the point where the change in taper begins is about equal to one-
fifth of the anal body diameter. The lateral fields appear to be a little more
than one-third as wide as the body. The nerve-ring surrounds the oesopha-
gus obliquely. The excretory pore is located a little behind the nerve-ring, a
little more than half way from the base of the neck to the middle of the
median bulb. From the slightly elevated, rather massive vulva the vagina
leads inward at right angles to the ventral surface nearly half way across
the body, where it joins the two uteri. Apparently the ovaries are out-
stretched. A single egg has been seen in one of the uteri. It is about twice
as long as the body is wide and about one-third as wide as long. It is thin-
shelled and apparently undergoes segmentation before being deposited.
3.1 13.5 20.5 -M 3 89.1
2.2 3.6 3.9 4.2 3.2
The tail of the male is like that of the female in form. From the raised
anus it is arcuate-conoid to the terminus, which is concave-conoid and ends
in an exceedingly fine slender point. The length of the terminus is about
one-third as great as the anal body diameter, while its diameter is about
one-fourth as great as the anal body diameter. There are no supplementary
organs, nor have any special papillae been seen either in front of the anus
or behind it. There is a fairly well developed, but not very prominent bursa,
which extends but little beyond the ventral contour at any point. It springs
from the submedian lines at a distance as far in front of the anus as the
middle of the tail is behind it. The bursa is striated like the cuticle, and its
margin is entire; it extends to near the end of the tail. Near the middle
of the tail there appears to be a bursal rib on each side, which does not
reach to the margin of the bursa. The ejaculatory duct is about one-third
as wide as the body. The blind end of the single outstretched testicle lies
a short distance behind the base of the neck.
Habitat : Marsh in black clay with much decayed vegetation, near Im-
patiens, Arlington Farm, Virginia. Flemming solution to glycerine.
RHABDITIS, Dujardin, 1845.
7i
1.2 10.8 16.8 '55' 93.8
25. Rhabditis punctata, n.sp. - 1.8 mm.
1.2 3.3 4.3 4.9 1.6
The thin layers of the transparent, naked, colorless cuticle are traversed
by transverse striae, which are resolvable with high powers and appear to be
resolvable into rows of dots, but there is some doubt about this. The cuticle
FREE-LIVING FRESH-WATER NEMATODES 79
is longitudinally striated. Near the middle of the male there is a lateral area
nearly half as wide as the body, which is nearly destitute of striations. On
either side of this field the cuticle may be seen with high powers to be dis-
tinctly longitudinally striated. This lateral field narrows toward both ex-
tremities so as to be hardly wider than the spicula, so that the main portion
of the cuticle of these regions appears there to be longitudinally striated.
The neck is conoid, becoming almost imperceptibly convex-conoid toward
the head, which is somewhat rounded and bears six lips, which are fairly
well separated from each other, and each of which appears to be papillate.
The simple, unarmed pharynx is cylindrical and one-third as wide as the
base of the head. Its cavity is four to five times as long as wide. No amphids
have been seen, and there are no eye-spots. The oesophagus receives the
base of the pharynx and becomes at once about two-thirds as wide as the
base of the head. It continues to have this diameter until it expands to
form the ellipsoidal median swelling, which has a distinctly radiated fibrous
structure. This swelling is about two-thirds as wide as the corresponding
portion of the neck, and is separated from the portion of the oesophagus
preceding it, as well as the portion succeeding it, by a refractive division in
the internal musculature. Behind the median swelling the oesophagus has
a diameter less than half as great as that of the corresponding portion of
the neck, and it narrows continuously until it reaches the pyriform cardiac
bulb, which is three-fourths as wide as the base of the neck and contains a
well developed, complicated, chitinous valvular apparatus half as wide as
the bulb itself. There is no distinct cardia. The somewhat transparent and
colorless intestine, which is separated from the oesophagus by a distinct
constriction, is composed of cells containing scattered granules of variable
size, the largest of which have a diameter somewhat less than the thickness
of the cuticle, and the smallest of which are very much smaller. The anus
is slightly raised, and from it the rectum, which is one and one-half times as
long as the anal body diameter, leads almost directly forward. The body
tapers for some distance in front of the anus; from the anus onward it is
conical to the acute terminus. There is no spinneret, and there are no caudal
glands. Nothing definite is known concerning the renette cell. The excre-
tory pore is located about half way between the median and posterior bulbs,
just behind the oblique nerve-ring. The two uteri extend in opposite direc-
tions, and the ovaries are reflexed, the flexures occurring the one not far
behind the base of the neck and the other not far in front of the anus.
The mature females contain scores of eggs in various stages of development,
the most advanced containing well-developed embryos.
63
2.3 16.2 25.9 -M 96.3
i. mm.
i-9 34 3-5 3-7 2.6
The tail of the male is conoid from the anus in such fashion that at the
beginning of the posterior third it has become reduced to a mere striated
nearly straight spine, which is no wider than one of the ribs of the bursa.
8O NORTH AMERICAN
The dorsal contour of the tail continues as a more or less regular extension
of that of the body. The ventral contour, however, is elevated at the anus;
at any rate, when the spicula are partly extruded. This elevation appears to
be largely median, and there is a distinct groove on either side between it and
the bursa. When this groove is brought into optical section and the anal
elevation is disregarded the tail appears to be asymmetrically conoid. The
two equal, brownish, nearly straight spicula are fully twice as long as the
tail, or one and one-half times as long as the body diameter, measured oppo-
site the proximal ends of the spicula. The spicula in the distal three-fourths
taper to a blunt point. At their widest part, considerably in front of the
middle, they are one-fourth to one-fifth as wide as the corresponding portion
of the body. In the proximal fourths the spicula are rather suddenly nar-
rowed and terminate in bulbs or cephala, which have a diameter twice as
great as the portion of which they are expansions. Parallel to the spicula
there are accessory pieces. These are two-thirds to three-fourths as long as
the spicula, which they partially envelop. They are about as strongly chitin-
ized as the spicula themselves. The transparent, colorless bursa springs
from the submedian lines, nearly opposite the proximal ends of the spicula,
and when seen in profile only slightly exceeds the ventral contour in front
of the anus, but behind the anus exceeds the ventral contour of the tail
proper so much that nearly the entire length of the ribs comes plainly into
view. The ribs are arranged in three groups: (i) Two ribs close together
opposite the middle of the spicula. (2) Four ribs close together opposite to,
and a trifle behind the anus. (3) Four ribs of which three are very close
together, and one a little farther forward, the whole group being opposite
the middle of the tail. Most of these ribs reach to the margin of the bursa,
which is entire and is not distinctly striated. The outer members of the
middle and posterior groups do not reach quite to the margin. The ejacu-
latory duct is nearly one-half as wide as the body. The single, outstretched
testicle has its blind end located about half as far behind the base of the
neck as this latter is behind the anterior extremity. At its blind end the
testicle is about one-third as wide as the body. It gradually increases in
width, so that it occupies four-fifths of the diameter of the middle of the
body. The spermatocytes are of large size, one-third to one-half as wide
as the body.
Habitat : About the roots of aquatic plants, Potomac River, Washing-
ton, D. C.
TRILOBUS, Bastian, 1865.
Fig. 15, Plate VI.
40
26. Trilobus longus, (Leidv), Bastian^ * 9 ' 46 ' ^ 1.2 mm.
2. 2.8 3.8 4.6 2.3
The thin, transparent layers of the colorless cuticle are traversed by
exceedingly fine plain transverse striae, more particularly visible in the
FREE-LIVING FRESH-WATER NEMATODES 8l
lower layers with high powers. There are short hairs to be found here
and there on the surface of the body, more particularly toward the ex-
tremities. The conoid neck ends in a somewhat rounded head not set
off by any constriction. The cephalic setae appear to be ten in number
(eight submedian and two lateral), outward pointing, each about one-
sixth as long as the head is wide, and placed on the outer margin of the
front of the head opposite the posterior portion of the pharynx. The
members of the submedian pairs are, however, of unequal size. There
are six small, pointed lips surrounding the mouth opening. It is cer-
tain that these lips bear papillae, but the number is not known. Lat-
eral organs in the form of somewhat stirrup shaped markings one-
fourth as broad as the corresponding portion of the head, occur at a
short distance behind the base of the rudimentary pharyngeal cavity.
This latter is a more or less triquetrous cyathiform cavity having its
walls distinctly chitinized and bearing at its base one or more protuber-
ances near the point where the lumen of the oesophagus begins. One
of these is a ridge, the others minute teeth. The average width of the
main pharyngeal cavity is about one-third that of the head. The oeso-
phagus is slightly expanded to receive the pharynx, but otherwise be-
gins as a tube about three-fifths as wide as the anterior part of the
neck, and expands very gradually to the end, where it is a little more
than half as wide as the base of the neck. The lining of the oeso-
phagus is a distinct feature throughout its length. There is a distinct
rounded cardia. The intestine, which becomes at once about two-fifths
as wide as the body, is separated from the oesophagus by a distinct
constriction, in which lie the three granular bodies whose presence
gave origin to the name of the genus. The intestine is relatively thick
walled, its small cells containing scattered granules of small size, which
are not arranged in any very definite manner. The intestine frequently
contains diatoms in large numbers, thus indicating that these are a
common source of nourishment for this species. From the slightly de-
pressed anus the rectum, which is about as long as the anal body
diameter, extends inward and forward to join the intestine, which is
narrowed at its extremity so as to be about two-fifths as wide as the
body. Nothing is known concerning the ventral gland. The longi-
tudinal fields are distinctly developed, being about one-fourth as wide
as the worm itself. The nerve-ring surrounds the oesophagus some-
what obliquely. The tail is conoid in the anterior third in such fashion
that at the beginning of the middle third it has a diameter about one-
fourth as great as at the anus. Thence onward it tapers gradually to
the slightly swollen spinneret or outlet for the caudal glands. These
latter, three in number, are located tandem in the tail opposite to and
slightly behind the anus. From the slightly elevated vulva the vagina
leads inward at right angles to the ventral surface fully half way
across the body. The vagina is bifurcated and extends in opposite di-
82 NORTH AMERICAN
rections, the reflexed ovaries passing about two-thirds the way back to
the vulva. Two or three eggs may occur in each uterus at one time.
These are somewhat ellipsoidal and thin shelled, being about two-thirds
as long as the body is wide and about two-thirds as wide as long. The
eggs appear to indicate at least the early stages of segmentation before
being deposited. The walls of the vagina present the peculiarity of being
very thick, and composed of concentric layers to the number of six or
seven, so that the organ is considerably broader than it is deep. Its in-
ternal wall presents the peculiarity of staining strongly with carmine.
1.3 8.3 137 -M- 92. ^ ^
2. 2.6 3.2 3.8 2.7
The tail of the male is very much like that of the female in form
and size. Supplementary organs are found in front of the anus only.
These are six in number, of which three are very prominent. The an-
terior member of this group of three is about twice as far in front of
the anus as the spinneret is behind it. The members of this group are
equidistant, the distance between consecutive members being about twice
as great as the diameter of the organs themselves. All three occupy
a distance about twice as great as the corresponding body diameter.
Each of these organs consists of an internal and an external portion, the
internal portion being a flattish, hemispherical mass of tissue of very
fine, or at least uniform texture. These have a diameter about two-
fifths as great as that of the body at the same part. The external
portion of these organs consists of a ring slightly raised, from which
projects a mammiform papilla which bears a minute median seta or
nerve-ending. When this mammiform portion is traced inward it passes
through the ring on the surface of the body and then bends forward
and ends rather indefinitely in the anterior contour of the internal por-
tion of the organ. These organs possess the peculiarity of staining
strongly with carmine. In addition to the organs already described
there are three others of smaller size, two very minute, one near the
anus and the other opposite the proximal portions of the spicula. The
third, which has a size intermediate between those just described and
those first described, is located about half way between the anus and
the posterior member of the larger group. These smaller organs are
comparatively close counterparts of the larger, differing merely in size.
In addition it may be noted that the cuticle on the ventral surface of
the male throughout this region of the body, that is, as far forward as
the most anterior of these organs, bears about twenty exceedingly
minute structures on the ventral line, which appear to be innervated
papillae. These also stain strongly with carmine, although they are so
minute as to be difficult to observe. There are no papillae on the tail,
but there are several short hairs, more particularly near the ventrally
submedian lines. There is no bursa. The ejaculatory duct is coexten-
sive with the supplementary organs. It is on the average nearly half
FREE-LIVING FRESH-WATER NEMATODES 83
as wide as the corresponding portion of the body. It is connected with
the seminal vesicle by a narrow portion. The seminal vesicle is elon-
gated, about half as wide as the body, and extends to a point about as
far behind the neck as the base of the neck is from the anterior ex-
tremity. From this point the two nearly equal testicles extend in oppo-
site directions, and end blind, one not far behind the base of the neck,
and the other not far from the middle of the body. These possess the
peculiarity of being slightly swollen at their proximal ends just where
they join the vesicle. These swellings appear to constitute veritable
cavities of small size. That region of the body corresponding to the
ejaculatory duct is traversed by oblique striae, which, however, are ar-
ranged at right angles to the direction of such oblique striations as
are found in other genera, and it is probable that they are connected with
the duct itself, and are not muscles of the character which usually give
rise to these oblique striations on the males of other genera. The two
equal, arcuate slender spicula appear to be of rather uniform diameter
when viewed laterally, and are one and one-half times as long as the
anal body-diameter. Their proximal ends are cephalated by contrac-
tion. They are accompanied by accessory pieces two-fifths as long as
the spicula themselves, and arranged parallel to the distal portions of
the spicula.
Habitat: Mud, about the bases of aquatic plants, Potomac river,
D. C.
MESOMERMIS, Dady.
Fig. 18, Plate VII. Fig. 24, Plate VIII.
55
- ,, .8 6.3 ii. -M- 96.
27. Mesomermis virgimana, n.sp. 1.8 mm.
1.3 2. 1.8 2.3 2.2
The rather thick, transparent, colorless layers of the naked cuticle
are destitute of transverse striations. There are minute longitudinal
striations throughout the body. These are interrupted on the lateral
lines, where there is a distinct wing. The conoid neck becomes convex-
conoid toward the lip region, which is not set off in any way. There
are no cephalic setae, and there is no distinct pharynx. The mouth
pore is very minute, and is a little toward the ventral side of the middle
of the front of the head. The cuticle has about the same thickness on
the head as elsewhere, being only a trifle thicker. The cuticle is pene-
trated on the head by a number of innervations. These end in minute
depressions on the surface of the head. Near the mouth opening there
is one of these depressions on the dorsal side, and apparently a sim-
ilar one on the ventral side, while nearer the outer margin of the head
there are two ventrally submedian and two dorsally submedian similar
depressions. Pores occur also here and there on the body as well as
on the neck. There are no eye-spots. The lateral organs present the
84 NORTH AMERICAN
following appearance when seen from the side : They appear to project
from the surface of the body very slightly, beginning as a tube having
a length about one-third as great as the corresponding diameter of the
head. This tube has very thin walls, and a short distance in, appar-
ently near the surface of the body, a second element appears in the
form of a circle inside that representing the contour of the outer tube.
This appears to constitute a sort of core in the midst of which are a
number of refractive elements, resembling nerve fibers, which pass in-
ward and backward toward the lumen of the oesophagus. Some of
these elements are longer than others. The focus passing inward picks
up one, then two, then several more, so that by the time a view is ob-
tained that is wholly inside the body there are seen a half dozen or
more of these elements. It is impossible in this view to pick up an in-
ternal connection of these refractive elements. The oesophagus begins
just below the transparent cuticle as a very narrow tube, probably not
more than one-eighth as wide as the corresponding portion of the neck.
It continues to have this diameter until after it passes through the nerve-
ring. At a distance from the nerve-ring equal to about one body diam-
eter, the oesophagus begins to change gradually into intestine. The
intestine gradually widens out, so that at a point as far behind the nerve-
ring as the neck is wide it has a width one-third as great as that of the
body. It goes on increasing in this way until at a distance from the
nerve ring three times as great it is two-fifths as wide as the body.
Near its middle the intestine is half as wide as the body.
The cells of the intestine contain granules of variable size, the largest
having a diameter fully twice as great as the thickness of the cuticle,
and the smallest being very minute. The female has not been seen.
The tail of the male is slightly arcuate, and is conoid to the blunt,
rounded terminus, which has a diameter half as great as that of the
base of the tail. There is no spinneret, and there are no caudal glands.
The lateral fields are about one-third as wide as the body. The nerve-
ring surrounds the oesophagus somewhat obliquely. Nothing is known
concerning the ventral glands or the excretory pore. The tail of the
male bears several series of innervated papillae. These are sufficiently
elevated at the surface of the cuticle to slightly break the contour when
the tail is seen in exact profile. Where each nerve passes through the
cuticle there is a very low, almost imperceptible elevation at the sur-
face. These papillae are arranged on the ventral submedian lines as
well as on the ventral line. The ventral papillae just in front of and
just behind the anus are double. As to particulars of the submedian
group, there are four on the tail, one member opposite the anus; one
a little farther back, a third near the middle of the tail, and a fourth
considerably farther back. In front of the anus on each side are eight
submedian papillae. These occupy a distance more than twice as great as
the length of the tail, and the distance between successive papillae in-
FREE-LIVING FRESH-WATER NEMATODES 85
creases with the distance from the anus, so that the space between
the seventh and eighth is about two-thirds as great as the diameter
of the body. Of the median papillae on the tail there are three; two
near the anus, and one just in front of the middle of the tail, with pos-
sibly a fourth farther back. In front of the anus, of the median papillae
there are two near the anus, and ten additional ones about coextensive
with the submedian rows and distributed in the same manner, the dis-
tance between successive papillae increasing with the distance from the
anus. The two equal, arcuate, uniform, blunt spicula are about one and
one-third times as long as the anal body-diameter. Their proximal ends
are not cephalated. The ejaculatory duct is about one-third as wide as
the body. The vas deferens is about one-half as wide as the body.
There are two outstretched testicles, the blind end of the anterior being
about twice as far from the end of the neck as this latter is from the
anterior extremity. The posterior testicle is a little shorter than the
anterior.
Habitat: Cranberry bog, Arlington Farm.
ACHROMADORA, Cobb, 1914.
Fig. 11, Plate V.
28. Achromadora minima, Cobb.
For original description see Macleay Memorial Volume, Sydney,
1893; see also Journal Washington Academy of Sciences, Oct. 4, 1914.
86 NORTH AMERICAN
EXPLANATION OF PLATES*
PLATE II.
IOTA, Cobb, 1913.
Fig i. Iota octangulare, n. sp. Lateral view of a female specimen.
a, lip region; b, labial chitinous plate or expansion; c, protruding muscles of
the spear ; d, spear ; e, trilobed base of the spear ; f, lumen of the oesophagus ;
g, nerve-ring; h, beginning of the intestine; i, flexure in the single narrow
ovary; j, excretory pore; k, ventral row of modified cuticular elements; /,
submedian row of modified cuticular elements; m, ovum; n, muscular layer;
o, anterior extremity of the uterus ; p, uterus ; q, cuticle ; r, vulva ; s, sub-
median row of modified cuticular elements ; t, rectum ; u, anus ; v, terminus.
RHABDOLAIMUS, de Man, 1880.
Fig. 2. Rhabdolaimus minor, n. sp. I, lateral view of female; II, head
of the same, showing amphid. The head in I is twisted, so that the amphid
appears as if ventral, or nearly so.
a, amphid ; b, long, narrow pharynx ; c, anterior group of nerve cells ; d,
nerve-ring ; e, cardiac bulb ; /, wall of the intestine ; g, flexure in anterior
ovary; h, posterior group of nerve cells; i, body cavity; j, lumen of intestine;
k, ovum; I, blind end of posterior ovary; m, egg; n, flexure in posterior
ovary ; o, cuticle ; p, caudal glands ; q, subcuticle ; r, vulva ; s, rectum ; t, anus ;
u, nerve cells (?) ; v, duct of caudal glands; w, spinneret; x, lip region.
DIPLOGASTER, Max Schultz, 1857.
Fig. 3. Diplogaster fictor, Bastian. I, side view of female; II, head
of the same seen in dorso-ventral view, lips nearly closed ; III, head
of the same, lateral view, lips nearly wide open; IV, head of the same,
lateral view, lips partially closed; V, front view of mouth, partially closed;
VI, lateral view, posterior portion of a male specimen; VII, somewhat dia-
grammatic perspective view showing markings of the cuticle.
a, one of the lips ; b, one of the six cephalic setae ; c, amphid ; d, one of
the two more or less evertible pharyngeal hook-shaped teeth; e, median
oesophageal bulb ; /, nerve-ring ; g, anus ; h, rectum ; i, intestine ; j, terminus ;
k, posterior oesophageal bulb; /, nerve cells; m, renette cell (?); n, left
spiculum; o, lumen of the intestine; p', preanal male seta; p" , P' ' ' ,
p' ' ' ' , post-anal male setae and papillae; q, one of the cells of the intestine;
r, accessory piece ; s, flexure in anterior ovary ; t, blind end of anterior ovary ;
u, longitudinal striae of the cuticle ; v, vagina ; w, synapsis in egg in the an-
terior uterus, the reduced number of chromosomes being seven; x, one of the
spermatozoa in the ovary; y, uterus; z, vulva.
*The drawings are used by permission of the Secretary of Agriculture, and were
made by Mr. W. E. Chambers, under the author's supervision.
FREE-LIVING FRESH-WATER NEMATODES
9
Fig. 2. Rhabdolaimus minor, n. sp Fig. 3. Diplogaster fictor, Bastian.
PLATE II.
88 NORTH AMERICAN
PLATE III.
PRISMATOLAIMUS, de Man, 1880.
Fig. 4. Prismatolaimus stenurus, n. sp. I, lateral view of a female;
II, front view of head ; III, side view of head.
a, one of the six cephalic papillae ; b, one of the ten cephalic setae ; c,
one of the six thin lips; d, pharynx; e, amphid; f, lumen of the oesophagus;
g, nerve-ring; h, cuticle; i, nucleus of ovum; /, vulva; k, blind end of pos-
terior ovary; /, egg; m, beginning of the intestine; n, one of the cells of the
wall of the intestine ; o, rectum ; p, anus ; q, one of the caudal glands ; r, flex-
ure in anterior ovary; s, spinneret.
SPILOPHORA, Bastian, 1865.
Fig. 5. Spilophora canadensis, n. sp. Side view of male.
a, one of the lips ; b, dorsal pharyngeal tooth partly exserted ; c, pharynx ;
d, base of the pharynx ; e, lumen of the oesophagus ; /, nerve cells ; g, nerve-
ring; h, excretory pore; i, chitinous valve of the cardiac bulb; /, one of the
two lateral, longitudinal rows of cuticular markings; k, lumen of the intes-
tine; I, renette cell; m, nucleus of renette cell; n, cell accessory to the renette
cell ; o, blind end of single testis ; p, point in the cuticle where the striation is
reversed ; q, vas deferens ; r, one of the spicula ; s, anus ; /, one of the caudal
glands; u, spinneret.
MICROLAIMUS, de Man, 1880.
Fig. 6. Microlaimus fluviatilis, n. sp. I, lateral view of female; II,
head of the same.
a, Mouth opening; b, one of the six cephalic papillae; c, one of the four
cephalic setae; d, one of the small pharyngeal teeth; e, excretory pore; /,
spiral amphid; g, oesophagus; h, nerve-ring; i, cardiac bulb; /, preliminary
portion of the intestine ; k, renette cell ; /, body cavity ; m, lumen of intestine ;
n, one of the cells of the intestine; o, anus; p, flexure in posterior ovary; q,
uterus ; r, blind end of posterior ovary ; s, one of the three caudal glands ; t,
spinneret; uu, eggs; v, vulva; w, cuticle.
TRIPYLA, Bastian, 1865.
Fig. 7. Tripyla lata, n. sp. Lateral view, male specimen.
a, cephalic seta; b, one of the three lips; c, amphid; d, spermatozoa; e.
spermatocytes in anterior testis ; /, posterior extremity of the oesophagus ; g,
nerve-ring; h, cuticle; i, oesophagus; /, lumen of oesophagus; k, intestine;
/, spermatocytes in posterior testis ; m, one of the numerous ventral male
papillae ; n, vas deferens ; o, retractory muscle of spiculum ; p, one of the
spicula ; q, lumen of the intestine ; r, duct of one of the caudal glands ; s,
caudal gland ; t, spinneret.
FREE-LIVING FRESH-WATER NEMATODES
Fig. 6. Microlaimus fluviatilis, n. sp. Fig. 7. Tripyla lata, n. sp.
PLATE III.
QO NORTH AMERICAN
PLATE IV. '
TERATOCEPHALUS, de Man, 1876.
Fig. 8. Tcratocephalus cornutus, n. sp. I, lateral view of a female; II,
lateral view of head, more highly magnified; III, front view of head; IV,
dorso-ventral view showing lips wide open; V, cuticle showing lateral field.
a, one of the six movable, chitinous lips ; b, one of the four submedian
cephalic setae ; c, amphid ; A, nerve-ring ; e, excretory pore ; f, organ of un-
known significance ; g, cardiac bulb ; h, intestine ; i, anus ; /, rectum ; k, cu-
ticle ; /, one of the cells of the intestine; m, lumen of the intestine; nn, flex-
ures in ovary ; o, egg ; p, vulva ; q, blind end of posterior ovary ; u, terminus.
ALAIMUS, de Man, 1880.
Fig. 9. Alaimus simplex, n. sp. I, lateral view of a female; II, an-
terior extremity, lateral view; III, posterior extremity of a male, lateral view.
a, lip region ; b, pharynx ; c, amphid ; d, amphid, enlarged; e, group of
spermatozoa at the posterior portion of the ovary; f, blind end of ovary;
g, male supplementary papillae ; //, left spiculum ; i, terminus ; j, rudimentary
submedian elevation or flap of the cuticle, indicating rudimentary bursa; k,
egg ; I, vulva ; m, nerve-ring ; n, posterior extremity of oesophagus ; p, modi-
fied cells of anterior portion of the intestine ; q, cuticle ; r, wall of the in-
testine ; s, lumen of the intestine ; t, flexure in the single ovary.
The arrangement of the ova and eggs may need a few words of ex-
planation. The rounded blind end of the reflexed part of the single ovary
is shown near the group of spermatozoa, e. The blind end contains a large
number of oocytes of small size. These oocytes have more than doubled
in size by J;he time they have reached the position, /. Henceforth they be-
come arranged single file, always increasing in size until they pass the
flexure, t. "At k a deceptive appearance is shown, inasmuch as the ripe
ovum, k, has passed the flexure and in its passage to the uterus is pressing
two of the unripe ova apart. This accounts for the apparent anomaly in
relative size of the^ova in the vicinity of the flexure.
PLECTUS, Bastian, 1865.
Fig. 10. Plectus tubifer, n. sp. Male specimen, lateral view.
a, lips ; b, papilla-like cephalic seta ; c, amphid ; d, anterior chamber of
pharynx ; e, posterior chamber of pharynx ; /, lumen of the oesophagus ; g,
nerve-ring ; h, excretory pore ; i, renette cell ; /, cardiac bulb ; k, vulva of
cardiac bulb ; /, cardia ; m, lumen of intestine ; n, blind end of anterior testis ;
o, spermatocyte ; p, junction of testes; q, blind end of posterior testis; r, be-
ginning of vas, deferens; s, spermatozoon; t, male glands; u, one of the cau-
dal glands; v, anterior of the three tubular supplementary organs; w, spicula;
x, anus; y, one of the nine male papillae; z, spinneret.
FREE-LIVING FRESH-WATER NEMATODES
Fig. 8. Teratocephalus
cornutus, n. sp.
Fig. 10. Plectus tubifer, n. sp.
PLATE IV.
92 NORTH AMERICAN
PLATE V.
ACHROMADORA.
Fig. II. Achromadora minima, Cobb. I, lateral view of a female; II,
lateral view showing cuticular markings; III, lateral view of head.
a, cephalic papilla; b, cephalic seta; c, one of the ribs of the pharynx;
d, dorsal pharyngeal tooth; e, sub-ventral (?) pharyngeal tooth; f, pharynx;
g, cuticular markings ; h, amphid ; i, nerve cell ; /, nerve-ring ; k, spinneret ;
/, excretory pore ; m, flexure of ovary ; n, one of the caudal glands ; o, blind
end of posterior ovary; p, anus; q, intestine; r, vulva; s, one of the gran-
ules of the intestine ; t, egg.
DORYLAIMUS, Dujardin, 1845.
Fig. 12. Dorylaimus fecundus, n. sp. Side view of head and tail of
female, and tail of male.
a, spear or onchus; b, one of the six anterior cephalic papillae; c, one
of the six posterior cephalic papillae ; d, guiding ring of the spear ; e, oeso-
phagus ; /, intestine ; g, rectum ; h, anus ; i, one of the anal muscles ; ;', one of
the four lateral caudal, innervated papillae ; k, cuticle ; /, subcuticle ; m, mus-
cular layer; n, wall of the intestine; o, one of the numerous oblique ejacu-
latory muscles; p, one of the numerous ventral male papillae; q, ejaculatory
duct ; r, one of the two preanal papillae ; s, retractor muscle of one of the
spicula ; t, muscular layer ; u, right spiculum ; v, right accessory piece.
IRONUS, Bastian, 1865.
Fig. 13. Ironus americanus, n. sp. I, anterior extremity, lateral view,
oral organs everted: II, same, more highly magnified; III, anterior extremity
of a specimen about to moult, showing two sets of oral organs, the anterior
set in process of being replaced by the posterior; IV, posterior extremity of
a female, lateral view.
a, one of the three chitinous oral teeth ; b, cephalic papilla ; c, cephalic
seta; d, amphid; e, pharynx; /, anterior group of minute pharyngeal teeth;
g, posterior group of pharyngeal teeth ; h, oesophagus ; i, lining of oesopha-
gus ; /, nerve-ring ; k, intestine ; /, anus ; m, base of the tail ; n, terminus.
ONCHOLAIMUS, Dujardin, 1865.
Fig. 14. Oncholaimus punctatus, n. sp. Lateral view of head and tail
of male specimen.
a, terminal flaps of lips ; b, lip ; c, cephalic papilla ; d, one of the papilla-
like cephalic setae; e, right submedian onchus; /, left submedian onchus; g,
wall of pharynx; h, intestine; i, ejaculatory duct; /, one of the spicula; k,
dorsal onchus ; I, amphid ; m, duct of oesophageal gland leading into onchus ;
n, rectum ; o, beginning of the oesophagus ; p, anus ; q, lining of the oesopha-
gus; r, one of the caudal glands; s, one of the two male papillae; t, ducts of
the caudal glands; u, spinneret.
FREE-LIVING FRESH-WATER NEMATODES
93
Fig. 11. Achromadora minima, Cobb
Fig. 12. Dorylaitnus fecundus, n. ap.
A
Fig. 13. Ironus americanus, n. sp. Fig. 14. Oncholaimus punctatus, n. ip.
PLATE V.
94 NORTH AMERICAN
PLATE VI.
TRILOBUS, Bastian, 1865.
Fig. 15. Trilobus longus, (Leidy), Bastian. I, male specimen, lateral
view; II and III, head of the same, lateral view; IV, head, dorso-ventral
view; V, VI, and VII, enlarged views of the ventral supplementary organs.
a, lateral cephalic seta ; b, cephalic papilla ; c, submedian cephalic setae ;
d, pharynx; c, amphid; /, anterior pharyngeal tooth; g, posterior pharyngeal
tooth ; h, oesophagus ; i, nerve-ring ; /, excretory pore ; k, nerve cells ; / gland-
ular (?) organs; m, lumen of intestine; n, blind end of anterior testis ; o,
testis; p, junction of testes; q, blind end of posterior testis; r, vas deferens;
s, anterior male supplementary organ of the anterior series ; t, anterior sup-
plementary organ of the posterior series ; u, spicula ; v, accessory piece ; w,
caudal gland ; x, anus ; y, terminus ; z, nerve ending of papilla of the supple-
mentary organ.
DOLICHODORUS, nov. gen.
Fig. 16. Dolichodorus heterocephalus, n. g., n. sp. I, nearly side view of a
female; II, lateral view of surface of head, more highly enlarged; III, sagit-
tal section of head; IV, dorso-ventral view of head; V, front view of head;
VI, side view, posterior extremity of male ; VII, ventral view of posterior
extremity of female; VIII, ventral view of posterior extremity of male.
a, papilla ; b, cephalic organ of unknown significance ; c, spear ; d, base of
spear; e, median bulb; /, nerve-ring; g, excretory pore; h, cardiac swelling;
t, intestine ; /, anus ; k, lateral caudal pores ; I, terminus ; m, blind end of pos-
terior ovary ; n, ovary ; o, left spiculum ; p, accessory piece ; q, distal end of
Accessory piece ; r, left flap of bursa ; s, terminus of male ; t, ovum ; u, sper-
matozoa ; v, vaginal muscles ; w, uterus ; x, vulva ; y, anus.
CYATHOLAIMUS, Bastian, 1865.
Fig. 17. Cyatholaimus truncatus, n. sp. I, side view of a female ; II, side
view of head ; III, front view of the same head ; IV, ventral view of anal
region of male; V, lateral view of the same; VI, lateral view in the middle
of the body showing cuticular markings and pores.
a, submedian cephalic seta ; b, labial papillae ; c, amphid ; d, dorsal tooth ;
e, lateral cephalic seta ; /, one of the twelve ribs of the vestibule ; g, small
submedian pharyngeal tooth ; h, base of the pharynx ; i, ejaculatory duct ; /,
intestin* ; k, one of the four male pre-anal supplementary organs ; I, one of
the spicula; m, anal muscles; n, one of the accessory pieces; o, nerve-ring;
p, one of the cells of the intestine ; q, lumen of the intestine ; r, anus ; s, blind
end of reflexed ovary; /, egg; u, vulva; v, flexure in anterior ovary; w,
junction of the ovary and uterus; x, pores in the cuticle; 3;, one of the three
caudal glands; z, male gland (?).
FREE-LIVING FRESH-WATER NEMATODES
i /c I
Fig. 16. Dolichodorus heterocephalus, Fig. 17. Cyatholaimus truncatus, n. sp.
n. g., n. sp. PLATE VI.
96 NORTH AMERICAN
PLATE VII.
MESOMERMIS.
Fig. 18. Mesomermis virginiana, n. sp. Lateral view of head and tail.
a, mouth opening; b, one of the anterior rows of cephalic papillae; c,
one of the posterior row of cephalic papillae ; d, pharynx ; e, exterior of am-
phid; /, interior of amphid; g, oesophagus; h, innervated papilla; , gland-
ular cephalic organs; /, nerve-ring; k, lumen of oesophagus; /, intestine; m,
ejaculatory duct ; n, body cavity ; o, oblique copulatory muscles ; p, one of the
submedian supplementary organs; q, one of the median supplementary or-
gans; r, spicula; s, one of the median post-anal supplementary organs; t,
final submedian supplementary organs; u, submedian supplementary organ.
ETHMOLAIMUS, de Man, 1880.
Fig. 19. Ethmolaimus americanus, n. sp. Lateral view of a female.
a, lips ; b, minute dorsal and ventral pharyngeal teeth ; c, one of the
four cephalic setae; d, amphid; e, pharynx; /, nerve-ring; g, excretory pore;
h, nerve cells; \, cardiac bulb; j, beginning of the intestine; k, renette
cell (?); /, beginning of main portion of the intestine; m, one of two
pairs of unicellular organs of unknown significance; n, cuticle; o, one of the
cells of the intestine; p, subcuticle; q and r, body cavity; s, vulva; t, nuclei
of one of the muscle cells ; u, spinneret ; v, one of the caudal glands ; w, anus.
MONHYSTERA, Bastian, 1865.
Fig. 20. Monhystera sentiens, n. sp. I, side view of a female; II, side
view of head of the same; III, side view of posterior extremity of a male.
a, pharynx ; b, submedian cephalic seta ; c, lateral cephalic seta ; d, sper-
matozoon ; e, amphid ; /, lining of oesophagus ; g, oesophagus ; h, subcephalic
setae; i, lumen of intestine; /, nerve cells; k, nerve-ring; /, striated lip re-
gion; m, left spiculum; n, glandular structure associated with amphid; o,
blind end of single ovary; pp, the three caudal glands; q, anal muscles; r,
spinneret: s, beginning of intestine; t, anus; u, one of the cells composing
the intestine; v, vulva; w, egg, the spermatozoa "d" being outside of the egg
'''"; x, egg in synapsis ; y, vaginal glands ; z, ovum.
ONCHOLAIMELLUS, de Man, 1886.
Fig. 21. Oncholaimellus heterurus, n. sp. I, side view of head ; II, ven-
tral view of head; III, side view of tail end of male; IV, ventral view of
anal region of male.
a, excretory pore; b, submedian cephalic seta; c, pharynx; d, left flap
of bursa; e, oesophagus; /, left spiculum; g, accessory piece; h, amphid; ,
male post-anal seta and papilla; j, lateral seta; k, spinneret; I, thin lips.
FREE-LIVING FRESH-WATER NEMATODES
a
b
Fig. 18. Mesomermis virgimana, n. sp
Fig. 20. Monhys'tera sentiens, n. sp. Fig. 21. Oncholaimellus he ,n,
PLATE VI I. n " sp "
98 NORTH AMERICAN
PLATE VIII.
CEPHALOBUS, Bastian, 1865.
Fig. 22. Cephalobus sub-elongatus, n. sp. Lateral view of a female.
a, lips ; b, pharynx ; c, anterior portion of oesophagus ; d, posterior ex-
tremity of anterior portion of oesophagus; e, nerve-ring; /, cardiac bulb; g,
beginning of intestine ; h, one of the cells of the intestine ; i, lumen of the
intestine ; /, excretory pore ; k, cardiac valve ; I, renette cell ; m, flexure in
single ovary; n, cuticle; o, ovary; p, spermatozoon in uterus; q, vulva; r,
nucleus in ovum; s, body cavity; t, anus; u, ripe ovum; v, unripe ovum; w,
oocyte; x, blind end of ovary; y, rectum; z, terminus.
5k-
BASTIANA, de Man, 1876. %' ,
Fig. 23. Bastiana exilis, n. sp. Lateral view of a male specimen.
a, one of the six cephalic papillae; b, one of the posterior set of four
submedian cephalic setae ; c, one of the anterior set of six cephalic setae ; d,
oesophagus ; e, cervical seta ; /, amphid ; g, one of the cells of the intestine ;
h, one of the numerous male supplementary organs ; i, blind end of the two
testes; j, nerve-ring; k, posterior extremity of oesophagus, (pseudo-bulb);
/, left spiculum; m, cuticle; n, spermatozoon; o, anal muscle; p, treminus; q,
vas def erens ; r, intestine.
MESOMERMIS, Dady.
Figure 24. Mesomermis Virginia n. sp. Neck and head of the same
species shown in figure 18, showing how the deteriorated oesophagus changes
rather gradually into the intestine.
a, mouth-opening ; b, one of the anterior row of cephalic papillae ; c, one
of the posterior row of cephalic papillae; d, pharynx; e, exterior of amphid;
/, interior of amphid; g, oesophagus; h, innervated papilla; i, glandular
cephalic organs; j, nervering; k, lumen of oesophagus; /, intestine.
APHANOLAIMUS, de Man, 1880.
Fig. 25. Aphanolaimus spiriferus, n. sp. I, lateral view, anterior ex-
tremity of a female; II, lateral view, posterior extremity of a female; III,
lateral view of head, more highly magnified; IV, one of the male supple-
mentary organs ; V, lateral view of posterior extremity of male.
a, mouth opening ; b, amphid ; c, lumen of oesophagus ; d, pigmented eye-
spot (?); e, intestine; /, nerve-cell; g, rectum; h, nerve-ring; i, anus; k,
oesophagus ; /, caudal gland ; m, duct of one of the caudal glands ; n, gland-
ular body at base of neck; o, spinneret; p, ejaculatory duct; q, intestine; r,
anterior end of cloaca ; s, right spiculum ; t, backward pointing accessory
piece; u, nerve-cells (?) ; v, one of the numerous male supplementary organs.
FREE-LIVING FRESH-WATER NEMATODES
99
Fig. 22.
Cephalobus
subelongatus,
n. sp.
Fig. 24.
</ X *% ^
'MeTo'raermis virginiana, n. sp. Fig. 25. Alphanolaimus spiriferus, n. sp.
PLATE VIII.
THE
ASYMMETRY OF THE NEMATODE
Bunonema iiiequale, n.sp.
BY N. A. COBB
CONTRIBUTIONS TO A SCIENCE OF NEMATOLOGY, III
The genus Bunonema was established in 1905 by Dr. L. A. Jagers-
kiold for the reception of species from Kerguelen Island and from
the Schwarzwald. 1 Recently species belonging to this genus have
been found in Switzerland and examined by Dr. G. Steiner. 2
The present account deals with species found at Washington,
D. C., U. S. A., in the rotting wood of red oak. The specimens have
been examined with considerable care on account of their remarkable
asymmetry. It seems probable that this asymmetry is characteristic
of the genus. The following is an extended description of the generic
characters of Bunonema.
BUNONEMA Jagerskiold 1905
The rather thin layers of the transparent naked cuticle are tra-
versed by four hundred to five hundred transverse striae, rather diffi-
cult of resolution. In at least a part of the circumference the annules
are resolvable into dot-like elements, which apparently are the ends
of minute, radial, rod-like elements in the cuticle. These elements
are so arranged, at least on the right side of the body, as to give rise
to a tessellation, in the midst of which, on the lateral field, there is
usually a longitudinal series of tubercles of relatively large size, ar-
ranged in one or two rows, extending from near the head to near
the terminus. When two rows of tubercles are present, one or more
pairs at each end of the series are likely to be combined into a single
tubercle. When viewed en face the surface of these tubercles pre-
sents a punctate appearance, and their circumferences not infre-
quently show the presence of minute papilla-like elements, which do
not break the contour, but which appear to have passing to them,
from the body wall, linear elements, suggesting that the tubercles
are innervated. When seen in profile the tubercles appear to be made
1 "Bunonema richtersi, n. g., n. sp.," Zoologischer Anzeiger, 28 February, 1905.
2 "Freilebende Nematoden aus der Schweiz," Archiv fur Hydrobiologie und
Planktonkunde, 1913-14.
. 101
102 ASYMMETRY OF THE NEMATODE
of rods, or possibly laminae, corresponding in number with the annules
of the adjacent cuticle. The dot-like elements of the cuticle lose their
linear arrangement near the anterior extremity, where the somatic
cuticle joins the much thinner and more flexible cuticle of the head.
This junction is of such a nature that the lip region can be partially
withdrawn into the body cavity somewhat as into a shell. In other
words, where the somatic cuticle ceases, there is a rather distinct
shoulder and a rather rapid diminution in diameter to the base of the
lip region. The expanded lip region is thus set off by a very distinct
constriction. Apart from the transverse and punctate markings,
the cuticle is traversed by five distinct longitudinal wings, one lateral,
one ventral, one dorsal, and two left submedian. The existence of
each of these wings is indicated by the presence of their tw T o crenate re-
fractive margins, close together. These lines extend from near the
head to the anus, or beyond.
The posterior portion of the neck is more or less cylindroid, but
it becomes convex-conoid toward the truncated head, which bears in
the midst of the expanded lip region a somewhat depressed mouth
opening, surrounded by obscure, more or less amalgamated lips. There
are six inconspicuous, minute, innervated, more or less forward-point-
ing papillae, arranged in a rather asymmetrical fashion on the margin
of the head. There are six spreading, more or less curved, tapering
cephalic setae, arranged in an asymmetrical manner, the two largest
being apparently dextral, but possibly median, the two next smaller
left submedian, and the two smallest, which are in fact papilla-like,
right submedian. The longest of these setae are usually nearly as
long as the head is wide opposite the base of the pharynx. The setae
often present the peculiarity of being saccate at the base, more espe-
cially the largest ones. The more or less triquetrous, regular, narrow
pharynx is entered through a narrow vestibule, and has its walls rather
distinctly chitinized, so that it is a very distinct feature of the head.
There is no pharyngeal armature. No amphids have been seen, and
there are no eye-spots. The rhabditoid oesophagus has an ellipsoidal
median bulb, two-thirds as wide as the middle of the neck, and a pro-
late to pyriform cardiac bulb, two-thirds as wide as the base of the
neck. The lining of the oesophagus is a distinct feature throughout
its length, more particularly in its anterior half, where it is indi-
cated by refractive elements occupying a considerable portion of
the diameter. Both bulbs contain valves, that of the median bulb
being simple and elongated, that of the cardiac bulb more complicated.
BTJNONEMA INEQUALE 103
and three-parted, but destitute of striations. The more or less thin-
walled intestine, which is separated from the oesophagus by a very
distinct constriction, becomes at once about two-fifths as wide as
the body, and is made up of cells of such a size that about two are
required to complete its circumference. The lumen is often a dis-
tinct feature, on account of the refractive nature of the lining of the
intestine, and its zig-zag course indicates clearly the small number
of cells composing the circumference of the intestine. The intes-
tine often expands a short distance behind the cardiac collum, so
as to be two-thirds as wide as the bulb. The cells of the intestine
contain colorless, more or less scattered granules of variable size,
the largest of which have a diameter nearly equal to that of the pharynx,
the smallest of which are very much smaller. There is an indis-
tinct flattish cardia. There is no pre-rectum. The rectum is nar-
row and rather long and slender, usually about one and one-half times
as long as the anal body diameter. The anus of the female is usually
rather conspicuous, on account of the development of the anterior lip,
which in adults constitutes a flap extending backward over the anus
and outward from the surface of the body at a slight angle. This anal
flap is less pronounced in the young, and is almost altogether absent
in very young larvae. The tail begins to taper from some distance
in front of the anus, and is first convex-conoid and finally concave-
conoid, to the exceedingly acute, simple, unarmed, symmetrical ter-
minus. There is no spinneret, and there are no caudal glands, nor
have any definite lateral papillae, such as those of the female of Rhab-
ditis, been seen. The renette cell is probably located in the vicinity
of the cardia. The excretory pore occurs opposite the anterior por-
tion of the cardiac bulb, and usually empties on the right side of the
ventral wing. The rather inconspicuous nerve ring surrounds the
oesophagus somewhat obliquely. From the fairly well-developed
vulva the vagina leads inward at right angles to the ventral surface
about two-fifths the distance across the body, where it joins the two
symmetrically placed uteri, each of which is fully as long as the body
is wide. The reflexed ovaries extend back toward the vulva. The
eggs are of such a size that each uterus probably will hold only one
at a time. They appear usually to be about as long as the body is
wide, and about two-thirds as wide as long. The tail of the male has
the same general form as that of the female, but is characterized by
the development of the cuticle into a very rudimentary bursa. The
two equal, simple, frail, sub-arcuate, relatively long and slender, acute
104 ASYMMETRY OF THE NEMATODE
spicula are usually about two and one-half times as long as the anal
body diameter, and are accompanied by an accessory piece about
half as long, and arranged parallel to them. The spicula are more
or less cephalated by expansion. The accessory piece is usually quite
as conspicuous a feature as the spicula, since it is often slightly colored,
while the spicula are colorless. The male papillae are reminiscent of
those of Cephalobus. In the only males examined there appear to be
eight somewhat asymmetrically placed pairs, one pair opposite the
anus, two pre-anal, and five post-anal. These papillae are flattish,
innervated, minute, and inconspicuous.
The young larvae of Bunonema do not bear tubercles. On the
species that bear them the tubercles become permanent elevations dur-
ing the last two moults. Just previous to the final moult they ap-
pear to be smaller and simpler than when fully developed. There is
little if any evidence on the right side of very young larvae of the very
remarkable transformation which is to take place in the course of growth ;
the cuticle differs from that of the left side so little that it is only by
careful scrutiny that the differences can be detected. There are no
reticulations and there is very little evidence of punctation. Previous
to the two last moults the cuticle of the right side is differentiated from
that of the left to a greater or less extent. Probably at the first moult,
the dexter cuticle becomes slightly thicker and almost imperceptibly
colored. The anal flap does not exist, or at least is in no wise promi-
nent, on young larvae. The cephalic setae and other cephalic organs
are neither so strongly developed, nor so complicated, on the larvae as
on the adults.
When a specimen of Bunonema is mounted in water, with just suffi-
cient space between the coverglass and the slide for the nematode to
move about freely and without friction, it is seen to have the charac-
teristic movement of nematodes, that is to say, the normal flexures
of the body are in the dorso-ventral plane. This brings the tubercles
either squarely toward the observer, or squarely on the far side of
the body. At the same time the excretory pore, the anus and the vulva
come into exact profile.
In manipulating specimens on the microscope slides it sometimes
happens that a tubercle is torn loose, and in such cases the tubercle
often comes off entire, as if there existed a definite junction along its
periphery, or at least as if the peripheral attachment were weak.
Such losses may in part account for the occasional irregular arrange-
ment of the tubercles. Specimens are not infrequently seen in which
BUNONEMA INEQUALE 105
one member of a pair of tubercles is missing, or where one member
of a moniliform series appears to be missing, and the natural inference
is that such tubercles never existed. This inference may, however,
be incorrect, as there is very little evidence left to tell of the acci-
dental removal of a tubercle; no very definite scar remains to tell
the tale.
Bunonema can exert suction so as to attach itself by the aid of its
lips even to smooth surfaces like glass. Specimens sometimes may
be seen to attach themselves firmly by the head, and to wave back
and forth through the water in which they are mounted.
It is clear that Bunonema is cloeely related to Rhabditis. This
is shown by the structure of the pharynx, oesophagus, intestine, ex-
cretory system, and sexual organs. With reference to these latter,
there is the difference that in Bunonema the bursa is rudimentary
and the male papillae reduced in size so as to resemble those of
Cephalobus. Bunonema appears therefore to be related to Cephalobus,
especially that group of Cephalobi in which the labial structures are
somewhat elaborate.
The most obvious source of food for the species of Bunonema here
described is the mycelium of wood-infesting fungi, which is abundant
in the cells of the rotting wood inhabited by the Bunonema. It may
be that the peculiar modifications of the cuticle are triturating organs
enabling the nematodes to break down the walls of fungus mycelium
and so obtain the contents of the mycelial cells with greater ease.
No organized food has been seen in the intestine of Bunonema, but
occasionally granules have been seen that resembled those of the cell
contents of the fungi.
DESCRIPTIONS OF THE SPECIES
4.2 16. 23. '57. '29. 94.
1. Bunonema inequale, n. sp. 3^7 5^2 iu) 7~i 27e ' ' The cuticle of
about three-fourths of the right side of the body presents a rudely hexagonal
network or tessellation. The meshes of this network are of variable size, those
nearest the dorsal and ventral lines being the smaller. The division lines of
the tessellation of the cuticle are due to the peculiar arrangement of the minute
strongly refractive cuticular elements into which portions of the transverse striae
are resolvable. The tessellation becomes much finer toward the extremities of
the body, where the dot-like refractive elements are no longer arranged regularly.
Thence onward toward the extremities the cuticle is not striated and is more
nearly colorless, and very transparent.
Opposite the right lateral line there is a very prominent single series of slightly
yellowish, relatively large, projecting, cushion-shaped, striated, chitinous ap-
106 ASYMMETRY OF THE NEMATODE
pendages or tubercles, which through the middle of the body are about half as
high as they are wide. The tubercles are of rounded or ellipsoidal form, and
when seen en face sometimes show on their punctate surface the presence of three,
four, five, or more exceedingly minute papilla-like elements encircling the axis of
the appendage, this axis of course being radial and perpendicular to the surface
of the body. In the specimen from which the description was derived, which
appeared to be an average female about to undergo the final moult, there were
sixteen of these appendages, forming a dextral row extending from the lips to
near the anus. Those near the ends of the series were smaller than those near
the middle, that on the lips being the smallest of all. Throughout the middle
portion of the body the tubercles are of rather uniform size. Anteriorly they be-
gin to diminish in size near the base of the neck, so that the bluntly conoid tu-
bercle opposite the base of the pharynx has a diameter only one-third as great as
that of the one near the middle of the body. The posterior tubercle, near the
anus, is of about the same size as that opposite the base of the pharynx. When
seen in profile, that is, when the nematode is viewed dorso-ventrally, the tubercles
exhibit somewhat the same degree of striation as the adjacent cuticle, but the
striae, or elements thereof, appear as if arranged in a somewhat fan-shaped man-
ner. When the body is arcuate and twisted, so that the row of appendages is on
the outside of the curve, the distance between the appendages at the middle of
the body nearly equals the diameter of one of the appendages. When the body
is curved in the other direction, the tubercles may be nearly in contact. The ex-
terior of the tubercular appendages is distinctly striated, and sometimes tessel-
lated, the striae being of about the same size and nature as those of the rest of
the cuticle.
The following is a detailed description of these interesting tubercles as they
occurred on an adult male specimen fixed in Fleming's solution, and examined
soon afterward in water. The specimen was arcuate and the tubercles were on
the inside of the curve. The first or labial tubercle, standing halfway between
the two relatively large and apparently dextral submedian cephalic setae, ap-
peared somewhat thumb-shaped in contour, and when seen in optical section
seemed to have a refractive chitinous core of a slightly greenish color. This tu-
bercle was arcuate, and its apex was turned outward so as to be nearly at right
angles to the body axis. The second tubercle, slightly behind the base of the
pharynx, was bluntly conoid, the longitudinal optical section being approxi-
mately equilateral. The cap or outer half of the cone was a grayish green refrac-
tive chitinous element, whose structure showed comparatively little detail. The
contour of this cap when seen in optical longitudinal section indicated the pres-
ence of a slight constriction half way between its apex and its base. Inside the
cap the tubercle appeared as if radially striated, the number of striae being about
ten. As these striae appeared to be more or less visible in every longitudinal op-
tical section,it would seem as if they must be the optical expression of a columnar
or laminated structure. When the tubercles were viewed in longitudinal optical
section, the intermediate somatic cuticle, that is the cuticle between successive
tubercles, presented refractive features related to the tessellation so strikingly
displayed when the animal is viewed from the right side. The plainer or less
complicated portions of the cuticle, as thus seen in longitudinal section, repre-
sent the "lacunae" of the tessellation, while the refractive places represent the
BUNONEMA INEQUALE
107
Fig. 1. Bunonema inequale,
n. sp. I, ventral view of male;
//, ventral view of the head of
larva; ///, IV, V, ventral, front
and lateral views of the head of
adult specimens; the three fig-
ures are derived from three dif-
ferent specimens; VI, lateral
view of tail end of the male;
VII, cross-section taken near the
middle of the body and pass-
ing through one of the tubercles;
VIII, ventral surface view of a
segment of the body, showing
details of the tessellation, rod-
like structures, tubercle and
subtubercles.
Nearly all the figures illus-
trate the remarkableasymmetry
of Bunonema, but this feature is
most noticeable in figures I, III,
IV and VII.
a, forward projecting mem-
brane half encircling the
mouth-opening on the right side
of the front of the head; fc, dcx-
tral sub-median (?) cephalic
seta; c, labial tubercle; d, one
of the two left-hand sub-median
cephalic setae; e, pharynx; /,
anterior border of the dextra!
cuticular armament; g, mem-
bers of the dextral series of tuber-
cles; h, one of the subtubercles;
t, repetitive elements connected
with the large median (?) cephalic
setae; j, saccate base of one of
the largest setae; k, nerve ring;
I, excretory pore; m, cardiac
bulb; n, border of the dextral
cuticular armament; o, median
wing; p, reflexed blind end of
the single testis; q, spicula; r,
anterior pair of male papillae;
s, right hand member of the
second pair ot male papillae; t,
accessory piece; u, right hand
member of the third pair of
male papillae; , fourth pair of
male papillae; u, right hand
member of the fifth pair of male
papillae; x, sixth and seventh
pairs of male papillae, dorsaliy
submedian; y, hindermost pair
of male papillae subventral;
z, terminus, from which the pos-
terior end of the cuticular arma-
ment is separated by a furca-
tion.
108 ASYMMETRY OF THE NEMATODE
elements composing the net. There were about five of these refractive places
between the second and third tubercles, four between the third and fourth, two
between the fourth and fifth, and fifth and sixth, these numbers corresponding to
the increasing coarseness of the tessellation on the posterior part of the neck.
The third tubercle had the form of a truncated cone. It was a little higher
than the second, and the sides of the cone .were somewhat steeper. It had a chi-
tinous cap like that of the second tubercle but truncated, and the outer surface
of this cap bore on its margin exceedingly minute, round, flatish sub-tubercles
perhaps four only so arranged that in optical section the middle of the face
of the tubercle appeared almost imperceptibly depressed. The chitinous cap
was also hollowed on its inner concave face, the depth of the excavation being
about three-fifths the entire depth of the cap. This tubercle was also columnar
in structure, the number of elements appearing in the optical section being
slightly greater than in number two, perhaps 12. Tubercle number four was
shaped very much like number three, but was a little more rounded on its exterior
surface, so that the entire tubercle in optical section presented a rounded contour ;
its cap being about as thin as that of number three, but extending farther over
the surface of the tubercle, extending in fact, nearly to the general body surface.
The internal structure was like that in numbers two and three, except that the
number of elements was slightly greater, and the outer elements were spread
apart as they extended outward, so that the striation appeared somewhat fan-
shaped. This fourth tubercle stood half way between the median and cardiac
bulbs, and its surface bore the same kind of minute subsidiary surface tubercles
as were noted on the third. The number of these subsidiary tubercles was slightly
greater on the fourth than on the third; there appeared to be at least five or six
of them. The fifth tubercle was very much like the fourth, but slightly smaller,
and also bore the minute subsidiary surface tubercles mentioned in connection
with the third and fourth, but fewer of them, in fact there was perhaps only one.
The sixth tubercle was somewhat asymmetrical in optical section, wider than
any of the preceding, and composed of a greater number of elements. Its chi-
tinous cap was slightly thinner than that of number five, just as that of number
five was slightly thinner than that of number four. This tubercle was located
opposite the anterior portion of the intestine. It remained uncertain whether
this sixth tubercle bore any of the minute subsidiary surface tubercles. The
columnar structure of the third, fourth and fifth tubercles, especially the two
former, did not appear to be absolutely uniform, and it seemed likely that this
lack of uniformity was due to the optical effect of special elements passing radi-
ally through the tubercle to the minute subtuberclcs, and suggested the possi-
bility of the presence in the tubercles of nerve elements connected with the small
subsidiary tubercles. From the sixth onward the tubercles were of varying size,
sometimes a little smaller than number five, sometimes as large as number six,
the six or seven along the middle portion of the body tending to be smaller, and
two or three in the proximity of the spicula tending to be larger. The chitinous
caps were less pronounced through the middle of the body and, on account of
their retractive properties, appeared merely as an accentuated contour; that is
to say, when seen in exact optical longitudinal section the chitinous covering
gave rise to a sharp dark contour, which contrasted strongly with the contour pro-
duced by the corresponding portion of the somatic cuticle between the tubercles.
BUNONEMA INEQUALE 109
Through the middle of the body the tubercles showed an obscure tendency to
group themselves in twos.
Starting now at the other end of the body, the hindermost tubercle was a
broad flattish and rather inconspicuous affair, whose contour did not differ very
much from that of the remainder of the cuticle on the right side of the tail. This
posterior tubercle lay slightly in front of the anus. The penultimate and ante-
penultimate tubercles were rounded and closely resembled the majority of the
middle members of the series, though they differed in presenting more clearly
the subordinate minute tubercles on their surfaces. Here too, in some cases, it
was possible to demonstrate the presence of refractive elements perhaps nerve'
elements passing to the subsidiary tubercles. Behind the flattish posterior
tubercle the general character of the cuticle of the right side was maintained to
near the terminus, and the arrangement was such that the posterior extremity
appeared as if somewhat unequally bifurcated, one fork being the terminus
proper, that is, the end of the tail, the other being the slightly arcuate out-
turned loose terminal portion of the dexter cuticular armament.
The lip region is a rather prominently expanded markedly asymmetrical struct-
ure. The flexibility of the neck enables the lip region to be swung with com-
parative rapidity back and forth through an angle of nearly ninety degrees.
There are six tapering, spreading, nearly straight cephalic setae, arranged in
very unequal pairs, a left submedian slender pair, one dorsally submedian, the
other ventrally submedian ; a large pair, correspondingly arranged, but extending
in the opposite direction, thus appearing to be right submedian; and a very small
right submedian pair. The members of the large pair are two to three times as
long as those of the left hand pair; these latter being about one-third as long as
the pharynx, whereas the former are more than halt as long as the pharnyx.
The right submedian setae are reduced and papilla-like. Each of these six setae
has a swollen or even bladder-like base, which is very much more pronounced in
the case of the largest setae. The dexter labial tubercle is located between the
two small right-hand setae. Between these latter and the larger setae there
may usually be seen two or three exceedingly delicate refractive elements some-
what suggestive of the repetitive elements in the nematode genus Wilsonemq;
these are beyond question connected with the largest setae. Between the left
submedian setae, that is to say, on the left lateral line, careful focusing shows in
the optical longitudinal section of the head what appears to be a minute pore,
ending in a depression on the outer surface of a minute labial elevation. On
each side of this "pore" are two minute papillae, corresponding to two similar
ones on the right side of the head. Between the left-hand setae and papillae
and the border of the mouth opening, there is a thin semi-circular, curved, pro-
jecting oral membrane, extending forward and outward. This membrane is wid-
est, that is, extends farthest forward, in the lateral region, and at this point its
altitude is somewhat less than the length of the left-hand setae. At their bases,
which are relatively broad, the setae are inflated, more especially the largest ones,
and are so set on the margin of the head that their proximal parts produce a very
pronounced shoulder. The rather narrow triquetrous pharynx, which ends
abruptly at the base, is of equal diameter throughout, and has a length about
equal to the diameter of the head measured opposite its base; it is entered through
a rather narrow mouth opening. The anterior end of the oesophagus receives the
110 ASYMMETRY OF THE NEMATODE
base of the pharynx. The oesophagus begins as a tube about half as wide as the
corresponding portion of the neck. It continues to have this diameter, or a
slightly greater, until near the middle of the neck it expands to form the median
swelling, which is nearly two-thirds as wide as the corresponding portion of the
neck, and has a distinct, simple, elongated, chitinous valvular apparatus, the
length of which is nearly equal to the corresponding radius of the neck. Behind
this bulb the oesophagus diminishes suddenly in diameter so that it is only one-
fourth as wide as the corresponding portion of the neck. It finally expands to
form the pyriform cardiac bulb, which is tw r o-thirds as wide as the base of the
neck, and contains a distinct, three-fold, more or less complicated, non-striated
valvular apparatus. The intestine becomes at once three-fourths as wide as the
body. There is an obscure flattish cardia a little more than one-third as wide as
the corresponding portion of the body. The cells of the intestine contain a few
scattered granules of variable size, the largest of which, fatty granules, are rela-
tively large and have a diameter nearly equaling that of the pharynx; the small-
est, probably of another character, being very much smaller. They are less
numerous and smaller toward the posterior part of the intestine. Xo doubly re-
fractive granules have been seen. The lining of the intestine is somewhat re-
fractive, so that, especially toward the middle of the body, the sinuous lumen is
often quite a distinct feature. The excretory pore is somewhat behind the middle
of the neck. The tail end begins to taper from some distance in front of the
anus, and tapers at about the same rate until after it passes the anus, where it
soon begins to taper more rapidly, so that the posterior somewhat concave conoid
half of the tail is relatively narrow, and the terminus itself hairfine. The diame-
ter of the tail at the middle is about one-sixth as great as at the anus. From the
rather prominent, salient, two-lipped vulva the vagina leads inward at right
angles to the ventral surface nearly halfway across the body. A mature ovum
is about as long as the body is wide, and fully one-third as wide as long, and there-
fore of such a size as to indicate that each uterus can probably contain only one
egg at a time.
5.3 19. 28. 'M 45 - 88.
4.4 5.5 6.3 6.5 4.8 ' The tail of the male is like that of his mate
in form and size, though it tapers more regularly. The two equal, uniform, long
and very slender, slightly arcuate, colorless, inconspicuous spicula are about two
and one-half times as long as the anal body diameter. Their proximal ends are
slightly cephalated by expansion. They are accompanied by a more plainly visi-
ble, simple, somewhat wider, slightly colored accessory piece w r hich is nearly
straight, and about half as long as themselves. Springing from a little in front
of the anus there is a very weakly developed or rudimentary almost invisible
bursa, whose somewhat asymmetrically arranged ribs or papillae, difficult of
observation, are located as follows :
Almost exactly on the ventral line, in front of the anus, at a distance from it
equal to the corresponding body diameter, there is a circular marking (r, Fig.
1), which is larger than any other marking of this character, and seems to repre-
sent one of the male papillae. To the right of it, and a trifle behind it, rather
nearer the right submedian line, is another papilla of similar character, slightly
smaller. Opposite the anus, on the left submedian line, there is a small papilla;
the mate of this on the right submedian line (M), seems to be in the border of the
BUNONEMA IMPAR HI
thickened dexter cuticle, and is a little larger. Slightly in front of the anus,
and near the median line, both on the left and on the right, there is a papilla (s),
that on the right being a little the larger, and not quite so near the median line,
but still outside the dexter cuticle. A little behind the middle of the tail there
is a submedian pair (<;), of which the right hand one is in the edge of the thick-
ened dexter cuticle, while the left hand one is very inconspicuous and somewhat
farther forward. Considerably farther back there is a group of about eight
papillae, (w, x, y), arranged in four pairs, some of which are exceedingly obscure.
The anterior pair, (w), is ventrally submedian. This pair is followed by two dor-
sally submedian pairs, (x), nearly opposite to which is a ventral pair, (y), one
nearly in front of the other. It will be noted that these supplementary organs
are arranged much as in some species of Cephalobus.
The ejaculatory duct is about two-fifths as wide as the body. It has the
same width as the single testis, whose reflexed blind end is located not far behind
the base of the oesophagus, and extends backward a distance about equal to the
length of the body diameter.
Habitat. Found in the rotting wood of red oak, Washington, D. C., by Dr.
Howard Crawley.
5.3 18. 26. 'M58. 90.
2. Bunonema impar, n. sp. sTs <U <Ti T! si ' 32 mm ' On the right hand
side there are two rows of yellowish tubercles, each row consisting of about
eighteen to twenty members. The lip region bears a somewhat thumb-shaped
lateral, more or less forward-pointing, protuberance which is probably homolo-
gous with the dextral tubercles. Opposite the base of the pharynx is a single
tubercle, the first genuine pair of the lateral series being a little in front of the
median bulb; thence backward all the tubercles are in somewhat irregular pairs,
except one or two of those near the tail end. The members of each pair are placed
side by side. These tubercles are rounded elevations having a height about
equal to the width of eight of the annules of the cuticle. When the nematode is
in a straightened-out attitude the distance between the pairs of tubercles is
about equal to their width. The posterior tubercles tend to run together, and
are slightly lower and flatter than the anterior. The anterior tubercles, especi-
ally those on the neck, are capped with slightly thickened, rather uniform chitin,
which bears extremely minute markings similar to those noted on Bunonema
inequale. The face of the tubercles appears punctate, though on focusing deeper
they appear striated. The lip region is very similar to that of Bunonema inequale.
The largest setae are of about the same size and proportions as in inequale, as
are also the ventrally submedian setae, though the latter are hardly inclined to
be inflated at the base. Between the papillae there seem to be structures very
similar to those of inequale. When seen from the right side the adjacent lip region
presents the following appearances: the two setae with saccate bases appear to
be nearly at right angles to each other, and have their tips located at a distance
from each other equal to the length of the pharynx. Each of these setae is about
three-fourths as long as the chitinous portion of the pharynx. Between these
two setae is the very pronounced, concave-conoid, blunt, rather forward-point-
ing, almost thumb-shaped protuberance already mentioned, which is probably
homologous with the lateral tubercles, though it presents little or none of the
brownish or yellowish coloration characteristic of the tubercles. On each side
112 ASYMMETRY OF THE NEMATODE
of this lateral protuberance there is a rounded innervated papilla, which breaks
the contour of the curved line between the protuberance and the adjacent seta.
On the lateral line opposite the base of the protuberance there seems to be a
third papilla of the same character as the two last described. The head is sepa-
rated from the neck by a very distinct constriction. Where the somatic cuticle
ends, a little in tront of the middle of the pharynx, there is a rather distinct
shoulder, and from this shoulder the diameter decreases rapidly to the base of
the lips opposite the anterior end of the chitinous portion of the pharynx. Here
the diameter is only about three-fifths as great as at the shoulder before men-
tioned. The saccate basal portions of the large apparently dextral setae extend
backward somewhat from the collum or constriction separating the lip region
from the neck. Viewed from the left side the left submedian setae are' seen to
be not inflated at the base. Three labial papillae are also to be seen from this
side, one lateral and two submedian. These, together with those seen on the
right side, complete the complement of six minute and very inconspicuous labial
papillae encircling the head. Th,ere is no forward-pointing thin semicircular
border to the mouth opening, as in inequale. The pharynx is triquetrous, and
about as long as the posterior bulb, or a little longer, in other words about one
and one-third times as long as the diameter of the head measured opposite the
base of the pharynx. As seen in optical longitudinal section the pharynx is about
one-sixth to one-eighth as wide as long. Its cross-section is somewhat similar
to that of the oesophagus; in other words, it is not prismoid, and yet is more or
less triquetrous; each of the angles is composed of a thin, refractive, simple, chi-
tinous element. The mouth opening is hardly wider than the pharynx. There
are one or two innervated papillae on the dorsal side of the tail near the rectum.
Nothing is known concerning the female sexual organs, but from the rudiments
seen in male specimens which probably have yet to undergo a final moult, it seems
clear that the testis is single and has its blind end reflexed a distance about equal
to the diameter of the body.
Habitat. Found with Bunonema inequale in the rotting wood of red oak.
Bunonema impar is very closely related to Bunonema inequale, and may indeed
prove to be merely a variety of that species.
3. Bunonema dactylicum, n. sp. Species with about the same dimensions and
form as the two preceding. As only the young forms have been seen it remains
somewhat uncertain whether the thickened dextral cuticle
bears tubercles, but i1 is believed not. The cuticle is tessel-
lated and striated as in the first species described. The two
large saccate setae are arranged very much as in B. inequale,
and there is a dextral labial "tubercle" as in that species.
The left submedian appendages are palmate, as shown in
Figure 2, and have about five finger-shaped processes. In-
side the saccate setae is a forward-pointing, more slender
pair of equal length.
Head of Habitat. Found in the rotting wood of red oak, with the
n a dactylicum, two preceding, Washington, D. C., U. S. A.
n. sp.
May, 1915
SELACHINEMA
A NEW NEMATODE GENUS WITH REMARKABLE
MANDIBLES.
BY N. A. COBB
CONTRIBUTIONS TO A SCIENCE OF NEMATOLOGY, IV
SELACHINEMA, new genus.
Body slender; cuticle finely transversely striated; head armed with
powerful non-retractile dentate chitinous mandibles; amphids spiral;
tail armed with caudal glands and spinneret; oesophagus plain; renette
present; minute pores on the lateral lines.
3.7
9.0
8.1
49Y
89.
T.2
Selachinema ferox, n. g., n. sp. 3.1 3.1 3.1 3.4 2.2 " The rather thin
layers of the transparent, practically naked cuticle are traversed by exceedingly
fine transverse striae resolvable
only with the aid of the highest
powers under favorable condi-
tions. Only a very few minute
hairs, hardly more than twice
as long as the cuticle is thick are
to be found on the body. The
cylindroid neck ends in a head
which diminishes in size very
slightly just beyond the am-
; phids, and bears three (?) large,
solid, slightly inwardly arcuate,
projecting, powerful chitinous
jaws armed on the inner surface
with four longitudinal rows of
somewhat backward pointing
conical teeth, each row consist-
ing of four or five teeth. Each
f of the two submedian jaws is
composed of two parts of une-
qual size, that toward the dor-
sal side being the shorter, and
armed with two rows of teeth
Fig. 1. Selachinema ferox, n.g., n.sp. a, the two power- .
ful submedian chitinous jaws, each armed with tour rows of OI about equal Size, Whllje one
retrorse teeth ; b, rudiment or remnant ot ventral jaw; c, lateral f ., . rr . wa nn tv, p othpr
setae (restoration) ; rf. submedian setae (restoration)-behind ' tn e two TOWS on tne Otner
may be seen two ot the tour small subceohalic setae; e, spiral na lf o f the mandible is COm-
amphids; /, base ot the pharynx. The head is a correct cam-
era lucida drawing. The body and tail have been drawn in posed of exceedingly minute
perspective dotations. Between the two
113
114 SELACHINEMA
unequal halves of the mandible is a thin, arcuate, toothless element, which ends in
an incurved point forming the distal end of the mandible. The chitinous project-
ing portion of these jaws is slightly inwardly arcuate: Each jaw is somewhat
longer than the head is wide, although the projecting portion is only about half as
long as the head is wide. These jaws are permanently extended, and cannot be
withdrawn into the pharynx. They are used in a manner somewhat like that of
the projecting mandibles of certain insects. It appears as if a dorsal jaw or
mandible had been broken away from the only specimen so far seen a young one.
There is a circlet of cephalic setae opposite the base of the chitinous, extended por-
tion of the jaws. There are six of these setae in one circlet, and behind each of
the submedian setae of this circlet there is a smaller seta slightly farther back so
that the total number of the cephalic setae may be said to be ten. The length of
the six main setae is unknown, as they are all broken away from the only specimen
hitherto seen. A restoration of these six main setae is attempted in the illustra-
tion; hence these setae are shown by means of dotted lines. The spiral amphids
consist of about three and one-half winds, and are nearly half as wide as the head,
and are placed opposite the base of the pharynx, their anterior borders being
about half as far from the anterior extremity as are the bases of the before-men-
tioned naked chitinous portions of the jaws. There are no eye-spots. The phar-
ynx is of the form consonant with the strongly developed jaws, that is to say, it
is triangularly concave-pyramidal. Its base is rather plainly indicated by the
proximal ends of the chitinous roots of the jaws, and lies opposite the posterior
borders of the amphids. The oesophagus begins as a tube about two-fifths as
wide as the base of the head, and continues to have this diameter throughout the
greater portion of its length. It is separated from the oesophagus by a constric-
tion. There is no bulb and there does not appear to be any distinct cardia. The
intestine, which is made up of cells of such a size that probably four to six are
required to build a circumference, is rather thick-walled. The small granules in
the cells are of rather uniform size, and do not give rise to any distinct tessella-
tion. The rectum appears to be shorter than the anal body diameter. The
tail is convex-conoid in the anterior part in such fashion that at a distance from
the anus at least as great as the anal body diameter, it has diminished so that it
is only about one-eighth as wide as at the anus. Thence onward it is nearly
cylindroid, although it still diminishes slightly in diameter. It ends in a slightly
swollen terminus bearing a slightly elongated, plain, unarmed spinneret. It
seems likely that the tail is prehensile. The caudal glands are located in the
vicinity of the anus. The renette cell lies opposite the cardiac constriction, and
is somewhat dumbbell shaped, and placed transversely; the slender duct leads
forward from it, and connects with the prominent pyriform ampulla, which is
one-fourth as wide as the corresponding portion of the neck, and this in turn
leads to the excretory pore near by, opposite the nerve-ring. This latter sur-
rounds the oesophagus somewhat squarely. In front of the exceedingly incon-
spicuous anus there are two lateral rows of seven or eight minute, equidistant
pores. These occupy a space about equal to twice the length of the corresponding
body diameter. The distance between these small circular organs is three to
four times as great as the diameter of one of them. They appear merely to
penetrate the cuticle, so that the extejit of their chitinous outlines in a radial
direction is about equal to their width. There are three or four similar pores on
A NEW NEMATODE GENUS 115
each lateral line opposite the posterior end of the oesophagus, occupying a dis-
tance equal to the body radius. Nothing is known concerning the sexual organs,
as the description is derived from a single immature specimen.
Habitat. Found on calcareous algae, near low-tide mark, Colon, Panama;
where it was feeding on other nematodes.
Selachinema seems without doubt to belong to the family Enoplidae,
which may now be defined as follows: Free-living, marine, carnivorous
nematodes with three mandibles; head armed with setae and papillae;
body naked; cuticle transversely striated, sometimes also obliquely
striated; oesophagus plain; intestine with a variety of well-developed
specialized cells indicating definite division of digestive functions;
renette and caudal glands present ; male and female sexual organs double,
spicula two, equal; amphids usually small, inconspicuous, oval or spiral.
The following genera may be included in the family: 1. Demonema,
Cobb 2. Enoploides, Ssaweljev 3. Enoplolaimus, de Man 4. Eno-
plus, Dujardin type genus 5. Labyrinthostoma, Cobb 6. Selachi-
nema, Cobb 7. Triodontolaimus, de Man.
The sub-family Enoplinae should contain Enoplus, Enoplolaimus,
Enoploides and Labyrinthostoma; the sub-family Selachineminae, Se-
lachinema. Demonema and Triodontolaimus probably represent dis-
tinct sub-families. There is probably confusion of characters in
Enoplolaimus, Enoploides and Labyrinthostoma, and it may become
necessary to rearrange the species now included under these generic
names.
Enoplidae occur in all parts of the world, the following being the
present known geographical distribution of the various genera.
Demonema Italy, California Labyrinthostoma Ceylon
Enoploides . . Arctic, Massachusetts Selachinema Panama (Colon)
Enoplolaimus Cosmopolitan Triodontolaimus .English Channel
Enoplus Cosmopolitan
Demonema, Enoplus and Selachinema all contain species known to
devour other nematodes. The granules in the intestinal cells of the
Enoplidae give rise to the rather distinctly tessellated appearance which
I have observed to be more or less characteristic of the free-living
nematodes which feed upon animal organisms, or at least those which
feed in whole, or in part, upon other nematodes. The following de-
scription, derived from the examination of an Enoplus whose intestine
1 16 SELACHINEMA
contained nematode remains, indicates characteristics of these carniv-
orous species.
The cells of the intestine, separated from each other by thin refrac-
tive walls, had the form of rather regular polyhedrons, and each con-
tained a distinct subspherical nucleus having a diameter about one-
third as great as that of the cell itself. This nucleus was supplied
with a distinct nucleolus. Between its nucleus and the wall each cell
contained a large number of brownish-yellow spherical granules of
somewhat variable size, the largest having a diameter , one-fourth to
one-fifth as great as that of the nucleus, and the smaller varying from
this size downward. These granules had a tendency to gather next
to the intestinal lumen. The nucleus, therefore, lay nearer the outer
surface of the intestine than the inner. In the anterior part of the
intestine all the cells except the cardiac cells had the same character.
Through the middle of the body the intestinal cells varied from those
in the anterior part of the body in that the granules were somewhat
smaller, and less numerous, so that the clear spaces in the cells had
relatively greater volume. Behind the middle of the body certain of
the cells constituting the wall of the intestine were markedly different
from those just described, although these latter continued to consti-
tute the main portion of the intestinal wall. These markedly differ-
entiated cells were twice as large as the others and contained larger-
granules of more uniform size. One of these larger cells may be most
advantageously examined when it occurs opposite the lateral field,
where the refractions due to the muscular cells of the body wall do
not interfere with the view. It may then be seen to have an elliptical
contour, at least when seen face view, and to contain a nucleus half as
wide as itself. The nucleus in turn contains a nucleolus having a
diameter one-third as great as its own. The total number of granules
in one of these giant cells was between 50 and 100, and owing to the
relatively large size of the nucleus they were located more particularly
toward the ends of the cell. The granules were of rather uniform
size and had a diameter about twice as great as that of the largest
granules in the ordinary intestinal cells. There were 20 to 30 of these
scattered giant cells in the posterior fourth of the intestine.
May, 1915
NOTES ON NEMAS*
(1) Segmentation of Their Organs, Illustrated by three new free-living marine
genera. (2) Intravitam Color Reactions, (3) the Nema population of Beach
Sand, (4) Locational Terms for the Cytology of Descent, and
(5) Functions of the Amphids.
By N. A. COBB
CONTRIBUTIONS TO A SCIENCE OP NEMATOLOGY V
1
SEGMENTATION IN NEMATODES
OBSERVATIONS BEARING ON THE UNSETTLED QUESTION OF THE
RELATIONSHIP OF NEMATODES TO OTHER BRANCHES OF
THE ANIMAL KINGDOM
I have long been impressed by certain evidences of segmentation
in nematodes. My first impressions arose from a study of the dis-
tribution of the setae on aquatic forms. This distribution was in
those days, and is even yet, described as irregular; the setae are said to
be "scattered" on the body. Charting all the setae on a given speci-
men led to the conclusion that they were not scattered (" zerstreut") ;
that, rather on the contrary, they constituted a series of more or less
harmonious groups. The cephalic setae, it is well known, have an
orderly arrangement. The study of a large number of cases leads me
to the conclusion that those setae, some distance behind the cephalic
setae, denominated subcephalic setae, are also orderly in arrangement,
and might, in some instances at least, be regarded as repetitive of the
cephalic setae.
Later I was able to show that the transverse striae of the cuticle
are retrorse on the posterior half of the body, and the reverse on the
front half. (See Fig. 1.)
This reversal in the cuticle
at the middle of the body,
Or thereabouts, OCCUrS in Fig. 1. Diagram of the reversal of the striae of the cuticle
., .. of a nematode. The reversal is shown just above the letter F.
a very wide range of gen-
era, is independent of age and of sex, and seems a character of funda-
mental significance.
Waverly Press, Baltimore, May 8, 1917.
117
118
NOTES OX XEMAS
Recently I have discovered that the principal cephalic organs are
made up of segments which, while simple in character, bear no small re-
semblance to correspond-
ing features in segmented
organisms. The nature of
these segmented append-
ages will be more easily
understood by consulting
the illustrations in Fig. 2.
The articulations in the
TJ&&KS25^^ cephalic organs of nemas
are not easy to discover,
owing to the small size of the organs and the transparency of the tissues.
Some of these segmented organs are under muscular control, and can
be extended and inflexed.
This is true of some of the setcphyntr [ (| set Jit /] J set /pli t'xt
labial organs, which un-
fortunately are usually so
small as to be difficult to
observe. The cephalic
setae, however, are larger,
being particularly well de-
veloped on some marine
forms, and in this case ob-
servation on living speci-
mens affords evidence of
the articulations when they
might be overlooked if
they were sought by other
methods; for if a seta is
obstructed it takes on the
attitude natural to an or-
gan composed of flexible
joints and more or less in-
flexible segments, as shown
in the upper illustration,
.g., n.sp., a nema with
bling Cyatholaimus, but
. Fig. 3. Pomponema mirabile n
Jig. 2. Here again, Once jointed cephalic organs, and resem
with 3 onchi, more complicated amphids, long, jointed,
labial palps, wings as in Spilophora, spicula as in Cyatholaim-
us, with 20 chromadoroid, male supplementary organs.
Characters of P. mirabile, type species, given in the illustra-
tions and formula.
.
having established the fact
and learned hOW tO make
. . . .
the observations, it proves
that the setae of a wide range of genera are jointed, though the
number of segments is often reduced to only one or two.
SEGMENTATION OF THEIR ORGANS
119
One recalls that a number of observers have noted the presence
of longitudinal series of repetitive organs in the lateral fields of nem-
sct Cfh
set cph subin
Fig. 4. Scaptrella cincta n.g.
n. sp. 1 and 2 illustrate re-
spectively the inflexed and ex-
tended attitudes of one of the
jointed mandibles. Scaptrella
has the general appearance of
Axonolaimus de Man '89, but
has jointed mandibles, circular
amphids, a single ovary, and
spicula with only faint accesso-
ries. No supplementary organs.
Characters of S. cincta, type
species, given in formulae and
illustrations. Formula explain-
ed on p. 7.
atodes, though attention has never been called to the fact that these
organs on opposite sides of the body may be symmetrical to each
other. Sometimes they are exactly so.
How is the prominent trilateral
symmetry of the nematode head to
be expressed in terms of bilateral
symmetry? Selachinema and Cheir-
onchus assist in answering this ques-
tion. A second species of Selachi-
nema, not yet described, has little or
no trace of the vestigial dorsal jaw
present in S. vorax (p. 113), so that
the two projecting mandibles become
practically lateral, and are bilaterally
symmetrical. An even more com-
plete transformation occurs in Cheir-
onchus (Fig. 5), where by a complete
disappearance of the dorsal sector of
the pharynx the submedian ones
have become truly lateral. In both
these genera the resulting transfor-
mation to a two-jawed animal gives
rise to symmetrical mandibles, acting w
from side to side.
It WaS, Of COUrSe, Conceivable that
any such transformation might take
the form of a union of the submedian SS'J formX! pecie8 ' * lven
Mi/til.
Fig. 5. Cheironchus vorax n.g., n.sp., a nema
hose bilaterally symmetrical mandibles have
Arisen from the ventrally sub'median sectors
of the head at the same time that the dorsal
elements of the pharynx have disappeared.
Cheironchus has the general appearance of Selach-
120 NOTES ON NEMAS
sectors, these united elements then acting in opposition to the dorsal
sector, the two jaws thus developed becoming one dorsal and one
ventral. There is no evidence of such a transformation.
INTRA VITAM COLOR REACTIONS IN NEMAS
We have slowly come to have great confidence in the specificity of
certain physiological actions. The known cases of specificity are
relatively few, and have been discovered largely by accident. We
do not know the exact nature or cause of this specificity. We intro-
duce into an organism certain substances, and definite results follow;
about the only thing we know in the matter is that these definite re-
sults follow with certainty. What the reactions are that bring about
the result we do not know. Our ignorance is so great that even our
theories are very vague. In such cases, if only we could see what it
is that happens while it is happening, it seems certain that important
advances would be made in our knowledge of nutrition, growth, and
decay, of physiology, pathology and medicine.
If substances giving color reactions in living tissues could be applied
to small, transparent, varied and highly complex living organisms,
under circumstances that would permit microscopic examination while
the reactions are in progress, we might hope for more light on this
exceedingly important subject. Experiments I have made lead to
the belief that many of the conditions requisite for success in this
line of investigation can be much better realized than hitherto by
feeding colored substances, notably coal-tar dyes, to free-living
nematodes.
These minute, transparent animals are comparatively highly organ-
ized; not only this, but also extremely varied in their habitats and
mode of life. Some are exclusively vegetarian, others exclusively
carnivorous, and others omnivorous. They constitute a group com-
posed probably of hundreds of thousands of species, embodying an
almost inconceivable number of kinds of physiological action. Their
organs are enclosed in a thin transparent cuticle, and are strung out
so as to make them unusually suitable for intra vitam examination.
Under slight pressure the nema flattens out more or less without losing
its vitality sufficiently to preclude satisfactory intra vitam exami-
nation under the highest powers of the microscope.
INTRA VITAM COLOR REACTIONS IN NEMAS 121
Observing certain precautions, I find that a great variety of coal-tar
compounds and other colored compounds can be fed to nemas, ap-
parently without interfering materially with their normal metabolism.
Some nemas are resistant to chemicals that to most organisms are
poisonous. Often I have had the best results by cumulative action,
using small quantities of color dissolved in the medium in which the
nema lived, and allowing the dye to act for days or weeks.
Not infrequently the dyes prove to be highly specific in their action.
Only certain cells, or only definite parts of certain cells, exhibit visible
reactions in the form of colorations. The results obtained by the
use of any given dye may be quite varied. It is evident in many cases
that the dye is digested and assimilated, thereby undergoing molec-
ular changes by which it is converted into new compounds in a man-
ner analogous to the processes exemplified in chemical laboratories
devoted to the production of aniline dyes. Thus, a dye may give
rise to several different colors, none of them like that of the dye itself,
and all of them very likely due to new compounds. I have seen con-
siderable evidence pointing to the conclusion that in some cases the
dye fed is converted into colorless compounds during the process of
digestion (a reduction phenomenon?), and these colorless compounds
re-converted into colored substances after they arrive at certain des-
tinations or conditions. The number of changes these "living lab-
oratories" can ring on the molecular structure of a given dye must in
some cases be very considerable. Two or more dyes fed simultane-
ously sometimes produce results more or less independent of each
other. The spectacles are very brilliant.
Using these methods I have been able to demonstrate within the
confines of a single cell the existence of an unsuspected number of
kinds of "granules," manifestly playing different rdles. After the
differences among these bodies have been shown in this way, it is
sometimes possible to perceive corresponding morphological differ-
ences; but without the aid of the color reactions the differences "Would
never have been suspected.
The main thing to bear in mind is that on the basis of our present
more complete knowledge of the chemical and physical properties of
coal-tar compounds these color reactions in living nemas may be made
the index of physiological characters possessed by the cells and their
components. In view of the great variety of the known coal-tar
derivatives, and the wonderfully varied metabolism of the free-living
nemas, it seems to me a very reasonable hope that researches directed
122
NOTES ON NEMAS
along this line will lead to important results, and that the nemas may
become classical objects in cell and general physiology, as they have
already become in sex physiology.
A new and rather extensive nomenclature will become necessary.
It will be needful to distinguish between the results of intra vitam,
intra mortem and post mortem staining; for these three terms, the last
two new in this connection, represent as many different phases in the
reactions that take place during the course of the experiments. As
the cells lose vitality, new color reactions occur, and the death of the
cell is followed by further equally marked changes in the reactions.
The cell elements I have mentioned vary in size, but most of them
are exceedingly small, many so small
that they are on the limits of visibility
using the very best instruments with
the greatest skill and under the most
favorable conditions. On the other
hand, some of them are large enough
so that they can be examined in con-
siderable detail and their structures
made out. Among them are the bodies
currently referred to under the name
mitochondria, and other more or less
synonymous words.
As it will be some time before we
can establish a rational nomenclature
for these numerous intracellular struc-
tures it is desirable meanwhile to adopt
terms that will permit intelligent dis-
cussion of our discoveries as they are made. While the principles un-
derlying such a nomenclature are easily defined, it is by no means
easy, in the present condition of things, to suggest suitable short and
expressive loots to be used as a basis. In the long run there'll be
less confusion if meanings of the terms first employed relate to form,
size, and position rather than function.
Investigations of this character are not unlikely to stimulate further
research in connection with aniline derivatives. Present efforts are
directed toward the discovery of dyes of greater or less permanency.
Permanency, however, is of little moment in these investigations;
what is of moment is the chemical and physical nature of the dyes.
No doubt dyes of a greater range of composition can be produced if
Fig. 6. Diagram of a pair cf objectives,
the lower used as a condenser for the upper.
INTRA VITAM COLOR REACTIONS IN NEMAS 123
permanency be disregarded. Furthermore, as already hinted, color-
less compounds may be used if in the course of the metabolism they
are converted into colored compounds. The results of recent studies
of dyes as chemical indicators come into play, and give valuable evi-
dence in determining acidity and alkalinity.
I am almost ready to express the opinion that a small army of in-
vestigators should be engaged on the problems opened up in this way.
The equipment needed by the investigator is as follows: (1) He must
be a good microscopist, versed in physiology, cytology, and histology.
(2) He should be conversant with the chemistry of the coal-tar com-
pounds, not so much from the viewpoint of the maker of dyes as from
that of the broad-minded chemist, freed from the economic domina-
tion of the dye industry, for, as before remarked, fugitive dyes, and
even colorless compounds, are possible factors in such investigations
as are here under discussion. (3) He should have a working knowl-
edge of nemas.
ILLUMINATION
In order to distinguish with accuracy among intra vitam color re-
actions it is necessary to be very particular about illumination. The
most perfectly corrected lenses must be used, both as condenser and
objective, and the light used must be as nearly white as possible. The
best source of light known to me for these researches is bright sun-
light reflected from a plane, matte, white reflector. The reflector
should be several feet across, and placed at a distance from the micro-
scope several times its own diameter. It should be universally ad-
justable, so that it can be set to reflect a maximum of light to the mir-
ror of the microscope, all the better if it is heliostatic. A good
surface for the screen is made by whitewashing a rather finely woven
cotton cloth.
The best optical arrangement I have tried is the use of one apo-
chromat objective as a condenser for another apochromat. I have
been USing With s ?uare c^r ff / ass ^ u ^ eo^ry/aiss_
success a 2 mm.
apochromat as a
condenser for a 2
mm. Or 1.5 mm. Fig. 7. Microscope slide used for intra vitam examinations as indicated
apochromat ob-
jective. These precautions are necessary if fine color distinctions are
to be made with the greatest possible accuracy. If these precautions
124 NOTES ON NEMAS
are taken, it will be found that fine distinctions can be made with
such precision as to dispel all doubt as to the existence, side by side,
in the same cell, of bodies of quite different character that it other-
wise would be either impossible or exceedingly difficult to distinguish
from each other.
The use of an ordinary apochromatic objective as a condenser ne-
cessitates the use of a special object slide, consisting essentially of
a carrier, and two cover glasses. The object is mounted between the
cover glasses. Such a slide is shown in the accompanying illustration.
The substage of the microscope should have a centering arrangement
and a rack and pinion, or screw focusing adjustment. A little ex-
perience with an apparatus of this sort, in which all known precau-
tions are taken to remove color from the optical system leads one
to distrust the ordinary Abb6 substage condenser when fine distinc-
tions are to be made between colors in the microscopic object, espe-
cially if the colors are of similar character.
NEMATODE POPULATION OF BEACH SAND
Through the courtesy of the U. S. Bureau of Fisheries I was able to
make quantitative observations during the summer of 1916 on the
nemas of ordinary beach sand, between tide-marks, at Woods Hole,
Buzzard's Bay, U. S. A. Nemas were plentiful; it was calculated
that on one beach in the top 3 inches of sand there were at least 527
millions per acre. On another beach there were at least 1040 millions
in the topmost inch of sand. The nemas varied from a fraction of
a millimeter to 10 millimeters in length, averaging 2 to 3 millimeters.
On muddy shores where organic matter is more abundant, the riema-
tode population is much more dense, thousands of millions per acre.
Many of these nemas were strictly vegetarian, and fed on micro-
scopic plants present in the beach sand, plants both green and color-
less. Experiment showed that a considerable amount of light pene-
trates average beach sand to a depth of f inch, thus rendering possible
the growth of green protophytes and various algae at slight depths
in the sand. Some of the nemas were strictly carnivorous, feeding on
protozoa and other small animals.
On trial it proved that the top layers of sand, between high and low
tides, under ordinary circumstances, afford the nemas a habitat of
considerable stability, since the shifting of these layers during the
LOCATIONAL TERMS, CYTOLOGY OF DESCENT 125
rise and fall of the tides is so little as to interfere in no way with the
life activities of the nemas. On open ocean beaches, where the force
of the breakers is greatest the nemas take on forms and acquire habits
that protect them from destruction, a tougher cuticle, and the habits
of burrowing and of coiling themselves into a "ball."
Beach nemas in their turn are devoured by the larger animals dwell-
ing in and on the sand, and thus form one of the links in a chain from
the most minute forms of life to those of largest size.
Beach nemas lead a very active life, winding in and out among the
grains of sand as do snakes in a pile of stones. The earth's hundreds
of thousands of miles of beach sand, far from being barren, must be
reckoned as a productive area of some little importance.
LOCATIONAL TERMS FOR THE CYTOLOGY OF DESCENT
There is no satisfactory locational terminology connected with par-
thenogenesis, hermaphroditism and bisexuality; in other words, with
the space relationships of the reproductive cells and their essential
elements, a terminology enabling us to answer succinctly such ques-
tions as, "How are these cells and their elements located with reference
to each other?" Such nomenclature as we have for this purpose has
accumulated, bit by bit, through successive contributions of more
or less independent investigators, and, naturally enough, has become
a very heterogeneous mixture of terms and phrases.
Aside from standing open to the criticism of being inadequate and
an incongruous mixture, such terms as are in current use, at least a
considerable portion of them, date from a time when our knowledge
of the chromosomes and their relationships to each other and to hered-
ity was either non-existent or much less complete than at present.
Most of these terms, therefore, are based on the assumption that the
body or soma is the principal or predominant feature of the organism,
and, philologically speaking, they take little or no account of the mod-
ern view of the importance of the gametes and of the r61e they play.
As we seem in need of a more adequate and homogeneous set of
terms based on the relationship to each other in space of the gonads,
the gametes, and the chromosomes and other intra-cellular elements,
I call attention to the following series of terms, positional rather than
physiological, I have been using to meet this need: Just as we have
"cone" and "conic" evolved from the Greek KOVOS, I derive the
126 NOTES ON NEMAS
words "gone" and gome" from 70^05. Primarily the word "gone"
refers to the generative portion of a sexual organ. By metonomy
"gone" designates an organism or species having gones; thus we have
two kinds of organisms "gones" and "agones."
From "gone" come the verb "to gone," and the substantives "syn-
gone," "digone," "amphigone," "homogone," and "heterogone."
From syngone come the words "syngonic," syngonically," and "syn-
gony;" and corresponding words from digone, amphigone, homogone
and heterogone.
Gone. To produce gones.
Gonic. Of or relating to a gone.
Syngonic. Having macro- ("female") and micro- ("male") gametes in the same
gone; e.g. as in many nemas.
Digonic. Having macro- ("female") and micro- ("male") gametes in separate
gones in the same individual; e.g. as in many hermaphrodites.
Amphigonic. Having macro- ("female") and micro-("male") gametes in sep-
arate gones that are in separate individuals; e.g. as in all bisexual forms.
Homogonic. Having gones all of the same kind.
Heterogonic. Having gones of various kinds; e.g. as in a species presenting
both syngony and amphigony.
Syngone. A gone bearing both macro-("female") and micro- ("male") gametes.
By synecdoche syngone also designates an organism or species containing,
or characterized by, syngones; similarly with the following four terms.
Digone. A digonic individual or species.
Amphigone. An amphigonic species.
Heterogone. A species presenting both amphigony and syngony, or both di-
gony and amphigony, etc. A heterogonic species.
Homogone. A species or individual presenting uniformity in the space rela-
tionships of its gonic cells. A homogonic species.
Kinetogone. A gone whose gametes are active, aggressive, or "male."
Statogone. A gone whose gametes are passive or "female."
Entering now a more or less theoretical domain whose permanency
will depend on the results of future investigations, and carrying the
analysis a step farther by taking into consideration the space relation-
ships of the chromosomes and other intra-cellular elements that ac-
cording to an increasingly prevalent modern belief themselves carry,
or determine the factors of descent, and using the Greek word KVVTOS as
a basis, I derive, as may be necessary, "syncyst," "amphicyst," 'het-
erocyst," etc., and their adjective, adverbial, and substantive deriva-
tives ( e.g., syncystic, syncystically, syncysty) to aid in expressing
positional relationships. Thus the word "syncyst" refers to a gonic
cell, such as a parthenogenetic ovum, containing all the elements.,
LOCATIONAL TEEMS, CYTOLOGY OF DESCENT 127
factors, or determinants necessary to the production of an individual
(except, of course, the environmental ones), of which the chromosomes
are the familiar example, expressed in some physical form, often,
though not necessarily, of definite conformation. It is assumed that
these factors belong to two classes, having opposite, vital, chemical,
or physical properties. By synecdoche the word syncyst may also
designate a gone, individual or species containing, or characterized by
syncysts; similarly throughout the series of terms. In dicysty the
inheritance mechanism is such that the full complement of factors
necessary to the production of an individual is distributed to func-
tional cells of two kinds, the macro-(" female") and micro-("male")
gametes, neither normally capable of producing an individual, but which,
pairing, form zygotes capable of producing an individual.
Syncystic. Of, or relating to, a gonic cell containing all the factors necessary
to the production of an individual, as in the parthenogenetic ovum. The
word syncystic may also be applied to a gone, individual, or species bearing
syncysts. Syncysty, state of being syncystic; and so with the following
five words.
Dicystic. Of, or relating to, a gone bearing in separate cells the different fac-
tors necessary for the production of an individual; as in syngones. The
word dicystic may also be applied to individuals and species.
Amphicystic. Of, or relating to, an individual in which the different groups of
factors necessary for the production of a new individual occur in separate
cells that are in separate gones; as in many hermaphrodites.
Telecystic. Of, or relating to, amphicystic species in which the different groups
of factors necessary for the production of an individual are borne in separate
cells in separate gones that are in separate somas or individuals; as in all
bisexual forms.
Homocystic. Having or producing gonic cells all of the same kind.
Heterocystic. Having or producing gonic cells of more than one kind.
Syncyst. A gonic cell, or by synecdoche, a gone, individual, or species, present-
ing syncysty.
Dicyst. A gone, or by synecdoche, an individual or species, presenting dicysty.
Amphicyst. An individual or species presenting amphicysty.
Telecyst. A species presenting telecysty.
Heterocyst. An individual or species presenting both amphicysty and syncysty.
or both dicysty and amphicysty, etc.
Homocyst. A species presenting uniformity in the space relationships of its
different kinds of gonic intracellular reproductive elements.
Kinetocyst. A gonic cell whose elements are active, aggressive, or "male." A
"male" gamete; a spermatozoon.
Statocyst. A gonic cell whose elements are passive, or "female." A "female"
gamete; an ovum.
128 NOTES ON NEMAS
Digones, amphigones and heterogones, and many syngones, are
dicystic. The word syncysty and its immediate relatives may be
used to designate the conditions present in parthenogenetic organisms,
in which single gonic cells (not zygotes, at least not in the ordinary
sense of the word) contain all the factors necessary to the production
of an individual. My (thus far theoretical) cryptogenetic organisms
are syncysts.
5
FUNCTIONS OF THE AMPHIDS
My published observations emphasize the junction of each amphid,
by means of a duct, with a chain of internal lateral organs. Biitschli
and de Man each record an instance of definite outflow from the am-
phids. I now find this outflow in many different genera, when speci-
mens are fixed with Flemming solution; from a definite part of each
amphid there issues a coiled, or irregular "string" or "ribbon," the volume
of which precludes attributing it to an evagination. Occasionally an
"axis" is seen in the "string," but nothing warrants the belief that
this "axis" is other than a coagulation phenomenon, just as it is in the
similar coagulation "strings" occasionally seen at the spinneret. I
mention evagination because some investigators declare the amphids
to be supplied with special nerves, and because it is conceivable that
death spasms might so act on a nerve organ as to cause an evagination.
However, my numerous observations do not at all support the idea
that the appearances I have studied are evaginations. In many cases
I have traced inward and backward from the amphids structures
whose histology in no way suggests nerve organs, but does correspond
in every respect with the histology of ducts, especially those of nemas.
These new observations of mine afford, I think, a better basis for
speculation as to the function of the amphids, and lead away from the
idea that they are simply organs of sensation. I observe in Monon-
chus, and other genera, that invariably there is an innervated papilla
very close to the amphid. May not confusion have arisen here
through different observers having studied similar-looking, but un-
related structures?
I have instances of amphids so obscure that i would have been im-
possible to discover them had it not been for the issuance from them
during fixation of the fluid matter described.
THE MONONCHS 1
(Mononchus Bastian 1866)
A GENUS OF FREE-LIVING PREDATORY NEMATODES
CONTRIBUTIONS TO A SCIENCE OF NEMATOLOGY VI
(With 75 illustrations in the text) 2
BY
N. A. COBB
INTRODUCTION
Mononchs are Predaceous
No free-living nematodes have gained more in interest during recent
years than those constituting the genus Mononchus; this is because the
latest discoveries have led to a complete change of view concerning their
economic relationships. Careful examination, here recorded, of a large
number of specimens belonging to many different species of Mononchus,
has fully demonstrated the predaceous character of certain common and
widely spread soil-inhabiting species which are found to feed on other
small animal organisms, such as protozoa and rotifers, and, most interest-
1 Reprinted from Soil Science, May, 1917, with renumbering of pages and errata, (p. 184).
2 For the most part the illustrations were prepared under the author's personal supervision by
Mr. W. E. Chambers of the Bureau of Plant Industry. Many features set forth in them cannot
be seen in the natural object except with the aid of the best immersion lenses skillfully used
under favorable conditions. Frequently no further allusion is made to facts thus elucidated . So,
too, information contained in the key may not be repeated elsewhere; the key should therefore be
consulted in connection with each description. Most of the illustrations are original; when not
so, their source is indicated. The species figures are all at the same magnification, so that the
reader may judge of the relative sizes of the nemas. Explanatory abbreviations follow.
amp ampulla
amph amphid
an anus
an gl anal gland
ar dnt denticula
cav som body cavity
cl int intestinal cell
cl msc muscle cell
cl nrv nerve cell
cl nrv subm submedian nerve
cell
col crd cardiac collum
crd cardia
cst ph pharyngeal rib
cut cuticle
dct duct
dct gl cdl duct of one of the
caudal glands
dnt denticules
fix ovr post flexure of poster-
ior ovary
gl gland
gl an anal gland
gl cdl caudal gland
gl oe cesophageal gland
grn granule
gl sal salivary gland
ing ingested material
ing nematod ingested nema-
tode
int intestine
inc iunction
lam Ib labial lamina
Ib lips
lum int lumen of intestine
lum oe lumen of oesophagus
lum som body cavity
ms an anal muscle
msc oe cesophageal muscle
msc som body muscle
mur ex external wall
mur int intestinal wall
mur ph pharyngeal wall
mur ut wall of uterus
ncl nucleus
ncl cl int nucleus of intesti-
nal cell
ncl lat lateral nucleus
ncl ov nucleus of ovum
nrv nerve
nrv r nerver ring
oe oesophagus
oes lum oesophageal lumen
on dsl dorsal tooth .
on rtr dsl retrorse dorsal
tooth
on rtr subm retrorse submed-
ian tooth
on subm dxt right submedian
tooth
on subm snst left submedian
tooth
org orgnn
ov ovum
ov dct oviduct
ov frt fertilized esrg
(S. S.431) 129
ov im immature egg
p ex excretory pore
ph str pharyngeal striae
por pore
por gl oe pore of oeeophageal
gland
ppl papilla
ppl cdl caudal papilla
ppl intr interior papilla
ppl Ib labial papilla
ppl Ib extr exterior labial
papilla
ppl subm submedian papilla
opl subm sec secondary sub-
median papilla
ppl trm terminal papilla
rcpt sem seminal receptacle
ret rectum
reg vnt ventral field
set seta
spm spermatozoa
spn spinneret
str mur ph striae of pharyn-
treal wall
subcut subcuticle
sut Ib labial suture
teg ov egg shell
trm ovr Wind en-l of ovnrv
ut utenis
vag vagina
vagmsc vaginal muscle
vlv vulva
J30CS.S.432)
THE MONONCHS
ing of all, on other nemas and has made it practically certain that all
mononchs are predaceous.
Economic Importance. If, as is often the case, the nemas destroyed
by the mononchs are nemas injurious to agriculture, then the mononchs
are beneficial to man. The first definite instance of this kind was reported
in the Journal of Agricultural Research in September, 1914 : Mononchus
papUlatus was shown to feed upon Tylenchulus semipenetrans, the latter
a nema infesting the roots of citrus trees. Since that time the writer has
observed many similar instances, fourteen of which are recorded herein.
Formerly mononchs were considered harmful to vegetation. The
basis of this opinion was twofold: first, they were known to congregate
about the roots and between the leaf sheaths of plants, especially succu-
lent plants, in sufficient number to justify the opinion that they would be
harmful, provided they were vegetarians; second, vegetable matter was
often found in their intestines.
More careful investigation, however, has disclosed other facts incom-
patible with this opinion that mononchs are harmful to vegetation. The
food-habits of mononchs have now been more carefully investigated, as
herein recorded, and each species so studied has proved to be carnivorous.
The presence of vegetable matter in a mononch's intestine proves to be no
very definite criterion of its food habits, appearances to the contrary not-
withstanding. A deception has arisen that
is now easily explained. The occurrence of
vegetable organisms in the intestine of a
mononch is merely incidental ; in many in-
stances it would be impossible for the mon-
onch to devour its prey without at the same
time swallowing vegetable matter. For in-
stance, suppose a mononch to bolt, as one
of its victims, a monhystera a common
occurrence. Monhysteras are vegetarians,
some of them feeding almost exclusively
upon diatoms, others upon other kinds of
unicellular algae. Both on account of their
peculiar structure and their bright green
color, these diatoms and other algae are very
conspicuous objects in the intestine of the
monhystera. Imagine now the appearances
presented by the body of an ingested mon-
hystera, swallowed whole, or nearly so, and
lying lengthwise in the intestine of a mononch. Under such circum-
stances, which are entirely normal, the diatoms and other algae in the
intestine of the monhystera may be observed through the colorless tissues
FIG. 1
A mononch
about to seize
its victim.
The head is
drawn from
nature and
is exact in
every detail.
The body is
more or less
posed. The
strong teeth
and rasp-like
organs in the
mouth are
well shown.
FOOD HABITS (S.S.433)j3i
of both the mononch and the monhystera, without the body wall of either
nema being very plainly visible : it is somewhat as if one looked through
the walls of two glass tubes, one within the other, to view comparatively
conspicuous objects in the inner tube. Such an observation might easily
lead to the conclusion that the mononch had been feeding upon unicellular
algse. The deception is heightened after the body of the monhystera is
partially digested, for then all vestiges of the monhystera become practi-
cally invisible, and there are left as comparatively conspicuous remains
the less readily digested vegetable matter, lying loose in the intestine of
the mononch, the frustules of diatoms for instance, which of course
are wholly indigestible. Taking everything into consideration, it is not
in the least surprising that hitherto observers have been deceived as to
the food habits of mononchs.
As nematologists heretofore have not carefully studied the food habits
of mononchs, particular attention was given them in the course of these
investigations ; but in spite of the care exercised much remains to be dis-
covered. The mouth parts and digestive organs have come in for special
study, since it is mainly here that we get clues, faint and puzzling though
they be, that help interpret the little we can glimpse of the food habits of
these organisms in their natural state. Soil mononchs live in darkness
and, as might be expected, behave in a wholly unnatural way when placed
in water on a microscope slide and brought in a drowning condition
into the blaze of light necessary to a microscopic examination. The dif-
ficulties and delays attendant on such a line of research are manifest.
Nevertheless, certain fundamental facts have been established; new or-
gans have been discovered and light has been thrown on the true nature
and function of organs not hitherto understood. It has seemed best to
dwell on the various habits and functions while describing the structures
with which they are associated.
As we gain familiarity with the food habits of nemas, it becomes pos-
sible on this new basis to make comparative anatomical studies, the results
of which may be applied in determining the food habits of newly discov-
ered genera and species.
I
STRUCTURE, FUNCTIONS, AND DISTRIBUTION OF MONONCHS
The mononchs constitute a genus of free-living, predatory nematodes
inhabiting soil and fresh water, as well as the above-ground parts of cer-
tain plants. The average form and size of a mononch is indicated by the
2.2 7.4 25. '63 >2S 92.7
following average formula: 2 - 4 mm -*
2.1 2.6 3. 3.2 2.
* This formula, which is now coming into more general use, is simply a decimal method of
stating concisely the necessary measurements. The formula is fully explained in the appendix,
r. 184.
13 2(S-S.434)
THE MONONCHS
which corresponds very closel}
with that of the type species of the
genus, M. truncatus Bastian, and espec-
ially with M. papillatus Bastian.
Skin or Cuticle
Strics. While the skin of these nemas
usually described as smooth and
without striations, yet minute trans-
verse striae are probably always present,
though difficult of resolution except in
the new species reversus and similis.
Using a good objective of the highest
power under favorable conditions, I
have almost invariably been able to see
these striae, and as my examinations
have embraced the great majority of
the known species, it seems probable
that any specimen will reveal them if
examined with sufficient care. These
transverse striae, all alike on a given
specimen, are never sufficiently marked
, , FIG. 2. Female
of a typical mononch,
par Mononchus longi-
, caudatus, a syngonic
form. This individ-
ual had been feast-
ing on other nemas,
t h e remains of
which are shown in-
side the intestine.
Only the anterior
half of the sexual
organs can be seen
in the illustration;
an entirely similar
branch is hidden on
account of the coiled
attitude of the body.
The lettering of
the illustrations is
similar throughout
and is explained at
the bottom of page
129. The anatomy
and histology o f
various newly dis-
covered features are
shown:
GJsophageal glands
(gl. sal.), the pore
mlr Inf through which the
glands empty into
-. theossophagus (par.),
syngonic sperm
j, (spm.), formation of
"" polar body (ov.frt.),
ingested protozoon
(ing.), etc.
to disturb the plain, even contour of the body. It is rarely possible to
CUTICLE AND MOULTING (8.8.435)133
resolve the striae into components ; occasionally, however, they are resolv-
able into rows of excessively fine dot-like elements, as for instance in
bathybius, reversus and incurvus. Lateral wings to the cuticle are almost
unknown, and the striae are not perceptibly altered on the lateral fields;
papillatus and macrostoma furnish a slight exception to this rule.
Though the muscles of the body wall are relatively powerful, their
attachments to the subcuticle are not a conspicuous feature ; hence longi-
tudinal striae due to this cause, though of rather common occurrence, are
not very readily observed. There are no longitudinal striations in the
cuticle proper. This apparent complete absence of dermal markings often
imparts a glassy appearance to living mononchs when examined casually
under the microscope, an effect that is heightened by the fact that the
colorless body wall is, as a rule, of more than average thickness. Despite
their rather thick cuticle, mononchs are very flexible. They coil and un-
coil themselves with facility, a useful gift in a struggle with active prey.
Moulting. From researches on a considerable variety of genera, Mau-
pas concluded that nematodes undergo four moults, and that, correspond-
ingly, the life of each individual is divided into five periods. He exam-
ined no mononchs. The accompanying sketch of a portion
of the pharynx of a moulting Monochus brachyuris, from
Arlington, is therefore of interest, as indicating that this
specimen had yet to moult three times ; and since it was
already half-grown (0.8 mm. long) it is fair to presume it
had already moulted once, although of course there is no
proof of this. The sketch shows four successive dorsal
onchi, numbered in chronological order, each the represent-
ative of a separate cuticle. The fourth onchus is in a very lessive 'dorsal
rudimentary state. This record accords with the observa- :eth> *' 2> 3 ' 4 '
tions of Maupas, and indicates the probability that mononchs also moult
four times.
Strength and Activity. Various features of the cuticle and body-
muscles seem to stamp the mononchs as powerful nemas, and when they
are taken from their natural haunts and placed in a glass of water for
examination, their active serpentine movements fully justify the infer-
ence. Though less agile than species belonging to some other genera,
they are anything but sluggish. The movements of the anterior extremity
are especially striking, a certain suppleness of neck enabling them to
dart the head suddenly here or there in almost any direction, a faculty
enabling them with ease to capture their prey, even though it be active.
Nemas Sometimes Float
Distribution by flotation. Ditlevsen notes a very interesting trait of
his Mononchus spectabilis, namely, that of floating on the surface of
water. A number of free-living nemas belonging to other genera are
134(3.3.436) THE MONONCHS
known to have this faculty, which is due to repulsion between the cuticle
and water ; de Man found it to exist in the case of Oncholaimus viscosus,
and the writer has observed it in the case of the larvse of Diplogaster
aerivora, although a second larval form of this same species does not
exhibit the property, nor do the adults. Ability to float is known also of
a number of other species, and, as Ditlevsen's observations show, is not
absent in the genus Mononchus. Whether flotation plays any part in the
economy of such nemas is not known with certainty. Floating on the
surface of moving water, nemas would doubtless sometimes be quickly
and widely distributed, and it is therefore easily conceivable that flotation
has some definite bearing on the life history of species exhibiting it.
The surface of a mononch seems almost
*' Jfc ' >^^-^H -^T^ ' entirely destitute of setae and papillae, if
we except those on the lips. Neverthe-
less, future researches will probably re-
veal superficial nerve-endings hitherto
overlooked. In rare instances a few fairly
well-developed setae occur on the tail, as
in the case of M. sigmaturus; papillae also
occur sparingly on the tails of the males
of various species, and near the vulva on
the females of a number of species. No
the lips are nearly closed, but the dor- pores are known tO OCCUr in the CUticle,
Si", Sr~'SS except, of course, the spinneret pore, and
of papilla: are seen to good advantage, the pore observed near the nerve-ring and
to be the renette pore.
General Form of Body
Neck and Head. The various mononchs are considerably alike in
external form. In front the body tapers but little; the neck is nearly
always more or less cylindroid, and almost invariably ends in a head not
set off from the neck in any way, though there is usually a slight expan-
sion at the lip-region, due to the strong development of the labial papillae.
Tail and Spinneret. The posterior portion of the body usually tapers
from some distance in front of the anus, but in the pre-anal region the
diminution is slight and very gradual. The tail may be either simply
conoid, or first conoid and then cylindroid, and usually ends in a spin-
neret, though in about one-fourth of the species the caudal glands and
spinneret are absent. When the tail is conoid the spinneret is usually a
simple structure, whose existence is indicated mainly by the fact that the
terminus is sub-truncate in form, and presents an inconspicuous axial,
or sub-dorsal, or sub-ventral pore. This form of spinneret appears to be
entirely unarmed, though inconspicuous innervations probably occur.
LABIAL APPENDAGES (S. S. 437) 135
When the posterior portion of the tail is cylindroid, the terminus is
usually almost imperceptibly expanded, and the spinneret is then some-
what differently developed, and is usually armed
with obscure, innervated, submedian papillae or
setae.
Head
Lips. In the view usually obtained the six lips
appear to be more or less confluent, and if it were
not for their papillae it would be difficult to count
them ; but when thrown apart, an attitude in which, x 1000
however, they are seldom seen, they are more easily ,,
J J J ric. 5* opinncret ox
counted, since in this attitude the refractive "cerat- '"Ss^whos*' contrac-
inous" internal elements of the lips are separated Jon ^open s w the se spinneret
from each other and more readily distinguishable, as shown in figure 1.
When closed, these six, broad, flat lips meet together in such a way that
the star-shaped mouth opening usually lies in a slightly depressed area on
the middle of the front of the head. In some species the inner walls of
the lips are strongly "ceratinized," and may be developed into six rather
definite, retrorse, subacute points, which, in assaults on other animals,
serve as grappling hooks, and act in opposition to the dorsal tooth of the
pharynx.
Labial papilla. Each lip is supplied with at least two, usually more or
less conical, innervated papillae; one on the outer margin and somewhat
outward pointing, the other situated about half way between the outer
papilla and the centre of the head, and forward-pointing. The front of
the head therefore presents two circlets of papillae, one on its outer mar-
gin, and one more closely surrounding the mouth-opening, as shown in
figures 1 and 4, and many others. These papillae may be so flat as to
play no conspicuous part in the external conformation of the head, or
they may be conical and raised, so as to give to the front of the head a
more or less angular contour. The papillae are slightly mobile, and hence
vary somewhat in appearance at different times on the same specimen, a
matter depending on the attitude of the lips. Drowned specimens with
relaxed lips present a slightly different appearance from those that have
been fixed for examination by means of chemicals.
Some of the innervations that frequently occur on the head near the
lips may have special functions. Structurally they are sometimes indis-
tinguishable from the subordinate labial papillae. The species figures
show the location of some of these innervations. One pair of them is
very near the amphids the only nerves so far observed to be definitely
associated with the amphids. These particular papillae are so uniform in
their' occurrence that it seems likely they have a special function, con-
nected with the use of the amphids.
136<S.S.438) THE MONONCHS
I
Mononchus: Number of Labial Papillae in the Outer Set
14
10
6
' Doubtful:
said to be 6
acutus
bathybius
muscorum var.
brachyttris
dadayi
obtusicaudatus
macrolaimus
brachylaimus
brevicaudatus
obliauus
lacustris
digiturus
parvus
dentatus
consimilis
radiatus
megalaimus
dolichurus
punctatus
gracilicaudatus
denticulatus
reversus
minor
exilis
ex
major
gerlachei
sigmaturus
palustris
fovearum
pectabilis
monhystera
incurvis
subsimilis
sparsus
gymnolaimus
tuderi
muscorum
longicaudatus
angustus
teres
index
enuicaudatus
papillatus
longicollis
trichurus
tunbridgensis
intermedius
ridentatus
rapax
micrurus
vorax
japonicus
runcatus
regius
macrostoma
schokkei
Comparative morphology of the cephalic papilla. The outer set of
cephalic papillae is the morphological equivalent of the circlet of cephalic
setae often to be seen on other free-living nemas. In harmony with this
fact, the submedian papillae of this outer set are sometimes two or three
in number to each lip, the numerical and morphological factors harmoniz-
ing with the law of arrangement of the tactile cephalic setae of nemas,
namely: when six are present one is found on each of the two lateral
lines and one on each of the four submedian lines ; when more than six
are present the increase occurs first on the submedian lines, the common-
est number being ten, one on each lateral line and two on each of the
four submedian lines; when the number is in excess of ten the increase
is again more commonly found on the submedian lines. Illustrations of
this law of arrangement are seen on the heads of many mononchs. The
secondary submedian papillae of mononchs are sometimes minute and
more or less difficult to detect.
Method of Hunting
Senses of Smell and Taste. Obviously mononchs hunt by the aid of
some other sense than that of sight, since both they and their prey usually
live in subterranean darkness. It is, therefore, exceedingly likely that
the nerve endings on the head, terminating in the labial papillae of the
inner row, serve as organs of taste and smell, and that it is by the aid of
these senses that they trail their quarry.
Picture these ferocious little mononchs engaged in a ruthless chase in
the midst of stygian darkness. We may imagine them taking up the
scent of the various small animals upon which they feed, among which
almost anything they can lay mouth to seems not to come amiss, and
pursuing them with a relentless zeal that knows no limit but repletion.
How many acres have their organic balance determined by their millions
of prowling mononchs ?
PHARYNX
(S. 5.439)137
Pharynx
The six powerful lips arch together over a large characteristic
pharynx, consisting of a rather simple, ellipsoidal or elongated cavity,
whose cross-section is more or less irregularly circular, and of which
there are two distinct types.
Types of Maw. Teeth. In one type, characteristic of the larger
species, there are longitudinal ribs, sometimes simple, sometimes duplex,
situated mainly on the median and submedian
lines (subgenus lotonchus). 3 When these lon-
gitudinal ribs are well-developed there is a
tendency for the dorsal tooth or onchus to be
farther back, and for the submedian teeth,
smaller still, to be located toward the base of
the pharynx, and in extreme cases all three
teeth may be located actually at the base of
the pharynx, or indeed be quite vestigial. The
farther back the teeth, the smaller they are,
and when located actually at the base of the
pharynx they are often exceedingly small.
In the other type of pharynx the dorsal
tooth is usually strongly devel-
^pk, M oped, and is located midway or
fj H farther forward ; in which case
X750
FIG. 6. Dorsal view of the
throat of M. muscorum, to
show the arrangement of den-
ticles (dnt.) characteristic, of
the subgenus Prionchulus; 2 they
constitute a rude "saw." Com-
pare with Fig. 7.
o
the wall of the pharynx is strongly reinforced along the dor-
sal line, while the submedian longitudinal ribs are lacking,
or at any rate are faint. However, there often occurs on
each of the two ventrally submedian lines in this type of
pharynx an onchus of smaller size, located a
little farther back than the main onchus ; ex-
ceptionally these submedian onchi may be
nearly as large as the dorsal onchus. In
several species the onchi are retrorse (sub-
genus Anatonchus 5 } , and when of this char-
acter are sometimes more slender, even some-
what digitate.
Fangs. Denticles. The onchi act as fangs,
and are used in conjunction with the power-
ful lips in seizing and holding the prey. In
these maneuvers they are aided by minor
pharyngeal structures, prominent among
which in some species are two submedian
'lotonchus, insignificant tooth; 4 Prionchuhis. a small saw-tooth; B Anatonchus, reversed tooth.
FIG. 7. Above, profile and front
view of the same series of denticles
in the throat of M. muscorum. Be-
low, two cross-sections of the same
specimen, showing end view of the
same denticles; at left the section
is through the dorsal tooth (shown
black) ; at right the section is above
the tooth. The denticles are shown
in the upper part of these two lower
figures. The two joints shown in cross-
section impart a slight degree of
mobility to the pharyngeal walls.
Compare with Fig. 6.
138( s - s -440) THE MONONCHS
areas, armed with minute denticles arranged in transverse rows like the
teeth of a rasp (subgenus Mylonchulus 6 ). While these denticles are
usually distributed in two distinct areas, the two sometimes coalesce on
the ventral line, so that the denticulated area, or rasp, is continuous and
bilaterally symmetrical. As a rule, however, there is a distinct, narrow,
ventral interruption, so that the right and left rasps are rather clearly
separated from each other. These rasps are widest near the ventral line,
and become gradually narrower as they recede, and usually end near the
lateral line, or near the dor sally submedian line. On the margins of the
rasps the denticles are arranged in distinct rows ; elsewhere the arrange-
ment is more or less irregular, though in certain species the arrangement
is rather orderly throughout. Each rasp is composed of about six rows
of denticles, except in the species denticulatus, where the number of rows
is about twice (?) as great, and in the new species sparsus and reversus,
where there are only one or two rows. Often at the base of each rasp
there is an exceedingly minute submedian onchus.
Method of Attack. When used in conjunction with the strong dorsal
tooth and the powerful lips, the rasps are remarkably efficient organs.
The mononch glides up to its quarry and makes its onslaught by a quick
snap of the head, throwing its jaws suddenly wide open, and grappling
its prey by means of the inner armature of the lips. As the jaws close in,
the victim's body is jammed against the point of the dorsal tooth, as well
as against the rasps, and in this way is at once both punctured by the tooth
and lacerated or milled by the rasps. In most cases the onchi seem to be
solid bodies, containing no duct through which venom could empty. If
any poison is injected into the victim it would seem to be derived from
cesophageal glands emptying into the pharynx by some other road. The
axial element sometimes seen in the onchus is probably a nerve ending.
Minutia of the Wall of the Throat. In general the wall of the pharynx
is well developed and strongly refractive, and is usually thickest on the
dorsal side where it gives support to the dorsal onchus ; often it is very
finely transversely striated. In many species this striated appearance
seems to be due to a transverse lamination of the pharyngeal wall. The
striation, or lamination, may be so pronounced as to give rise to transverse
ridges on the interior surface of the pharynx like those of the teeth of a
mill-saw file, and no doubt these ridges have somewhat the same function
as the rasps just described. The onchi are sometimes seen to be longi-
tudinally striated. The striae of the pharyngeal walls are most clearly visi-
ble during the moulting period. In the original species-figures to follow,
what appears merely as shading on the pharyngeal wall is a carefully
worked-out chart of the position, number and direction of these lami-
nations.
8 Mylonchulus, a small mill-tooth.
PHARYNX
(s. s. 441) 139
Contour of the Maw. The contour of the pharynx differs somewhat
in the various species. If the dorsal onchus is strongly developed, the
profile indicates a roughly goblet-shaped or ellipsoidal cavity, and the
onchus extends well into the cavity so that its apex lies near the axis of
the head, sometimes up front and close to the inner margins of the lips.
If, on the other hand, the dorsal onchus is weak; and especially in species
FlG - 8. Female of M. papillatus, a common cosmopoli-
tan soil-inhabiting beneficial species, known to feed upon
plant-infesting nematodes. The cesophageal glands (gl.
oe.) are well developed in this mononch; they empty into
the oesophagus and no doubt "lubricate" it during the act
of swallowing. This mononch is also syngonic. Sperm of
female origin is shown in the uterus at spm. For expla-
nation of lettering see page 129.
M
mrit
dec
ad dot
where the wall is not much reinforced by longitudinal ribs, the contour of
the pharynx tends to be more or less oblong, so that its floor, lying in the
anterior end of the oesophagus, though irregular, is likely to be, on the
whole, more nearly flat. Opposite the dorsal onchus there is frequently
to be seen a faint transverse seam, most prominent along the ventral side
THE MONONCHS
of the pharynx, indicating a division of the wall into anterior and posterior
elements. Sometimes this pharyngeal suture is rather prominent.
Jaw Muscles. The pharyngeal muscles of various species of mononchs
have been observed, figured and commented upon by one or two investi-
gators, but only in a vague way. Much remains to be learned concerning
them. The following incomplete observations have been made in the
course of these investigations.
Under suitable conditions, and especially in some species, long, slen-
der muscles may be seen passing from the lip region backward and out-
ward, so that their proximal attachment is to the body-wall a short
distance behind the pharynx. These muscles are the flexor muscles of
X750
FIG. 9. Side view of
the head of M. regius.
The lips and their ap-
pendages are well shown.
The flaps (lam. Ib.) are
the same organs so well
seen in figure 4. The
amphid (amph.) extends
to the bottom of the
pharynx and beyond. The
labial muscles (msc.) are
so attached as to pull the
lips both inward and out-
ward about the stiff exter-
nal ring as a fulcrum.
Traces of this ring are
margin of the anterior
part of the head. Com-
ing up from the interior
of the oesophagus toward
the right is seen a light-
colored duct; this empties
into the pharynx at its
base. In this way appar-
ently the secretion of the
oesophageal glands has a
direct passage to the
throat
the lips. It is certain that each lip, probably each pair of adjacent lips, is
connected with a muscle whose function is to pull the lip toward the body
axis about a fulcrum near the surface of the head. These muscles, then,
shut the mouth. It seems likely that the elasticity of the various parts
composing the frame-work of the lips and pharynx may play some part
in mastication and deglutition, and act in opposition to some of the mus-
cular elements of the pharynx. The extent to which a mononch can
throw its jaws open is shown in the sketch, figure 1, made from a pre-
served specimen. This act is accomplished by the aid of a second similar
set of muscles acting on the outside of the same fulcra. It is unlikely
DEGLUTITION (S. s. 443) 141
that the sketch represents the maximum gape, for the effect of chemical
fixatives seems to be to lock the jaws tightly rather than leave them agape.
When examined alive mononchs are seldom seen to move their mouth
parts.
The Mononch and Its Victim
Fate of Victim. So far as I am aware, the struggle of a mononch
with its victim has never been witnessed by human eyes. A struggle it
must be, for mononchs are sometimes discovered that have gulped down
other nemas nearly half as long as themselves. Such a denoument must
be the result of a dramatic conflict. A similar gastronomic exploit on
the part of a man would be the gulping down of a string of bologna sau-
sage several feet in length. In one instance in the course of my experi-
ence, a mononch was caught with its quarry, another nematode, still
gripped in its jaws. Seized by its middle, the victim had been bitten
nearly in two. This is a common fate. Sometimes, however, the ingested
nema is but little mangled. I imagine the mononch swallows its prey
somewhat as the python does, though less deliberately. As the oesophagus
seldom occupies over one-fourth of the length of the body, and as the
mononch sometimes swallows other nemas nearly half as long as itself,
manifestly in such cases one end of the victim's body must reach the
mononch's stomach before the other end has disappeared down its
throat.
Gluttonous Appetite. While many mononchs bolt their food, it is
evident that the food of some among them receives
a certain amount of mastication, for the body of
the victim is bitten into fragments and swallowed
piece-meal. In some cases the degree of mastica-
tion may be greater still. Figure 10, for instance,
shows the head of a preserved specimen, in the
mouth of which lies a portion of the "gizzard" of a
rotifer, which has been almost completely denuded
of the muscular tissue originally attached to it. It
is the thick-lipped species like M. muscorum that
masticate their food in this way.
(Esophagus or Gullet
Lining of the Gullet. Salivary (?) Glands. The oesophagus is more
or less cylit?droid, a form of oesophagus common in nemas that engorge
relatively large objects. The anterior end of the oesophagus, where it
receives the base of the pharynx, is usually about one-half to two-thirds as
wide as the base of the head, and is occasionally somewhat swollen, so
that one may speak with propriety of an obscure pharyngeal bulb. The
oesophagus has nearly the same diameter throughout the greater portion of
14 2(S-S.444) THE MONONCHS
its length ; it may diminish a trifle in the vicinity of the nerve-ring, while
in the posterior half it usually expands a trifle, so that finally it is one-
half to two-thirds as wide as the corresponding portion of the body. The
refractive lining of the oesophagus is strongly developed, and is of such a
character that its longitudinal optical section often occupies as much as
one-third of the diameter of the whole organ, sometimes one-half, excep-
tionally even more. The radial musculature of the oesophagus is strongly
developed, and usually appears coarser posteriorly than anteriorly.
(Esophageal Glands. In some species, very likely in all, among the
interstices of the cesophageal muscles there exist glandular tissues, which
empty their secretion into the lumen of the oesophagus through minute
pores in the lining, situated from place to place throughout a considerable
portion of the length of the organ. Some of these glands appear to
empty into the pharynx, but the best developed ones occur in the dorsal
section of the oesophagus near the middle.
De Man and Micoletzky mention structures in the wall of the pharynx
of Mononchus, about the nature of which they seem doubtful, but sug-
gest the possibility that they are pores. My observations lead me to the
conclusion that some of the more minute so-called "teeth" or denticles
of authors, at the bottom of the pharynx, and even some of those higher
up, are in reality elevated pores connected with glandular structures in
the anterior part of the oesophagus. These pores appear to me to be the
homologues of the pores which I have demonstrated undoubtedly to
exist farther back in the oesophagus, and to be the outlets of glands
located in the interstices of the radial muscles. See fig. 9.
It is easy to believe that the cesophageal glands are salivary glands, and
that they serve the mononchs in gorging down food in somewhat the
same way as do the glands of serpents. This surmise
is based upon the structure and position of the
organs rather than upon definite and extensive physio-
logical experiment; intra vitam stains, however, have
shown that the secretions of these glands are alkaline,
evidence supporting the surmise.
Intestine
Cardia. There is usually a flattish cardia consist-
ing of 20 to 50 small characteristic cells that stain
cross' section of in- rather strongly with acid carmine, and manifestly dis-
Sdatiwto ?ho4 coi- charge a distinct function. The intestine, which is
thTiininK tr of tU th e e in- invariably separated from the oesophagus by a deep and
prominent constriction, becomes at once about three-
fourths as wide as the body, and is usually made up of cells of such a
size that about 8 to 20 are required to build a circumference. These cells
contain numerous granules of somewhat variable size, often so arranged
DIGESTION (S. S. 445) 143
about the large central nucleus as to give rise to a beautifully regular
appearance simulating tessellation. As a rule, the columnar lining of the
intestine (fig. 11) is not very refractive. Owing to the low visibility of
this lining, and the difficulty of seeing through the mass of granules con-
tained in the intestinal cells, the lumen is usually hard to decipher; to-
ward the anus, however, it may become more distinctly visible. Occasion-
ally, the granules are so few or so transparent that the contents of the
intestine can be seen with ease, but this is rather exceptional.
Granules. The structure and arrangement of the granules in the
intestinal cells of Mononchus lacustris may be taken as somewhat typical.
The granules of this species are numerous and packed rather closely in
the cells, and give rise to a more or less distinct tessellation. Specimens
fixed with Flemming solution, and mounted in glycerine jelly, show many
of the granules as refractive shells, enclosing a relatively large inner
spherical mass, which appears dark or light according to the nature of
the focus of the microscope. This structure is characteristic of some of
the smallest, as well as some of the largest, granules. These appearances
are not uniform throughout the intestine, the shell-like structures being
more apparent in the posterior part than elsewhere, and less apparent
through the middle portion of the body, where the granules are largest
and most abundant.
These intestinal granules play an important role in the economy of
the nema some of them are in fact indispensable intracellular organs.
Little as we know about their functions in detail, it is
already certain that they have to do not only with the ,,_,
secretion of various digestive fluids, but also with the
transformation and storage of the digested matter. The \| c // ^
granules in any given cell may be of several kinds, doubt-
less serving entirely different functions. These facts
the author has demonstrated by intra-vitam staining.
Digestion
Food Remnants. The digestive fluids of the mon-
onch must be well fitted for dissolving ceratin, suppos-
edly the main component of nematode cuticle, for the
cuticle, as well as most other parts of the ingested victim,
disappears completely in the course of digestion. The parts that resist
digestion longest are the spicula of male nemas and the oral spears of the
spear-bearing sorts. These organs, the spicula and the spear, are com-
posed of relatively thick layers of solid "ceratin," and furthermore are
protected from the action of the digestive fluids because of their situation
in the interior of the ingested nema, and hence are among the last to be
dissolved. Such an undigested remnant, a spear or a spiculum, consti-
144CS.S.446) THE MONONCHS
tutes one of the most frequent, as wJl as most reliable, bits of evidence
concerning thi food-habits of mononchs.
Voracity. Mononchs are voracious. Often the remains of several
other nemas are to be seen in the intestine of a single one of them. The
writer once had under observation a specimen that had swallowed four
large rotifers in quick succession, all tail-end first. The file of rotifers
could be clearly seen in the intestine of the mononch. Aquatic mononchs
are fond of rotifers. The characteristic "gizzards" of the rotifers, being
rather indigestible, are often found in the posterior part of the intestine.
Rectum. From the slightly depressed anus, the lips of which are
sometimes rather pronounced, the refractive rectum, usually about as
long as the anal body diameter, extends inward and forward, and is sep-
arated from the intestine by a distinct constriction. There is no pre-
rectum, though the contrary impression is sometimes created by a con-
striction caused by a mural commissure (?) some little distance in front
of the rectum.
Feces. From the region of the anus relatively powerful transverse
muscles pass obliquely backward to the body wall, and find their proximal
attachment in the dorsally submedian regions. These anal muscles are
more strongly developed in mononchs than in most nemas. A powerful
defecating apparatus is needful to such gluttons, since their feces are
sometimes bulky, owing, apparently, to the fact that the contents of the
intestines of their victims often prove indigestible. Probably this indi-
gestible material is to a considerable extent vegetable in its nature; at
any rate, it frequently happens that the feces are bulky, and this fact
seems to account for the strong development of the rectum and the anal
muscles.
Caudal Glands; Spinneret
The Cement. The caudal glands, when present, are always three in
number, and are arranged in a cluster or series opposite to or immedi-
ately behind the anus. If the tail is short, the foremost gland is usually
dorsal while the two submedian glands are arranged
side by side; if the tail is long all three may be ar-
ranged tandem. Apparently there are always three
separate ducts, one from each gland, each having a
separate ampulla; these latter are arranged side by
X750 ^^^^ side in a group at the spinneret. Often, however, the
spinneret is simple in form and presents ducts that
FIG. 13. Mononch . . J
tail showm* the three form only indistinct ampullae. Some idea of the man-
caudal glands, their , ..,
ducts, the spinneret, ner and rate of secretion of the caudal glands may be
and its secretion . .
<*<*.). derived from an examination of the adjacent illustra-
tion, which shows a spiral mass of the cement substance secreted by them.
This spiral mass was coagulated by the fixing fluid in which the specimen
met its death.
SPINNERET (S. s. 447) 145
Action of Spinneret. The structure of the spinneret is very similar
to that of Mononchulus, a related genus whose unusually large spinneret
has proven especially favorable for detailed study, and may be described
as follows. The three somewhat elongated ampullae at the ends of the
caudal ducts empty into a single sac located in the spinneret. From the
front wall of this sac there projects backward into its cavity an elongated
element whose free conical distal extremity fits into the outlet of the
spinneret, where it acts as a plug or valve. Apparently, this valve must
arise through an invagination of the sac during development. The plug
is withdrawn by muscles attached to it and to the dorsal body-wall near
the end of the tail. A contraction of these muscles elongates the sac con-
taining the caudal secretion and draws the plug away from the aperture
of the spinneret, thus allowing the secretion to flow out through the termi-
nal pore. The plug appears to be returned to its position and held there '
either by the pressure of the secretions in the sac, or by the general in-
ternal body pressure exerted on it through the sac. Figure 5 shows the
similar spinneret of a mononch.
Use of Spinneret. In any genus consisting of many species most of
which have caudal glands, aberrant species usually occur in which these
organs are absent. This is true of Mononchus. A spinneret would ap-
pear to be a particularly useful organ to a predaceous nema, permitting
it at will instantly to cement itself to a relatively fixed object, and thus
more easily master an active victim ; nevertheless, about one-fourth of the
mononchs have no trace of such an organ.
The lateral fields are always comparatively well-developed, and are
usually one-third to one-fourth as wide as the body. The cells composing
them often contain spherical granules not differing greatly in size from
those of the intestinal cells. No cuticular pores have ever been seen con-
necting elements of the lateral fields with the exterior.
Renette
Nothing is known about the structure of the renette in fact, it is not
yet definitely known to exist in mononchs. In most species there is a
ventral pore immediately behind the nerve-ring, which bears a close re-
semblance to the excretory pore of nemas possessing a well-developed
renette; but no internal structures have as yet been found to connect
with this pore.
Central Nervous System
The nerve-ring surrounds the oesophagus somewhat squarely near the
front end of the middle third of the neck. It is usually well developed
and easily seen a distinct refractive collar with groups of nerve cells
both in front of it and behind it. Otherwise than this very little is known
about the central nervous system of Mononchus.
- S. 448)
THE MONONCHS
FIG. 14. Female M. tri-
churus. This mononch
has only one ovary. The
tail is very long and slen-
der and quite likely is
more or less prehensile.
1*
Nerve Commissures. A constriction in the intestine is sometimes ob-
served at a point not far in front of the rectum, say at a distance equaling
3 to 5 body diameters. This constriction is sometimes so pronounced as
to cause the posterior portion of the intestine to simulate the pre-rectum
of Dorylaimus. There is here, however, no true pre-rectum. The con-
striction seems to be caused by mural commissures surrounding the
intestine. The writer can
only suggest the possibility
of the existence of special
nerves at this point, which
leave the ventral field, pass
slightly backward, then al-
most immediately become
squarely transverse, encir-
cling the intestine until they
are very near the dorsal
field, where they turn sud-
denly backward.
Amphids
If is almost certain that
small amphids occur on all
mononchs ; the writ-
er found them pres-
ent on three-fourths
of the known spec-
ies. As their gen-
eral characters have
never been adequate-
ly described, their
form and position
are specially noted
here, as well as more
explicitly in the var-
ious illustrations.
The external indica-
tions of the amphid
are always located
GO the lateral lines somewhere between the base of the lips and a poin*
opposite the middle of the pharynx. The periphery, which in some .cases
may be unclosed behind, is usually more or less elongated or elliptical in
form, its long axis lying transversely on the head. These amphids are
seldom more than one-sixth as long as the head is wide, and are usually
ttflal
X450
SEXUAL ORGANS (8.5.449)147
very difficult of observation. They are most easily detected when viewed
dorso-ventrally, and then appear as refractive oblique elements leading
from the surface of the head inward and backward through the trans-
parent cuticle, as shown for instance in the cases of subtenuis and regius
(p. 167 and 140). They can seldom be followed more than a short dis-
tance inward, and their ultimate internal connections are unknown. A
nerve-ending is nearly always to be seen in the cuticle immediately behind
each amphid.
No Eyes
Mononchs have no definite organs of vision.
Female Sexual Organs
Organs Mostly Double. Eggs. Ovaries and Ova. From the slightly
elevated and rather small vulva, the prominent refractive vagina leads
inward at right angles to the ventral surface about one-third the distance
across the body. Though comparatively small in size, the vulva is usually
easily located on account of the refractive nature of the walls of the
vagina. In nine-tenths of the species, the internal female organs are
double, and symmetrically reflexed, though in some cases the posterior
branch is somewhat smaller than the anterior. In the exceptional species
the single ovary is also reflexed (fig. 14). The ovaries occupy relatively
less space than is usual in nemas less than one-fourth of the length of
the body. Owing to the comparatively great length of the neck, the vulva
is usually located somewhat behind the middle of the body even when
the sexual organs are double and symmetrical, and may occur as far
back as the junction of the third and final fourths. Each of the two uteri is
about twice as long as the body is wide, that is to say, of a size to receive
one or two eggs only. These latter are nearly always smooth, thin-shelled,
ellipsoidal or elongated in contour, and appear about twice as long as the
body is wide, though they are sometimes somewhat shorter, and more
rarely longer. Only in a single species are the shells known to be sculp-
tured. The shells are thick in obliquus. In all the species examined by the
writer, the eggs are deposited before segmentation begins, and this is
presumably true of the great majority, if not of all the species. The
reflexed ovaries extend one-half to three-fourths the distance back to the
vulva and contain a score or so of ova, which near the blind ends are
packed in several rows ova that by increase in size come, each one in
turn, to occupy the whole of the width of the organ in its proximal half
near the flexure. The ovaries are rather broad, and taper relatively little.
Syngonism. A considerable number of the mononchs are syngonic,
and it is probable nearly all of them are so, since the males, if found at all,
are nearly always rare. Only on a single occasion, so far as records go,
have males been found to be as common as the females. Of most species
14 8(S.S.4SO)
THE MONONCHS
the males never have been seen. At a time previous to the development
of the vulva the gonads of the female produce minute spermatozoa, which
are sent forward and stored in a special portion of the uterus next the
proximal end of the ovary. In the only species so far carefully examined
in this regard these minute spermatozoa are known to be functional, at
least to the extent that they enter the ova, which then proceed to form
polar bodies and begin to segment. However, these particular investiga-
tions, made by the author and further recorded in figure 2, have been
confined to the single species M. longicaudatus. Possibly the phenomena
are different in other species.
Male Sexual Organs
Spicula. The tail end of the male is invariably like that of the female
in general form and size, except that it is more strongly arcuate; it
differs however, in some instances, probably in all, in the possession of
comparatively well-developed papil-
FIG. 15. Tail end of .
M, obtusus after Biitschii. IK. and particularly and universally
The spicula in this spe-
cies are exceptionally long in the existence of a ventral row of
and slender. The male o ^_ ...
papilla (ppi.) and supple- 8 to 20 more or less equidistant sup-
mentary organs are very . .....
well shown. The spicula plementary organs immediately in
pr0tudabndare front of the anus. The two well-
gude
bysiend e racces
S*.eft 1 e." iiE developed arcuate spicula are
of
equal size, and are always accompa-
nied by two distinct though small accessory pieces, a
right and a left. Only exceptionally are the spicula
long and slender; usually they are somewhat uniformly
arcuate, and appear to be subacute and of somewhat
uniform width throughout, at least when viewed in
profile, and about one and one-half times as long as the
anal body diameter. Usually each is strengthened by a
median longitudinal refractive piece. They are never
prominently cephalated. The accessory pieces are lo-
cated some little distance inside the anus, alongside the
spicula, which they may appear to cross when viewed
in profile. These accessory pieces are usually a little
narrower than the spicula, and 2 to 4 times as long as
wide. Distally they usually end in two subacute points,
often so arranged as to form a small U-shaped figure. When at rest the
accessory pieces usually appear as if at about right angles to the axis of
the body. They are not cephalated.
Supplementary Organs. Sperm. The supplementary organs vary in
number up to twenty. The hindmost is located immediately in front of
the anus, and may be a little farther removed from its nearest neighbor
SYNGONISM
(S. s.451) 149
FIG. 16. Mononchus ma-
jor. I Side view of male.
II Side view of head of
same. Ill Front view of
head. IV Side view of tail
V. Details of male supple-
mentary organs.
a, mouth
b, lip-papilla
c, lip
f, pharyngeal tooth
S, innervated papilla of skin
h, oesophagus
, base of pharynx
flexure in testicle
blind end of testicle
vas deferens
lip
*, accessory piece
u, post-anal i
v, spicula
papillae
iv, ejaculatory duct
x, ventral row male papillae
y, an
than is usually the case in the remainder of the series ; thence forward
the organs are about equidistant. Usually they are more or less con-
tiguous, though occasionally they are separated by short spaces, especially
anteriorly. When most highly de-
veloped, each is a convex-conoid,
innervated, very minutely papil-
lated or echinulate, more or less
protrudable organ, connected with
the interior by an oblique, indis-
tinct element along the axis of
which a nerve passes inward and
forward to join the ventral nerve
of the body (v, fig. 16). It would
appear that these organs are partly l ; n>
tactile and partly excitatory in *;
function, and act as the comple- J; ^jacSatM^duct
ments of the vulvar papillae of the r ; ^"fetory duct
female. There is no bursa. The
series of oblique copulatory mus-
cles is always coextensive with
the series of supplementary or- s - three anal R lands
gans. The rather short testes seem to be invariably two in number and
are outstretched in opposite directions. The spermatozoa of males are
minute and present a more or less vermiform nucleus.
Self -Fertilizing Females; Syngonism
Males Rare. Conjugation of Syngonic Gametes. No trait of mon-
onchs is more interesting than the capacity of the female to reproduce
without the intervention of a male by a peculiar sort of hermaproditism
called syngonism. Of most of the species no males are known; in the
remaining species, almost without exception the males are very scarce,
and only in exceedingly rare cases are they present in anything more
than small numbers. Usually hundreds, and even thousands, of speci-
mens may be examined without the discovery of a single male. How
then do the females reproduce? The answer is singularly interesting,
for, as already explained, the females fertilize their own eggs by means
of spermatozoa which they themselves produce in the same gonad. In
the mononchs these spermatozoa produced by females are so exceedingly
minute that they have hitherto escaped notice (fig. 2). Notwithstanding
its small size, the syngonic sperm cell appears to be functional. It enters
the egg, expands, and approaches the nucleus of the egg, which mean-
while throws off polar bodies and later proceeds with segmentation.
Observations have not yet extended beyond this point, but it saems alto-
150< S -S.4S2) THE MONONCHS
gether likely that these minute spermatozoa produced by mononch
syngones act in what would be called a normal manner, and as the sperma-
tozoa are known to do in other syngonic nemas in which they are of much
larger size, e. g. Rhabditis.
Abundance; Distribution
Frequency of Mononchs. Long ago Biitschli declared mononchs to
be among the commonest of nemas, an assertion that has been corrobo-
rated by all investigators in this field, hardly any of whom have failed to
note a number of species, occasionally new ones. Our knowledge of the
genus has been augmented in this way by de Man, Micoletzky, Ditlevsen,
Steiner, Hofmanner, Menzel, Daday, and the writer, until at the present
time about sixty species are known. Doubtless this number will be very
largely increased by future researches.
Geographic Distribution. Variety of Habitat. Mononchs are found
in all the habitable regions of the world. They inhabit the soils and
fresh waters of every clime, occurring even at great depths in lakes and
at very high altitudes on mountains. While we have only just begun to
learn the details of their geographic distribution, it is already manifest
that some species are cosmopolitan. Several species occur both in Europe
and in North America, and a few of these same species are known also
from Australia. Considering the small number of observations hitherto
made along this line, it seems safe to predict that many of the species
will be found to be cosmopolitan. Some species adapt themselves to sur-
prisingly varied conditions. Mononchus longicaudatus, for instance, is
known from the tropics, from temperate regions, and from very cold
regions, and inhabits both soil and fresh water. Another species, Mon-
onchus brachyuris, is known both from warm springs and from cold
Alpine lakes.
Abundance in Arable Soil. Mononchs occur in great numbers in
arable soil. On one occasion the writer estimated that at least thirty
millions of mononchs per acre were present in the top six inches of a
field of maize in New Jersey, and the actual number present may have
been much greater. They are regularly present in practically all arable
land of a sandy or loamy nature.
The very numerous introductions of living plants into the United
States, through the agency of the Office of Seed and Plant Introduction
of the Department of Agriculture and other agencies, has brought about
simultaneously the introduction of many species of Mononchus. Nemas
existing in the soil about the roots of introduced plants are often
placed under favorable conditions for propagation in this country. It is
therefore certain that an unusual variety of mononchs exists in the soils
of the United States.
GENUS MONONCHUS (S.S.453)i5j
Interplay of Organisms. There are regions where certain nematode
diseases of crops are very destructive, while other regions, the climate
and soil conditions of which are apparently similar, suffer but little, or at
least to a lesser degree, so far as we know. In such cases it is permis-
sible to suppose that the nematodes in the area where the lesser damage
is done are held in check by some as yet unknown agent. Is it not pos-
sible that the mononchs play some such role as this, and that just as cer-
tain insects hold other insects in check, so certain nemas hold other nemas
in check?
We know relatively little about the life history of most of the mon-
onchs, and as yet very little about the possibility of controlling their
growth. One species, Mononchus longicaudatus, occurs at certain times
in almost inconceivable numbers in the sand of the slow filter beds of the
water works of cities. Near the end of the period of use the top layers
of the sand in these filter beds sometimes become in reality a huge culture
of this species. The observations suggest at least the possibility of culti-
vating this species on a large scale, should it prove desirable to do so.
The discovery that the genus Mononchus is very large and to a con-
siderable extent composed of common and cosmopolitan species that feed
upon injurious plant-infesting organisms, suggests so many new lines of
research in soil biology as to make it desirable that a clear and connected
account of the members of the genus be available to investigators. This
need is increased by the fact that the literature is a scattered and frag-
mentary one, difficult to assemble. To these facts it must be added that
most of the new observations herein recorded have been made upon
species previously unknown.
II
GENUS MONONCHUS BASTIAN, 1866
This genus is composed of non-marine, free-living nemas, with naked
cuticle and obscure amphids, and having a plain oesophagus preceded by
a broad that is, non-tubular pharynx, armed with 1 to 3 more or less
immobile teeth of which the dorsal is largest, and supplied with 6 power-
ful papillated lips. Ovaries reflexed, usually two. Testes two, out-
stretched ; spicula two, equal, simple, as are their small accessories ; there
is a pre-anal ventral row of supplementary organs.
GENERA SIMILAR TO MONONCHUS, WITH DISTINGUISHING CHARACTERS
Oncholaimns
Anonchus
Microlaimtts
Irottus
Nannonchus
Oionchus
Mononchtilus
Marine; sometimes found in brackish soils. Has cephalic setse.
Has spiral amphids, and cephalic setse.
No thick muscular lips; amphids circular.
Pharynx tubular; teeth movable radially.
Has spiral amphids and cephalic setae.
Pharynx filled by single tooth, which is really spear-like.
Quite similar. Has much larger (ventral) spinneret; strongly developed
lateral fields; smaller pharynx; female organ single.
152 (s-s- 45-0
THE MONONCHS
Mononchus Bastian, 1866
ay in pharynx or higher, usually massive
MONONCHUS Cobb;
Subgenera
and
Species
1. MONONCHUS
DORSAL TOOTH midw . _ ,
Tooth not opposed by denticles; subg.
type, M. truncatus Bast.; pharynx about 2 to 3 times as
long as wide, goblet-shaped or ellipsoidal; wall smooth or
transversely striated; spinneret usually present; males of
about half the species known; female organs double (except
monhystera)
Dorsal tooth faced by 2 ventrally submedian teeth
Teeth retrorse (tridentatus de Man 1876)
Teeth not retrorse
Tail conoid, then cylindroid; body 7 mm. long (rex Cobb 1904)
Tail simply conoid; body 3 mm. long or less
Spinneret and caudal glands absent exilis n. sp.
Spinneret and caudal glands present . .
Contour of the head angular; labial papillae 16 radiatus n. sp
Contour of the head rounded; labial papillae 12
Pharynx longer than the head is wide palustris n. sp.
Pharynx only as long as the head is wide teres n. sp.
Dorsal tooth not faced by submedian teeth
Ovary 1; pharynx not much longer than wide monhystera n. sp.
Ovaries 2; pharynx toward twice as long as wide
Tail simply conoid, 8 per cent or less
Spinneret none
Pharynx over half as wide as the head vorax n. so.
Pharynx not over half as wide as the head
Length about 1 mm.; tooth midway, small, digitate parvus de Man 1879
Length 1.5 to 2 mm.; tooth beyond midway, massive papillatus Bastian 1866
Spinneret present
Body 2 mm. long
Form of the tail regular
Form of the tail somewhat irregular
Body 3 to 4 mm. long
Tooth midway, amphids a little behind the lips maior Cobb 1893 11
Tooth and amphids at the base of the lips gerlachei de Man 1904 12
Tail conoid, then cylindroid, about 10 per cent or more
(Esophagus 15 per cent fovearum (Dujardin) Bastian '66 13
intermedius Cobb 1893
tenuicaudatus Stefanski 1914
obtusus n. sp.
tunbridgensis Bastian 1866
longicaudatus Cobb 1893
2. SPORONCHULUS
(Esophagus 22 per cent or more
Buccal cavity toward 2 times as long as head is wide
Spinneret armed with 2 very small setae megalaimus n. sp.
Spinneret not armed with setae macrostoma Bastian 1866
Buccal cavity only about half as long as head is wide
Labial papillae setose
Labial papillae, at least the outer, not setose
Pharynx 54 as wide as head; body 1.5 mm. long
Pharynx */ 2 as wide as head or more; body 2
to 3 mm.
Cavity about 2 times long as wide; tooth acute truncatus Bastian 1866
Cavity about 3 times as long as wide; tooth
sub-acute
Inner labial papillae large; tail sub-conoid., dadayi Micoletzky 1904
Inner labial papillae normal; tail finally
cylindric
Tooth opposed by numerous denticles on opposite wall
Arrangement of the denticles irregular; characters otherwise
as in Mylonchulus; subg. nov. SPORONCHULUS;
type S. dentatus n. sp.
The tooth behind midway; spinneret present; anus at 92; 'f recessus n. sp.
The tooth in front of midway; no spinneret; anus at 96;
Denticles about 20; pharynx half as wide as the head; T dentatus n. sp.
Denticles about 50; pharynx one-third as wide as the head
Arrangement of the denticles orderly
Denticles along a ventral, longitudinal pharyngeal rib;
subg. PRIONCHULUS Cobb; type Pr. muscorum
(Dui.) Bast.; pharynx ellipsoidal, about 2 times long
as wide; males of one species known; female organs
double; no spinneret
Eggs punctate or echinulate punctatus
Eggs not punctate or echinulate
Length 2.5 to 3.4 mm.; vulva at 65 per cent; anus at
94 per cent
Width 3.6 per cent; denticles forward pointing muscorum (Duiardin) Ba
Width 2.3 per cent; denticles inward pointing longicollis n. sp.
Length 4 mm.; vulva at 55 per cent; anus at 97 per cent spectabilis Ditlevsen 1911
Denticles in transverse rows on 2 sometimes confluent, sub-
median, rasp-like areas, often with 2 very small sub-
median teeth at their bases; subg. MYLONCHULUS
Cobb; type M. minor Cobb; pharynx goblet-shaped,
tooth more or less arcuate; smaller species of which
iecurrens n. sp.
21a
21c
3. PRIONCHULUS
sp.
'66 23
24
25
KEY TO GENUS MONONCHUS
(S. S. 455) 153
the males are unknown (except tennis) ; female organs
double (except index and reverses) ; spinneret present
(except similis)
Ovary 1; tail rapidly diminished, then digitate
Vulva behind the ovary; denticles normal
Vulva in front of the ovary; denticles few
Ovaries 2; tail not digitate (Ex. perhaps sigmaturus)
Dorsal tooth somewhat digitate, relatively small
Refractive ring about pharynx in front of tooth
Refractive ring about pharynx not prominent
Dorsal tooth massive, not digitate
Head rounded, denticles in about 12 rows
Head truncate, denticles in 2 to 6 rows
Rows of denticles 2
Rows of denticles 4 to 6
Denticles about 4 rows; spinneret small
Denticles about 6 rows; spinneret larger
Tail bent ventrally near the middle
Caudal setae none ; tail conoid
Caudal setae (3 pairs) present; tail not conoid
Tail arcuate or straightish
Width of adults 2.3 per cent
Width of adults 2.7 per cent or more
8audal glands and spinneret absent
audal glands and spinneret present
Eggs thick shelled
Eggs thin shelled
Buccal striae faint if any; anus 94 to
96 per cent
Species aquatic
Species not aquatic
Buccal striae more pronounced; anus 98
per cent
Spinneret finally dorsally recurved..
Spinneret not dorsally recurved
DORSAL TOOTH and others small, basal or nearly so (Exc. 44)
Teeth retrorse, small, basal, exceptionally midway; subg.
ANATONCHUS Cobb; tvpe A. tridentatus de Man; large
species with roomy elongated pharynx and smallish retrorse
teeth; tail long and usually becoming cylindroid; female
organs double; males of most of the species known
Body 2 to 4 mm.; teeth equal, midway; anus 90 per cent....
Body 5 to 6 mm.; teeth sub-basal; anus 80 to 85 per cent
Submedian teeth equaling the dorsal; body 6 mm
Submedian teeth smaller than the dorsal; bodv 5 mm
Teeth not retrorse, small, 9r even minute; subg. IOTONCHUS
Cobb; type I. gvmnolaimus Cobb: large species with roomy
elongated -harynx having longitudinal ribs; tail rather
long, and often slender; males of more than half the
species known: female organs double or single; most
species with spinneret
Ovary single; 1 to 3 rudimentary basal teeth
Tail digitate; 3 sub-equal vestigial teeth
Tail not digitate- 1 dorsal tooth, remainder faint or none
Posterior extremity setaceous
Posterior ext-mity slender but not setaceous
Pharynx as long as wide; few submedian denticles...
Pharynx about 2 times long as wide; faint submedian
teeth
Amphid simnle; buccal wall thin, transversely striated
Amphid duplex; buccal wall thick, not striated
Ovaries 2; 1 t" 3 small, sub-basal teeth
Body 4 to 7 mm.; tail finally cylindroid; 3 teeth
Spinnerer present; lips rather plain
Length 4 mm.; anus 90 per cent; the 3 teeth subequal
Length 6 to 7 mm.; anus 80 per cent; submedian teeth
smaller
Spinneret none; lips striated lengthwise . . ._
Body 1 ti 4 mm.; tail conoid; 1 tooth, sometimes denticles
Anus .-* about 86 per cent; tail conoid, or at last sub-
cylindroid
Lips not set off by constriction; onchi unequal or one
Onchus with small companions; head rounded
Onchus one only; head truncate; pharynx striated...
Lips set off by a deep constriction; onchi three, equal
Anus at about 94 per cent; tail simply conoid
Dorsal tooth small, others basal, minute, indefinite. . . .
Dorsal tooth distinct
Buccal cavity half as wide as long: tooth sub-basal..
Buccal cavity as wide as long; main tooth basal
Spinneret present
Spinneret none
4. MYLONCHULUS
index Cobb 1907
reversus n. sp.
obtusicaudatus Daday 1901
brachyuris Biitschli 1873
denticulatus n. sp.
sparsus n. sp.
micrurus n. sp.
incurvus n. sp.
sigmaturus n. sp.
subtenuis n. sp.
subsimilis n. sp.
obliquus n. sp.
lacustris Cobb 1915
polonicus Stefanski 1915
minor Cobb 1893
brevicaudatus n. sp.
japonicus n. sp.
ANATONCHUS
tridentatus de Man 1876
gracilicaudatus n. sp.
dolichurus Ditlevsen 1911
6. IOTONCHUS
digiturus Cobb 1893
trichurus n. sp.
(bathybius Micoletzky 1913)
gvmnolaimus Cobb 1893
consimilis n. sp.
rex Cobb 1904
regius n. sp.
bathybius Micoletzky 1913
similis Cobb 1893
fasciatus n. sp.
studeri Steiner 1914
zschokkei Menzel 1913
brachylaimus n. sp.
acutus n. sp.
THE MONONCHS
1. M. exilis, n. sp. The cylindroid neck ends in a rounded head with a dis-
tinctly expanded lip region. The large pyriform pharynx is armed with three sub-
equal teeth. The wider anterior part of the pharynx is two-thirds as wide as the
* head. The apices of the teeth are midway,
1.8 6.2 27. '78' 15 98.2 the dorsal one being a little the farthest for-
1.6 1.8 2. 2.3 \. m ward. Amphids somewhat behind the lips,
1.6 6. 24. -M- 38 98. but farther forward than the teeth, consisting
1.6' 1.8 2. 2.2 1.2 of somewhat rectangular markings one-fifth
as wide as the head, longest in the transverse direction, and with the lateral and
front margins plainer than the posterior. Lining of the oesophagus not so promi-
nent as in most mononchs. Intestine greenish, finely granular, obscurely tessellated.
Cardia long and plainly to be seen through the flat, colorless pseudo-bulb at the
beginning of the intestine. The rectum has a thick lining of highly refractive
ceratin, and is a prominent organ one and one-half times as long as the anal body-
diameter. Terminus about one-fourth as wide as the base of the tail. The very
broad vulva is only slightly elevated. Posterior sexual branch only two-thirds as
long as the anterior. On the male there is a row of about 14 equidistant, rather
closely approximated ventral ridges in front of the anus, extending forward a dis-
tance equal to 3 tail-lengths. These do not bear any prominet papillae. The body
is somewhat thicker in the region of these ridges. Spicula linear, uniformly 5 /j. in
diameter when seen in profile, the proximal end being in no way distinguished from
the rest of the shaft. The accessory pieces appear to rest rather closely against the
distal halves of the spicula.
Found about the roots of moss, Moss Vale, New South Wales, 1894. Examined
in water after fixation with osmic acid.
2. M. radiatus, n. sp. The
amphids of this rather small
3.3 9.
30.
95.
.8 mir
2.2 2.8 2.8 2.3 2.2
but elegant species are minute and inconspicuous, about one-
eighth as wide as the corresponding part of the head. The
granules of the intestine are largest posteriorly, where they are
about one-half as wide as the spinneret. The intestine is not
tessellated. The tail is markedly arcuate, its spinneret about
one-fifth as wide as its base. Anus very slightly raised. Caudal
glands rather small, elongated. Sexual organs apparently double and symmetrically
reflexed.
Description derived from a single young specimen from a cranberry bog in New
Jersey, U. S. A. Flemming solution to glycerine. Fig. 17.**
3. M. palustris, n. sp. Intestine 12 to 15 cells in girth, more or less distinctly
"# J 2.7 8. 30. '62' 15 97. tessellated. Tail arc-
jT 27s 27e 27? 1.9 > 1-4 IBra uate, its rather conoid
spinneret about one-fifth as wide as its base. Caudal glands
broad and saccate, their ampullae occupying most of the
posterior half of the tail. The elongated eggs are about
twice as long as the body is wide, and occur one at a time
in each uterus. The rather small, tapering ovaries contain
8 to 10 ova arranged more or less irregularly.
From a white cedar swamp, Jefferson County, Wis-
consin, U. S. A. Feeds upon rotifers and probably upon
other nematodes, which it appears to masticate (page 443,
fig. 10). Sublimate to balsam. Fig. 18.
^* This decimal formula for nemas is explained in the appendix.
** The species figures have the same magnification throughout, so that the reader may guage the
relative sizes.
SUBGENUS MONONCHUS
(S.S.457) 155
4. M. teres, n. sp. This comparatively small, simple form has 2 submedian
teeth of equal size. Walls of the intestine with numerous granules of rather uni-
form size, giving rise to a faint tessellation ; the granules such that 2 to 3 would be
required to span one of the 3.9 12. 35. 60 Y 94.
amphids. Tail rather strongly 3~4 37 375 372 2.^ ' "
arcuate, its fairly well developed spinneret about one-fifth as wide
as its base. Caudal glands somewhat elongated, their small but
rather conspicuous ampullae nearly filling the posterior fifth of
the tail.
Description prepared from a single, more or less shrunken speci-
men, found in the sphagnum of a pot in which blueberry plants
were being cultivated. Bears a general resemblance to papillatus, but differs in the
form of the pharyngeal teeth and of the terminus. Flemming solution to glycerine.
Fig. 19.
5. M. monhystera, n. sp. Amphids not seen. Lining of the rectum and of the
intestine rather distinct and refractive. Intestine only faintly tessellated, if at all.
3.3 9.7 27. '78 19 94 Tail arcuate . rather
37 37s 76 372 27s~ 1-1 M blunt, without spin-
neret. From the rather conspicuous, more or less elevated
vulva, the vagina, which is two-thirds as long as the body is
wide and tubular, extends obliquely inward and forward.
Nothing definite is known with regard to the eggs or the
form of the ovary.
Found about the roots of orange trees, Bahia, Brazil. Bears
a general resemblance to M. papillatus, but has only one
ovary. This species is nemativorous. Flemming solution to
glycerine. Fig. 20.
6. M. vorax, n. sp. This voracious species has a large mouth cavity and the
oesophagus is therefore at first slightly swollen. Intestine 12 to 20 cells in girth,
not tessellated. The 2 .7 8. 27. >67' 22 92.
terminus of the arc-
1.4 BE
2.1 2.3 2.7 2.6 1.6
uate tail is about one-seventh as wide as its base. The
elongated eggs are about twice as long as the body is
wide. Each ovary contains about 30 developing ova,
arranged irregularly. Small sperm cells were seen in
abundance at the flexure, in a condition indicating that
the species is syngonic.
Found in soil from a white cedar swamp in Wiscon-
sin, and from a cranberry bog in New Jersey, U. S. A.
This is apparently a voracious feeder on other nema-
todes. Remains of Dorylaimus
and Ironus were seen in the
intestine. Resembles M. mac-
mr t* -~fl \^~ft rnstoma, but the tail is conoid and has no spinneret. Sub-
limate to balsam. Fig. 21.
T. M. parvus de Man. De Man mentions the presence
of minute teeth at the base of the pharynx, near the be-
3.1 - 9.5 29. *63< 93. ginning of the oesoph-
17 ^ ^ gTj; ^7 l.l n agus. Lining of the
oesophagus well developed. Intestine apparently about 10
to 12 cells in girth, tessellated. Rectum somewhat shorter
than the anal bodv-diameter. Tail arcuate; its terminus only about one-eighth a
156( s - s - 458 > THE MONONCHS
wide as its base. An egg seen in the uterus measured 100 ^ in length. It is not
certain that caudal glands are present.
Knowledge of this species rests very largely on the observations of Dr. J. G. de
Man, who says that it is an active species, common in sandy soils of the dune dis-
tricts of Holland. Occurs also in Germany, according to Brakenhoff, whose speci-
mens, however, have the dorsal tooth close to the lips instead of midway as in the
type form. Fig 22, previous page (after de Man).
8. M. papillatus Bastian. Glands are present in the segments of the oesophagus,
and are most strongly developed in the posterior half. The secretion of the glands
co , 2 7 in the dorsal segment
3. 9.3 2b. *bl"-' 93. . .
2.6 3.5 3.8 4.3 2.4 pours into the lumen
of the oesophagus through a minute pore near the middle of
the neck, a short distance behind the nerve-ring. Under favor-
able conditions lenses of the highest power show transverse
striae to be interrupted on the lateral lines, where there are 2
^ refractive longitudinal striations very close together. What
appears to be an ordinary ventral renette pore is found a short
xfso distance behind the nerve-ring. The writer's investigations
prove this species to be syngonic. The longitudinal ribs of the pharynx, probably
3 in number, are a little more prominently developed than usual. Occasionally a
subventral or submedian rib of the pharynx shows traces of most exceedingly fine
denticles. Only the most careful examination of favorable specimens shows these
denticles. The writer has never observed a denticulated ventral rib like that of
muscorum, as mentioned by Menzel.
A common, voracious, cosmopolitan, nemativorous species. Found in many parts
of Europe and of the United States, and also in Hawaii, Australia, South America
and Asia. Fig. 23. See also fig. 8.
9. M. intermedius Cobb. Truncate head having 6 lips, each with 2 papillae.
The elongated-oval amphids are half as wide as the base of the lip. The rather
long, goblet-shaped pharynx is half as long 2.5 7.4 24. '6i' 35 94.
as the head is wide, and presents a mod- 2.4 2.4 2.8 3.3 2.4
erate-sized dorsal tooth two-thirds the way from the base to the lips. The intes-
tine, whose commencement is marked by the presence of a pseudo-bulb, shows a
rather indistinct tessellation. What appears to be a ventral renette pore occurs
just behind the nerve-ring. The lateral fields are one-fourth as wide as the body.
Caudal glands are present in the conical, arcuate tail. Spinneret almost pointed.
Anus depressed, consequently conspicuous. Vulva conspicuous. The reflexed por-
tions of the ovaries extend one-half way back to the vulva.
Found about the roots of sugar cane, Harwood, Clarence River, New South
Wales, Australia.. Examined in water after fixation with osmic acid vapor.
10. M. tenuicaudatus Stefanski. The lips are said to bear 6 large, spheroidal
papillae. A transverse element is said to traverse the wall of the pharynx opposite
? ? 21. '50+* 94. the apex of the
4 - ^ dorsal tooth, and
to bear 2 slightly curved projections. The oesophagus
is muscular. At first the tail diminishes regularly in
diameter, but presents 2 swellings in the posterior part.
Found among algae, in the Rhone River, Switzer-
land. This species is said to resemble M. macrostoma
Bastian in the form of the buccal cavity, but to differ
from that species in the details of the structure of
the mouth, as well as in the form and length of the
tail. Fig. 24, after Stefanski. \\\ ^O> X 750
SUBGENUS MONONCHUS
(s. s. 459) 157
ii. M. major Cobb. Labial papillae of the inner row each with 3 (?) nerve-
endings. Amphids slightly farther forward than the apex of the dorsal tooth,
small. Lateral fields one-fifth as wide as the body. Intestine composed of rather
small cells,
3.4 mm ,
snowing an
.6 6.
19.
'55
25
95.
2.6
2.9
-M- 45
1.5
indistinct tes-
2.3 2.9 2.8 2^ sellation. The
eggs are probably less than twice as long as
wide. Each of the 12 rather conspicuous,
echinulate, mammiform accessory organs is
situated on the posterior side of a transverse
ceratinous ridge extending one-fourth the dis-
tance around the body. The anterior two or
three and the posterior one of these organs
are smaller than the others. There are 2 pairs
of ventrally submedian papillae, also inner-
vated, on the anterior third of the tail, the
posterior pair being near the end of the an-
terior third, and the other pair half way be-
tween- that point and the anus. There are
other papillae faintly visible on the dorsal side
of the tail and elsewhere (fig. 16). The fe-
males of this species also present papillae near the vulva: 3 small, ventrally
submedian papillae on each side of the body, one opposite the vulva, one a short
distance in front of it and another a short distance behind it, and in addition a
tandem series of 3 papillae, both in front of and behind the vulva, on the ventral
line. The location and conformation of these papillae is shown in figure 12. Doubt-
less the females of other species possess similar papillae. Fixed with osmic acid;
examined in water.
Found about the roots of plants, in damp soil, Moss Vale, New South Wales,
Australia. Also about turnips in Tasmania. This species resembles the following.
Fig. 25.
12. M. gerlachei de Man. Lateral fields about one-third as wide as the body.
In transverse section the buccal cavity, though nearly round, is obscurely three-
sided, and shows the existence of 3 small, longitudinal grooves in the wall of the
2. 5.2 18. '50' 33 92.5 _
1.8
2.
2.
95.5
1.8 ? ? 3.7 2.3
pharynx, presumably so functioning as
to increase the elasticity and mobility of
the pharyngeal walls. What appears to
be a renette pore occurs immediately
behind the nerve-ring. Anal muscles
are well developed in the female. Spic-
ula arcuate, tapering both ways, about
one and one-third times as long as the
anal body-diameter, and in their widest
part about one-sixth as wide as the
corresponding portion of the body. The
accessory pieces are about one-third as long as the spicula, relatively small and
poorly developed, appearing to be parallel to them when viewed in profile. The
1 5g(S.S.460) THE M ON ON CHS
pre-anal ventral row of supplementary organs is essentially the same as in major
(fig. 16). According to Steiner's observations the number of supplementary organs
in this species may at times be as great as that noted in major. Steiner calls atten-
tion to the existence of a submedian row t> pre-anal papillae, lying on either side
of the ventral row. The tail bears 3 pairs of papillae, one submedian or subventral
pair near the anus ; a second subventral pair slightly behind the middle ; and a third
dorsally submedian pair at the beginning of the final fourth of the tail. In the
male the slightly conoid spinneret is one-sixth to one-seventh as wide as the base of
the arcuate tail. The proportions are about the same as in the female, although the
tail of the female is slightly longer and more slender, and not so strongly arcuate.
Found among fresh water algae, Cape Van Beneden, Banco Land. It is rather
difficult to point out satisfactory differences between this species and major. The
pharynx of gerlachei is relatively smaller and is thicker walled, and its dorsal tooth
is slightly farther forward. The number of labial papillae sixteen appears to be
the same in each. The amphids are perhaps slightly farther back in major than
in gerlachei. The number of papillae noted on the tail of the male of major is
greater than that noted on the tail of gerlachei, but so far as the distribution of
the dorsal papillae on the tail of gerlachei is concerned, they appear to accord very
closely with those of major. The two species appear to be closely related. Fig. 26
on the previous page (after de Man).
13. M. fovearum (Dujardin) Bastian. This is an insufficiently known species
and may have to be declared nomen nudum. Head a trifle angular. Pharynx
angular, "armed with 2 to 3 straight pieces, each ? ? is. ^50' 93. 2 5 ,
(?) with a pronounced tooth in front of the ? - ? ? 3. ?
middle." Tail tapering at first but retaining the same diameter through its pos-
terior half, and ending in a sort of spinneret (?). Eggs in single series.
Found at Rennes, France, in a fresh water ditch, along with Branchipus, ento-
mostrica, Eitglena etc. De Man suggests that this species is related to tridentatus.
14. M. megalairnus, n. sp. Labial papillae obscure. Amphids obscure, half way
between the apex of the dorsal tooth and the anterior extremity. Cardia large and
2.9 9. 28,. 's:?' 38 86. conspicuous, more or
1 - 8 2 - 6 3- 1 3 - 5 I- 7 ' less cylindroid, three-
fourths as wide as the body. Intestine about 12 cells in
girth, more or less distinctly tessellated. At the end of
the anterior third the tail is one-fourth as wide as at
the anus. Spinneret slightly swollen, with 2 very small digi-
tate setae.
About the roots of plants, in a tamarack swamp, Wisconsin,
\J. S. A. This mononch is peculiar in the relatively meager
development of the labial papillae and the pharyngeal teeth,
and the weakness of the pharyngeal muscles. Flemming solu-
tion to glycerine. Fig. 27.
15. M. macrostoma Bastian. Inner set of labial papillae inconspicuous; outer
set fairly well developed. The neck tapers but little. The head, however, is rather
markedly convex-conoid. De Man describes and figures 2 exceedingly minute
submedian teeth at the base of the pharynx. CEsophageal lining strongly devel-
oped. Intestine 12 to 15 cells in girth, tessellated. Posterior half or two-thirds of
the tail of the female of practically uniform diameter, tapering but very slightly.
Spicula arcuate, very slender, about twice as long as the anal body-diameter. Their
proximal ends are not cephalated. They are accompanied by 2 accessory pieces,
hardly one-third as long, arranged parallel to their distal parts. Supplementary
organs, about 20, in the form of innervated papillae, spread over a distance nearly
SUBGENUS MONONCHUS
(S. s.461) 159
equal to the length of the tail, the posterior member of the series being a short
distance in front of the anus. There are 3 pairs of somewhat equidistant subven-
tral post-anal papillae on the anterior part of the tail. There are also lateral
papillae on the tail.
This beautiful, ac- ^ ^ 6 *| '& *|^ 2- M ^-7^-7-^^ _ ^
tive, rather common 2 6 ? 25 M 92
species is found in ? ? ^ ? T~~^ ll8 BB
the soils of meadows and marshes in many parts of
Europe ; it is also aquatic. The writer has followed
Dr. de Man's rehabilitation of Bastian's macrostoma.
Corresponding females which the writer has found at
the Arlington Farm, Virginia, U. S. A., indicate the
presence of exceedingly fine transverse striae, and of in-
conspicuous wings. Amphids obscure, just behind the
lips, difficult to see except in dorso-ventral view. The
oesophagus receives the basal fourth of the pharynx,
and in this region is very slightly swollen. The writer
failed to see the minute basal onchi mentioned by de Man. The thin-shelled eggs,
which occur in the uteri one at a time, are about one and one-fourth times as long
as the body is wide and about half as wide as long, and are apparently deposited
before segmentation begins. The writer has no doubt this species is syngonic. A
female which had yet to undergo the final moult contained an egg which had its
shell completely formed, and was evidently in a state preparatory to segmentation.
Flemming solution to glycerine. Fig. 28 (after de Man).
According to Bastian -the following differences exist between macrostoma and
truncatus; macrostoma is 50 per cent longer, and is relatively narrower in the ratio
of 3.5 to 5.3. Macrostoma tapers less in the neck, and has papillae, while truncatus
has none. While macrostoma is the larger, its pharynx is no longer ; the onchus is
a little farther forward. The intestine in macrostoma is less distinctly tessellated.
The posterior part of the oesophagus in macrostoma is figured as having an internal
expansion. These characters seem to the writer sufficient to separate the two
species. It is probable that papillae on the head of truncatus were overlooked by
Bastian. This would have been easy, for instance, if the papillae on truncatus are
similar to those on megalaimus. See figure 27.
16. M. obtusus, n. sp. Papillae setose. The adjacent figure (29) is after
2.4 > 25. ^50+^ 87. Biitschli, whose
275 ? 472 ? 3.3 1-7 " figures seem to
represent a different species from that figured by de
Man under the name macrostoma, notwithstanding the
general resemblances. The proportions of the tail and
of the spicula are different in the two forms; the dis-
tribution of the papillae on the tail is also different, and,
while the number and position of the pre-anal ventral
supplementary organs are about the same, their form as
shown by Biitschli is decidedly different from that
shown by de Man. In addition, Biitschli's figure shows
3 pairs of pre-anal, ventrally submedian papillae coex-
tensive with the ventral row. Biitschli's data may there-
fore, the writer thinks, be taken as establishing this new
species. Synonym, M. truncatus Bastian of Biitschli.
Found in the River Main, Germany ; common in mud
and in aquaria and among aquatic plants, in moving water not foul. See also fig. 15.
1(30 (S. S. 462)
THE MONONCHS
17. M. tunbridgensis Bastian. The Tunbridge mononch is interesting histori-
cally as well as intrinsically, for it was an examination of numerous specimens of
this aquatic nema that marked the beginning of the classical researches of the
6.7 24. '52' 20
2.4
2.1
2.4
2.8
7.8
24.
3.6
23.
3.7
89.
2.3 -
90.
1.3 n
2. 3.5 ?.6 ?.7 1.7
well-known English nematologist, H.
Charlton Bastian. The upper formula
is the average of glycerine specimens
from the Arlington Farm, Virginia,
U. S. A., while the lower formula is
the average of the writer's balsam
specimens from Tunbridge Wells, Eng-
land. As a rule the 4iead is rather suddenly contracted opposite the pharynx, and
this is perhaps the best distinguishing mark of the species. Bastian, who had an
abundance of specimens, emphasizes this character. The adjacent figures are those
of Dr. de Man, and show the pharynx relatively a little narrower than is usual. The
tails of the writer's Tunbridge Wells specimens accord rather with Bastian's figure
than with his description. As is often the case in other mononchs, the labial papillae
stain more strongly with carmine than do adjacent tissues, so that the lip region as
a whole appears strongly colored. Opposite the dorsal tooth there is an exceed-
ingly minute, low, subventral projection. The form of the amphids is not fully
determined ; they are located nearly opposite the base of the pharyngeal tooth, and
have a width one-half to one-third as great as that of the pharyngeal cavity. Near
the cardia the cesophageal lining occupies about one-fourth of the optical longitudi-
nal section of the oesophagus. The intestine, which ma}' present a certain amount
of tessellation, is about 10 to 12 cells in girth. The anterior two-fifths to one-half
of the tail is conoid in such a fashion that at the middle the diameter is about
one-sixth as great as at the anus. Thence onward the tail is nearly cylindrical, and
ends in a very slightly expanded terminus armed with one or two very inconspicuous
papillae. That a sticky substance often exists on the surface of the terminus of the
tail is evident from the accumulation there of minute particles of foreign matter.
Caudal glands appear to exist immediately behind the anus, but their nuclei have
not been definitely made out as yet. The lateral fields appear to be one-third as
wide as the body. Each ovary contains a score or more of developing ova, ar-
ranged in several tiers in the distal half of the organ, but single file elsewhere.
The somewhat elongated eggs are about one and one-third times as long as the
body is wide, and about half as wide as long, and occur in the uteri one at a time.
This seems to be primarily an aquatic species, though the writer has found it also
in soil in the vicinity of rivers and streams. Fig. 30 (after de Man).
18. M. truncatus Bastian. CEsophagus conoid, its lining well developed. Intes-
2.5 ? 25. '50+* 86. tine about 12 cells
? if; sTa 3.4 ' 1 - 8 BB i n girth, more or
? 25. M 92.\ less distinctly tes-
? ? ? ? ' sellated. Lateral
fields broad and distinct. It is a question whether to
retain this species on the basis of Bastian's original
description, or to accept Biitschli's description as a
rehabilitation of Bastian's species. It is hardly likely
that any species of Mononchus is destitute of labial
papillae, and in this respect Bastian's description
seems defective. The extreme reduction of the
SUBGENUS MONONCHUS
labial papillae so far recorded is shown in megalaimus. Biitschli and later authors
describe and figure the papillae of truncatus as setose. It seems hardly likely that
Bastian would have overlooked setose papillae such as those figured by Biitschli.
In that case Bastian's truncatus should be retained as a species, probably having
very inconspicuous labial papillae similar to those of megalaimus, while the data
given by Biitschli may be taken as establishing a new species, for which the name
obtusus is proposed. (See No. 16.)
Found in a small pool, among decaying moss and liverwort, England. Fig. 31
(after Bastian).
19. M. dadayi Micoletzky. A striking character of this species, "M. macrostoma
Bastian var. armatus Daday," as described by its author, is the presence of 6 small,
? ? 22. ? 86. tooth-like cuticular spines close
H 1 ? ? ? 4~72 2.6 K6 '" around the mouth. No such
structures have been seen in other species, and accordingly
Micoletzky has proposed for the form the name dadayi.
This is a littoral species. The description and drawings
rest upon the examination of a single specimen. The original
, m description is very brief and the accompanying illustrations,
one of which is here reproduced, are meager sketches of the
head and tail ends. A more complete examination of further
750 specimens is desirable. Fig. 32 (after Daday).
20. M. longicaudatus Cobb. Opposite the apex of the dorsal tooth there are
refractive transverse thickenings of the wall of the pharynx in the ventrally sub-
median region, and in front of these thickenings there are a few transverse striae.
The lateral fields are two-fifths as wide as the body, and are distinctly to be seen,
since they have definite lateral contours, doubtless owing to the thickness of the
muscular layer. The lateral fields contain scattered, nearly colorless granules
somewhat smaller than those contained in the intestinal cells. In young specimens
the vagina is distinctly separated from the uterus by a deep constriction, and the
uterus itself is bulbous near this constriction and narrower farther away. Longi-
caudatus is a syn- 3. 6.? 26. ^55*23 88.
gonic species. In 2~! 274 3~l 3~! 2.4 '
the adult and egg-producing specimens the eggs are
seldom or never seen more than two at a time, one in
each uterus.
A predacious species, feeding upon other nematodes,
upon rotifers and protozoa. It is cosmopolitan, and is
found in rivers, ditches and pools, as well as in the
soils of swamps and meadows. It occurs, sometimes in
vast numbers, in the sand of the slow filter beds of the
water-works of cities and towns. Flemming solution
to glycerine. Fig. 33 ; also fig. 2, p. 132.
Longicaudatus suffers from an internal disease caused
by a fungus having a branched mycelium. The width
of the mycelium is about half as great as the thickness of the body wall of the
nema, and the septa oi the cells are separated from each other by a distance equal
to the diameter of the body. There are two other diseases affecting this nema,
one of microbe origin, the other of fungous origin; they appear, however, to be
confined to the cuticle. One consists of short-styled, elongated-ellipsoidal elements
on the surface of the body extending outward at right angles. These have been
seen on the tail end. The microbe growth appears as a coating, sometimes of
considerable thickness, and occurs on various parts of the body. It has been seen
ff/OW
. 464)
THE MONONCHS
at both extremities. The adjacent figure (34) depicts the tail end of a male found
in Hawaii about the roots of sugar-cane. The general resemblance to the male as-
signed by Biitschli to M. truncatus Bastian is very striking, yet
the differences in detail are also pronounced. The number of
supplementary organs is 16 instead of about 20, and the organs
themselves relatively shorter and more plump. The spicula and
their accessory pieces have the same general proportions and size.
The tail also has the same form and proportions, but the termi-
nal portion is more slender in the Hawaiian specimen, and the
distribution of the papillae thereon is decidedly different, as will
be seen by comparing figures 15 and 34. Male mononchs are so
rare that the amount of variation that may exist in a given
species is a nearly unknown quantity, so that it is not exactly
easy to make intelligent comparisons between the males in
these two cases. The Hawaiian male is supposed to be the
male of M. longicaudatus, the only one that has ever been
seen. It is interesting to note that when the spicula become
long and slender the accessory pieces also become long and
slender, but maintain their general form and are bifurcated at
the distal end. Fig. 33 (on the previous page) and fig. 34. It is
a curious fact that this, the only male of M. longicaudatus
ever seen among the many thousands examined, should have
come from soil, since longicaudatus is much less common in
soil than in water.
2ia. M. dentatus, n. sp. This representative of a new subgenus is especially
interesting as a guide to speculation concerning the relationship of Mononchus to
27. '62' 14 95.
1.1 mm
3.6 2.8 3.3 3.3 1.9
other genera. The scattered denticles are
paralleled in certain marine nemas. The
arcuate tail is conoid from the raised anus.
The rather blunt terminus is about one-
fourth as wide as the base of the tail. There
is a pair of ventrally submedian, innervated
papillae a little in front of the middle of
the tail. The amphid is sometimes more elongated than shown in the illustrations.
Description of a young female, from roots of orange trees, Bahia, Brazil. Fig. 35.
For 21b, M. recessus, and 21c, M. decurrens, see Appendix, p. 184.
22. M. punctatus, n. sp. This species is proposed for the reception of the
specimen described by Brakenhoff under the name M. papillatus Bastian, which
appears to differ from 2.6 ? 25. 65' 26 93.
any mononch hitherto ^2 ? ? 3~75 ?
described in that the shells of
the eggs are echinulate. It is
placed in the subgenus Pri-
onchulus, though with some
doubt, principally because both
the description and the figure
of Brakenhoff show the pres-
ence of denticles on the ven-
tral rib of the pharynx. The
author says: "Hier findet sich
namlich cine, in der Mitte (und an den 2 Seiten) fein gezahnelte Leiste. Diese
SUBGENUS PRIONCHULUS
(S. S. 465) 163
Zahnelung erstreckt sich iiber eine etwa 0.016 mm. lange Strecke und beginnt
distalwarts etwa in der Hohe der Spitze des dorsalen Zahns." The ellipsoidal
eggs occur in the uteri one at a time, are about as long as the body is wide, and
two-thirds as wide as long.
Found among the roots of Alopecurus denticulatus , as well as aquatic habitats
in the bottom of ditches and lakes in Germany. Fig. 36 and 36a (after Brakenhoff)'
23. M. muscorum (Dujardin) Bastian. The oldest, and one of the best known
species. Intestine tessellated. Tail conoid and arcuate. The reflexed ovaries, each
containing about a dozen ova arranged
more or less in single file, extend half way
fpl
mrpt
2.
24.
;,32
2.5-3.
92.
1.9 rain
2.1 2.7 3.2 3.6 1.6 2. 3.2 3.7 4.4 2.5
back to the projecting vulva. The eggs are one and one-half times as long as the
body is wide and three-fourths as wide as long. The anterior sexual organ is
somewhat the larger. Fig. 37, left.
This is a beautiful and rather common cosmopolitan species, occurring in swamps,
marshes, meadows and moorlands. It has been found in various parts of Europe
and is not uncommon in the United States. It was first found by DujardinWn the
Jardin des Plantes, Paris, where it still thrives ; the writer recently found it about
the roots of some heather imported thence. It feeds on smaller animal organisms,
among them other nematodes. The following is a variety :
M. muscorum (Dujardin) Bastian macrolaimus, n. var. Besides differing slightly
in proportions from the type form of the species, the variety has a somewhat larger
pharynx, with smaller denticles on the ventral rib. The submedian papillae of the
outer sets are apparently double instead of triple, though at
some distance behind the outer submedian papillae there is a
special submedian innervation. Most of these minor differences
are set forth in figures 36 and 37.
Found in Cladonia rangiferina, tamarack swamp, Wisconsin, m
U. S. A. Fig. 38, right.
24. M. longicollis, n. sp. A species resembling M. mus-
corum, but which differs in the proportions of the various parts *"-
and in the conformation of
m ikl
3.1
10. 27.
93.
the pharynx, the denticles 2.2 2.4 2.3 2.1 1.8 i> ""
of which are irregular and inward pointing. Submedian papil-
lae of the outer row double, instead of triple as in muscorum. Amphids relatively
154 (S- S. 466)
THE MONONCHS
?
20.
?
M ?
- 3.6 an
larger than in muscorum. Striae very difficult of resolution. Found about the
roots of pitcher-plants and tamarack, in a swamp, Wisconsin, U. S. A. The differ-
ence between this and muscorum may not be very important. Both are nema-
tivorous. Flemming mixture to glycerine. Fig 39 (at bottom previous page).
25. M. spectabilis Ditlevsen. The muscular oesophagus encompasses the proxi-
mal third of the pharynx, and has a conspicuous lining. The uteri may contain
? ? 20. '55' 96.8 , __ from 2 to 4 eggs,
usually 2. The
acute conical tail
? ? ? is strongly arcu-
ate. The male is a little more slender than
the female, and increases in size from a point
where the supplementary organs commence, in
such a way that the body assumes a maximum
circumference near the anus. The copulatory
muscles are strongly developed, and the num-
erous, prominent, supplementary organs appear
to have a subventral position, forming two
longitudinal rows, between which is a groove.
Fourteen of these supplementary organs are
figured by Ditlevsen manifestly not the whole
series. The arcuate spicula, which have a
strengthening piece in their distal halves, are
about one and one-half times as long as the
anal body-diameter. Their proximal ends are
not cephalated. At the widest part, toward
the proximal end, they are about one-fifth to one-sixth as wide as the body ; thence
toward the distal end they taper gently. The obscurely bifurcated accessory pieces,
which in profile view appear to cross the spicula, are of the usual form, and are
about one-third as long as the spicula, and about one-third to one-fourth as wide as
long. Their distal extremities lie somewhat in front of the tips of the spicula and
toward the ventral side of the body. The elongated eggs are nearly one and one-
half times as long as the body is wide, and less than half as wide as long.
Numerous specimens, the males as numerous as the females, found at Hellerup,
near Oresund, Denmark. This species exhibits the phenomenon of flotation. Dit-
levsen says : "If some material (meadow soil) is spread in a flat glass cup and
water is poured over it, the mononchs will mount rapidly and be lying on the sur-
face dry and shining." Fig. 40 (after Ditlevsen).
26. M. index Cobb. No striae seen. The .neck diminishes opposite the base of
the pharynx to form a rather cylindrical, truncated head which is slightly expanded
at the lip region. Amphids, one-fifth as wide 2.1 8.8 30. *69 15 95. 6 N
as the head, are indicated by transverse mark- 2.4 3.2 3.5 3.6 2.
ings, bent backward at each end, and located opposite the middle of the dorsal
tooth. Denticles in about five rows, the outer rows more distinct. Pharynx half
as wide as the head, and about three times as deep as wide. CEsophagus more or
less conoid, with a massive lining occupying about one fourth of the optical sec-
tion. Cardia pointed. Intestine few cells in girth; rather obscurely tessellated.
Rectum half as long as the anal body-diameter. Longitudinal fields are visible
throughout most of the length, and are about two-fifths as wide as the body. The
diameter of the body increases somewhat just in front of the anus, and then dimin-
ishes suddenly at the anus, so that the beginning of the tail is very considerably
less in diameter than the portion of the body immediately in front of the anus.
SUBGENUS MYLONCHULUS
(S.s.467)
The diameter of the cylindrical portion of the tail is about one-fourth that of the
body at the anus. Caudal glands 3, egg-shaped, opposite the anus. Spinneret
slightly apiculate and apparently unarmed. The eggs are evidently of large size.
A single egg, not yet passed on to the uterus, was four-fifths to five-sixths as wide
as the body, and about three times as long as wide.
Common about the roots of sugar cane on various plantations on the island of
Hawaii. Flemming solution to glycerine.
27. M. reversus, n. sp. This very interesting abnormal form possesses striae
that appear resolvable into rows of dots. Intestine about 6 cells in girth, faintly
tessellated. Tail more or 2 94 26 40' 1? 96
less cylindroid in the pos- 2.2 2.3 27? 74 2. ** l>1 n
terior half, its terminus one-fourth to one-fifth as wide as
its base. Lateral fields two-fifths as wide as the body. The
eggs are of relatively large size, since an ovum not yet
passed on to the uterus is 5 to 6 times as long as the body is
wide. It is therefore likely that the eggs occur in the uterus
only one at a time. The relatively broad ovary tapers but
little; it contains about a dozen developing ova.
Rio Janiero, Brazil, about the roots of Platonia insignis Mart. In general this
species resembles incurvus and minor, but is readily distinguishable by the form of
the sexual organ, and by the sparseness of the pharyngeal denticles, only a few of
which are to be seen. When the female sexual organs reduce to one, this remain-
ing one usually extends forward from the vulva. Here the reverse is the case;
hence the specific name. Flemming solution to glycerine. Fig. 41.
28. M. obtusicaudatus Daday. Tail conoid, slightly arcuate; toward the end
rather suddenly di-
#- ------ ........ -~-V\ /N ^ 7 M- _ 1?Z!_JL1^ 1<9 M minished in size. The
spinneret well marked.
Found at Berlinhaven, Island of Salao, New
Guinea, in fresh water. It seems probable
from Daday's description that there are 3
teeth in the pharynx, 1 dorsal and 2 smaller
submedian ones just at the base of the rasps.
Probably fhe junction between the posterior
and anterior elements of the pharyngeal walls
is unusually prominent ; this would account for
the "bogige leiste" mentioned in the original
description and shown in the original figure
along the anterior margin of the rasp. Fig.
42 (after Daday). Assuming Daday's drawing
to be more or less conventionalized, this species
might be regarded as identical with minor.
29. M. brachyuris Biitschli. Amphids appear as transverse slits opposite the
onchus. Lining of the oesophagus strongly developed. Cardia plainly to be seen.
28.
'62
18
96.
Intestine tessellated. 2.2
Rectum half as long 274 i79 371 379 2.2
as the anal body-diameter. Caudal glands more or less
saccate, opposite the somewhat raised anus. Tail some-
what arcuate. Spinneret pore a little to the dorsal side of
the middle of the terminus. The vulva is a conspicuous
feature, owing to the thickness of the walls of the vagina,
which is one-half as long as the body-diameter. Series of
166 (S. S. 468)
THE MONONCHS
male supplementary organs, according to de Man, about 12, mammiform and appar-
ently protrudable except the two anterior and the posterior, which are more or less
rudimentary. Series about twice as long as the tail.
A cosmopolitan species. In Florida, the writer found this species feeding on the
larvae of Heterodera radicicola, an extremely serious root pest. Fig. 43, bottom p. 467.
30. M. denticulatus, n. sp. Onchus opposed by two small subventral onchi
farther back, the left a little farther forward than the right
Found in the Zambezi River, South Africa, among fresh
water algae. The peculiar form of the head and pharynx,
and the unusually large number of denticles are the promi-
nent characters of this species. Only a single mutilated
specimen has been seen by Dr. Micoletzky. As it is un-
likely that the large number of denticles shown in the
original figures can be due to moulting phenomena, it
would seem that this form differs distinctly from all others.
Fig. 44 (after Micoletzky). As neither Micoletzky's text
nor figure suggests moulting, the numerous rows of den-
ticles are assumed to be normal,
sp. Each rasp consisting of but 2 rows of denticles. The
12. 32. 54 Y 94.
31. M. sparsus, n.
tail diminishes suddenly in size 2.9
behind the elevated anus, and 3.4
4.3 4.2 3.8 2^7^
tapers somewhat in the posterior three-fourths. The terminus
is about one-fourth as wide as the base of the tail. The cau-
dal glands (?) lie opposite the rectum.
Found in sphagnum from greenhouses, Department of Agricul-
ture, Washington, D. C., U. S. A. Flemming solution to glycer-
ine. Fig. 45.
32. M. micrurus, n. sp. This odd form appears to have no submedian onchi.
Rasps of only about four rows of denticles. Amphids not seen. Lining of the
esophagus well-developed, occupying three-fifths of the optical longitudinal section.
3. 12. 33. Y 98. Intestine about 5 cells in girth,
27? 37i 3.7 3. 2.2 not tessellated, or only faintly
so. Tail very short and strongly arcuate or bent. Spinneret
about one-fifth as wide as the base of the tail. Rectum some-
what shorter than the anal body-diameter; longer than the tail.
Caudal glands not clearly seen, probably opposite the rectum.
Ampullae of the caudal glands not very strongly developed.
Described from young specimens found about Litchi roots,
Fukien, China. Resembles bremcaudatus. Characterized by the
extremely small and very strongly arcuate tail. The
spinneret is sometimes turned nearly at right angles to ^
the axis of the tail. Flemming solution to glycerine. ,
Fig. 46.
33- M. incurvus, n. sp. Striae resolvable with diffi- adsl
culty and into rows of dots. Dorsal onchus opposed
by 2 inconspic- 2 . 7.4 28. *63' 2 t 96.2 .
uous, ventrally 2.1 2.5 2.9 3.2 2.f^ " msiln
submedian onchi of smaller size opposite its base.
The lining of the oesophagus is a prominent feature, strnurph
occupying about two-thirds of the apparent width of
the oesophagus. Intestine 12 to 15 cells in girth, not "^
tessellated, its granules numerous and fine. Caudal ^
glands 3, broadly saccate, opposite the anus, their
ampullae long and filling the posterior part of the tail. XTSO
SUBGENUS MYLONCHULUS
(S. S. 469)] 57
There is a flattish cardia. Anus raised. Longitudinal fields two-fifths to one-third
as wide as the body. From the more or less elevated vulva the vagina leads inward
at right angles to the ventral surface one-third the distance across the body. The
eggs are one and one-half times as long as the body is wide, and occur one at a
time in each uterus. The ovaries contain about a dozen developing ova.
Sandy soil in a cranberry bog, Arlington Farm, Virginia, U. S. A. Also on the
margin of the spring that gives rise to Salt River, Jamaica. Flemming solution to
glycerine. Fig. 47 (at bottom of previous page).
34. M. sigmaturus, n. sp. Two very inconspicuous submedian onchi are found
opposite the base of the dorsal onchus, just at the base of the rasps. Intestine 10
cells in girth, comparatively distinctly tessellated. The rectum is about as long as
the anal body-diam- 2.3 12. 30. >64' 14 96.3
eter, and is some-
what sigmoid.
ll2 """
2.4 2 3s 2.4
The anus is very distinctly visible on
account of its contour, and on account of the refractive
nature of the lining of the rectum. What appears to be
a renette pore exists immediately behind the nerve-ring.
The distinct lateral fields are about one-fourth as wide
as the body, and are characterized by the presence in
them of scattered granules much smaller in size than
those of the intestine. The posterior part of the tail is
somewhat digitate, and the whole is slightly sigmoid. From the anus the tail
tapers rapidly to near the middle, so that if the posterior half were lacking the
tail would be rounded. The diameter of the tail at the middle is about one-third
as great as at the base. From the middle onward the tail for a short distance is
of uniform diameter, and then tapers rather rapidly in the posterior fourth to a
rounded or subtruncated spinneret. Small, somewhat finger-shaped setae are found
on the tail ; one dorsally sublateral pair, a trifle in front of the anus ; another dor-
sally sublateral pair near the middle of the tail but located on the more bulky part ;
finally, a third ventrally sublateral pair a little in front of the digitoid part of the
tail. The caudal glands are opposite the rectum. The eggs are about two and one-
half times as long as the body is wide. The tapering ovaries contain 10 to 12
developing ova, arranged irregularly.
Found in various parts of the United States and Mexico. Resembles minor and
brachyuris, from which it may be distinguished by the form and structure of the
tail. Flemming solution to glycerine. Fig. 48.
35. M. subtenuis, n. sp. Wall and dorsal tooth of the pharynx rather strongly
developed. When the lips are closed the pharynx is hardly half as wide as long.
Dorsal tooth slightly arcuate, its point located close to the base of the lips. The
1.5 5.6 26. ^72' 22 97. x submedian teeth
- 75 1>3 ; l. are easily con-
-Mi 2 97. . fused with the
He TTa TA 272 fTer denticles. Lining
of the oesophagus well developed, occupying one-fourth
of the longitudinal optical section. There is a small
conoid cardia. Intestine probably about 6 cells in girth,
not definitely tessellated. Anus raised and conspicuous,
the anterior lip somewhat massive and overhanging.
The arcuate, conoid tail ends in a spinneret one-fifth to one-sixth as wide as its
base. The ovaries, of which the posterior is somewhat the smaller, appear to
contain about a dozen ova. Inconspicuous papillae appear on the ventral side of
the female near the vulva. Two were noted behind the vulva and one or more in
1.5
6.2 25.
*" r/ *
168 (S-S.470) THE MONONCHS
front of it. The tail of the male is somewhat like that of the female but dimin
ishes very suddenly behind the anus. Five pairs of innervated papillae have been
seen on the tail of the male, two of them, however, exceedingly inconspicuous and
easily overlooked : Of the three more conspicuous, one ventrally submedian pair
is located a short distance behind the anus ; a second dorsally sublateral pair occurs
a little behind the middle of the tail, and a third subventral pair occurs a short
distance in front of the spinneret. Of the two more inconspicuous pairs, one is
nearer the spinneret than that just mentioned, and the other, lateral, and slightly
behind the middle of the tail. The arcuate spicula are about one and one-fourth
times as long as the anal body-diameter. At their widest part, near the middle,
they are about one-fifth to one-sixth as wide as the corresponding part of the
body and thence taper in both directions ; they are not cephalated. The distal ends
are obscurely two-pronged. The obscurely bifurcated accessory pieces are of
typical form and size, about one-third as long as the spicula and about one-fourth
as wide as long. Fourteen rather closely approximated, equidistant supplementary
organs occur in front of the anus, occupying a distance about three times as great
as the length of the tail. Internally the organs seem to be short, broad tubes of
slightly varying diameter ; these are probably slightly protrudable. The protrudable
portion is not hispid as is the case in M. major; on the contrary, it appears to be
smooth. The anterior one and the posterior three of these organs are not so well
developed as the others, that near the anus being reduced to a mere innervation ;
the distance between this latter and its nearest neighbor is about twice as great as
between any other adjacent members of the series. These organs give to the ven-
tral contour a crenate or serrate appearance. The anal muscles are prominently
developed. The ejaculatory duct is often filled with elongated spermatozoa, some-
what resembling those of Dorylaimus, and similar in form to those figured by
Dr. de Man for M. gerlachei. Each one may be one-fourth as long as the body is
wide, or thereabouts. There are two outstretched testes. The blind end of the
anterior is about as far behind the base of the neck as the latter is behind the anter-
ior extremity. The blind end of the posterior seems to lie about twice as far in
front of the foremost supplementary organ as this latter is in front of the anus.
The spicula have a median stiffening piece, and their proximal ends lie toward the
dorsal side of the body.
Found about the roots of plants on the Arlington Farm, Virginia, U. S. A. Re-
sembles M. minor, but in the proportions of the pharynx there are notable differ-
ences. The walls are here thicker; the amphids are larger and farther back; the
lips and onchus are strongly developed, so that when the pharynx is closed the
cavity appears smaller than in minor. Opposite the anterior supplementary organ
there is a fibrous ring, probably nervous. A similar structure has been noted in
other species. There probably exist at this point in the body special nerve com-
missures. Flemming solution to glycerine. Fig. 49 (near bottom of previous page).
36. M. subsimilis, n. sp. Striae of the cuticle more or less
easy of resolution. Lining of the resophagus strongly developed,
3. 10. 34. Y 96. occupying three-fifths of the
3.1 3.6 4. 3.8 2.6 ' m longitudinal optical section.
Anus slightly elevated, especially the anterior lip. The scat-
tered granules in the cells of the intestine are small, but varia-
ble in size, and do not give rise to tessellation. The more or
less arcuate tail is conoid to the blunt terminus, which is about
one-fourth as wide as the base of the tail. A ventrally sublateral innervated papilla
occurs on each side near the middle of the tail. There are no caudal glands. De-
scription derived from a single young female.
SUBGENUS MYLONCHULUS
(S.S.471) 169
About the roots of banana plants imported from Paris, France. Resembles
brachyuris and minor, but differs in having no spinneret. The dorsal onchus is set
farther back in the pharynx than in either of those species, and there are no traces
of submedian teeth. The rasps also are less strongly developed. Flemming solu-
tion to glycerine. Fig. 50 (at bottom of previous page).
37. M. obliquus, n. sp. Two small, ventrally submedian onchi present, opposite
the base of the dorsal onchus. (Esophagus at first a little swollen; its lining well
developed, and occupy- 2.6 9. 31. ^63'^ 98.
ing one-fourth of the 27i 374 374 471 2.4 1>4 M
optical longitudinal section. Intestine about 8 cells in girth,
as a rule not distinctly tessellated. The conoid tail is slightly
arcuate, and obliquely truncate at the spinneret, which is
about one-third as wide as the base of the tail. The three
caudal glands are located opposite the rectum, which ends
externally in a slightly elevated anus. The ampullae of the
caudal glands are well developed, and occupy the posterior
two-thirds of the tail. Though the vuiva is more or less con-
tinuous with the ventral surface, it is conspicuous on account
of the refractive nature of the walls of the vagina. The
elongated thick-shelled eggs are two and one-half times as long as the body is
wide, and appear to be deposited before segmentation begins. The ovaries contain
about a dozen developing ova, arranged partly single file, partly irregularly. A pair
of ventrally submedian innervated papillae were noted near the middle of the tail of
the female.
From soil from Germany, along with specimens of Heterodera schachtii. Re-
sembles brachyuris, from which it seems easily distinguishable by the large thick-
shelled eggs. Flemming solution to glycerine. The habitat led to the suspicion that
it was feeding on H. schachtii, but the writer was unable to establish the fact from
the few specimens available for examination. Fig. 51.
38. M. lacustris Cobb. The amphids have the form of "slits," 3 to 4 times as
long as wide, and are placed at the base of the lips nearly opposite the apex of
the dorsal onchus. They 2.7 8. 28. *63* 96. /-^p^SscC H*
are about one-sixth as 275 372 379 472 2.3 '
wide as the corresponding portion of the head. Intestine
from 15 to 20 cells in girth, the cells closely packed with
granules of variable size in such a manner as to give rise
to a close and obscure tessellation. The well developed
lateral fields are one-third as wide as the body. The anus
is 'slightly raised. The lining of the rectum is distinctly
refractive. The tail is ventrally arcuate, and ends in a
blunt spinneret one-fourth as wide as its base, containing
a well developed, internally ceratinized spinneret. The
three caudal glands are arranged tandem in the anterior
half of the tail, the foremost being opposite the rectum. The spinneret appears to
have a needle-shaped valve. A pair of ventrally submedian innervated papillae has
been noted a little in front of the spinneret on the female. The eggs, which appear
to occur one at a time in the uteri, are about one and one-third times as long as the
body is wide and four-fifths to five-sixths as wide as the body.
Found in fresh water lakes, Michigan, U. S. A. ; about the roots of ferns, Panama
Canal Zone ; and in the Silver Springs, Florida. Resembles M. brachyuris Biitschli,
from which it differs in the form of the tail and spinneret. M. polonicus Stefanski
seems to closely resemble this species. Sublimate to balsam. Fig. 52.
17Q(S.S.472)
THE MONONCHS
KM
39. M. polonicus Stefanski. Two minute teeth are found at the base of the
buccal cavity. The conoid tail is somewhat arcuate from the raised anus, and ends
in a truncated spinneret one-fourth as wide as its base. The three caudal glands
are located in a tandem series in the anterior third of the tail.
Description derived from young specimens found in vegetable detritus in the
Czarna River, Poland. Said by its author to resemble the next species, No. 40.
40. M. minor Cobb. There are 2 minute, submedian onchi, easily overlooked.
Amphids, only one-sixth as wide as the corresponding portion of the head, are
2.3 7.5 26. eo*"> 96.7 present opposite the
274 275 27& 371 2~7T^ """ apex of the dorsal
tooth, and consist of arcuate, refractive markings hav-
ing their convex side toward the lips. They appear to
be about one-fourth as wide as the corresponding por-
tion of the head. There are excessively minute striae or
dentations of the inner surface of the margins of the
lips; these structures are so fine that they might easily
escape observation much finer than tne rasp-like teeth
of the pharynx. The lining of the oesophagus occupies
nearly one-third of the optical longitudinal section. The
cells of the intestine contain small, somewhat uniform.
rather evenly distributed granules. The anus is slightly raised, the anterior lip
being a little more pronounced than the posterior. The conoid tail is rather
strongly arcuate, or even more or less bent near the middle. The comparatively
well developed spinneret is one-third as wide as the base of the tail, and pos-
sesses a valve similar to that found in Mononchulus. The caudal glands are
located opposite to, or a little behind the rectum. The lateral fields are two-
fifths as wide as the body.
This is a cosmopolitan species, found in tropical and temperate regions. It closely
resembles M. brachyuris of Biitschli, but is smaller and differs somewhat both in
the structure of the tail and in that of the pharynx. Osmic acid to water. Fig. 53.
41. M. brevicaudatus, n. sp. Walls of the pharynx unusually thick. Two ex-
ceedingly small, ventrally submedian onchi, opposite the middle of the dorsal onchus.
2.7 9.3 32. >69' 18 96. Lining of the cesoph-
2.2 2.7 3.1 3.4 2.2 l ' 5 Bl11 agus prominent, oc-
cupying one-third of the optical section. Intestine 6 to 8
cells in girth, faintly tessellated. Contour of the tail like
that of the head of a duck whose beak is very short; from
the anus onward having roughly an equilateral contour.
Spinneret more elaborate than usual. The ceratinized
walls of the vagina are plainly visible. The elongated
eggs are two to two and one-half times as long as the
body is wide. The ovaries taper but little. About a dozen
females have been examined. No males have been seen.
Sperm has been seen at the flexure in the ovaries. The
species is probably syngonic.
Found about the roots of plants in a cranberry bog, New
Jersey, U. S. A. Resembles micrurus and brachyuris in its general form, but
differs in the details of the pharynx and in those of the tail. The species is nema-
tivorous, and also feeds upon rotifers. Sublimate to balsam. Fig. 54, in which, as
m many of the original illustrations used in this chapter, what at first sight appear
to be merely lines used as shading, are in reality carefully charted striae or lamina-
tions of the wall of the pharynx.
SUB GEN US ANATONCHUS
(S. s.473) 171
42. M. japonicus, n. sp. The head is not set off in any marked fashion. Am-
phids present in the form of elliptical markings nearly opposite the apex of the
single dorsal tooth ; the length of their long 2.1 e.9 30. >67* 98.
axes, which are placed transversely on the 274 271 279 27? 2~* l ' 2 ma
head, is probably about one-sixth as great as that of the diameter of the head. The
capacious pharynx is somewhat deeper than the head is wide; the anterior portion
has a diameter more than half as great as that of the corresponding portion of the
head, while the posterior portion has a diameter about two-fifths as great as that
of the base of the head. The single, highly refractive dorsal tooth has its apex
somewhat in front of the middle of the pharynx. The rasps consist of 5 to 6 rows
of teeth, forming a group whose width is about one-fifth as great as the depth of
the pharynx. The wall of the pharynx is strongly developed, and is very finely
transversely striated in the posterior part. The lining of the oesophagus is an
exceedingly distinct feature throughout its length, and appears to occupy about
one-fourth of the optical longitudinal section. There is a small cardia. Intestine,
about 8 cells in girth, very obscurely tessellated. The short, blunt, arcuate conoid
tail is truncated at the terminus, which has a diameter about one-fourth as great as
that of the base. The lateral fields are about one-third as wide as the body, and
are composed of 2 rows of cells containing relatively large nuclei.
This species rather closely resembles a number of others, and it is by no means
certain that it is not identical with some one of them, perhaps consituting a variety.
Curiously enough, it was found in Mississippi Bay, Yokohama, Japan. Sublimate
to balsam.
43. M. tridentatus de Man. At the base of the pharynx are 2 minute denticles.
Amphids unknown. Pharynx more or less triquetrous, with three well developed,
2. 6.5 22. '62' 26
2.1
2.
2.6
6.5
3.
22.
3.1
3.2 mm
2.7
2.1 2.6 3. 3.1 2.
double, longitudinal ribs reaching from
end to end. (Esophagus at first slightly
swollen. Intestine distinctly tessellated.
The arcuate tail is conoid to the termi-
nus, which is about one-sixth as wide as
the base of the tail. Each of the slen-
der, arcuate spicula is cephalated by
contraction and is supplied throughout
its length with a median stiffening piece,
and is crossed near its distal extremity
on the outside by one of the rather
broad, two-pointed accessory pieces,
which are one-half as long as the spic-
ula. Supplementary organs 15 to 17,
apparently conical, 2 to 3 times as far
apart anteriorly as posteriorly, where they are nearly contiguous. The posterior
member of the series, the whole of which is about one and one-half times as long
as the tail, is somewhat smaller than the other members, and is located a short
distance in front of the anus. On the tail itself are a number of papilhe, dorsal as
well as ventral ; 2 pairs on the anterior half, ventral, and 2 pairs on the posterior
half, dorsal. It remains uncertain whether there is a spinneret and caudal glands.
This striking species seems to be widespread in Europe in moist soil, and i
rath-er common. Fig. 55 (after de Man).
j 72 < s -
THE MONONCHS
44. M. gracilicaudatus n. sp. Intestine about 12 cells in girth. The anterior
fifth of the tail is arcuate conoid in such fashion that at the beginning of the second
fifth the diameter is about one-third to one- 1.4 4.8 z\. -M^ 8 65.
fourth as great as at the anus. Thence on- FTs fTi fTa TTs i.e' D-l B
ward the tail tapers very gradually through the middle third, the posterior portion
being cylindroid and somewhat narrower than the spicula. These latter are uni-
formly arcuate, and about one and one-fourth times as long as the anal body-
diameter. At their widest part, toward the proximal end, they are about one-
fifth as wide as the corresponding part of the body. They taper gently in each
direction, and are not cephalated. The small accessory pieces are of typical form,
only about one-fourth as long as the spicula. The series of 19 contiguous supple-
mentary organs is twice as long as the spicula, or equals 3 body diameters. Anteri-
orly the organs are somewhat larger and also somewhat farther apart. The conical
exterior portion of each organ seems to be more or less protrudable. These organs
X750
inn
are similar in form to those of major, though they are not echinulate. The anal
and post-anal muscles are strongly developed. The anal muscles are found through-
out the bulkier portion of the tail. The protruding muscles of the spicula extend
backward in the tail to near the point where the tail diminishes rapidly in diameter,
and there join the ventral part of the caudal wall. The post-anal papillae are con-
fined largely to the more massive anterior fifth of the tail. On each side there is
a ventrally submedian row about as long as the spicula, consisting of 4 to 5 mem-
bers. Coextensive with them is a ventral row of 3 to 4 papillae. A little distance
behind these, Avhere the tail begins to be smaller, there are 2 dorsally submedian
SUBGENUS ANATONCHUS
(S.s.475) 173
innervated papillae of smaller size. The supplementary organs are plainly inner-
vated and the nerves can be traced through the cuticle and through the body mus-
culature, and seem to be connected with internal more or less ellipsoidal cells whose
nature remains unknown. The spinneret is very inconspicuous. The nature of the
caudal glands remains uncertain.
Found in marshy ground, Arlington Farm, Virginia, U. S. A., about the roots of
fmpatiens, in black, clayey soil, with mud. Resembles M. dolichurus to a certain
extent. It is regrettable that only a few specimens have been available for exami-
nation, as it is a species well adapted to throw light on various features of mon-
onch anatomy. Fig. 56 (on the previous page).
Examination of the pharyngeal muscles of this species leads to a partial under-
standing of the mechanics of the lips. The muscles which move the lips are long
and slender, and pass from the lips backward along the surface of the pharyngeal
capsule. They join the body wall some distance behind the pharynx. There are 2
separate groups of muscles, extensors and flexors. Of the 6 extensors 2 are shown
in the illustration ; these are furcated opposite the middle of the pharynx, one half
of each going to the lateral lip; the other half to a submedian lip. The joined
fulcra of the 6 lips form a framework encircling the head. The extensors pass
outside this framework. The flexor muscles are less clearly shown, but are mani-
festly better developed. A group of 3 is shown lying between the 2 extensors.
They appear as faint bands outside the pharynx passing forward, and beyond doubt
are attached to the lips inside the ring of fulcra. The musculature of the lips is
shown in the illustration and is further explained on page 140 in connection with
the general description of the head.
45. M. dolichurus Ditlevsen. Neck tapering but little. Pharynx probably
prismatic, and in transverse section somewhat triangular. About 7 denticles about
the base, or near the base, of the pharynx. The arcuate tail tapers to the terminus,
which is about one-eighth as wide
as the base. The author mentions
* ' ? . 2.5 1.8
the presence of 3 or 4 inconspicu-
ously developed lobes at the base
of the oesophagus, and it would
appear from his figures that a spin-
neret and caudal glands are pres-
ent, the latter forming a tandem
series near the anus. Menzel finds
in the pharynx of Swiss specimens ^
of this species 3 teeth of equal size ;
that is to say, the ventrally sub-
median teeth are equal in size to
the dorsal tooth. His specimens
are / 2 to 5}/2 mm. long, and this
probably represents the adult size, a
Found in moist soil and meadow
land, Jutland; Switzerland. Fig.
57 (after Ditlevsen). Menzel shows
the papillae as much less conspicu-
ous, and without the spherical tips.
The original material consisted of
but a single immature female.
174 (S '
THE MONONCHS
46. M. digiturus Cobb. Amphids occur opposite the anterior part of the
pharynx. What appears to be a renette pore occurs just behind the nerve- ring.
The anal region 3.3 8 . 26. 70 12 92.
is somewhat
1.4
in..
3. 3.4 3.4 2.3
raised. Behind the anus the tail diminishes rapidly
in diameter, so that at the end of the anterior fourth
it is about three-fifths as wide as at the anus.
Thence, for some distance it is cylindrical, but be-
comes somewhat abruptly convex-conoid in the pos-
terior fifth and ends in a rather narrow, inconspicu-
ous .spinneret. The lining of the oesophagus is a con-
spicuous feature. Intestine not tessellated. The
longitudinal ribs of the inner wall of the pharynx
are rather conspicuous features, and extend from
end to end of the pharynx.
Found about the roots of banana plants, Fiji.
Fig. 58. .
47. M. trichurus, n. sp. This outstanding form has an oesophagus that is
slightly swollen where it receives the pharynx. The lining of the oesophagus is
2.6 7. 21. '52 11 67. prominent, occupying
2.3 . 2.4 278 279 1.8 l " * three-fifths of the op-
tical section. Longitudinal fields one-fourth as wide as the
body. Characters well set forth in fig. 14, p. 146.
Found about the roots of orange trees, Bahia, Brazil.
Bears considerable resemblance to M. gymnolaimus. It ap-
pears possible from these investigations that the tropical
mononchs, when more fully known, will prove especially
interesting. Nearly all the more striking species here re-
corded are from the tropics. The warm soils of the tropical
regions teem with nematodes, many of
them no doubt, especialy adapted to the
peculiar conditions found there. The
predatory mononchs in such soils will
naturally enough have responded in
structure not only to the climatic con-
ditions, but also to the form and habits
of their quarry. Fig. 59 (just above). / i' : :$Viar ""
48. M. gymnolaimus Cobb. The
more or less triquetrous pharynx is
strongly three-ribbed. Cardia of such
2.6 6.8 24. '67 16 86.
2.S mm
2.2 2.3 2.7 2.5 1.6
a nature as to give rise to a double
constriction in the cardiac region. In-
testine about 12 cells in girth. What
appears to be a renette pore occurs
immediately behind the nerve-ring.
The lateral fields are about one-fifth
as wide as the bodv. The tail tapers
regularly to near the terminus ; it is,
however, cylindroid for a short distance in front of the spinneret. Vulva not
prominent. The uterus is as long as the reflexed portion of the ovary, which
SUB GENUS IOTONCHUS
(S. S. 477) 175
reaches two-fifths the way. back to the vulva. The ova are for the most part
arranged single file.
This nemativorous species will probably prove cosmopolitan. About roots of
banana, Fiji; of Platonia insignis, Rio Janeiro, Brazil; roots of various plants,
Arlington Farm, Virginia, U. S. A. Fig. 60 (on the previous page).
49. M. consimilis, n. sp. Amphids, unlike those of gymnolaimus, apparently
duplex, located a little behind the base of the lips ; one-fourth as wide as the cor-
responding portion of the head. Wall of the pharynx strongly developed.
Rather closely resem- 3.2 9.1 26. 68' 86.
bles M. gymnolaimus, 2.4 2.7 2.7 2.4 2.1 1-1 M
but has the walls of the pharynx much more strongly cer-
atinized, and is of much smaller size. The pharynx is j~ela-
tively SO per cent longer. The spinneret is not swollen as
in gymnolaimus. Description and figures derived from a
single, immature female specimen from about the roots of
Platonia insignis Mart., Brazil. The figure of gymnolaimus
shows, on the ventral side, near the front of the pharynx, an
inward projection, probably representing the optical section
of the junction of elements in the pharyngeal wall. No
such appearance was observed in consimilis. Fig. 61.
50. M. rapax, n. sp. Intestine about 12 to 20 cells in girth, faintly tessellated.
The female organs 'are probably double and symmetrical. The conoid tail tapers
somewhat in front of the anus to a
plain, symmetrical, unarmed spin-
2.5 6.5 21. 61. 90. ,
27 272 276 271 fTT^* dl
neret about one-sixth as wide as its
base. One and one-half tail-lengths
in front of the anus there is a con-
striction in the intestine, which ap-
pears to be due to the presence in
that region of ' commissures, as if,
possibly, nerves encircled the intes-
tine at that part.
Found about the roots of plants,
Arlington Farm, Virginia, U. S. A.
Nemativorous. Only young females
have been seen. As its name, rapax,
indicates, this species is a rapacious
one, swallowing other nemas whole,
even when half as long as itself.
Fig. 62.
51. M. rex Cobb. This "king" of the mononchs has low, broad, inconspicuous
labial papillae that do not interfere materially with the rounded contour of the
front of the head. The lips are bulky and powerful. No amphids have been seen.
The pharynx is armed with very powerful 2. 6. 20. 'se* 37 ei.
muscles. The intestine is tessellated. The fTe UT 2~. ?72
lateral fields are one-fifth as wide as the 2 5>5 20> M 50
body. The conoid tail tapers more rapidly us F79 271 iTa t.5 ' - a - y - mB
at first, being nearly cylindroid in the posterior two-thirds, where it is about one-
eighth as wide as at the anus. The spinneret, which is slightly expanded, bears two
ventrally submedian papillae, after the manner of longicaudatus , but slightly larger
1.4
86.
THE MONONCHS
in proportion. Three caudal glands are present. Each uterus is capable of carrying
one and possibly two eggs at a time. These are about one and one-fourth times as
long as the body is wide, and half as wide as long. The tail of the male tapers
more rapidly at first than that of his mate. Supplementary organs 17, prominent,
closely approximated, equidistant, occupying a space equal to one and one-half
times the length of the tail. The spicula are about twice as long as the anal body-
diameter.
Found at depths of from about 200 to 1200 feet in Lakes Manapouri and Wak-
atipu, New Zealand.
1.6 8. 17. <63' 26 9<V
1.4
5.2
52. M. regius, n.
sp. Amphids rela-
tively small, con-
nected with a nar-
row, internal, appar-
ently tubular ele-
ment passing back-
ward past the base
of the pharynx.
Pharyngeal muscles
strongly developed,
extending backward
from the base of
the lips to the body
wall behind the
pharynx. Each of
the six lips with a
flat, flap-like outer
accessory part,
which is longitudi-
nally striated at the
base. Onchi sub-
equal, the dorsal
Found about the roots of plants, Arlington Farm, Virginia,
X750
slightly the stronger.
U. S. A. Fig. 63.
53. M. bathybius Micoletzky. In the figure the onchus labeled "submedian" is
really a subdorsal onchus. In addition to this subdorsal onchus there are still
others, probably 4.9 t o. 30 . 63 Y 8 7.
2 to 3 pairs, which 3.3 3.6 3.9 3.4 2.5 ' 6 mn
in profile view have a double contour. It remains
uncertain whether the other markings seen on the
wall of the pharynx are projections or pores.
The author considers this species to be related to
M. gerlachei de Man, the lip region and vestibule of
the two species being similar. However, the armature
of the pharynx in the two species is quite different.
Found in mud at a depth of about 300 feet in the
Atter Lake, Austria. The description and figures rest
upon the examination of a single immature specimen, and it is probable that the
examination of further specimens will improve our knowledge of this interesting
form. Fig. 64 (after Micoletzky). For 53b, M. fasciatus, n. sp., and 53c, M.
similis Cobb, see Appendix, p. 184.
SUBGENUS IOTONCHUS
(S. S.479) 177
.._ on?
54. M- studeri Steiner. Wall of the pharynx presenting 5 longitudinal ribs,
four of them in 2 pairs, the fifth single. At the base of the pharynx numerous
small denticles, arranged in rows of from three to four. (Esophagus powerful.
2.8? ? 26. 67. 94. . A little in front
? ? ? 3.4 ? O f the posterior
2.8? ? 27. H 95.4. end of the cesoph-
? ~ ? 3TI Te^ ' agus there are 3
powerful teeth which, according to Steiner, "are
similar to those seen in Mononchus dolichurus."
Tail of the male arcuate, conoid to the spinneret,
which is about one-fourth as wide as the base. The
three caudal glands form a tandem series in the an-
terior half of the tail. The slightly arcuate spicula
in their widest part are about one-sixth as wide as
the corresponding portion of the body. They taper
slightly at either end, and are about one and one-
third times as long as the anal body-diameter. They
are not cephalated. The accessory pieces appear to
be of the usual character. The twelve short, tubular,
equidistant supplementary organs, occupying a space equal to twice the length of
the tail, do not interfere materially with the ventral contour. The internal tubular
parts are about as long as the spicula are wide. Distance from the anus to the
posterior supplementary organ is nearly twice as great as the distance between the
adjacent organs. Two pairs of post-anal papillae were noted.
Found on the island of Ufenau in the Zurich Lake, under moss. Fig. 65 (after
Steiner).
55. M. zschokkei Menzel. This species, one male to each three to four females,
is found in various parts of the Austrian and Swiss Alps. Neck and oesophagus
3.? ? 25. '66' 95.
25.
3.4
96.
2.4-3.5 mm
denticles
? ' ? 3.6 2.4
tapering but little. Small
often occur at the base of the pharyn-
geal cavity. Uterus capable of con-
taining one or two eggs. The blunted
terminus of the conoid arcuate tail is
about one-eighth as wide as the base.
The slightly arcuate spicula are rather
slender, each, however, having a stif-
fening piece in its distal half. Acces-
sory pieces as figured by de Man for
his M. brachyuris Butschli. Beginning
near the anus the 21 projecting, ob-
liquely conical, equidistant, contiguous
supplementary organs, each as high as
wide, occupy a space 3 times as long
as the tail.
Found in the high Swiss Alps. Fig.
67, after Menzel, who considers that
of'all the European mononchs at present known, zschokkei has close affinity only
with M. parvus de Man, from which it differs in the position of the onchus and
the relative abundance of males.
THE MONONCHS
56. M. brachylaimus, n. sp. There are two exceedingly minute, almost invisible,
apparently rudimentary, ventrally submedian, conical, forward-pointing toothlets at
the base of the pharynx. These are not shown in the illustration. Three slightly
2.4 7. 21. 65 14
10 it
(fee
2.4
2.3
2.4
7.4
2,8
19.
94.
1.9
94,
2.5 2.5
> 3.5 m
arcuate, duplex, longitudinal ribs
strengthen the walls of the phar-
ynx and reach from end to end,
one being dorsal, the other two
ventrally submedian. Amphids
difficult to see. (Esophagus at
first slightly expanded. The ces-
ophageal lining is not so promi-
nent as in many other species; its
optical section finds expression in
3 or 4 parallel lines, occupying
about one-fourth of the longitu-
dinal optical section. There is an
inconspicuous, flattish cardia. In-
testine about 8 to 12 cells in girth,
faintly tessellated. The tail is
conoid to the plain, unarmed con-
oid terminus. The base of the spinneret is about one-fifth as wide as the base of
the tail. The clavate caudal glands form a close tandem in the anterior third of
the tail. The anus has rather conspicuous, with well developed, though not protrud-
ing lips. There is a pair of innervated lateral papillae near the middle of the tail of
the female. Both in front of and behind the vulva, especially behind, there are
inconspicuous papillae, occupying a distance equal to twice to thrice the length of
the body-diameter. The two equal, arcuate, rather slender spicula are one and
one-half times as long as the anal body-diameter, and are of nearly uniform size
throughout the greater part of their length. However, beginning near the slightly
truncated tips they taper slightly in the distal sixth. The proximal ends are also
narrowed slightly and lie well toward the dorsal side of the body, at any rate when
the body is incurved. The two accessory pieces, each about two-thirds as wide as
the spicula, are located opposite the distal portions of these latter. When seen in
profile they appear to lie nearly at right angles to the body axis, and seem to cross
the distal parts of the spicula. They are about two to three times as long as wide,
and their distal extremities are diminished and bifurcated, the two prongs of the
fork forming a U-shaped figure. When at rest these accessory pieces, as usual,
are well inside the anus, in fact appear as if lying immediately under the lateral
fields. In front of the anus there is a uniform series of about 16 equidistant,
closely approximated, innervated supplementary organs, occupying a distance about
equal to the length of the tail. When the tail end of the body is incurved, each
organ appears on the ventral contour as a flattish cone, at the apex of which is a
nerve ending, which from this point extends inward and forward.
Brown, sandy soil, Arlington Farm, Virginia, U. S. A. This nemativorous 'mon-
onch is distinguished from all others by the relative broadness of the pharynx,
and by the position and size of the basal onchi. Especially well adapted to show the
structure of the lip muscles and other organs of the head. Fig. 67.
SOIL FERTILITY
(s. s. 481) 170
57- M. acutus, n. sp. CEsophagus bulbous at first, the swelling being prolate.
Intestine about 10 cells in girth. The arcuate conoid tail is practically acute. There
is a pair of 2.6
sublateral, 2.7
7.5 23.
94.
8.1
Hi.
3.2 3.3 3.4
innervated papillae near the beginning of the pos-
terior third of the tail. Anus not raised. Fig. 68.
Found about the roots of rhubarb in loose,
brown, sandy soil, Arlington Farm, Virginia,
U. S. A. Nemativorous. One specimen was ob-
served which had swallowed another mononch.
This is one of the most instructive forms. It is
desirable that the more minute structural details
of nemas be very carefully investigated with a view
to increasing our knowledge of their comparative
anatomy. The different parts of the digestive or-
gans of nemas, small as they are, are as pro-
foundly modified in harmony with the nature of the
food as those of higher animals. The digestion of starch requires a different
organic mechanism from that for digesting meat. The nemas have specialized to
a high degree in the matter of food, and their digestive organs are correspondingly
diversified.
NEMAS AND SOIL FERTILITY
No one with a grain of imagination can engage in such studies as the
foregoing without sooner or later asking himself questions of a general
nature concerning the biology of the soil, for he gradually comes to sec
how almost infinitely numerous and varied are the organisms inhabiting
it; a population in which the nemas are but an element. The answers to
these questions will lead to a new view of soil fertility.
The revolution wrought by Liebig's ideas concerning the chemistry of
the soil spent itself only to show us that, grand as it was, it was little
more than an overture. Subtler forces and more intricate relationships
than any indicated in these earlier conceptions must be considered. We
now see, or are beginning to see, that the value of manure and of the ro-
tation of crops is to be explained not simply on the basis of the exhaus-
tion of certain elements in the soil, but also, and probably in some in-
stances mainly, on the basis of an opposite process, an accumulation of
certain organisms and substances in the soil. Who knows but that the
existence of annuals may be due in some measure to this latter fact? May
not these elaborate provisions for the distribution of the seeds of annuals
be in some measure a means of escaping these accumulated hostile forces
in the soil ?
After all the word Agriculture is more or less of a misnomer. We
cultivate, not so much the field, as plants. What we are really after is
sunshine, for we are lost unless we can convert our infinitesimal part of
the energy of this nearest star into food, clothing and shelter. This we
do by utilizing the life forces of certain plants and animals, and these are
not so few as we dreamed in our older philosophy, for none of our
"domesticated organisms" can any longer be considered by itself. Every
lgQ(S.S.482) THE MONONCHS
such organism is reared in the midst of a host of other organisms, visible
and invisible, and often it is these others that determine agricultural suc-
cess or failure.
The soil is the habitation of a vast community of beings with all the
attributes of other huge agglomerations of living things having varying
needs, instincts and aspirations; and it is just as inappropriate to look
upon it as inorganic as it would be to look upon a great city as merely an
agglomeration of hills, streets and houses. Here in the soil are beings in
enormous variety; multiplying, growing, dying; competing, fighting, co-
operating one with another, with an activity almost if not quite defying
the imagination, and we need what may be called soil biologists or geo-
biologists, who shall understand, as far as possible, this interplay of life
forces that gives us food, fiber and fuel. To a considerable degree our
progress in agricultural knowledge in the not distant future will be in pro-
portion to the firmness with which we lay hold of and act on this idea.
SUMMARY
1. The genus Mononchus is composed of scores, possibly hundreds,
of species, divisible into distinct subgenera. The number of known
species is hereby more than doubled.
2. The genus is of world-wide distribution, and many of the species
are cosmopolitan. Mononchs occur in all kinds of arable soil, sometimes
in hundreds of millions per acre.
3. Most mononchs, probably all, are strictly carnivorous. They feed
on a variety of living microzoa, prominent among which are other nemas.
4. Injurious nemas are devoured by mononchs, and it is desirable that
this trait of mononchs be carefully investigated with a view to utilizing it,
if possible, in diminishing the enormous crop losses due to plant infesting
nemas losses amounting to many millions of dollars annually.
5. The lips are moved by long muscles, connecting proximally with
the body wall behind the pharynx. These muscles lie along the outer
surface of the pharyngeal capsule and act in such a way as to pull the
lips inward and outward radially about a series of fulcra existing in a
framework encircling the head along the margin of the pharynx. The
lips are the mechanical complements of the dorsal tooth and denticles.
While most mononchs bolt their food, some give it a certain degree of
mastication. The appetite is sometimes voracious.
6. Many mononchs, probably most, are hermaphroditic, even to the
degree of syngonism. In the typical case investigated the minute sperm
cells of female origin are functional.
7. Well developed glands, salivary in character, occur in the mon-
onch oesophagus, and empty duectly into its lumen, and both indirectly
and directly into the mouth cavity.
BIBLIOGRAPHY (S. s. 483) jgl
8. What appears to be an excretory pore of the usual type seems
universal near the nerve ring.
9. The outer labial papillae are the homologues of the ordinary cepha-
lic setae of other nemas, and are therefore most probably tactile in func-
tion. This leaves it probable that the inner papillae are devoted to the
senses of taste and smell.
10. Amphids are always present in the form of small lateral more or
less elliptical structures near the lips, and are connected with internal
elements extending inward and backward.
11. A functional spinneret is present in a majority of the species.
12. The cuticle is always finely transversely striated.
13. Mononchs probably moult four times.
BIBLIOGRAPHY
(1) ANNETT, DUTTON, and ELLIOTT.
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1866. Monograph on the Anguillulidae. In Trans. Linn. Soc. London,
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1914. Nematodenfauna des Nordwest-deut. Flachlandes. In Abhandl.
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(4) BUTSCHLI, O.
1873. Beitrage zur Kenntnis der f reilebenden Nematoden. In Nova Acta
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1876. Freilebenden Nematoden und die Gattung Chaetonotus. In Ztschr.
Wiss. Zool, Bd. 26, p. 363-413, 4 pi.
(6) COBB, M. V.
1915. Nematodes of the Michigan Lakes. In Trans. Amer. Micros. Soc.,
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(9) COBB, N. A.
1893 Plant diseases and their remedies; sugar cane. In Agr. Gaz. N. S.
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(10) COBB, N. A.
1893. Plant diseases and their remedies; sugar cane. Separate Ed. for
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(11) COBB, N. A.
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(12) COBB, N. A.
1904. Free-living fresh-water New Zealand nematodes. In Proc. Cam-
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132(3.3.484) THE M ON ON CHS
(13) COBB, N. A.
1907. Fungus maladies of the sugar cane. Hawaiian Sugar Planters'
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1914. Nematodes and their relationships. In U. S. Dept. Agr. Yearbook,
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(S. S. 486)
THE MONONCHS
APPENDIX
r^
oox ^ U>
t 7> " 14 >
^ : F
8 p"^-- ^^-v-f'M $$
.! ! j"
#? >5!r/?er oe lit w tic OP im an spn
The above diagram illustrates the decimal formula used herein. 6, 7, 8, 10, 6 are
the transverse measurements, while 7, 14, 28, 50, 88 are the corresponding longitudi-
nal measurements. The formula in this case is : - 14- 28 ' 50- 88- . The unit of
6. 7. 8. 10. 6.
measurement is the hundredth part of the length of the body, whatever that may be.
The measurements become, therefore, percentages of the length. The absolute length
is given in millimeters as a final non-paired term. The measurements are taken
with the nema viewed in profile ; the first are taken at the base of the pharynx, the
second at the nerve-ring, the third at the cardiac collum or end of the neck, the
fourth at the vulva in females and at the middle (M) in males, the fifth at the anus.
Fig. 68. M. recessus, n. sp. No. 21-b. Striae excessively
fine. Lips with 14 papillae. Intestine about 5 cells in girth,
2.8 6.9 30. '63 12 91.5 faintly tessellated. Cau-
2^ 27i 27? 274 TF^ dal glands small and
inconspicuous. Tail tapering rapidly on the ventral side
behind the anus ; thence onward arcuate and conoid, with
spinneret. Habitat: soil of a tomato field, Naranjo, Fla.
This species, together with decurrens and dentatus, constitute
the new sub-genus Sporonchulus; it is interesting to note
that so far as known all of them are tropical and below the
x 750 ^ m ^ i" average size.
Fig. 69. M. decurrens, n. sp. No. 21-c. Striae excessively
fine. Intestine 7 to 8 cells in girth, the cells packed with
granules, which, however 2.9 9. 24. Y 95.9
do not give rise to a tessel- 2 - 9 4. 4.2 4.6 2.
lated appearance. Tail arcuate conoid, tapering from in front
of the anus. No spinneret, or doubtful ; no caudal glands. Ex-
cretory pore (?) just behind the nerve ring. Anus more or
less elevated. Habitat : Plant Introduction Gardens, Miami, Fla.
53-b. M. fasciatus, n. sp. Like M. bathybius, No. 53. Characterized by large,
powerful lips, set off by a deep constriction, in 2.4 5.6 16. '64'=" 90. ^ ^ ^
the depths of which is a double refractive line. 2.3 2.3 2.4 2.4 1.8
Teeth 3, small, equal, sub-basal ; tail conoid, no spinneret. Papillae 14. Habitat :
About roots of camphor, Florida. Nemativorous.
Erratum.
After Soil Science went to press it was found that similis and tenuis are invalid
as designations of new mononchs, owing to Mononchus similis Cobb 1893, and
Mononchus tenuis Daday 1908, the latter not a mononch. The present M. similis is
therefore hereby changed to M. subsimilis, and M. tenuis to M. sub tenuis. The ref-
erence to M. megalaimus in "Nematodes mostly Australian and Fijian," Cobb, is a
misprint for M. gymnolaimus. The overlooked M. similis is as follows :
53C. M. similis Cobb. 3.3 8. 24. u '58' u 86. Pharynx three-fifths as
wide as the head, two- 3. sTs 471 4~5 2A 1-8 mni thirds as wide as long ;
tessellated intestine fifteen cells in girth ; anus conspicuous, depressed ; spinneret
one-eighth as wide as the base of the tail.
Clarence River, Australia.
Habitat : About roots of cane, Harwood,
MONONCHUS
SUBGENERA
MYLONCHULUS
PRIONCHULUS
longicollis
GENUS
MONONCHUS
IOTONCHUS
consunilis bathybius
fff flrf
SUBGENERA
SPORONCHULUS ANATONCHUS
acutus
FILTER-BED NEMAS:
NEMATODES OF THE SLOW SAND FILTER-BEDS
OF AMERICAN CITIES
(Including new genera and species)
WITH NOTES ON HERMAPHRODITISM AND
PARTHENOGENESIS*
CONTRIBUTIONS TO A SCIENCE OF NEMATOLOGY, VII
BY N. A. COBB
United States Department of Agriculture
The nemas here described were collected from the filter-beds of
several American cities, incident to a rather extensive investigation
of nemas of economic interest. A study of them has afforded me such
an interesting and suggestive glimpse of the biological conditions in
slow sand filter-beds that I venture to think an account of it may be
of some slight use to sanitarians, and to engineers connected with city
and town water works. The biological observations, more particu-
larly those on the vanishing series of spermatozoa in syngones, may
prove of interest to zoologists and geneticists.
NATURE AND NUMBER OF THE ORGANISMS FOUND
Few Green Organisms. Comparatively few green organisms occur
in covered slow sand filter-beds, especially if the water passes through
a subsidence reservoir before entering the beds. Practically all the
living forms found are colorless or nearly so, and most of the larger ones
are animal. To me the most striking organisms in every sample of
sand examined were the nemas.
Period of Use. Renewal. From time to time a few inches of the
topmost sand of slow filter-beds is renewed; the old sand is removed and
fresh sand spread in its place. The period of use, the time between
any two successive renewals, varies from a few weeks to a few months,
according to the practice of the engineer in charge. Toward the end
of a period of use the number of nemas in the topmost three inches of a
bed often mounts to hundreds of millions per acre, and sometimes
exceeds a thousand millions per acre. At this latter figure each glass
of drinking water must percolate through sand containing at least
about a thousand nemas.
Dozens of Species Found. Often the nema population is of a mixed
character, but sometimes it is comparatively homogeneous. On
*Waverly Press, Baltimore, Jan. 11, 1918.
190 FILTER-BED NEMAS
one occasion, at the end of a period of use, I found ninety-six per cent
of the nemas to consist of but a single species. About thirty species
were found inhabiting the various beds examined, twenty-five species
being found to inhabit the beds of one city. My observations make
no pretence of being exhaustive, and I presume further research may
easily double these numbers. Most of the species are of only occasional
. occurrence ; those figuring prominently in the activities of the beds are only
about half a dozen in number, and of these not all are equally important.
THE MORE COMMON SPECIES
Commonest Species Carnivorous. Of the four more important species,
(1) Mononchus longicaudatus, (2) Ironus ignavus, (3) Tripyla monohystera
and in a lesser degree (4) Ironus longicaudatus, I have shown that all
are carnivorous, that they feed upon a variety of living organisms,
and that no one of them confines itself to a single kind of food. Mon-
onchus longicaudatus, for instance, feeds upon several species of nemas,
upon rotifers, and upon a variety of protozoa. The same is true of
Tripyla monhystera. In the struggle among these filter-bed organisms
it appears that sometimes one species may almost annihilate others.
This accounts for such cases as that in which Mononchus longicaudatus
constituted ninety-six per cent of the nema population of a bed.
ROTATION OF THE FLORA AND FAUNA
Seasonal Fluctuations. I know little about the seasonal fluctuations ;
merely that they exist and that sometimes they are very marked.
For instance, on January 6 samples of sand were gathered from various
locations on a Washington filter-bed. This bed had been in operation
about six months, a period longer than in the case of any previous
examination (summer collections). About the same range of species
was found in this sand as had been found in all previous experience
taken together, but the smaller nemas, including Monhystera, were
much more abundant in this than in previous collections, and seemed
to be thriving. A large Dorylaimus that had been extremely rare
in previous collections was fairly common in this January collec-
tion. Achromadora minima was also more common. Finally there
were one or two small species not hitherto found, Cylindrolaimus ob-
tusus and a Rhabdolaimus. Whether these faunal differences were
due to the winter season or to the long time the bed had been in use
remains in certain instances undetermined, very likely some of them
were due to both causes.
Economic Bearings. Apart from seasonal fluctuations, there is a
rotation in the fauna and flora incidental to the management of the
FILTER-BED NEMAS AND PUBLIC HEALTH 191
beds. Beginning with a new period of use, it appears that minute
species, e.g., bacteria and protozoa, having a short life cycle and suited
to the new conditions, first make their appearance; these multiply
and become the food of succeeding species, which in their turn give
place to others. The problems presented are of great biological interest,
and may not be without some bearing on public health. Beyond
doubt they have a more or less important relation to the economical
and effective management of the filter-beds.
DETERMINING FACTORS OF FILTER-BED POPULATION
Organisms other than Nemas. Many other kinds of organisms are
found in filter-beds, some of them in far greater numbers than the nemas.
Bacteria, fungi and protozoa occur, of course, in abundance, and are,
I believe, the organic basis on which is built up the later animal pop-
ulation consisting of organisms of larger size, such as the nemas.
Rotifers are not uncommon. Small oligochaetes, earthworms, occur,
especially after long use, but never in such myriads as in sewage. Small
crustaceans, such as daphnia and cy clops, sometimes occur, but I have
never seen them in large numbers. Occasionally aquatic insects are
found. The filter-beds of each city present biological peculiarities
dependent upon the source of the water supply, for the biological
characteristics of filter-beds depend to a considerable extent on the
climatic and geological conditions prevalent on the water-shed from
which the supply is drawn.
PHYSIOLOGICAL SIGNIFICANCE OF FILTER-BED NEMAS
Illness from Change of Water. It is a well-accepted idea among
physicians, as well as laymen, that a change of drinking-water may
cause intestinal disorders; why they are thus caused is not always clear.
If the waters in question are widely different in composition, for instance
one soft and the other hard, it is easy to understand how intestinal
derangements might follow a change from one to the other; but are
the derangements due to change of water always associated with such
marked chemical differences? Do not intestinal disturbances follow
changes of water in which the usual tests would show but very slight
differences?
Soluble Excreta in Drinking-water. Is it possible that slight quantities
of organic substances found in drinking water and of a character as
yet unknown, might, under some circumstances, exert a powerful
physiological influence? If this question be answered affirmatively,
a wide field of investigation is opened up in connection with potable
waters, and it is in this connection that the present researches are
192 FILTER-BED NEMAS
definitely suggestive. The filter-beds, after they have been cleaned
and again put to use, soon become the habitat of a succession of various
organisms, animal as well as vegetable, so that at the end of a period
of use it is no exaggeration to say that the sand through which the water
percolates swarms with them. To state a definite case quantitatively,
it has been shown during these examinations that such filter-bed sand
may contain hundreds of millions of nemas per acre in the top three 1
inches. Each of these nemas is excreting material of which the soluble
portions must pass into the city's water supply, and if in the course
of its passage through the filters, flumes, and delivery pipes this soluble
matter is not precipitated or otherwise altered, it is present in every
glass of drinking-water.
FLAVOR OF DRINKING WATERS
Drinking-water Connoisseurs? The excreta of any given filter-bed
organism must be different from that of any other, and though the
differences may be slight between similar organisms, there are good
reasons for thinking that the differences among the organisms of the
filter-beds of different cities are great enough to cause material dif-
ferences in the nature of their excreta. Such soluble parts of the excreta
as pass into the drinking-water must play a role in imparting to the
water its flavor and other qualities. This is enough to make one wish
that we had connoisseurs to assist us in the selection and control of
drinking-water, as we have connoisseurs in wine and tea, connoisseurs
or experts capable of distinguishing minute differences in the flavor of
drinking-waters. At first thought this may seem too fine-spun, and yet
when we think of the care exercised in selecting wines, teas, and other
beverages, and compare their actual importance with that of drinking-
water, it may not be going too far to suggest that consideration be
given to the possibility of determining th qualities of drinking-water
by flavor and other tests in addition to those now in use. I think
experienced persons with a delicate sense of taste will bear out the
statement that the drinking-water of each city has its characteristic
flavor. If half a dozen glasses of fresh drinking-water could be assem-
bled from the water supplies of as many cities, I have little doubt that
a person with a delicate sense of taste w r ould be able to tell one from
another blindfolded, at any rate where the differences were most
pronounced.
In this discussion it matters little that the amount of the dissolved
substances thus suggested as a possible cause of differences in the physi-
ological action of drinking-water is minute, for it is a well-established
fact that very minute quantities of various substances may have a pro-
CONTROL OF FILTER-BED NEMAS 193
found effect upon the human organism. Such reflections lead to the sug-
gestion that the study of filter-bed organisms is one that should be
prosecuted more vigorously. We have developed a few excellent chemical
tests, and, so far as it goes, an excellent system for determining the
bacterial content of drinking-water. Why not go a step farther and
make at least an attempt to determine the nature of the minute quan-
tities of soluble organic substances of physiological significance which
may be present, and the origin and nature of these substances.
POSSIBLE CONTROL OF FILTER-BED ORGANISMS
If it should be found that the presence of a particular micro-organism
in filter-beds is deleterious, is it possible so to manage the beds
as to exclude the micro-organism, or counteract its effect? Already I
feel sufficiently conversant with some of the facts to predict that such
control will prove feasible, at least in some instances. In the case of
Mononchus longicaudatus for instance, as soon as we know the natural
distribution of the Mononchus; its relationship to the seasons of the
year, if it has any significant relationship of that kind; the period of
its life cycle; its rate and method of reproduction; its food; its enemies;
then, almost beyond doubt we shall be able to suggest means for its
control. So with other organisms.
To secure a reliable filter-bed census it is necessary to examine the
sand as soon as collected. After a short period under laboratory con-
ditions the population begins to change: e.g., sand which at the time
it was removed from the bed contained many specimens of Mononchus
and a few of Ironus ignavus, after ten days yielded no Mononchus, though
it continued to yield Ironus, and in addition a few adult specimens of
Tripyla and Monhystera, differences no doubt due in part to the fact
that in stagnant collections Mononchus longicaudatus is subject to the
attacks of a variety of fatal diseases caused by fungi and microbes.
NEMAS A CLUE TO THE FLOW
Nemas Unequally Distributed in Beds. The distribution of organisms
in filter-beds is not uniform. For example, if a series of samples be col-
lected, one each from near the main drain-pipe, near a lateral, between
the laterals, and at the margin of the bed, the numbers and kinds of
nemas will be found to differ in the various samples. This unequal
distribution is doubtless a function of the flow of the water, for where
the flow is rapid the biological environment differs from that where it
is slower; there is a greater supply of oxygen, a greater supply of water-
soluble food, and a greater supply of such free micro-organisms as may
pass between the grains of sand. It follows that to some extent the
194 FILTER-BED NEMAS
fauna and flora of filter-bed sand may be made a criterion of the rate
and nature of the filtration.
The general appearance of the sand in any particular part of the bed is
a clue to the rate and nature of the filtration there, but this rough method
is capable of refinement through the aid of a biological census. The
difficulty is we do not yet know what significance to attach to the
presence or absence of particular species. Should an attempt be made
to devise and apply such a method, it might be found that the presence
or absence of a few species would constitute a sufficient test.
PARTIAL LIST OF THE NEMAS FROM AMERICAN SLOW SAND
FILTER-BEDS*
Achromadora minima Cobb Washington, D. C. Mononchulus ventralis n. g., n. sp.
Actinolaimus radiatus Cobb... .Washington, D. C. Washington, D. C.
Aphanolaimus ? Philadelphia Mononchus longicaudatus Cobb
Apheltnchus ep Pittsburg Washington, D. C.
Atylenchus sp New Bedford ,, , ,.. . . ,.
Cephalobustp Philadelphia Mon h * Philadelplua
Cylindrolaimus obtusus Cobb... Washington, D. C. Plectus clrratus Bastian Washington, D. C.
Dorylaimus fecundus Cobb Washington, D. C. Prismatolaimus sp Philadelphia
Dorylaimus sp Washington, D. C. Rkabditis sp Philadelphia
Dorylaimus sp Philadelphia Rhabdolaimus sp Washington, D. C.
Dorylaimun sp Philadelphia Spilophora sp Harrisburg
Dorylaimus Bp Washington, D. C. Teratocephalus sp Pittsburg
lota simile n. sp Washington, D. C. Trilobus longus Leidy Philadelphia.
Ironus americanus Cobb Philadelphia THpyla monohystera de A/ an ... Washington, D. C.
Ironus ionavus Bastian Washington. D. C. Tylencholaimus sp ^^ Bethlehem,
Ironus longicaudatus de M an. . .Washington, D. C. p. ,
Monhystera subfiliformis n. sp . .Washington, D. C.
Monhystera dispar Bastian Washington, D. C. Tylenchus filiformu Butschh (?)
Monhystera sp Philadelphia Washington, D. C.
Monhystrella plectoides n. subg., n. ep. Tylenchus sp Philadelplua
Washington, D. C. Xiphinema americanum Cobb Philadelphia
* The larger number of species from the Washington beds is due to the examination of a larger num-
ber of samples than from beds elsewhere. The more important of these species are described below.
The drawings are from nature and were made under the author's personal supervision by Mr. W. E.
Chambers.
MONONCHUS Bastian 1865
1. Mononchus longicaudatus Cobb (See p. 161). The feeding habits of Monon-
chus are distinctly different from those of either of its frequent companions,
Tripyla and Ironus. In capturing food Mononchus depends largely upon the
grip of its powerful jaws. Tripyla depends upon its agility and its flexibility,
and possibly coils itself about its victim, after the manner of a boa constrictor.
Mononchus and Tripyla bolt their food, but Ironus feeds in an entirely different
way; attaching its lips to its food, it rips a hole in the external layers by the
outward stroke of its three, extremely sharp, radially acting onchi. As these
move forward their points move outward, and two or three such movements serve
partially to imbed the head of the Ironus. It would appear that then the more
or less fluid parts only are imbibed, for the contents of the intestine of Ironus
hardly ever present optically identifiable substances. It is manifest, however,
that the contents of the intestine are animal in character, and so it seems beyond
reasonable question that Ironus is carnivorous. I have never found the con-
tents of the intestine to respond to the starch test.
MONONCHULTJS VENTRALIS
195
Intro, vilam staining shows the existence of a
dorso-ventral physiological differentiation in the
intestine of Mononchus longicaudatus.
Renette. When this well-known mononch was
stained inlra vitam with trypan blue, the ampulla
and a short portion of the duct of the renette was
so distinctly seen as to leave almost no shadow of
doubt that this portion of the renette structure
is normal. I am inclined to think that the duct
soon takes a lateral turn, and possibly becomes
connected with the lateral field; thus far it has not
been possible to follow it more than a distance
mrfi
p/i..
Fig. 1. Man-
chulus ventralis,
/*'
,
rl or til
mil
a very interesting
nema, found in
the Washington irltirtil
filter-beds. The
lateral fields are
shown with great
clearness; they fm
are made up of
about three rows
of cells, d ar lat,
each cell with an
egg-shaped nu-
cleus, nd ar lat.
The intestinal
nuclei, of about
the same size, are
shown darker.
Oesophageal
glands, sal, as in
Mononchus. The
small posterior
gonad, appar-
ently serving as
a testis, is shown
at 1st. Nearly the
whole of the tostis
is shown in the il-
lustration. The
spinneret is unus-
ually large, and
gives us for the
first time some
clue to the struc- w,,,.!,/
ture and me- a
chanics of this
organ. The de-
tailsaremorefully
illustrated in Fig.
2. For abbrevia-
tions see p. 212.
am of
n-lm-liil
////// m .
mr am .
about equal to the radius of the nsck, so that the
size and structure of the glandular part remain
unknown. nlylcdl.
MONONCHULUS gen. nov.
Characters. Possessing the form and general
appearance of Mononchus, but having the spinneret
on the ventral side of the tail near the terminus,
and the pharynx smaller and narrower with thicker
walls, and with forward pointing onchi or teeth, of
which a subventral one dominates. The labial
papillae are smaller than is usual in Mononchus, in fact are barely visible.
196 FILTER-BED NEMAS
The entire pharynx is about twice as long as the cavity bearing the onchi, but
the posterior part is narrower and somewhat obscure.
Anterior gonad reflexed. Posterior gonad outstretched, very small, producing
spermatozoa. The development of the oocytes follows about the same course as
that of the spermatocytes, which they resemble to a certain extent, though
they are larger. Occasionally the oocytes so closely resemble the spermat-
ocytes that it is rather difficult to make a clear distinction. The very youngest
stages of the female gonad have not been seen, but in the youngest stages ob-
served there were no indications of spermatozoa; yet at the same time sper-
matozoa were developing in the minute posterior straight gonad.
2. Mononchulus ventralis n. sp. ^ ^7 ^ f^j trs' 1 The thick
layers of the transparent, colorless, naked cuticle appear to be devoid of any
but the very finest of transverse striae; but longitudinal striations are visible
throughout the length of the body. Six rather thoroughly amalgamated lips
of considerable thickness arch together over the pharynx and normally nearly
close the mouth opening. There are six slightly spreading inconspicuous papillae
scarcely interfering with the rounded contour of the front of the head; in addi-
tion, surrounding the mouth, there are six forward pointing papillae. There
are no eye-spots. Very inconspicuous amphids occur opposite the middle of the
largest pharyngeal tooth in the form of small semi-circumferences opening back-
ward and having a breadth about one-fifth as great as that of the corresponding
part of the head. The anterior main thick-walled portion of the pharynx is
about as long as the head is wide. When the pharyngeal organs are at rest
this front cavity is comparatively well filled by the large, acute, forward
pointing right submedian tooth. There are two other teeth, a small dorsal, for-
ward pointing tooth having its apex near the middle of the pharynx, and an ex-
ceedingly minute inward pointing tooth, or spur, in the left submedian portion
of the cavity near the base. Opposite the anterior portion of the main tooth
the walls of the pharynx are armed with several dozens of minute, rasp-like
teeth or denticles.
Close scrutiny of that part of the wall of the pharynx immediately behind
the rasp-like area discloses that it is transversely striated to near the base.
These pharyngeal striae can be seen only with the highest powers of the micro-
scope under favorable circumstances. Behind this anterior portion of the
pharynx is a narrower, unarmed portion, of equal length, making the total length
of the pharynx about twice as great as the diameter of the head. The cells of
the thick walled, narrow-lumened intestine contain scattered brownish granules.
There are three unicellular caudal glands; two opposite each other immediately
behind the anus, and a third, more or less dorsally located, behind and between
the first two but emptying through a submedian ampulla and hence really sub-
median. The single reflexed ovary, except when pushed forward by the presence
of an egg in the uterus, reaches nearly back to the vulva.
Habitat: This interesting digonic species has been found in peat soil, west
of Fort Lauderdale, Fla., along a canal for drainage of land formerly covered
with water, and at Miami, Fla.; in the sand of the filter beds at Washington, D.
C.; and also in the Potomac River.
A species that appears to belong to the genus Mononchulus is described by
Daday under the name Prismatolaimus nodicaudatus, n. sp., in his "Mikro-
skopische Siisswasserthiere aus Deutsch Xeu Guinea."
MECHANICS OF THE SPINNERET
197
sub ait
STRUCTURE OF THE SPINNERET
I am not aware that anyone has ever attempted to explain the mechanism of
Ihe spinneret of nemas. Manifestly the flow of the caudal secretion is controlled
at will. Watching this operation as performed by a free-living nema, one is
forcibly reminded of the facility with which spiders regulate the operation of
their spinnerets, and, as in spiders, so in nemas, there must be a definite con-
trollable mechanism for performing these operations. The structure of the
spinneret in Mononchulus venlralis may at least suggest the mechanical prin-
ciples exemplified.
The Needle-Valve. As a rule the nema spinneret is so extremely minute that
its details cannot be deciphered. In Mononchulus ventralis the spinneret is
relatively large and its elements more or less resolvable, but since it is ventral
in this species instead of terminal, as is usual, its form may not be entirely typical.
In M. ventralis we find the duct of the spin-
neret to end externally in a conical depres-
sion near the end of the tail. This conical
depression leads to a short oblique tube
terminating internally at the valve of the
spinneret, vlv-vlv, Fig. 2. The valve belongs
to the class known as needle-valves, and the
needle, if such it be called, is an acute, fusi-
form affair, duplex in cross section, and
nearly half as long as the terminus of the
tail is wide. It is placed at an angle of
about 45 degrees with the axis of the tail, and
while its acute free distal end lies loose in a
cavity of obverse mold, its more or less
cephalated proximal end is connected with
the dorsal side of the tail by means of oblique
muscular fibres. The proximal part of the
valve is located in the midst of a vesicle (?)
to the dorsal side of which its proximal ex-
tremity seems to be attached; the embryo-
logical development has not been investi-
gated, but conceivably the needle is formed
by an invagination of the wall of the "vesi-
cle." Into the base of the more or less
ellipsoidal "vesicle" the ducts of the caudal
...
glands empty. 1 he operation of the needle- part of the spindle-shaped
valve is now easily understood. The internal
body pressure will of itself keep the needle-
Valve closed. Contraction of the muscular
fibres already described serves to pull the
needle loose from the mouth of the valve,
and so permit an outflow of the secretion. The "needle" is composed of two
elongated, ceratinous lateral elements joined side by side, and the orifice of the
valve is composed of three elements, disposed in the form of a hollow cone
about the distal half of the needle.
Nervous Apparatus of Valve. Most of the foregoing features are shown in
Fig. 2. Necessarily the apparatus is supplied with the appropriate sensory and
motor nerves. The details of these latter have not yet been made out with
x2ooo -::."."! <l jar aS
Fig. 2. Spinneret of Mononchulus ven-
tralis, with coagulated secretion attached.
The valve is partly open and the secretion
is pouring out. The three ampullae empty
into a common space round the proximal
jpindle-shaped valve-plug,
pulled open by the muscle, msc vlv. All
198 FILTER-BED NEMAS
certainty; however, innervated papillae occur near the terminus, doubtless
tactile in function. The shortest, i.e., dorsal, unpaired caudal gland empties
through a dorsally left submedian duct. Of the two longer and paired glands,
one, the left submedian, empties through a ventral ampulla, while the other
empties through a dorsally right submedian one; the details of the debouchment
remain somewhat obscure and no attempt has been made to indicate all of them in
the illustration. The three pores, however, are just in front of the "equator" of
the valve.
Digonic. This species presents the unusual peculiarity for an hermaphroditic
nema of developing its ova in one gone, and its sperm in another gone of much
smaller size, in a word is digonic. So great is the disparity between these two
branches of the sexual apparatus that at first glance one almost inevitably con-
cludes that the very small posterior branch is a mere functionless vestige.
A careful examination seems to prove that only ova are produced in the anterior
branch, while the very small outstretched posterior gonad functions as a testis;
the evidence for this latter conclusion being the occurrence of spermatozoa and
spermatocytes in small numbers arranged in the order to be expected if the
organ were a small gonad devoted solely to the production of sperm. The cells
in this minute gonad are so few that their precise order is not a striking feature,
and yet an examination of a series selected from among individuals in which the
ova in the anterior gonad are still quite young and small, enables one to demon-
strate that the cells near the blind end of the small gonad correspond in structure
with primary spermatocytes, and that the succeeding cells, sometimes as few as
two to three in number, represent successive steps in the development of the
spermatozoa. Occasionally one finds here a pair of gonic cells lying side by side,
each containing about six chromosomes, practically as definite as those to be seen
in the testes of male individuals of typical free-living amphigonic nemas. Often
the perfected spermatozoa appear not to exceed eight to twelve in number.
There is an obscure tendency for them to be located in groups of four, such as
should exist if they were produced in situ in quartets in the manner character-
istic of the spermatozoa of nemas. Once an egg was observed containing near
its equatorial periphery a body corresponding in size and staining properties to
one of the spermatozoa to be seen free in the uterus. The nucleus of this egg
showed signs of being affected by the presence of the spermatozoon, though it
appeared not yet to have produced polar bodies. All these appearances are in
harmony with the supposition that the posterior branch of the sexual apparatus,
small as it is, functions as a testis.
TRIPYLA Bastian 1865
3. Tripyla monohystera de Man. /o [79 T. 271 T7? 1 ' 4 """ Few nemas
are more agile than this. Its movements are extremely rapid, especially those of
the head end. It is unusually flexible, coiling and uncoiling all parts of its body
with great rapidity. It is of a restless disposition, at least so appears when
brought under the microscope for examination.
I have often seen this Tripyla attach itself to glass and then exhibit the evolu-
tions characteristic of nemas possessing well developed spinnerets, but in spite
of careful examination of living specimens, and specimens preserved both in
glycerine and balsam, I have seen no definite traces of caudal glands. The
cephalic setae are segmented and consist of two or more joints.
Harbors a Parasite. Tripyla monohystera of the Washington filter-beds often
contains what appears to be a peculiar spherical parasite. The parasites (?)
TRIPYLA MONOHYSTERA
199
seem usually to gain entrance to the body at or near the caudal extremity, for
in almost all cases where their number
is few they are confined to the tail.
See Fig. 3. Thence they seem to work
their way forward, especially along the
lateral fields, so that finally they may oc-
cur throughout the length of the body
in hundreds of thousands. These ob-
jects are extremely minute and can be
satisfactorily examined only with the
aid of the highest powers of the micro-
scope. At first sight they appear to be
crescent shaped, a deception due to their
peculiar refractive properties. Careful
focusing shows that the greater portion
of the sphere, an eccentric portion, is
but slightly refractive. The remaining
Fig. 3. Tripyla
This active, voraciov
monohyslera.
s little nema
is very common in filter-beds.
Often the remains of several other
nemas are to be found in its intes-
tine. The specimen figured had
been feeding on a variety of micro-
zoa. To be seen in the intestine
are a nema, nematod ing: the
"gizzard" of a rotifer, rot ing; and
a number of protozoa, ing. The
egg shown has just received one of
the syngonic sperm cells sp, and has
thrown off the first polar body, corp
plr I. The beginning of a sporo-
zopn (?) infestation is shown in the
tail, par. The renette of this nema
(ran; ex p) has hitherto remained
unknown. An organ of consider-
able size, but of unknown signifi-
cance, org ?, is also now for the first
time shown to exist in the neck.
For abbreviations see p. 212.
mini/nil IIHJ
niin inl
nclint
nclint
dint
ijniinlL
"iH I
ia
portion is more easily seen, and, when
it comes into view in optical section,
presents the contour of a crescent; is
therefore in reality bowl- shaped. I have
made no serious attempt to classify these
objects and can only suggest that we
have here a new sporozoon. If so it
may be the cause of a serious disease of
the nematode; often 10 to 20 per cent
of the individuals appear to contain it.
In some collections it occurs in practi- ^
cally every individual. *"*
Nemativorous. Nematodes having a nd mt
plain oesophagus, such as Tripyla, ^
Mononchus, and Monhystera, often ex-
hibit a marvelous capacity for swallow-
ing relatively large objects. Some spe-
cies of Monhystera are able to swallow diatoms one-half to two-thirds as wide as
themselves, and one-fifth to one-sixth as long. Tripyla monhystera is rather
200
FILTER-BED NEMAS
The . excret
pore is at the li
The submedi
em'pty 1 ' oppos
remarkable in this respect. It has lit-
tle difficulty in swallowing nemas half
as wide as itself; and the partly di-
gested remains of several such may
sometimes be seen in its intestine.
(See Fig. 3.)
IRONUS Bastian 1865
4. Ironus longicaudatus de Man.
.! _ 7.1 15. '36"3 66.
/1.6 1.9 2. 2.2 1.2
As regards the pronounced dorso-
ventral differences in the intestine of
Ironus longicaudatus, when specimens
of this species are stained in acid car-
mine it is noticeable that the large
granules characteristic of the dorsal
side take the stain. From an exami-
nation of living specimens one would
think these granules
probably fatty in their leJkt./JS
nature. The fact that
.11
they Stain as they do
seems to exclude this
supposition.
No Sperm keen. In back. The
spite of very careful ex- &* o
amination I was unable
to discover spermatozoa
in the females of this
species. Nevertheless I
am strongly inclined to
think that further in-
vestigation will reveal
the presence of sperma-
tozoa, and show that this
species also is syngonic.
I have seen no males.
I believe the food-
habits of Ironus longi-
caudatus to be much the
same as those of Ironus
ignavus, but having had
less opportunity to in- ^
vestigate them I have '*
fewer data from which *"
to form an opinion.
Habitat: Washington *
filter-beds; sometimes v
abundant. Quite active, ;/
ay'
rail
xl.ii
very much from
thevantral.
tfjer
r! a
EVIDENCE THAT IRONUS IS CARNIVOROUS 201
5. Ironus ignavus Bastian. TiTi TI [76 ~Ti iTT 2 ' 7 "' The pharyngeal
onchi are tissue tearers. The three onchi of Ironus ignavus are of unequal form
and size. At first glance they appear equal, but even when the onchi are drawn
in and the head viewed in profile it is sometimes possible to see that the dorsal
onchus differs from the other two in being duplex. When the onchi are exserted
the expansion necessary to this operation throws the two apices of the dorsal
onchus wide apart, and they can then with ease be brought separately into
focus. A front view of the head also emphasizes this double structure of the
dorsal onchus. Either half of this onchus when seen in profile seems to be of
almost exactly the same size and contour as one of the submedian onchi. The
action of the onchi in Ironus is like that in some species of Diplogaster, of most
species of Axonolaimus and of one or two other marine genera, and is the exact
reverse of that of the onchi of Enoplus and its relatives. The outward action
of the onchi in Ironus is adapted to tearing open the tissues upon which it feeds,
the fluid and semi-fluid portions of which are then imbibed. In harmony
with this is the liquid or finely divided character of the contents of the intestine
in Ironus. Enoplidae, on the other hand, bolt their food. The movements
of the onchi do not appear to be so quick as those of the onchi of Diplogaster.
The outward throw and return occupied about one-quarter second in a specimen
which though stained intra vitam with neutral red, yet appeared to be as active
as the average living specimen.
Characteristic Intestinal Crystals. The doubly refractive crystals found in
the intestinal cells of Ironus are different from those found in certain Rhabdites, to
which I have given the name Rhabditin. The doubly refractive crystals of Ironus
are not spherical, on the contrary are distinctly angular in contour and have a
definite polyhedral form. These doubly refractive bodies are absent from the
anterior part of the intestine for a distance about equalling half the length of the
neck, indicating a different physiological condition here. Some of the intestinal
cells are very distinctly specialized. (See Fig. 5.)
Carnivorous. The following are strong reasons for regarding Ironus as car-
nivorous; (1) Recognizable plant remains are rarely if ever found in the intestine.
(2) Ironus abounds in places where there is little plant food of any kind, but where
animal food is plentiful. (3) The peculiar mouth parts can hardly be ex-
plained in any other way than by supposing them to be special organs for rip-
ping open tissues of the food, and the only filter-bed plants that could furnish
adequate food for Ironus are entirely too small to be operated upon by these
mouth parts.
A very noticeable feature in the development of the eggs of Ironus ignavus
is the appearance in the ripening ova of numerous protoplasmic structures which
stain rather strongly in acid carmine. Toward a dozen of these structures
may be seen in the full grown ovum when about to turn and pass into the uterus.
The younger ovum immediately following it also shows these same structures,
more closely packed together, but of about the same size. After the egg has
passed into the uterus these bodies sometimes completely disappear.
Newly Discovered Organs. Among the numerous new facts here brought to
light in connection with Ironus none appear more interesting than the pro-
nounced dorso-ventral differentiation of the intestine. In both ignavus and
longicaudatus this differentiation is pronounced, especially in the latter, where
from one end of the intestine to the other the difference in structure between the
dorsal and ventral sides is very striking. In ignavus the same quality of dif-
202
FILTER-BED XEMAS
f erentiation occurs,
but the cells having
the coarser struc-
ture are more scat-
tered. They never-
theless are here
also commonly dor-
sal or sub-dorsal.
What seems to
be a very long and
narrow tubular or-
gan (org f) exists
in ignavus. I have
been unable to de-
termine the func-
tion of this inter-
esting organ. The
mycelium of vari-
ous parasitic fungi
is not altogether
uncommon in the
bodies of fresh
water nemas, and
sometimes presents
highly deceptive
appearances, but it
. did not seem possi-
ble to me that this
tubular structure
could be other than
an integral part of
the Ironus.
It is interesting
to note that the
most common spe-
cies of Ironus in
American filter-
beds are identical
with those of Eu-
rope. Ironus igna-
vus is widely spread
inthe United States,
as I have collected
it from spring, lake
and river waters of
many of the north-
ern states, from the
Atlantic as far west
as Colorado and
from widely vary-
ing altitudes.
Fig. 5. It
.TI&. a. 1 c//t lynuvux. Jiiiure- fjfj v
tory pore and salivary glands as in /"*'
longicaudatus, q. y. The differ- ''/ ,
entiation of the intestinal cells , /*
though marked is not so pro- /*
nounced as in longicaudatus.
Common in filter-beds. See p. 212. /**'JH/
6 Ib H t
MONHYSTRELLA
203
Fig. 6. Monhyslrella plec-
toides n. subg. n. ep. For some
distance in front of the nerve-
ring the oesophagus is dis-
tinctly though slightly altered.
A critical review of the Mon-
hysteras so far discovered and
described will undoubtedly re-
sult in the establishment of a
number of fairly well defined
groups, some of subgeneric
rank, some of generic. The
divisions may be made on the
basis of the anatomy of the
male organs as well as on that
of the mouth parts. These
anatomical differences are the
outward expression of differ-
ences in food habits, and of
special activities due to differ-
ences in habitat. The Mon-
hysteras constitute a hu_
group, of considerable biologi-
cal significance. Some species
are specially adapted to stud-
ies of problems in genetics.
The mode of development of
the spermatozoa of certain
species is worthy of study.
Ol A.
(/it.,
mui-int.
him at.
nil . . .
at tut
inn or.
mam.
mw mi
tty fir
it
nl
rim
lit MONHYSTRELLA subg. nov.
Subgeneric characters. Has the
general form and appearance of
Monhystera, but differs in the fol-
lowing respects: The pharynx is
more elongated, somewhat resem-
bling that of Cylindrolaimus, but
tapers slightly. The oesophagus
is not quite of uniform diameter,
in this respect somewhat resem-
bling that of Plectus in the ante-
rior part, but with all the varia-
tions less pronounced, so that, at
first glance, the oesophagus seems
to be rather uniform in structure
from the pharynx backward to the
cardiac swelling. There is a
rather distinct pyriform cardiac
swelling, with clear indications
of the presence of glands among
its muscular tissues. One or two
problematical unicellular organs
exist in the lateral fields on each
side of the body some distance
in front of the anus. Otherwise
very much as in Monhystera.
Possibly Monhystera bulbifera de
Man belongs to this sub-genus.
6. Monhystrellaplectoidesn. sp.
1.2 10. 17. '-44. 65.
i75 274 t76 371 ITT
The rather thin, transparent,
colorless cuticle is traversed by
exceedingly fine transverse striae,
resolvable only with high powers
under most favorable conditions.
The thin-shelled eggs appear to
be deposited before segmentation
begins.
Habitat: Sand, Washington
filter beds; uncommon. Nemas
of the character represented by
Monhystrella and Monhystera are
largely, if not entirely, vegeta-
rian. As a rule they are not
abundant in covered slow sand
filter beds. On one occasion,
however, after a long period of
winter use, I found such nemas
to be fairly abundant.
204 FILTER-BED NEMAS
They appeared to have been feeding upon bacteria and other similar micro-
phytes. Monhysteras are more common in open filter beds and in reservoirs,
where they appear to feed principally on green unicellular algae, which naturally
do not flourish in covered filter beds, since sunlight, direct or diffused, is
necessary to their growth.
IOTA Cobb 1913
7. Iota simile, n. sp. ~ 8 79 o7~ ~7<)7s~^~i7I 676 ' 6 "" T ne colorless layers of
the thick cuticle are traversed by ninety to one hundred plain, transverse
striae of such a nature as to give a relatively coarse serrate-crenate appearance
to the contour of the body. The annules of the cuticle are complete rings.
Only at rare intervals is there a trace of anastomosis; occasionally it will
happen that two semi-annules on one side of the body are joined to one on the
other. The convex-conoid neck ends in a somewhat rounded head surmounted
by a flat lip region composed probably of six very flat lips placed in the slightly
depressed front surface of the first annule. The first two or three annules are
packed closely together, and the prevalent crenate-serrate appearance of the
contour begins probably with the fourth annule, possibly with the third. No
labial papillae have been seen. Nothing is known concerning the amphids.
Spear. The spear is rather more slender than in most Iotas, and tapers
throughout the main portion of the shaft, which constitutes fully two-thirds of
the length. Where it reaches its maximum development this shaft has a diameter
about half as great as the width of one of the neighboring annules of the cuticle.
Behind the shaft the hilt of the spear has a diameter only a trifle larger than that
of the main portion of the shaft. The hilt increases in diameter steadily
posteriorly, and finally expands suddenly into a large three-fold bulb nearly
one-fourth as wide as the corresponding portion of the neck. The central canal
of the spear is plainly visible, and is continuous with that of the oesophagus.
Oesophagus and Intestine. The oesophagus is about as wide as the base of
the spear, and appears to present no very definite median bulb, though there
is a slight change near the middle of the neck which probably indicates the
position of some such structure. The details of the intestine are somewhat
obscure, but it appears to begin as a tube about half as wide as the body, and to
continue at this width for some distance. The anus seems to be located
between the fourth and fifth annules, counting from the posterior extremity.
The excretory pore is located near the twenty-sixth annule counting from the
head end where the annules first become distinctly developed; this means prob-
ably at about the thirtieth annule counting from the mouth itself. The tail is
conoid to the blunt terminus, which is destitute of a spinneret.
Sexual Organs. The depressed vulva is located at about the seventh annule
from the caudal extremity. The vagina leads inward and forward a distance
fully equal to the corresponding body width. In front of this is the uterus,
which appears to be once and one-half to twice as long as the corresponding
body-diameter. The ovary extends directly forward and its blind end lies
some little distance behind the base of the neck. The eggs occur one at a time
in the uterus. They are thin-shelled, a little longer than the corresponding
body diameter and about half as wide as long.
Habitat: Aberrant in filter beds, Washington, D. C. ; roots of grape-vine,
Herman, Mo. Synonymous with Iota are Ogma Southern and Criconema Hof-
manner and Menzel. Iota consists of many species. I have specimens and full
MS. descriptions of a number of new species collected during the last twenty
years in widely different parts of the world. All are -f and have the vulva
hidden among the annules near the anus; tiny, wide nemas with retrorse annules.
FOOD HABITS OF MOXHYSTERA
205
MONHYSTERA Bastian 1865
M. subfiliformis n. sp.
2./ 2.
This form, which appears to be new, is closely
related to Monhystera filiformis Bastian, but dif-
fers from the descriptions given by various authors
in the following respects: There are 10 cephalic
setae on subfiliformis instead of six. The am-
phids are somewhat larger than given by most
authors for filiformis. In the cardiac region I
have noticed in the single specimen of the present
species so far examined, a very definite pseudo-
bulb. There is a definite renette, as shown in the
figure, with an excretory pore opposite the nerve
ring. The eggs are relatively larger than de-
scribed for filiformis. The anatomical details are
clearly shown in Fig. 7. This species also shows
a certain amount of resemblance to Monhystera
vulgaris, de Man, but differs in having setae on
the body, and in having 10 cephalic setae, and in
the amphids being slightly different in position,
form and size. The tail of vulgaris also seems to
be more slender.
Habitat: Sand, Washington filter beds; j|/^Jf
usually uncommon. Of the numerous ^ .
species of Monhystera I have had occa- Uncm-
sion to examine with respect to their
food habits, all appear to be largely if
not wholly vegetarian. The various spe-
cies specialize to a considerable degree in
the matter of food. For instance, many
marine species feed almost exclusively
on diatoms. If the filterbed Monhysteras
are not an exception to the rule, they
would seem to be dependent on fungi and
bacteria as a source of food, except in
open beds, where of course they would
find an abundance of green microphytes.
CYLINDROLAIMUS de Man 1884
Sexual Organs. Cylindrolaimus typi-
cally has but a single outstretched ovary;
from the observations of various authors
it would appear that this may extend
either forward or backward, usually for-
ward. As there is some doubt about the
shape of the organ in the type species
communis, it is desirable that specimens
of that species be reexamined. Inasmuch
as the male of only one of the six true
species of Cylindrolaimus has been seen, it
would seem that the genus is typically
,////
206
FILTER-BED NEMAS
syngonic or digonic. Such observations as I have been able to make upon
glycerine specimens of obtusus lead me to conclude that this species at least
is probably digonic; if it is syngonic we are confronted with the phenomenon
of the ovary first acting as a testis and sending over into the rudimentary
posterior part spermatocytes, probably primary spermatocytes, there to con-
tinue their development.
9. Cylindrolaimus obtusus Cobb.
- 58?
3.5
Fig. 8 Cyl-
indrolaimus
2.6 3.3 3.5 Z.8 '
The moderately thin cuticle
is traversed by five to six hun-
dred transverse striae, which do
not appear to be further resolv-
able. In glycerine specimens
there are very faint indications
of longitudinal striations, which
are more pronounced toward the
anterior extremity; these may be
due merely to the attachments of
the somatic muscles. There ap-
pear to be no very distinct lips,
though probably minute lips are
present, so small and so closely
amalgamated as easily to escape
observation. Occasionally six
excessively minute papillae have
been seen immediately round the
mouth opening; though no doubt
always present, these papillae
usually escape observation.
When the lips are closed the
small mouth opening appears as
a simple pore in the middle of
the front of the head, where
there is an exceedingly minute
depression. Four submedian,
somewhat papilla-like, widely-
spreading cephalic setae occur
on the margin of the head about
half way between the anterior
extremity and the front of the
amphids; each of these setae is
about one-fourth as long as the corresponding diameter of the head. The
well-developed lateral fields are about one-third as wide as the body. There
do not appear to be any distinct wings.
Intestine. Ovary. The somewhat cylindroid cardia is of relatively large
size, and is separated from the oesophagus by a constriction; it is about two-
fifths as wide as the base of the neck, and is surrounded by about seven uni-
cellular organs, probably glandular in nature. There is a small posterior branch
of the sexual apparatus, extending backward a distance about equal to the length
of the body diameter, serving either as a testis or spermatheca, apparently the
former. The ellipsoidal, thin-shelled, smooth eggs are five-sixths as wide as
X675
PLECTUS CIRRATUS 207
the body, and about two to two and one-half times as long as wide. They appear
in the uterus one at a time and seem to be deposited before segmentation begins.
Habitat: Sand, Washington filter beds, early in January 1916, at the end
of about five months' use. Not common. No males seen.
PLECTUS Bastian 1865
10. Plectus cirratus, Bastian. ~iT? ?!,4 - 47? TT "iV 1 - "" Taking the de-
scriptions and figures of de Man as the basis of his identification, Maupas
made numerous and very careful observations upon this species; he never
found males, and concluded from this and his other observations that the species
is purely parthenogenetic. As my own observations do not agree with those of
Maupas, it is well to consider carefully whether the species observed by us are the
same. My specimens came from the Potomac River near Washington, D. C., U.S.A.,
and in size and proportions agree in all respects with the figures and descriptions
of de Man. The anatomy of my specimens also appears to agree in all essential
respects with that set forth by de Man. There is a little uncertainty about the
number of cephalic setae as reported by de Man; in one instance he says four,
in another six. Bastian's original description, made from specimens ^ in.
long, says four. In the description in which de Man placed the number at six
his corresponding illustrations are possibly open to the interpretation that four
only were present. The Potomac specimens always present four cephalic setae.
The caudal setae of the Potomac specimens are not so prominent as indicated in
de Man's figures. My specimens present the amphids at precisely the point
indicated by de Man, and of very nearly the same size. De Man does not give
a very clear indication of the shape of the amphids, but I see no reason to consider
the two forms specifically or varietally different on the basis of the shape and
position of the amphids. There exists, therefore, only the uncertainty with
regard to the cephalic setae, and this may not in fact be a discrepancy. Maupas
shows five eggs in each uterus. It is uncommon for the Potomac specimens to
present as many eggs as this in the uterus; the common number is one or two, but
it may rise to four. De Man describes the egg-shells as smooth ; Maupas, however,
says they are covered with minute points. The Potomac specimens agree
with Maupas' description. I am therefore most strongly inclined to believe that
the forms examined by Maupas and myself are the same.
Maupas, in his description of the development of the egg, notes the following
points: In one case only among a large number of developing ova examined
did he see more than a single nuclear figure. He considers this an important
point in his demonstration of the parthenogenetic character of the develop-
ment. He observed that when the egg entered the uterus it lost its definite
nucleus for an hour or more, and concluded that during this period the polar
bodies were formed, although, as he says, he never saw any polar bodies, but
observed amoeboid movements in the ovum during the absence of the nucleus.
Maupas says that it was with much difficulty that he convinced himself that no
spermatozoa were present in the sexual organs of this Plectus, but that in spite
of careful examination he never succeeded in seeing any. Nor did he see the
slightest trace of spermatozoa on removing the sexual organs and treating them
with acetic acid. He therefore took the species to be parthenogenetic. Never-
theless, he noted occasionally in the distal end of the uterus refractive bodies
of exceedingly small size. As will appear later, it is not at all improbable that
these minute bodies were really spermatozoa which he failed to recognize as such.
208
FILTER-BED NEMAS
xtqt
Chromosomes. Zygosis. Using the best modern instruments, under favorable
conditions, it is possible to see the spermatozoa of Plectus cirratus in living
Fig. 9. Plectus specimens of the right age and
cirratus, which
like many other
species of Plectus
is syngonic. An
egg is seen in 2nd
maturation divi-
sion, chrsm (6 + 6).
SHiut
da;
condition. The most suitable
age for such observations ap-
pears to be that at Avhich the
spermatozoa are about to enter
the uterus, the stage when the
sexual organs appear quite sim-
ple, and the uterus has the form
of a rather narrow empty tube.
On searching for spermatozoa or
spermatocytes near the large or
proximal end of the ovary it
will usually be possible to find
them without examining many
specimens. It may be necessary
to view the specimens at a par-
ticular angle, and it may require
a number of trials to secure a
favorable specimen. Fixation
with hot corrosive sublimate,
followed by an acid carmine
stain and long destaining, de-
monstrates the presence of sper-
matozoa at almost any stage
after they are formed, up to the
time when all have
been utilized. Using
such material, I have
been able to trace the
spermatozoon into the
egg, and show that the
spermatozoon displays
about six chromosomes
at a time when its two
centrosomes appear on
the side next the egg-
nucleus, which under
its influence divides,
and forms two distinct
groups of chromosomes
consisting of six each.
Indefinite bodies are
formed in the vicinity
of the egg nucleus which
appear to have the sig-
nificance of polar bodies; see Fig. 9, where one is show r n faintty at corp plr (/.!.
Syngonic. My observations leave me without the slightest doubt that this
Plectus is syngonic, and that the spermatozoa are functional. Rather casual
observations I have made on other species of Plectus prove that syngonism is
HERMAPHRODITISM IN NEMAS 209
common in this genus, and that similar spermatozoa are present in a number of
other species, but thus far I have no proof that in these other species the sperma-
tozoa are functional. These results lend additional emphasis to my suggestion,
made in previous papers, that parthenogenetic species in general be reexamined
with a view to ascertaining whether some of them do not present spermatozoa
of minute size. As in the present case, species hitherto regarded as partheno-
genetic may prove to be syngonic. Probably thousands of nemas are syngonic.
Hermaphroditism in Nemas. Dr. E. Maupas in 1900 summarized to that date
a list of 34 hermaphroditic species belonging to 12 different genera, as follows:
Rhabditis, Diplogasier, Cephalobus, Plectus, Allantonema, Bradynema, Micro-
laimus, Angiostomum, Strongyloides, Dorylaimus, Aphelenchus, and Alaimus:
four of them parasitic, the remainder free-living. These 34 species represent
varying degrees of hermaphroditism, from species with two sexes, both func-
tional, but presenting also females capable of developing their own spermatozoa,
to those in which only female forms are known, but in the gonads of which first
spermatozoa then ova are produced, the spermatozoa serving to fertilize ova
from the same gonad. Of these 34 species, over half belong to Rhabditis.
Syngonic Forms.* I have recently taken occasion to look somewhat carefully
into the embryology of a number of species, all of which prove to be syngones
or digones. These are the filter-bed species Mononchus longicaudatus Cobb,
Ironus ignavus Bastian, Ironus longicaudatus de Man, Plectus cirralus Bastian
and Tripyla monohystera de Man, all species that have been repeatedly investi-
gated by different observers in various parts of the world. To three of them
males are unknown; in the case of the fourth, Ironus ignavus, the males have been
seen but rarely. In addition I have examined an interesting new genus, Monon-
chulus, also hermaphroditic. In the course of my investigations extensive
series of individuals have been examined, in nearly every case several hundred,
all of which proved to be syngonic females (digonic in Mononchulus). As in
most of the other hermaphroditic nemas, the spermatozoa are produced in the
young gonad and are early sent forward,' often to a special receptacle, where
they await the arrival of the ova.
Potency of Syngonic Sperm. In the light of recent researches on the fertili-
zation of the ovum several interesting questions again arise in connection with
the origin, development and function of these spermatozoa produced by gones
which simultaneously or subsequently produce ova. Are these spermatozoa
functional? That is to say, do they fertilize the ova in the "regular" manner?
Do the syngonic spermatozoa enter the egg and behave in every respect like those
produced in a separate male organism, or do they behave in some other way?
To answer these questions, among other things the history of the chromosomes
throughout the ripening of both sperm and ova should be accurately known,
and then compared with the corresponding facts in typical amphigonic species.
]'(in.ishing Series of Spermatozoa. Mainly, previous researches have given
us the records of species in which the spermatozoa produced by syngonic females
were of the same size and form as those produced by the few males that a so
occurred, that is to say relatively of very considerable size. In some species the
males of which are unknown, the recorded spermatozoa, found in the female,
are relatively small and difficult ^o observe. My own researches have led me
to cases more and more difficult to decipher, owing to the smaller and smaller
size of the spermatozoa discovered, and ended in cases in which I was left com-
pletely in doubt as to the existence of spermatozoa; I could find none, but the
nature of my experience did not permit me to conclude that therefore none
For the terminology used in the following discussion, see pp. 126, 127.
210 FILTER-BED NEMAS
existed. Sometimes the spermatozoa are so small, and so difficult to observe,
even under the best of conditions and with the best instruments used by ex-
perienced observers, as to lead me to begin to question the adequacy of the evi-
dence upon which we base our belief in some cases of alleged parthenogenesis.
May it not be that sperm cells, small and difficult to observe, have escaped notice?
Potency. As to the efficacy of these small spermatozoa, in all the cases I
have observed there seems to be a fair volume of evidence that the eggs are fer-
tilized by the entrance of a body so closely resembling one of these small sperma-
tozoa as to leave either no or little doubt that, so far, the phenomena are identical
with those of bisexual fertilization. Spindles and polar bodies are formed, though
sometimes the evidence is not complete. Unfortunately, in most of the cases I
have observed, the chromosomes are so small and crowded as thus far to preclude
exact counting; I am therefore unable to say, on the basis of fully satisfactory
observations, that fertilization always takes place in the same manner as in the
case of females fertilized by copulation with males. I can only say that my
evidence, as far as it goes, points that way in a considerable number of species.
In view of the present developments this would seem to be a matter in which
it is well to keep clearly in mind that no amount of not seeing a thing proves that
it does not exist. It is no longer the case, as it formerly was, that non-existence
of males may be regarded as proof of parthenogenesis. We must prove that
there are no functional spermatozoa produced by the females themselves. Has
this always been done? I think the answer must be "No," or "Not satisfactorily."
Road to Parthenogenesis? With Maupas one may suspect syngonic nemas to
be on the road to parthenogenesis. This suspicion may be justified on the
ground that we find species producing two groups of sexual cells, one male, the
other female, variously arranged with respect to each other all the way from
amphigony to the most intimate syngony, a series at once suggesting the hypoth-
esis that bisexual nemas may be evolving along this road to parthenogenesis.
What would be the ulterior (post-parthenogenetic) steps in such an evolution?
Consider for a moment the origin of the gonic cells in a syngonic nema: At
some time in the growth of its gone all the future ova and spermatozoa exist
in the form of a single or primary gonic cell, destined to give rise both to sper-
matocytes and oocy tes. The spermatocy tes usually take the lead in development
and give rise to spermatozoa that are lodged in the uterus. In some cases almost
simultaneously, in others only a few hours later, the oocytes begin to develop,
and give rise to ova, which in turn pass onward to be fertilized by the sperma-
tozoa already produced by the same gone. Admitting the crudeness of the
questions, Is not this conceivably a wasteful method? Under the circum-
stances might it not be more "economical" to produce only one kind of cell,
each such cell to contain both male and female elements? Why separate these
complements only to bring them together again so soon? These queries are of
course merely suggestive, and are not meant to outline the whole subject.
The original gonic cell of a syngone gives rise to both spermatozoa and ova;
hence there exist in it, among other things, both male and female potentialities:
these must have some physical embodiment, of course not necessarily dis-
cernable. Should these potentialities, male and female,* be separately embodied
in the original gonic cell in numbers suitable* each to each, why might they not
there and then, in ways harmonious with those familiar in amphigony, segre-
gate their parts and regroup them, and afterward develop in the form of some
fractional number of syncysts? Is this anything more than following to what
would appear to be a logical conclusion, the tendencies apparently existing in
* "Potentialities, male and female", being, of course, merely members of a series of potentialities
subject to heredity.
CKYPTOGENESIS, PARTHENOGENESIS 211
syngonic nemas? Proof of the existence of this form of genesis, for which I have
suggested the name cryptogenesis.* will place parthenogenesis in a new light.
Evidence for or against cryptogenesis should be sought in the structure and be-
havior of the "oocytes" and "ova" of syncystic forms. From some forms of syn-
gony it would appear to be hardly more than a few steps along this road to par-
thenogenesis, itself perhaps, as it were, a waystation en route to cryptogenesis.
There have been three main theories of natural parthenogenesis:
1. Owen's, that not all the germinal matter is necessary for the production
of the new organism, and that after the new organism has matured, a left over por-
tion of the germinal matter within it proceeds to develop new organisms.
2. Huxley's, that the parthenogenetic "egg" is not in reality an ovum, and
that its development is comparable to the growth of an organism from a bud.
3. Hertwig's, that parthenogenesis is a degenerate fertilization.
Parthenogenesis as commonly understood may be said to be of three kinds:
a, The resultant generation is all female (homocystic). b, The resultant genera-
tion is all male (homocystic). c, The resultant generation is heterocystic. Fur-
thermore it may be divided into three cases:
1. The parthenogenetic generation alternates strictly with a bisexual one.
2. Several parthenogenetic generations occur between the bisexual ones.
3. Pure syncysty; i.e., no reproduction other than parthenogenesis is known.
A common supposition is that the parthenogenetic gamete is an ovum or
macrogamete pure and simple. It seems more difficult to explain the three kinds
of parthenogenesis on the supposition that the gamete of the parthenogenetic
organism is essentially or only an ovum or macrogamete, than on the supposition
that this gamete is syncystic ; for this latter supposition makes it easy to imagine
the different results of natural parthenogenesis to arise by processes similar to
those already familiar in heterocysty.
Cryptogenetically considered even parthenogenesis may be conceived of as a
concealed, (often perhaps unseeable or at least hitherto unseen) but more or
less "normal" genesis.
A strict construction of the phase of cryptogenesis discussed rests on the
supposition that what we have been calling parthenogenesis is one phenomenon,
and not a collection of more or less related phenomena. My own present view
is that this latter clause probably comes nearer the truth, and that partheno-
genesis as we have broadly understood it may possibly cover cases in accord
with most of the theories that have been proposed.**
Cryptogenesis may not exhibit all the phases investigation has disclosed in
heterocysty; the suggestion is rather not only that all the results accomplished or
supposed to be accomplished in natural parthenogenesis may be explicable along
the lines of ordinary fertilization, but that parthenogenesis, and cryptogenesis
if it exist, is not so much a distinct method of generation, or even a degenerate
fertilization, as an evolved amphigony.
There is a certain amount of evidence often interpreted as showing that
fertilization cannot be superimposed on parthenogenesis, e.g., parthenogenetic
eggs may "resist" sperm of the same species. In normal fertilization once an egg
entered by a spermatozoon it thereafter "resists" the entrance of other sper-
matozoa. If what we have been calling parthenogenesis is, in any given case,
in reality cryptogenesis, then the parthenogenetic eggs may be regarded as
* This conception differs from earlier ones in its space-and time-limits, (time, antecedent; space
the confines of ancestral gonic colls), and in that its methods and mechanism are extended to possibly
include all the phases known for, or postulated of, the forms of genesis from wnich it is supposed to ho
evolved.
** Here we seem unconsciously dominated by our terminology, some of which is outgrown and, as ap-
plied, even misleading. The facts and ideas need critical analysis, as well as the benefit of an adequate
terminology, as Sir E. Ray Lankester has just indicated in the August number of "Nature" (1917).
212
FIETER-BED NEMAS
already having the substances or factors imparted by the spermatozoon,
or their equivalent, and we might therefore expect such eggs to be, as they are,
"resistant" to sperm. Whether or not this suggestion has a basis of fact, the
theory of cryptogenesis harmonizes with what is known about the incompat-
ibility of parthenogenesis and fertilization. Of course ova may be too young
to be fertilized, or too old to be fertilized, and their parts may be so acted upon
by a variety of forces as to bring them into a more responsive or less respon-
sive condition; needless to say, these various facts must also be taken carefully
into account in any such speculation as the foregoing.
Abbreviations Used in the Illustrations
Amp, ampulla
amp sal dct, ampulla of
~fng, ingested material
- 1 - ing nematod, ingested noma-
ov dct, oviduct
ov frt, fertilized egg
salivary duct
tode
ov im, immature egg
amp subm, submedian ampulla
int, intestine
ovr rud, rudimentary ovary
amp vnt, ventral ampulla
int cryst, intestinal crystal
ov ut, uterine egg
ompA, amphid
int lum, intestinal lumen
an, anus
an gl, anal gland
apic, apiculum
Tnc. junction
ID spn, mouth of spinneret
-*- par, parasite
ph, pharynx
ar dnt, rasp
ar la!, lateral field
ar vnt, ventral field
Lam Ib, labial lamina
Ib, lips
H> ppl, labial papilla
ph str, pharyngeal striae
por or p, pore
por gl oe, pore of oeso;>hasoal
gland
Bos ph, base of pharynx
W6 crd, cardiac bulb
lum int, intestinal lumen
1 urn oe, oesophageal lumen
lum som, body cavity
por sal, mouth of the salivary
gland
por sal dsl, mouth of dorsal sal-
Cav som, body cavity
chrsm, chromosome
cl ar lot, cell o f the lateral field
rl crd. cell of cardia
cl int, intestinal cell
cl lot, lateral coll
cl msc, muscle cell
TVTrt, mitosis figure
- LVJ - msc an, anal muscle
msc oe, oesophagus muscle
msc ph, pharyngeal muscle
msc som, body muscle
msc valv, valve muscle
msc tlv. vulva muscle
ppl, papilla
ppl cdl, caudal papilla
ppl cph, cephalic papilla
ppl intr, interior panilla
ppl lat, lateral paoilla
ppl Ib, labial papilla
ppl Ib extr, exterior labia! pa-
cl nrv. nerve cell
mur int, intestinal wall
pilla
cl nrv an, anal nerve-cell
cl nrv cdl, caudal nerve-cell
cl nn crd, cardiac nerve-cell
mur ph, pharyngeal wall
mur ut, wall of uterus
ppl subm. submedian papilla
ppl subm sec, secondary subme-
cl nrv dsl, dorsal nerve-cell
d nrv lot, lateral nerve-cell
cl nrv subm., submedian nerve-
cell
cl nrv vnt, ventral nerve-cell
"M"ci, nucleus
A1 ncl ar lot, nucleus of lat-
eral field
ncl cl int, nucleus of intestinal
cell
ppl trm, terminal papilla
"D cpt sem, seminal receptacle
** ret, rectum
reg vnt, ventral field
cntr, centrosome
corp pol I, 1st polar body
cpA ppZ, cephalic papilla
cph set, cephalic seta
nd cl nrv, nucleus of nerve cell
ncl gl cdl, nucleus of a caudal
gland
ncl lot, lateral nucleus
ren, renette
rot, rotifer
rot ing, ingested rotifer
crd, cardia
cst ph, pharyngeal rib
ncl msc, nucleus of muscle
ncl nrv, nerve nucleus
CJa?, salivary gland
sal dct, salivary gland duct
cut, cuticle
nd oe, oesophageal nucleus
ncl ov, nucleus of egg
sal dsl, dorsal salivary gland
sal gl dsl, dorsal salivary gland
TV', duct
ncl ov im, nucleus of ovum
sal subm, submedian salivary
*-> dct gl cdl, duct of caudal
ncl ren, renette nucleus
gland
gland
ncl ut, nucleus of an uterine cell
sec, secretion
dct ren, renette duct
ncl vlv. nerve nucleus of valve
sec cdl, caudal secretion
dct sal dsl, dorsal salivary duct
div red, reduction division
nd vnt, nucleus of the ventral
field
set, seta
set cph, cephalic seta
dnt. denticles
nr, nerve
set sub-cph, subcephalic seta
nrv, nerve
sp, spiculum
Ex p, excretory pore
nrv af, afferent nerve
spm, spermatozoa
nrv r, nerve ring
spn, spinneret
nrv vnt, ventral nerve
spndl, spindle
~C*lx ov, flexure of ovary
* flx ovr post, flexure of pos-
terior ovary
r\e, oesophagus
J oes lum, oesphageal lumen
spthc, sperm atheca
str mur ph, striae of pharyngeal
wall
on t onchus
subcut, subcuticle
n.1, gland
on dsl, dorsal tooth
siit Ib. labial suture
^ gl an, ana! gland
on rtr dsl, retrorse dorsal onchus
gl cdl, caudal gland
on rtr subm, retrorse submedian
Trm, terminus
gl cdl subm, submediau caudal
tooth
trm ov, terminus of ovary
gland
on submd xt, right submedian
trm ovr, blind end of ovary
gl oe, oesophageal gland
tooth
gl sal, salivary gland
gng, ganglion
on subm snst, left submedian
tooth
TTf, uterus
grn, granule
oocyt, oocyte
grn int, intestinal granule
orgf, organ of unknown signifi-
\Tag, vagina
grn int maj, larger intestinal
cance
vag msc, vaginal muscle
granule
org elast, elastic organ
valv, valve
grn int min, smaller intestinal
org int, intestinal organ
vlv, vulva, valve
granule
ov, ovum
tstbl vag, vestibule of vagina
THE ORDERS AND CLASSES OF NEMAS* ,
CONTRIBUTIONS TO A SCIENCE OF NEMATOLOGY, VIII
BY N. A. COBB
Our first adequate conception of the nema phylum will come from
a study of the free-living forms, for in parasitic nemas it frequently
happens that the structure of important organs, especially those of the
mouth and alimentary canal, is greatly simplified through degenera-
tion. This degeneration proves to be relatively as marked among the
parasitic nemas as it is among parasitic species in other phyla con-
taining both free-living and parasitic forms, so that from the standpoint
of comparative morphology, they are often very highly perplexing.
On the other hand, it is already possible, through comparative study
of the known free-living genera, to begin formulating some of the prin-
cipal features of the orders and classes of nemas and to do it with suffi-
cient truth and clarity to make the results useful to investigators,
teachers and students.
The following table outlines a classification of the phylum, based
on a study of several hundred genera. It is a comprehensive classi-
fication I have long employed, that has proved useful in many ways.
It sets forth relationships based on and correlated with the mouth-
parts. In most animal phyla where there is a distinct mouth, oesoph-
agus and stomach, experience has amply proved the utility of these
portions of the anatomy as a guide to phylogenetic relationships.
While some parts of the following scheme appear to outline clearly and
permanently certain fundamental truths, other parts undoubtedly will
have to be expanded or altered,f since our knowledge of details is still
inadequate to a clear view of all the larger relationships.
In the table, the order columns are staggered, in an attempt to
indicate relative importance, the farther to the left the words, the
more comprehensive or significant is the meaning to be attached to
the corresponding order name.
* Waverly Press, July 19, 1919.
t Perhaps it may not be going too far to suggest that, in any such expansion and alteration, the aim
be, among other things, to make the terminology of the phylum both euphonious and characteristic.
Too few appear to realize how important it is that such a terminology be (1) As descriptive and as nearly
self-explanatory as possible. (2) Few, short and consistent in its roots. (3) Simple and brief in its
terms. (4) Characteristic and euphonious. (5) Such as lends itself readily to modern inflections and
derivations.
213
214
OEDERS AND CLASSES OF NEMAS
Phylum NE MATES
(Nematoidea sensu restricto)
Subphylum ALAIMIA*
Class Alaimia
Subclass Manitinia
1. Order
Subclass Kinetinia
2. Order
Subphylum LAIMIA
Class Anonchia
Subclass Anodontia
3. Order
4. Order
5. Order. . . .
Subclass Odontia
6. Order
7. Order
Class Onchia
Subclass Homonchia
8. Order
9. Order
10, Order
11. Order
Subclass Heteronchia
19. Order
13. Order...
Anglicised
Litini a Litinian forms ; the Litinia
Bolbinia Bolbinian forms; the Bolbinia
Cytolaimia Cytolaimian forms; the Cytolaims
Isolaimia Isolaimian forms; the Isolaims
Polylaimia Polylaimian forms ; the Polylaims
. . Apodonlia Apodontian forms; the Apodonts
. . Synodontia Synodontian forms ; the Synodonts
Synonchia Synonchian forms; the Synonchs
Mesonchia Mesonchian forms; the Mesonchs
Aponchia Aponchian forms; the Aponchs
Triplonchia Triplonchian forms; the Triplonchs
Axonchia Axonchian forms; the Axonchs
Anaxonchia Anaxonchian forms; the Anaxonchs
*The names are the plurals of latinised Greek diminutives of the words, 'to,
\aifji6o-, 'byx<r> with descriptive prefixes.
ALAIMIA
Nemas without distinct pharynx
Nemas devoid of pharynx may be conceived to be so either because
they have never developed a pharynx or have evolved ("deteriorated")
from forms having a pharynx. In the latter case, the group ALAIMIA
may contain obscured equivalents of the subdivisions of the LAIMIA,
the nemas with pharynx. It may therefore be possible to subdivide
the ALAIMIA more fully after these forms, many of which are para-
sitic, have been further considered in their broad relationships. In
this article only two subdivisions are suggested, of more or less super-
ordinal rank, the Litinia, having a simple oesophagus without bulb or
swelling, and the Bolbinia, having an oesophagus with a posterior or
median swelling, or both.
ORDERS AND CLASSES OF NEMAS 215
LAIMIA
Nemas having a more or less distinct pharynx
A distinction is here made among the mouth-parts of nemas, based
on their origin, location and method of use. Sometimes these organs
are labial, and sometimes they arise from elements deeper in the pharynx
and more closely associated with the oesophagus proper. When aris-
ing by modification of the labial region they are here termed odontia,
singular odontium. The odontia are usually of smaller size than the
second class of mouth-parts that arise from elements farther back and
more closely associated with the oesophagus proper, and called onchs
or onchia, singular onchium. The odontia are seldom less than
three in number, and may constitute a labial circlet of a dozen or more
elements. The onchia are almost never more than three in number,
and even then often only one of them is well developed.
According as they are characterized by the absence or presence of
onchia, LAIMIA may be divided into two classes, the Anonchia and
the Onchia. The Anonchia may in turn be divided into the subclasses
Anodontia and Odontia, according as they lack or possess odontia.
There are three anodontian orders, Cytolaimia, Isolaimia and Poly-
laimia; and two odontian orders, Apodontia and Synodontia. Of these
five orders, the first three are characterized by the pharynx being
wholly unarmed, the pharynx of the cytolaims being a plain conoid,
subspheroidal, or somewhat irregular cavity, the pharynx of the isolaims
being mainly cylindroid or prismoid, i.e., parallel-sided, and the pharynx
of the polylaims being more complex and composed of two or three
successive chambers more or less distinctly separated from each other;
while the latter two orders have a pharynx armed with odontia, the
odontia of the Apodontia having an outward stroke, while those of the
Synodontia have an inward stroke.
The second class of the LAIMIA, the Onchia, is characterized by a
pharynx armed with onchia or with a spear composed of amalgamated
onchia, and is divided into two subclasses, the Homonchia and the
Heteronchia, differentiated from each other by the fact that in the
homonchs the onchia are similar to each other and symmetrically
arranged and nearly always three in number, while the heteronchs are
characterized by asymmetrical onchia, the number of which may be
reduced to one. There are four orders of homonchs and two of heter-
onchs. The four homonchian orders are the Synonchia, in which the
onchia, nearly always three in number and of equal size, have an in-
ward stroke; the Mesonchia, composed of forms intermediate between
216 ORDERS AND CLASSES OF NEMAS
the aponchs and the synonchs, and having three usually equal onchia,
movable in a direction parallel to the body axis; the Aponchia, in which
the onchia, separate and nearly always three or six in number, have an
outward stroke; and the Triplonchia, having a spear composed of three
more or less equal, slender onchial elements which have become amal-
gamated. The heteronchian orders are, Axonchia, having a single
axial onchium or spear, and the Anaxonchia, in which the main onchium
is not axial and may or may not be accompanied by one or two others,
usually of smaller size.
Onchia and odontia seem more or less mutually exclusive, but the
presence of one does not necessarily exclude the presence of the other.
When both are present, experience appears to indicate clearly that the
onchia are the more advantageously used as a guide to broad relation-
ships.
In a later publication the proposed orders will be further denned by
describing new type genera. In the meantime, the following table
gives a tentative assignment of a few known genera, for explanatory
purposes only. Reference to families composing the orders is omitted,
because it appears to me after studying a very large number of unde-
scribed species in addition to those described, that a number of the
families that have from tune to time been proposed may have to be
recast.
Order Genus Order . , Genus
LITINIA Bastiana SYNONCHIA Enoplus
BOLBINIA , Laxus MESONCHIA Fimbrilla (?)
CYTOLAIMIA. .. Monhystera APONCHIA Chromadorella
ISOLAIMIA Rhabdolaimus TRIPLONCHIA Tylenchus
POLYLAIMIA.. . Bathylaimus, Plectus AXONCHIA Dorylaimus
APODONTIA.. . . Axonolaimus ANAXONCHIA Oncholaimus
SYNODONTIA.. Teratocephalus
The above linear tabular arrangements of the orders do not bring
out fully the natural relationships of the different groups. These
relationships will be discussed more fully later.
While the nomenclature here proposed is dominated by a few linguis-
tic roots, it of course by no means follows that in assigning genera to
the orders designated, due attention should not be given to other por-
tions of the anatomy than those indicated by the nomenclature. This
is a commonplace of taxonomy. The relationships of an organism are
fully disclosed only on consideration of all its parts, and undue weight
given to a particular feature will here, as elsewhere, result in confusion.
ONE HUNDRED NEW NEMAS
(Type Species of 100 New Genera)
CONTRIBUTIONS TO A SCIENCE OF NEMATOLOGY, IX
BY N. A. COBB
The arrangement of the genera in the following pages will serve,
to a considerable extent, to define and illustrate the orders proposed
on page 214. This is especially true of all except the Litinia, Bol-
binia, Mesonchs and Aponchs. In each order, a genus has been
selected and given a name philologically connected with that of the
order, in fact, the singular of the order name, and, in most cases,
these genera may be considered as genera typical of the orders, for
instance, Axonchium may be taken as typical of the order Axonchia.
So far as it is found advisable to accept the classification proposed, it
might be well to keep in mind in the establishment of the many new
genera which the future will undoubtedly disclose, the application of
similar names to those genera which most nearly represent the average
structure of the order. In carrying out this idea, such names as Cyto-
laimella, Isolaimella, and other derivatives at once suggest themselves.
It is already becoming evident that some of these groups may prob-
ably early be advantageously subdivided; e.g., Cytolaimia, Anaxonchia.
In case of subdivision, the principles alluded to in the footnote to page
213 might lead to some such action as the following: Amending the
definition of the existing order and segregating the new order, and util-
izing for the new order-name the roots already suggested (see p. 214,
lines 27-28) together with appropriate prefixes. This would result in
building up a comparatively simple, rather homogenous and character-
istic nomenclature for the nema phylum.
In each order the genera are arranged somewhat in accordance with
their relationships. Genera of doubtful relationship are usually placed
near the beginning or near the end of the order series, and not infre-
quently appear, in the light of our present knowledge, to be intermedi-
ate, or indeterminate, forms. "Thus, Rhadinema flexile at the beginning
of the Isolaimia, p. 256, is doubtfully placed, and may be a cytolaim;
so Nannolaimus, p. 255, may perhaps be a litinian form. Most of the
order series present these special cases.
217
WAVEHLY PRESS, BALTIMORE, Nov. 1, 1920.
218 KEY AND CHARACTERS
PHARYNX ABSENT, or so obscure as easily to escape notice* New Genera
Oesophagus with median or posterior bulb or swelling, or both
Amphids none, so far as known; or difficult to see and therefore easily overlooked
Lateral wings to cuticle present; naked; striae fine; spinneret none; pharynx obscure
Mouth depr.; faint apophyses in pharyngeal bulb; -f-; excretory pore behind neck.Hyalaimus 13
Mouth not depr.; pharynx obscure, not apophysate; oesophagus faintly cephaloboid
Head with papillae, minute lat. markings (amphids?) ; exert, pore front of nerve ring . Litonema 12
Head without papillae or lateral markings; excretory pore behind the nerve ring Choronema 14
Lateral wings to the cuticle none
Spinneret abs.; naked; oesoph. faintly cephaloboid; striae very fine; faint wings . . (Choronema') 14
Spinneret present; cephalic setae present
Amphids invisible, known only as outlets of secretion; striae coarse; setae long. (Leptoncmella) 21
Amphids tiny, tubular, labial, forward-pointing, easily overlooked; striae plain
Striae fine; male postanal tubular organs submedian ; pharyngeal swelling present. (Catanema) 56
Striae coarse; pharyngeal swelling none; cephalic setae 4 or more; head nonstriate
Mouth cavity present, very small; males without supp. organs; nema 10mm. ..(Laxonema}
Mouth cavity none ; vent, row acornshaped organs toward head ; setae numerous . (Stilbonema)
Amphids present
Form of the amphids more 9r less irregular, symmetrical to at least one line
The amphids linear ; cephalic setae 12 + 6 small ; striae coarse ; spinneret present . (Leptonemella) 21
The amphids not linear; no spinneret; naked; labial region with papillae only
Winged ; ' f ; striae rather coarse ; amphids semi-ellipses ; oesoph . faintly cephaloboid . lotalaimus 15
Wings none; striae very fine; amphids with large internal connections Bolbinium 16
Form of the amphids spiral, circular, or elliptical ; spinneret present
Shape of the amphids distinctly spiral; striae fine, resolvable
Pharynx devoid of teeth; head expanded; cephalic setae 4; body setose Bplbonema 49
Pharynx with 3 minute teeth; setae in longitudinal rows (Alaimonema) 107
Shape of the amphids circular; sometimes small, well forward on the head, and obscure
Lateral wings present; cephalic setae 4; amphids large
Striae coarse, altered on the lateral fields; lateral wing distinct Antomicron 17
Striae fine, not altered on the lateral fields; lateral wing faint Cyartonema 18
Lateral wings none or faint
External amphid circular, at least apparently, well developed; head set off
Body setose ; amphids really spiral, on the head ; striae rather fine, resolvable (Bolbonema) 49
Body naked; amphid circular
Position of amphid, on head; striae fine; contour not crenate; wings faint (Cyartonema) 18
Position of amphid, behind head; striae coarse; contour crenate Cincionema 22
External amphid minute, on the front of the head, tubular, easily overlooked; neck 2-5%
Striae fine; male postanal tubular organs submedian; rjharyn. swelling present. . (Catanema) 56
Striae coarse, plain; cephalic setae 4 or more; head without striae
Mouth cavity very small; nema 10mm; males without supplementary organs. . (Laxonema) 20
Mouth cavity none; cephalic setae in 3 or more circlets; males without caudal supplements
Supplementary organs of acorn shape, found in a ventral row near the head. . (Stilbonema) 1
Supplementary organs none, but with special pre- and postanal submed. setae . (Stilbonema) 19
Oesophagus plain, i.e. without median or posterior bulb or swelling of palpable size
Amphids none so far as known, or difficult to see and easily overlooked
Wings 10-42; spinneret present; f=; striae fine, plain; ceph. setae 6, subceph. 4 Porocoma 11
Wings 2, if any, lateral only, in any case faint
Spinneret abs.; oesoph. faintly cephaloboid; striae very fine; no setae; faint wings. .(Choronema) 14
Spinneret present; amphids minute if any, unclosed
Female organ single, -f ; 6 cephalic papillae only; spinneret doubtful; nema 0.28 mm. .Litotes
Female organs double, 'f; striae fine, plain; cephalic setae 4; 2 huge somatic glands. . (lonema) 9
Amphids present
Form of the amphids more or less irregular, often symmetrical to at least one line
Contour of the amphids linear, i.e. long and narrow
Lateral wings none ; cephalic setae 6, subcephalic 4 ; ' f Tycnodora 3
Lateral wings present; head naked or its setae irregular; spinneret present
Wings prominent; striae coarse; ' f ; inconspicuous pharynx (?) (Actinonema) 117
Wings faint; striae fine; -f-; mouth oblique Campylaimus 5
Contour of the amphids not linear
Striae interrupted on the lateral fields by wings, plain
Spinneret absent; oeosphagus faintly cephaloboid; 'f (lotalaimus) 15
Spinneret present; oesophagus narrow, one to two-fifths as wide as neck
Anterior extremity mitriform, very distinctly set off; wings to the cuticle 6-8 Xennella
Ant. extremity not mitriform; coarse c'uticular elements in rows like tiles; ' f ' . . (Ceramonema) 48
Striae uninterrupted, fine, plain; spinneret present; slender nemas, up to 1.2%
Head without setae; amphids relatively large and deep; not ocellate Schistodera 4
Head with 4 cephalic setae; amphids small with obvious internal elements; ocellate . Nemella 10
Form of the amphids spiral, circular, or elliptical (doubtful in Litotes)
Shape of the amphids spiral; striae resolvable, not altered on the lateral fields
Spinneret absent; striae coarse; probably f (?); contour crenate (Alaimella) 7
Spinneret present; striae rather coarse; amphids large
Head expanded; lip-region elevated, not papillate; ceph. setae 6 plus 10; 'f'.. . (Nannolaimus) 36
Head not expanded; lips 6, papillate; cephalic setae 4; f (?) Alaimella 7
Shape of the amphids circular or elliptical; spinneret present except perhaps in Litotes
Lateral wings perhaps pres.; f ; striae plain; lipless; pharynx very minute, conoid. . Nemanema 2
Lateral wings none (or very faint); head rounded; striae none, or very fine
Cephalic setae ten or more, in two circlets
Contour of amphids unclosed behind; setae 12, 4 subcephalic; mouth a mere pore . TMinium f 8
Contour of amphids closed; setae 10, no subcephalic ; pharynx minute, conoid. (Linhomoella) 35
Cephalic setae none, or small (4 or 6)
Setae 4, small; ocellate; amphids small, labial, unclosed; body contains huge glands. lonema 9
Setae none; nemas of very simple structure; wings none or doubtful
Papillae representing 6 setae; amphid (?) minute; -f ; nema 0.28 mm; width 5%. .Litotes 1
Papillae none ; amphids fairly developed, closed ; f ' ; nema 2.5mm; width 1 .4% . (Nemanema) 2
*For abbreviations used in the Key, see foot-note p. 223.
KEY AND CHARACTERS 219
PHARYNX PRESENT New Genera
Wall of the pharynx unarmed (for alternative see page 221, midway)
Cavity of the pharynx conoid, or irregular
Oeosphagus with median or posterior swelling or both
Amphids none, or obscure; striae plain, not altered on the lateral fields
Spinneret none ; head subtruncate, naked ; contour almost imperceptibly crenate . Cephalobellus 23
Spinneret present
Striae coarse; pharynx minute (none?) without swelling; head non-striated. . . . (Leptonemella) 21
Striae fine; pharynx narrow, enclosed in a swelling; amphids minute labial tubes . (Catanema) 56
Amphids present
The amphids linear; pharynx (?) ; striae coarse, plain; no wings; setae, 3 circlets . . Leptonemella 21
The amphids spiral, circular, or elliptical; when tubular, surface contour circular
Form of the amphids a distinct spiral; spinneret present
Striae coarse; oesophagus =*= oxyuroid; wings 8; cephalic setae 6, subcephalic 4. . ..Dasynema 34
Striae fine, plain
Lateral wings only on tail of male; ' f ; pharynx somewhat zigzag; setae minute. . (Zalonema) 7
Lateral wings absent
Head with numerous scattered setae ; pharynx small, narrow ; onchi vestigial . (Alaimonema) 107
Head not with numerous setae; pharynx fairly well developed; teeth unobvious; 'f
Cheeks thickly outinized ; cuticle thick Zalonema 57
Cheeks, if thick, not heavily cutinized ; lips 2, large, lateral Pseudonchus 58
Form of the amphids a circle or ellipse; striae unaltered laterally
Spinneret absent; striae fine
Intestinal cells with crystals; 6 lips, appendiculate; -f ; cephalic setae 10. ... (Crystallonema) 67
Intestinal cells not with crystals; lips none; -f-; cephalic setae papilloid Anlicyathus 24
Spinneret present
Head swollen, unstriated; no pharyngeal swelling; striae coarse, plain
Cephalic setae 4; lips none; no labial papillae; amphids a single circle (Cinctonema) 22
Cephalic setae none; lips 6, unipapillate; amphids two concentric circles. . . .Micromicron 104
Head not swollen or set off; pharyngeal swelling anon present; striae fine, plain
Pharynx narrow; amphids minute; male postanal organs tubular; setae 4 + 6. (Calanema) 56
Pharynx capacious; amphids well developed, opposite the pharynx or behind it
Lips 2, lateral; pharyngeal ridges simulate teeth; 'f ; cephalic setae 4 (Pseudonchus) 58
Lips 6, each with a digitate appendage; cephalic setae 10 (Crystallonema) 67
Oesophagus plain, i.e. without median or posterior bulb or swelling
Amphids irregular
Spinneret none; striae unaltered laterally; -f-; spiral amphid placed on a deltoid p&rt.Didelta 33
Spinneret present
Striae altered laterally ; ' f ' ; head naked, set off; cuticle thick ; pharynx armed (?) .(Actinonema) 117
Striae not altered on the lateral fields
Cephalic setae 12 + 6, in two circlets; -f ; amphid inconspicuous Leplogastrclla 28
Cephalic setae 6, in one circlet; amphid 1 the width of the head; spinneret (?) . .Rhabdocoma 32
Amphids spiral, circular, or elliptical
The amphids in the form of a spiral; striae not altered on the lateral fields
Spinneret none (?) ; amphid J the width of the head; naked; wings two Neurella 25
Spinneret present
Buccal cavity with cutinous frame, and 3 apophyses with small apical teeth. . (Trogolaimus) 75
Buccal cavity without distinct framework and without teeth of any kind; striae fine
Ovaries 'f; striae resolvable; amphid of 4 winds; cephalic setae 6 + 10 Nannolaimus 36
Ovaries -f-; striae plain; amphids simulating a circle
Mouth cavity large and obvious; cephalic setae unknown, in any case few Margonema 27
Mouth cavity small; head rounded; cephalic setae large, 4 (special) plus 6. . . .Linhomoella 35
The amphids in the form of circles or ellipses
Striae altered on the lateral fields by wings: spinneret present
Head set off by a groove, its appendages varied ; striae coarse ; wings numerous . . Xenolaimus 30
Head not strongly set off, though usually well developed
Ovaries reflexed, f ; naked; striae fine, plain; pharynx small, obsolescent. . . . (Nemanema) 2
Ovaries outstretched; pharynx well developed, but not large; cephalic setae present
Striae fine, plain; cephalic setae 6, segmented; -f- (Cytolaimium) 31
Cuticle rough from subdivided wings; setae many; lips 3, mandibulate (?).... (Xyala) 72
Cuticle normal; lips 6, papillate, appearing somewhat fimbriate; striae plain . Daptonema 66
Striae not altered on the lateral fields
Spinneret absent; striae fine, plain; female organs outstretched, except Rhabdocoma
Ovaries two, -f-
Cephalic setae 6, plainly segmented; lips three, papillate Cytolaimmm 3
Cephalic setae 4, not segmented; lip-region punctate, amalgamated Didelta 33
Ovary one, subcephalic setae 4
Cephalic setae 6: f ' ; lips 3, flattish, not digitate Rhabdocoma 32
Cephalic setae 10; -f ; lips 6, small, digitate
Cells of intestine with crystals; amphids not raised; excretory pore labial Crystallonema 67
Cells of intestine without crystals; amphids raised; tail with spicate setae Zanema 68
Spinneret present
Pharynx obscure
Lips in two sets, outer large, low; inner soft extensions of the oesophagus. .JygonemeUa W
Lips not in 2 sets, amalgamated; ceph. setae 4, 3-jointed; phar. prismoid cup.(Rhadinema) tf
Pharynx more or less obvious; striae plain
Female organs reflexed, f; striae fine; head naked; pharynx small (Memanema)
Female organs outstretched
Mouth cavity small, inconspicuous; cephalic setae 4 (special) plus 6 . . . (Linhomoella) 35
Mouth cavity moderate , in a swelling ; ceph . setae 6 , plainly segmented ; -f- . Cytolaimium 31
Ovary one, -f; striae coarse; setae 12; lips 6, striate
Lips conoid, striated, large, tipped with setae, and with a seta near base. Dactylaimus /
Lips flat, papillate, appearing fimbriate, three-ribbed (Daptonema) 66
Cavity of the pharynx more or less prismoid or cylindroid (not conoid or very irregular)
220 KEY A.ND CHARACTEES
Oesophagus with median or posterior bulb or swelling, or both
Amphids none so far as known, or diflicult to see and easily overlooked
Lateral wings present; spinneret absent
Striae none; wings 2; naked; pharynx like oesophagus lumen (Litonema) 12
Striae fine; wing 1; seta-like papillae 6; pharynx contains glottoid organ Cephalobium 54
Lateral wings absent; striae plain
Spinneret present
Striae very coarse; phar. cupshaped; nema 10mm; male, no supplement, organs. (Laxone.ma) 20
Striae fine; phar. small, enclosed in bulb; male postanal tub. organs submedian. . (Catanema) 56
Spinneret absent; setae none
Phar. very long, nar., ending in cylindroid bulb; 'f'; nema 1mm; lips conoid Myctolaimus 61
Pharynx very short; cardiac bulb oblate or spherical; f"
jNema 3.3mm; width 9%; pharyngeal apophyses present; oesophagus clavate .Blattophila 55
Nema 6mm; width 3%; pharyngeal apophyses absent; oesophagus cylindrical. Protrellus 38
Amphids present.
The amphids are somewhat irregular, symmetrical to one line; striae fine, plain; wingless
Form of amphids not lin.; no spinneret; naked; lips 6; phar. tub.; amphids large. Colpurella 39
Form of amphids linear
Ovary one, 'f ; spinneret absent; cephalic setae 6 plus 4; pharynx tubular. . . . (Myolaimus) 60
Ovaries two, -f-; spinneret present; ceph. setae 4; ventral (?) onchus near mouth. Pseudolella 53
The amphids are spiral, circular, or elliptical
Shape of the amphids a distinct spiral
Striae coarse; oesoph.=toxyuroid; wings 8; ceph. setae 6, subceph. 4; head unstr. . (Dasynema) 34
Striae fine
Lateral wings present; striae plain; spinneret present; head thick-walled. . . .Pycnolaimus 40
Lateral wings absent
Spinneret none; -f-; cephalic setae 10, subcephalic 4; pharynx obscure Laimella 44
Spinneret present
Phar. armed in front with 3 obscure equal teeth; setae numerous on head. . (Alaimonema) 107
Pharynx without teeth ; head rounded
Lips 2, lateral; 'f; striae plain; pharyngeal ridges simulating teeth (Pseudonchus) 58
Lips none, or very indistinct
Cephalic setae 10. subcephalic 4; pharynx obscure, has minute onchus Laimtlla 44
Ceph. setae four ? (or none); lips set off; phar. 2-chamb., 2d tapering (Polylaimium) 59
Shape of the amphid circular or elliptical (anon tubular) ; striae unaltered laterally
Spinneret absent; striae plain, fine
Ovary one, -f ; ceph. setae 10, subceph. 6; amphids circular; pharynx broad. (Crystallonema) 67
Ovaries two
Cuticle naked; spear (?) minute; ceph. setae 0, 6 pap.; amphids ellip.; T. . (Tripltmchium) 80
Cuticle not naked; without spear; ceph. setae present; amphids circular; -f-. Anticyathux 24
Spinneret present
Buccal cavity very small and easily overlooked; cephalic setae present; striae plain
Striae coarse; phar. minute, cupshaped; males without supplementary organs , Laxonema 20
Striae fine; phar. narrow, bulbed; males with postanal rows of tubular organs. Catanem a 56
Buccal cavity very long; 'f; striae fine; cephalic setae small or none
Cephalic setae four (?) or none ; amphids large, deep ; pharynx 2-chambered. . . Polylaimium 59
Cephalic setae 10, short; amphids small; ocellate; pharynx very long (Catalaimus) 89
Oesophagus plain, i.e. without median or posterior bulb or swelling
Amphids none so far as known, or difficult to see and easily overlooked
Wings present; spinneret present; striae fine; ovaries two, f=; phar. vestigial. .(Porocoma) 11
Wings absent; striae fine
Ceph. setae 10, long, segmented; lips 6, thin, each with seta; amphid minute slit. . (Trilepta) 92
Cephalic setae none, or not long or obviously segmented; lips without setae, or lipless
Buccal cavity tubular; spinneret absent; 'f; lipless; papillae depressed. ... (Isolaimium) 41
Buccal cavity not long and tubular; spinneret present
Ceph. setae 10; lips 6, obvious; dorsal phar. element bent in at lips; 'f (?) . . (Asymmetrella) 70
Cephalic setae 6, papilloid; lipless; -f (Litotes) 1
Amphids present
Structure of the amphids more or less irregular, usually symmetrical to at least one line
Contour of the amphids linear; striae not altered on the lateral fields
Ceph. setae long, segmented; lips 6, thin, each with seta; amphid minute slit. .(Trilepta) 92
Cephalic setae none, or not long and not obviously segmented
Spinneret absent; 'f; striae fine; phar. tub.; lips confluent; papillae depressed. .Isolaimium 41
Spinneret present; female sexual organs double; striae fine
BUG. cavity tub.; amphids long; striae resolve; onchus ventral (?), obscure. . (Pseudolella) 53
Buccal cavity not tubular; amphids more or less stirrup form; striae not resolvable
Ocellate; cephalic setae none; lips faint; amphids distinct, though small (lllium) 45
Ocelli 0; setae 10; cutinized dorsal pharyn. element bent inward at lips. . (Asymmetrella) 70
Contour of the amphids not linear
Striae altered on the lateral fields; ovaries two, reflexed; spinneret present
Lateral wings present; striae coarse, like rows of tiles; pharynx narrow Ceramonema 48
Lateral wings none; striae fine, plain; onchia vestigial; six cervical glands. (Anoncholaimus) 93
Striae not altered on the lateral fields, fine
Spinneret none
Cephalic setae 4, forward-pointing; amphids more or less deltoid (Didelta) 33
Cephalic setae 0; amphids more or less reniform Colpurella 39
Spinneret present
Cheeks thickly cutinized; head conoid; small forward-pointing onchia (?) . (Isonemella) 109
Cheeks not thickly cutin.; head not prom, conoid; no small onchia exc. in Anoncholaimus
Ovaries outstretched, -f-; ocellate; phar. tubular; nearly lipless; ceph. setae 4. (Coinonema) 42
Ovaries reflexed, 'f; striae fine, plain; pharynx not tubular; head truncate
Cephalic setae none; ocellate; lips faint; amphids distinct, though small lllium 45
Cephalic setae 10; ocelli none; amphids indistinct
Dorsal cutinized element of the pharynx bent inward at the lips (Asymmetrella) 70
Dorsal wall of the pharynx not differentiated; onchia minute (Anoncholaimus) 93
Structure of the amphids spiral, circular, or elliptical
KEY AND CHARACTERS 221
Form of the amphids a distinct spiral; spinneret present
Winged; 'f ; striae coarse, plain; spinneret heavily cutinized; cephalic setae 4 Cynura 46
Wings none; female sexual organs double; striae fine, plain
Ovaries reflexed; no lips; pharynx none or nearly obsolete; osellate (lonema) 9
Ovaries outstretched, -f-; cephalic setae 4; pharynx tubular, narrow
Spiral amphid of one wind, somewhat hook-form; ocellate; pharynx obscure. .Coinonema 42
Spiral amphid of several winds; not ocellate; pharynx well developed Xinema 47
Form of the amphids circular or elliptical
Striae interrupted on the lateral fields; lateral wings present; spinneret present
Female organs single, -f; amphids 2 concentric circles; setae in groups of 3 (Omicronema) 50
Female organs double, 'f; amphids not 2 concentric circles; setae not in groups
Spinneret heavily cutinized; cephalic setae 4; amphids really spiral (Cynura) 46
Spinneret simple, normal; cephalic setae 10; amphids small, elliptical (Anoncholaimus) 93
Striae not interrupted on the lateral fields
Spinneret none; striae fine, plain
Ovaries 2, -f-; setae 4; amphids more or less deltoid; phar. irregularly napiform. . (Didelta) 33
Ovary 1, outstretched; amphids not deltoid
Amphids very small; ceph. setae in 3 circlets of 6; f-; cuticle reticulated. . . .Halanonchus 51
Amphids large; setae 10, with 6 subcephalic; -f; lips with digitate processes
Intestinal cells with crystals; caudal setae none; amphids not raised (CrystaUonema) 67
Intest. cells without crystals; amphids raised; about 10 thorn-like caudal setae . (Zanema) 68
Spinneret present
Ceph. setae in 3s; coarse, transverse striae resolvable into elongated elements. .Omicronema 50
Cephalic setae not in groups; striae, if resolvable, not into elongated elements
Buccal cavity more or less obscure, easily overlooked; wings none
Ceph. setae 4, 3-jointed; lips confluent; amphid i wide as trunc. head, closed. Rhadinema 37
Cephalic setae 6 or more, minute or papilloid
Lips none; amphid (?) unclosed behind, minute; head rounded; -f (Litotes) 1
Lips soft and rather obscure; amphid fairly well developed, closed (Zygonemella) 26
Buccal cavity obvious; setae only in Halinema long, then twice as long as head is wide
Ocelli present; ceph. cuticle thick; head distinctly conoid; minute onchia (?) .Isonemella 109
Ocelli none; cephalic cuticle not thickened; head not distinctly conoid; no onchia
Ovaries two, ' f ' ; striae fine, plain ; onchia vestigial ; 6 cervical glands Anoncholaimus 93
Ovary one, -f ; striae usually rather coarse; pharynx quite unarmed
Head end diminished to form a sort of beak; pharynx tubular Rhynchonema 43
Head end not diminished to form a beak; pharynx not tubular
Setae and amphids large; phar. shorter than head is wide; caudal setae pres. . Halinema 52
Setae and amphids medium size ; lips conoid , tips with minute ' ' claws' ' . (Dactylaimus) 29
Wall of the pharynx armed with teeth or onchia
Armature spear-like; caudal glands and spinneret typically (usually) absent
Spear with a bulbous base; striae fine, plain
Oesophagus plain, faintly cephaloboid; -f ; cuticle with wings Aphelenchulus 81
Oeosphagus with a posterior bulb or swelling; cuticle without wings
Amphids ellip., well devel. internally; ' f ' ; spear faint; lips 6, faint, unipapillate. Triplonchium 80
Amphids linear, transverse; oesophagus dorylaimoid; f'; no labial papillae Doryllium 84
Spear plain, i.e., without bulbous base; striae fine, nearly always plain
Oesophagus plain, i.e. without median or posterior swelling; spinneret present
Amphids 0; -f ; cephalic setae 0; head truncate; lip-region set off; spear small " prod" . lotonchium 82
Amphids present; lip-region not set off
Amphids symmetrical to one line only; setae 10; pharynx long; spear toothlike (Catalaimus) 89
Amphids spiral, sometimes faint; 'f; striae unaltered laterally; cephalic setae 4
Ocellate; amphids labial; "spear" slender in nar. phar.; lips and papillae none.Onchulella 87
Ocelli none; lips 3, papillate; "spear" toothlike, in an open cavity (Digitonchus) 95
Oesophagus with posterior swelling which sometimes occupies 5 the neck
Spinneret present ; amphids spiral (?) ; eyes present ; ceph . setae 4 ; lipless Onchium 83
Spinneret none; striae fine
Amphids 0; -f ; no ceph. setae; head truncate; lip-region set off; speara small prod. lotonchium 82
The amp^Tds "lliptical ; spear-tip bent ; ' f ; lips 6, bipapillate Campydora 88
The amphids symmetrical to one line only; lips set off by constriction
Female organs double, f ; spear long and very slender; pre-rectum very long. . .Leptonchus 85
Female organ single, f; spear short, not slender; pre-rectum short
Posterior oesophageal swelling short, not set off by constriction in front. . . . (Doryllium)
Posterior oesophageal swelling long, set off by constriction from previous part. Axonchium t
Tooth one (for alternative see top Page 223: "Teeth two"
Oesophagus with a median or posterior bulb or swelling, or both (for alternative see Page 222)
Amphids none or unknown, or so inconspicuous or faint as to be difficult to see
Striae fine, plain; spinneret none; 'f ; naked; lips 6, bipapillate; spear bent at apex. Campydora t
Striae altered on the lateral fields
Wingless; spinneret present; onchulus with large dorsal muscle; setae small. . . . (lotadorus) 115
s'piMerefpresent; striae coarse, resolvable; 'f ; lips retractile; setae 4 (Ptycholaimellus) 116
Spinneret absent; striae fine, plain; ' f ; lips not retractile, naked; spear bent. . (Campydora)
sTnicturfofamphids more or less irreg., often symmetrical to one line (for alternative see Page 222)
Contour of the amphids not linear; spinneret present
Striae altered laterally; onchus small, well forward; setae obscure; lips 12 lotadorus 115
Striae unaltered laterally; 'f , Qa
Setae fasciculate; cuticle thick; lips faint jiantnoaora
Setae not fasciculate; cuticle notthick _......... Bolbella
Contour of the amphids linear; appearing as transverse slits opposite the pharynx
Striae altered laterally; spinneret present; 'f; striae coarse, resolvable
2 KEY AND CHARACTERS
New Genera
Lip-region retractile; cephalic setae 4, rather obviously segmented Ptycholaimellus 116
Lip-region non-retractile; cephalic setae 10, not obviously segmented Rhips 118
Striae not altered laterally, or very little; cephalic setae 10
Lips thin and flap-like; cephalic setae long and obviously segmented Trilepta 92
Lips not thin or flap-like; cephalic setae shorter, not obviously segmented; 'f
Striae resolvable ; pharynx not subdivided ; onchus not spear-like ; no cervical setae . Rhips 118
Striae plain ; pharynx in distinct chambers ; onchus spear-like ; cerv. setae long . (Bolbella) 90
Structure of the amphids spiral, circular, or elliptical
Form of the amphids more or less distinctly spiral; spinneret present, doubtful in Laimella
Striae altered on the lateral fields; cephalic setae 4
Wings present; striae fine, resolvable; lips 6, confluent, bipapillate; -f- Pepsonema 77
Wingless; tooth with apophysis faintly y-shaped; striae coarse; amphids labial. . Ypsilon 96
Striae not altered on the lateral fields
Onchus one, with its apophysis somewhat y-shaped; striae coarse; setae 4 Ypsilon 96
Onchus not y-shaped, often with small companions
Amphids distinctly spiral
Setae 0; body striated (exc. head); pharyn. bulb faint, cardiac napiform. .Amphispira 103
Setae, cephalic 10, subcephalic 4; non-striated; -f-; onchus spear-like (Laimella) 44
Amphids appearing circular
Lips 12-fold; onchus somewhat spear-like; cephalic setae small, 6 plus 10-12. .Mesodorus 105
Lips faint, not over 6; onchus not spear-like
Ovaries -f-; phar. bulbous; amphids circular (?); setae 6 + 6; striae fine . (Bolbolaimus) 100
Ovaries reflexed, 'f
Striae fine, plain; onchuli minute; lips faint, 6; papillae conical; setae 4. . (Polysigma) 106
Striae coarse; head not striated; cuticle thick; cephalic setae fasciculate. .Xanthodora 98
Form of the amphids circular or elliptical
Striae altered on the lateral fields; spinneret present
Wingless; labial amphids elliptic; striae resolvable; pharyngeal bulb one-sided. lotadorus 115
Wings present; striae coarse
Female sexual organs single, -f ; cephalic setae 4, labial setae 6; wings numerous. .Nudora 113
Female sexual organs double, 'f
Head expanded, naked; striae not retrorse; tooth small; lips minute, obscure . Xenonema 102
Head not expanded, its setae 4 ; lips obvious; striae appar. retrorse throughout. Rhinema 114
Striae not altered on the lateral fields
Cephalic setae none
Head hemispher . , expanded ; lips 6 , conoid ; spinneret pres . ; onchus obscure . (M icromicron) 104
Head not expanded; lips set off, confluent; no spinneret; 'f ; "spear" bent. . (Campydora) 88
Cephalic setae and spinneret present
Onchus spear-like; amphids resemble concentric circles; setae in 2-3 rows (Mesodorus) 105
Onchus not spear-like; amphids not concentric circles; setae, if numerous, fascicled
Female sexual organs outstretched
Ovaries two; cephalic setae 6+6; submedian onchia present (Bolbolaimus) 100
Ovary single; ceph. setae 4; submed. onchia none or vestigial Synonema 110
Female sexual organs reflexed, 'f; amphids really spiral
Submedian onchi present; labial papillae conical; setae 4; striae fine (Polysigma) 106
Submedian onchi abs.; setae in fascicles; head non-striated; cuticle thick . (Xanthodora) 98
Oesophagus plain, i.e. without median or posterior bulb or swelling; amphids present
Form of the amphids more or less irregular, usually symmetrical to at least one line
The amphids linear; spinneret present; 'f; striae coarse, altered laterally
Striae plain; head naked, set off by constriction; wing 1, prom.; cuticle thick. .Actinonema 117
Striae resolvable into rods; ceph. setae 10; wingless; amphid 5-6 times as wide as long. Rhips 118
The amphids not linear; striae not altered on the lateral fields
Head conoid; cheeks thick; ocellate; onchus minute; phar. narrow; setae 10 (Isonemella) 109
Head not conoid; cuticle of the cheeks not thick; 'f; striae fine, plain
Spinneret absent; lips 6, unipapillate; cephalic setae 6; amphid behind pharynx . Onchulus 94
Spinneret present
Buccal cavity extending beyond the nerve-ring; onchus spear-like; ocellate. Catalaimus 89
Buc. cavity not unusually long, its dors, element bent at lips; not ocellate. Asymmetrella 70
Form of the amphids spiral, circular, or elliptical
The shape of the amphids a more or less distinct spiral ; spinneret present ; ' f ' or -f
Striae altered laterally, fine, resolvable; wings present; cephalic setae 10; 'f. .Acanthonchus 101
Striae not altered on the lateral fields, coarse, plain
Spinneret unknown, abs. (?); -f ; setae 10; onchi submedian ; contour crenate. .(Gonionchus) 97
Spinneret present; T
Lips three; setae 6; amphids labial; onchus digitate Digitonchus 95
Lips more than 3 ; setae num . , scattered ; amphids not lab . ; onchi more than 1 . (Croconema) 112
The shape of the amphids circular or elliptical
Striae altered laterally; wings numerous with retroree bristles; cephalic setae 4.. Rhinema 114
Striae not altered on the lateral fields
Head conoid; cephalic setae 10; spinneret present
Ocelli none; 'f; rear portion of oesoph. succession of bulbs; striae fine, plain. (Bolbella) 90
Ocelli present; no succession of bulbs in the posterior part of the oesophagus
Cheeks thick; onchus appressed, minute; pharynx rather long and narrrow . (Isonemella) 109
Cheeks not thick; onchus digitate, well developed ;pharynx not narrow, short . Cophonchus 108
Head not conoid; not ocellate; pharynx not long and narrow
Spinneret unknown; amphids spiral; -f ; setae 10; onchi submed.; contour cren. (Gonionchus) 97
Spinneret present
Onchi 3, clustered; phar. unobv.; setae scattered; cuticle thick ; contour cien.. (Croconema) 112
Onchus single, dorsal; -f ; cuticle thin
Setae 4; pharynx small, closed; diameter of amphid J the width of the head. . Synonema 110
Setae in 2s and 3s; phar. obv., open; diam. of amphid about i width of head. Anticyclus 111
Teeth two or more
KEY AND CHARACTERS 223
New Genera
The teeth more or less equal in size, and usually mobile
Oesophagus with median or posterior bulb or swelling, or both
Onchi or teeth have an outward throw; amphids circular; spinneret present- -f Aponchivm 79
Onchi or teeth have an inward throw
Amphids none, or so obscure as easily to escape notice; f-; teeth (?) 12 (Synodontium) 65
Amphids present
The amphids horse-shoe shaped, faint; striae fine, unaltered laterally; f- Synodontium 65
The amphids spiral, circular, or elliptical; striae fine, plain
Shape of amphids spiral; winged; spinneret pres.; naked; head expanded. . (Pycnolaimus) 40
Shape of amphids round or elliptical
Terminus hamate; amphid minute, & the width of the head; winged Chambersiella 64
Terminus not hamate; amphid J the width of the head; wingless; -f (Aponchium) 79
Oesophagus plain, i.e. without median or posterior bulb or swelling
Onchi or teeth have an outward throw; amphids present; spinneret present
Form of amphids symmetrical to one line only; striae fine, plain; pharynx bulbous
Ovaries two, 'f; onchi 3, duplex; cephalic setae 6 plus 6; head not set off Ironella 63
Ovary single, f ' ; lip-region set off; lips 6, bipapillate; spinneret ventral Trissonchulus 78
Form of the amphids spiral, circular, or elliptical
The amphids spiral ; winged ; ' f ' (or -f-) ; lips bipapillate ; cephalic setae 4 Mesonchium 76
The amphids elliptical; striae fine, resolvable, unaltered laterally; setae 4 Apodontium 62
Onchi or teeth have an inward throw
Amphids or unknown ; onchi small, apophysate, lips 12, appendiculate Gammanema 74
Amphids present; spinneret present (questionable in Crystallonema)
Contour of the amphids circular
Wings many; 3 mandibulate lips; setae in 3 circlets; cuticle rough Xyala 72
Wing one or none; striae not altered on the lateral fields
Cephalic setae none; armature of three biting plates or hooks; wingless Tripylium 71
Cephalic setae ten
Armature, 18 duplex radiating refractive ribs; winged; -f Monhystrium 69
Armature, 6 talon-like or digitate labial elements; -f (Crystallonema) 67
Contour of the amphids spiral; striae resolvable
Winged ; ovaries reflexed or outstretched ; cephalic setae 4 ; pharynx cylindroid . Mesonchium 76
Wings absent; the 3 onchia enclosed in a bulb
Onehj small, with heavy apophyses;, encl. in swelling; amphid of 2j-3J winds. Trogolaimus 75
Onchi large, without apophyses; phar. bulb spheroidal, amphid of li winds. .Synonchium 73
The teeth usually unequal in size, not mobile
Oesophagus plain, i.e. without median or posterior bulb or swelling
Amphids none, or obscure and escaping notice ; pharynx with many denticles ; ' f ' . (Thoo'nchus) 91
Amphids present
The amphids irregular, usually symmetrical to one line; spinneret present; 'f
Form of the amphids not linear; striae fine, plain; pharynx denticulate ThoSnchus 91
Form of the amphids linear; striae coarse, resolvable; cephalic setae 10 (Rhips) 118
The amphids spiral, circular, or elliptical
Form of the amphids spiral; striae coarse, plain, unaltered; spinneret present
Pharynx and onchi minute, obsc.; lips not thin; setae scattered ; amphids small. Croconema 112
Pharynx obv.; onchi plate-like, submedian; lips thin; setae 10; amphids large . Gonionchus 97
Form of amphids circular or elliptical; spinneret present (unknown in Gonionchus)
Winged; amphids large, faint; lips appendiculate; striae coarse, resolvable. .Anaxonchium 99
Wings none; cephalic setae 10; striae plain; lips thin
Ovaries 'f; striae fine; phar. with many denticles; amphids obscure, ellip.. . (ThoSnchus) 91
Ovary -f ; striae coarse, contour cren. ; onchi plate-like; amphids spiral (Gonionchus) 97
Oesophagus with median or posterior bulb or swelling, or both
Amphids none or unknown; pharynx bulbous; striae fine, resolvable (Bolbolaimus) 100
Amphids present
Form of the amphids linear; wingless; ovaries reflexed
Spinneret present; 'f; striae coarse, resolvable; cephalic setae 10 Rhips 118
Spinneret absent; 'f ; striae fine, plain; cephalic setae 6 plus 4 Myolaimus 60
Form of the amphids spiral, circular, or elliptical
Shape of the amphids circular; striae fine, unaltered laterally; spinneret present
Ovaries reflexed, 'f ; lips bipapil.; setae 4; submed. onchi minute; striae plain . (Polysigma) 106
Ovaries outstretched
Pharynx with distinct spherical bulb; striae resolvable; setae 6 + 6 + 4 . . Bolbolaimus 100
Pharyngeal bulb a faint swelling; striae plain; cephalic setae 4 (Aponchium) 79
Shape of the amphids a distinct spiral; cuticle wingless; spinneret present
Onchus spear-like; lips minute, 12; cephalic setae 6 + 12 + 6; striae fine, plain. Mesodorus 105
Onchus very small, not spear-like; lips none or obscure
Lips bipapillate, papillae conical; 'f; amphids labial; cephalic setae 4 Polysigma 106
Lips non-papillate
Setae in 6 longitudinal rows ; amphids opp. pharynx, \ the width of the head . A laimonema 107
Setae none; amphids not opposite the pharynx, J the width of the head. . . . Amphispira 103
Abbreviations used in Key, not found on p. 341
abs, absent
cutin, cutinized
lin, linear
sim, simple
apophys, apophysate
depr, depressed
nar, narrow
swol, swollen
appar, apparently
arc, arcuate
devel, developed
digit, digitate
numer, numerous
obsc, obscure
spin, spinneret
term, terminus
buc, buccal
chamb, chambered
dist, distally
ea, each
obv, obvious
pap, papillae
thr, through
tub, tubular
clav, clavate
encl, enclosed
pres, present
uni, uniform
col, colored
cren, crenate
lab, labial
prom, prominent
unstr, unstriated
224 KEY TO THE MALES
TJRSA PRESEN: spcua two, equa; ta more or ess arcuate-cono; no sp
Accessories pres.; no suppl.; spicula li long as anal body width, straightish; -m
Accessories none; spicula 2 CC as long as anal body diameter, cephalated by con
Supplements 0; spicula L-form; -m; post, half of tail cylindroid; terminus rou
New Genera
BTJRSA PRESENT: spicula two, equal; tail more or less arcuate-conoid; no spinneret
-m. . Aphele.nchulus 81
nstriction
Supplements 0; spicula L-form; -m; post, half of tail cylindroid; terminus rounded. lotonchium 82
Supplements 2()2,1 ;2, clav.-digit., apic.; ?'m; spicula obsc., straight; terminus blunt. Myolaimus 60
BURSA NONE
Spiculum one, straight, uncephalated, 'm; spinneret none; tail acute
Accessories pres.; 1;()1;1, simple (postanals, single); spicula 2 ee anal body width. .Cephalobellus 23
Accessories none; supplements present, papilloid; found in insects
Supplements 2();2; spiculum one-fourth as long as anal body diameter; tail conoid. Blattophila 55
Supplements simple; spiculum twice as long as anal body diameter
Anus 90; 1(),1;1; small access. (?); tail hemispheroid, then conoid; terminus conical. Protrellus 38
Anus 80; accessories (?) ; tail conical, its terminus pointed ...................... Cephalobellus 23
Spicula two, equal, more or less arcuate (exc. Cophonchus, Synonchium, lotalaimus, Ironella, Bol-
binium, Myctolaimus?)
The spicula jointed, long, not distinctly cephalated, of uniform width; spinneret present
Supplements none; -m-; terminus clavate; spinneret armed; accessories apophysate ---- Xinema 47
Supplements 25, vent., preanal, simple, rather faint; -m: tail conoid; aces, not &pophys..Rhips 118
The spicula not jointed; tail conoid or subconoid (cylindroid posteriorly in Amicyathus, Anti-
cyclus, Cophonchus, Cyartonema, Gonionchus, Daptonema, Halanonchus, Ironella, Anaxon-
chium, Monhystrium, Schistodera, Pepsonema, Myctolaimus, Rhabdocoma, Bolbella, Thoonchus,
Trilepta, Mesonchium, Cytolaimium, Tripyliu'm, Zygonemella, Synodontium and (?) Xennella)
Accessories to the spicula none, or very faint
Supplements present; spinneret absent, except in Synonchium
Supps. dorylaimoid; spic. cephalated by expans., width unif.; -m-; term, rounded . Beryllium 84
Supps. all ventral; spicula about H-2 ce as long as anal body diameter, uncephalated
Position of supps. not preanal only; 4 preanal, simple; 1 postanal, not simple; =m? . Colpurella 39
Position of supplements preanal only; supplements simple
No. of supps. 4; spicula not of uniform width; ? = m; tail rather irreg. conoid .Colpurella 39
No. of supps. 2; spicula straight, width rather unif.; tail conoid-hemispherical Synonchium 73
Supplements none or exceedingly faint
Spicula slightly cephalated by expansion, unif.; tail conoid, then cylindroid; -m-. Zygonemella 26
Spicula not cephalated
Width of the spicula not uniform; spinneret absent (?)
Spicula straight; about \ as long as anal body diam.; tail short, bluntly conoid. Bolbinium 16
Spicula arcuate; -m ; tail conoid, then cylindroid, its term, rounded, J as wide as base . Trilepta 92
Width of the spicula more or less uniform; spinneret present, except in Triplonchium
Spicula straight; tail conoid-hemispherical; term, broad; spinneret a pore. . (Synonchium) 73
Spicula arcuate
Spinneret absent
Spicula very strongly arcuate; bursa (?) ; terminus broad, rounded; -m ---- (Triplonchium) 80
Spicula not very strongly arcuate; no bursa; terminus not broad ............ (Rhabdocoma) 32
Spinneret present; spicula not strongly arcuate; no bursa
Anus 85; tail conoid, then cylindroid; width over 5%; spic. only slightly arcu.. Zygonemella 26
Anus 97; term, broad, rounded; width about 1%; -m; single questionable supp. . Nemanema 2
Accessories to the spicula present
Supplementary organs present near the anus (for alternative see middle opposite page)
The supplements not all ventral; spicula 1J-1| as long as anal body diameter
Position, preanal; not simp.; 2 rows 38 ea.; non-unif. spic. uncephalated; -m ...... Polysigma 106
Position, not preanal only; no spinneret (except in Catanema and (?) Cytolaimium)
Form of supplements simple; -m-; spicula uncephalated, width rather uniform
Supplements papilloid, 5 preanal, 4 postanal in pairs .......................... Isolaimium 41
Supplements discoid, 11 pre-,5 postanal pairs; spic. 1J long as anal body diam.. Cytolaimium 31
Form of the supplements not simple
Spicula not cephalated ; 16 pairs of supplements; terminus barely swollen ; -m- . Cytolaimium 31
Spicula cephalated
Cephalated by constriction, straight?, width not uniform; 9 pairs papillae; ' m. Myctolaimus 61
Cephalated by expansion: width of spicula rather uniform
Arrangement of papilloid supps. 1,1,1,1,1.1,1(1),2,1,1;3,; 'm; term, hooked . CJiambrsi(lln 64
Arrangement of tub. supps. postanal, submed., about 7 prs.;-m; term, straight Catanema 56
The supplements all ventral; spinneret present (exc. Anticyathus, (?) Anticyclus, Neurella)
Position, preanal 17, postanal few, simple; spicula uncephalated, tapering (?); -m-.Anticych>s 111
Position of supplements preanal only
Structure of supplements not simple (for alternative see page 225)
Proximal ends of the spicula not cephalated
Width not uniform, length 1? anal body diam.; 37 " campanulate " supps.; -m. Alaimonema 107
Width of the spicula more or less uniform
No. of supplements 1; spicula 2| times as long as anal body diam. .straight; =m (Ironella) 63
No. of supplements 4 or more; terminus more or less blunt
Apophysis present; spicula 3 ce as long as anal body width; supps. 12; 'm. . Aponchium 79
Apophysis none; spicula long as anal body diam. ; ace. prom. ; supps. 4 ; -m . Acanthonchus 101
Proximal ends of the spicula cephalated
Spicula cephalated by constriction, twice as long as anal body diameter
Supplements 2, not simple; spicula rather uniform, their cephalation faint; -m- . Bolbella 90
Supplements 6, mammiform; width of spicula not uniform; -m(?) .......... Xanthodora 98
Spicula cephalated by expansion or contraction; width of spicula rather uniform
Cephalated by contraction, strongly arcuate, as long as anal body diam. ; -m . (Stilbonema) 19
Cephalated by expansion
Supplement one, tubular; spicula nearly straight; tail conoid, then cylindroid
Length of spicula 5-6 anal body diameters; -m-; spinneret bluntly conoid. . .Cophonchvs 108
Length of spicula 2j anal body diameters; =m; supplement bent toward anus. .Ironella 63
KEY TO THE MALES 225
New Genera
Supplements numerous, 8-21
Length of spic. 2 ce anal body width; proximae hooked; supps. 21, flat; -m-. Trogolaimus 75
Length of spicula 1-1 i times as great as the anal body diameter
No. of protrusile(?) tub. supps. 8; ace. | as long as spic., bends away; -m' . Antomicron 17
No. of faint, non-tubular supps. 16; ace. parallel, J as long as spicula ;-a\-.Gammanema 74
Structure of supplements simple
Proximal ends of the spicula not cephalated
Width of spicula not uniform
No. of supplements one, flat, faint; accessories, simple, faint; =m(?) Neurella 25
No. of supplements 17, low, papilloid ; spinneret (?); term, slightly swollen. .(Anticyclus) 111
Width of spicula more or less uniform
No. of supplements two, obscure; accessories stout; term, convex-conoid, acute. .Nudora 113
No. of supplements 15-20; terminus not acute
Length of the spicula twice as great as the anal body diameter; 'm Anaxonchium 99
Length of the spicula as great as the anal body diameter; -m- Halanonchus 51
Proximal ends of the spicula cephalated
Cephalated by constriction, about 1J as long as anal body diameter; supplements 6-40
Width of spicula rather uniform; accessories 2, apophysate; -m; term, blunt. Margcnema 27
Width of spicula not uniform
Accessory with apophysis; -m-; tail fine, cylindroid; term, blunt; no spin. (Anticyathus) 24
Accessories without apophysis, two; terminus convex-conoid, acute Bolbolaimus 100
Cephalated by expansion or contraction
The cephalatiqn is by expansion
Width not unif.; supps. 5-6; -m-; accessory with apophysis; spinneret armed . Halinema 52
Width of spicula uniform or apparently so
No. of supplements 3; spicula 15 times as long as anal body diameter; -m Rhynchonema 43
No. of supplements 25-65; spicula 1 or 1J times as long as anal body diameter
Apophysis to the accessory present; -m-; spinneret armed, 3-lobed .... Synvdcnlium 65
Apophysis to the accessory none; -m; spinneret unarmed; anus raised Mesodorus 105
The cephalation is by contraction; width of the spicula not uniform
No. of the supplements 1-3
Spicula lj times as long as the anal body diam; supps. mere innervations Ypsilon 96
Spicula twice as long as the anal body diam; single elevated supp; -m- Thoonchus 91
No. of the supplements 4 or' more; spicula tapering both ways
Spicula long as anal body diam; accessory apophysate; -m-; no spinneret.. Anticyathus 24
Spicula twice as long as anal body diameter; accessory not apophysate
Anus 98; width 1.6%; -m-; single elevated supp; 2 dozen innervations. . . .Thodncfius 91
Anus 92; width 3.8%; -m; series of ventral supps.; nar. spinneret-tube. .Micromicron 104
Supp. organs 0; spinneret pres. (exc. Crystallonema, Triplonchium, lotalaimus, Cephalobium)
Inner ends of the spicula not cephalated, or not obviously so
Width of spicula not uniform; spicula 1-li times as long as anal body diameter
Form of spic. subarcuate; spin, midway on tail, ventral; 'm-; term, rounded . ..Trissonchulus 78
Form of spicula arcuate
Apophysis to accessory extends backward; spicula 1-1 J long as anal body diameter
Spinneret none; term, unarmed; -m; spic. strongly arcuate; no caudal setae. Crystallonema 67
Spinneret present; term, faintly armed; -m-; minute, inconspic. caudal setae . Linhomoella 35
Appphysis to accessory none
Wings to the cuticle present, also in anal region; spicula strongly arcuate Xennella 6
Wings to the cuticle none
Accessory inconspicuous; spinneret (?); terminus j as wide as base of tail; -m. .Trilepta 92
Accessories parallel, then bent away ; spin, armed; term. J wide as base; -m. . . . (Stilbonema) 19
Width of the spicula more or less uniform
Length of spicula 2-3 times as great as anal body diameter; ace. with backward apophysis
Form of spic. straight thr. middle, arc. dist.; 3 ce long as anal body diam.; -m-.Mesonchium 76
Form of spicula arcuate throughout, about twice as long as anal body diam. ; -m . Cyartonema 18
Length of the spicula 1-J-1J times as great as the anal body diameter
Accessories massive; supps. 2, obscure; term, convex-conoid; spin, large, acute (Nudora) 113
Accessories obscure; no suppelments; terminus blunt
Form of spic. very strongly arcuate; rudiment, bursa pres.; no spinneret ;-m Triplonchium 8
Form of spic. not strongly arcuate, rather stout, blunt; no bursa; spinneret?. Rhabdocoma 32
Inner ends of spicula cephalated; spinneret present, except in lotalaimus and Cephalobium
Proximal ends of the spicula cephalated by constriction, width not uniform
Length of the spicula twice or nearly twice or great as anal body diameter
Apophysis to ace. tapering; tail not striated; spinneret swan's-head form, unarmed . Nemella 10
Apophysis to ace. none; tail striated; spin, elongated-conoid, armed; -m. .Ptycholaimellus 116
Length of the spicula 1J times as great as anal body diameter
Form of spicula straightish; 'm; term, blunt, nearly J as wide as base; no spin.. lotalaimus 15
Form of spicula arcuate
Spinneret none; -m; terminus acute, unarmed; width of the body 3% Cephalobium 54
Spinneret present
Spinneret tub.; anus 90; width of body more than 3%; term, unarmed; -m. .Monhystrium 69
Spinneret simple; width of body less than 1%
Termjnus swollen ; accessories 2 ; anus 95% ; caudal setae faint, anal only ; -m-? . Schistodera
Terminus not swol.; ace. 1, more massive dist.; anus 97.5; setae not anal only Laxonema 20
Proximal ends of the spicula cephalated by contraction or expansion
Ends of the spicula cephalated by contraction (for alternative see top next page)
Width of the spicula uniform ; spicula about as long as anal body diameter
Anus 98; -m ; cephalum short, faint; anal annules strongly modified ventrally. .Stilbonema 1
Anus 94; -m-; cephalum elongated, contraction distinct Cinctonema 22
Width of the spicula not uniform
Length of the spicula twice the anal body diameter; -m-; terminus rounded. . (Thoonchus) 9
Length of the spicula equaling anal body diameter
Cuticle = | radius; annules \ anal body width, elements not tile-shaped. Achnonema 117
Cuticle less than } radius; annules } anal body width, elements tile-shaped Ceramonema 48
226 KEY TO THE MALES
Ends of the spicula cephalated by expansion ffew Genera
Width of the spicula not uniform
Length of spic. equal to 2 anal body diams.; -m-; tail finally oylindroid; spin.? .Gonionchus 97
Length of spioula equal to IJ-li anal body diameters
Apophysis to ace. backward-pointing; spic. 1J long as anal body diam; -m-.Coinonema 42
Apophysis to accessory none
Accessories 2, bending away from the spicula; spinneret unarmed; -m Zalonema 57
Accessory 1, parallel to the spicula; spinneret armed; -m-(?) Leptonemella 21
Width of the spicula more or less uniform
Length of the spicula about 1-1$ times the anal body diameter
Form of the spicula only slightly arcuate
Tail diminished to a narrow terminus; -m-; accessory i as long as spicula. .Zygonemella 26
Tail not diminished t9 a narrow terminus; accessory j long as spicula, sigmoid . Rhinema 114
Form of the spicula distinctly arcuate, or bent
Apophysis to the accessory present
Term, swol.; spin, rounded, unarmed; -m; proximal 3rd of spic. straight. Campylaimus 5
Terminus apiculate; spinneret acute, armed; -m-; ace. soon bends away. . (Coinonema) 42
Apophysis to the accessory none
Spicula not L-shaped; ace. slender, parallel, \ &s long as the spicula; ^m.Alaimella 1
Spicula L-shaped; striae resolvable into elements
Accessory f as long as dark-colored spicula; tail without wings Omicronema 50
Accessory \ as long as spicula; tail with wings Xyala 72
Length of the spicula about twice to thrice that of anal body diameter (Tripylium, 1 f)
Form of spic. normally straightish, arcuate in strong ace. ; spinneret blunt. (LeptoQastrella) 28
Form of the spicula arcuate
Apophysis to the accessory present
The accessory surrounds posterior J of hamate spicula; -m; caudal setae few.Iotadorus 115
Theaccessory parallel to narrow spicula; -m-; caudal setae many, in 4 TovfS.Pepsonema 77
Apophysis to the accessory none
Accessory tub., strongly developed, enveloping spic.; numer. setae; -m.LeptoQastrella 28
Accessory not tubular
Accessory bends away from spic., J long as spic.; -m; term, blunt, armed. Apodontium 62
Accessory parallel to the spicula
Anus 85; ace. surrounds laterally bent, dark-col, spic.; -m-; spin, armed. Daptonema 66
Anus more than 90; spicula not laterally bent, not dark-colored; spinneret unarmed
Spinneret blunt, tubular; anus 93; -m; accessory f as long as spicula Tripylium 71
Spinneret conical, plain; anus 96; -m; accessory parallel to distal halves. Psevdonchus 58
THE NEMA FORMULA
Nema dimensions sometimes vary perceptibly with varying technique.
As a rule, information conveyed in the keys, formulae and illustra-
tions is not repeated elsewhere. Following other authors, the measure-
ments for the ovaries are given separately instead of in the form of a
single measurement as formerly. Furthermore, the oblique stroke indi-
cating the presence and position of the excretory pore is here, in No.
IX, placed below the formula line, the assumption being that the for-
mula shows the nema ventral side down. The general form of the spic-
ula and accessories is shown in the formula for the male, as is also the
presence, number and position of the supplements, indicated by small
suffixes before and after the anal measurement figure. The spicula dia-
grams are of three different degrees of curvature, indicating nearly
straight, arcuate and strongly arcuate spicula. The nature of the prox-
imal ends of the spicula is indicated, i. e. whether cephalated, and if
cephalated, whether by contraction, constriction or expansion. Also,
if it exists, the presence of an apophysis to the gubernaculum is indi-
cated. The short, horizontal marks indicating the wings and the pres-
ence and relative diameter of the oesophageal swellings are only dotted
when these features are not of a pronounced nature. The mark indi-
cating the presence of a spinneret is either plain or so conventional-
ized as to indicate that the spinneret is supplied with setae. The
absence of any particular mark in the formula is practically always
to be taken as indicating that the particular feature in question is
non-existent. Doubt is expressed by a question mark. The reason
BURSAL FORMULA FOR NEMAS
227
to the millimeter
text term
formula line
100 dom
250
Very coarse
Coarse
750
1000
Rather fine
Fine
2000 to
None
for calling attention to these special marks is that until one becomes
accustomed to them they may appear rather insignificant. Once rec-
ognized, they may save the reader considerable time and trouble.
The adjacent table shows the various formula lines by which the
number of striae per millimeter is indicated. See also pages 6 and 7,
where the various signs used in the formula are explained in full.
In this number, the presence of a bursa
is indicated by a curved stroke under the
transverse anal measurement figure, and
the number of bursal ribs in front of and
behind the anus is indicated by suffixes
in front of and behind the anal measure-
ment figure. Furthermore, as already
noted, the form of the spicula and gubernacula is indicated by conven-
tionalized sketches appropriately placed. See, for instance, page 279.
BURSAL FORMULA FOR NEMAS
In the following rather arbitrary designations, which are expressed in
a written formula, only the papillae and ribs on one side of the bursa
are considered. They are designated according to their proximity to
each other and not according to their anatomical and physiological
characters. They are regarded as either anal, pre-anal, or post-anal,
according as they are opposite to, in front of, or behind the anus. In
the graphical bursal formula, the anus is rep-
resented by a pair of parenthesis marks; all
papillae opposite the anus are indicated in
the parenthesis, the pre-anal papillae are
indicated in front of the parenthesis, and the
post-anal papillae after the parenthesis.
The papillae and ribs are considered as a
single longitudinal series, and each group is
indicated by a digit representing the number
of ribs or papillae in the group. The longitudinal spaces separating
the groups of papillae and ribs are indicated by commas and semicolons,
the comma representing a short space, the semicolon a longer space. In
some cases before and after the parenthesis, the punctuation mark may
be omitted, thus indicating that the ribs or papillae are even nearer to
the anus than in those cases where the separation is indicated by a
comma or semicolon. A blank space in the type after the comma, or
after the semicolon, indicates a longer space than is indicated by the
comma or semicolon alone. By such simple means it is possible to indi-
cate with considerable accuracy the grouping and latitude of these vari-
ous organs and groups of organs. A glance at the above illustration,
Fig. 0, and formula immediately underneath will make the matter clear.
I; (2),
228 "UNLESS OTHERWISE INDICATED"
GENERAL Unless otherwise indicated,
1. The species described under a generic name is to be regarded as the type
species of the genus; where more than one species is described, the type
species is specifically designated.
2. The text terms and formulae apply to the nemas as viewed in profile. Ref-
erences to stain are restricted to acid carmine.
3. The cuticle is colorless.
4. The cuticle is striated, sometimes, however, so finely striated as to be
resolvable only with the highest powers of the microscope used skillfully
under favorable conditions. The division line of the formula is used to
indicate approximately the number of striae per millimeter. (See page 227.)
5. The striae are approximately uniform in width throughout the length of
the body except toward the extremities.
6. The contour is plain.
7. The striae are not resolvable into secondary elements. The presence of
secondary elements is indicated in the formula. (See page 7.)
8. The longitudinal striations are due to the attachments of the musculature.
9. There are no obvious series of pores in the cuticle.
10. There are no eye-spots.
11. There are no definite valves in the oesophageal bulbs.
12. The lining of the oesophagus is a distinct, but not conspicuous, feature,
practically throughout its length.
13. The intestine is set off from the oesophagus by a distinct constriction.
14. The arrangement of the granules in the cells of the intestine is not such
as to give rise to a tessellated effect.
15. There is no pre-rectum.
16. The rectum extends inward and forward at an angle of about thirty to forty
degrees.
17. The tail, at least that of the female, is straight, or nearly so.
18. The somatic, as well as the posterior cervical, setae, are perpendicular to
the cuticle, or nearly so.
19. The renette cell lies behind the base of the neck.
20. The nerve-ring surrounds the oesophagus rather squarely.
21. Absence of the formula for either sex indicates that that sex is unknown
at the present time.
FEMALE -Unless otherwise indicated,
22. The vagina is understood to lead inward at right angles to the ventral
surface.
23. The uterus is more or less straight.
24. The eggs are thin-shelled and smooth, and are deposited before segmenta-
tion begins.
MALE Unless otherwise indicated,
25. There is no bursa.
26. The tail of the male is similar to that of the female in form.
27. The spicula are two in number, equal in size, and appear moderately arcu-
ate when viewed in profile, and are simple, i.e., without obvious extra
component longitudinal stiffening elements.
28. The accessory piece (or pieces), gubernaculum, lies more or less parallel
to the spicula, and has no inward or backward-pointing apophysis.
NEW MORPHOLOGICAL AND PHYSIOLOGICAL DATA 229
New Data
Apart from indicating that the nema phylum can be divided into valid, nat-
ural orders on the basis of the structure of the mouth parts and related organs,
this article records numerous additions to our knowledge of the morphology of
nemas. Facts announced in a sentence or two, or through the medium of illus-
trations, might perhaps have been advantageously made the subject of separate
papers. Among these additions to our knowledge, the following may be
mentioned:
1. In a miscellaneous lot of over one hundred new genera of nemas, thirty per
cent prove to have jointed setae. Probably a much larger percentage have
jointed setae. Among the nemas having setae, jointed setae are probably
the rule rather than the exception.
2. The distal ends of the cephalic setae sometimes exhibit considerable com-
plexity, indicating that they are specially developed sense prgans; e.g., in
Linhomoella and Crystallonema.
3. Additional evidence that bilateral mouth-parts arise by elimination of dorsal
elements exists in Pseudonchus.
4. There is a large group of nemas with six well-developed onchia having an
outward stroke, adapted for digging; e.g., Apodontium and relatives.
5. More than ever, it is clear that amphids are practically universal among the
free-living nemas. They may be small and difficult to see; as in Stilbonema
and Laxonema. In the p_ast, they have been sometimes overlooked. Some
Triplonchs possess amphids; e.g., Onchium, Triplonchium.
6. All amphids have backward connections, often, perhaps always, tubular and
containing coagulable substance. Of unusual interest are the huge glands of
lonema.
7. Lateral series of organs occur in so many of the genera described, as to lend
additional weight to the opinion that such series are a normal element of the
nema structure.
8. There is much additional evidence of differentiation of form and structure
among the various cells of the intestine.
9. The presence of oesophageal glands is established for Axonchium and its rela-
tives, (Dorylaimus, etc.) They occur in the posterior enlargement of the
oesophagus, one emptying into the lumen dorsally in its anterior part, and
often two others emptying into the lumen farther back.
10. Non-terminal spinnerets and mouth openings seem practically always ven-
tral; e.g., Trissonchulus, Campylaimus.
11. A large unicellular gland is connected with each supplement of the males of
Bolbella and Eurystoma.
12. The presence of pairs of cloacal glands in the male, first observed by de Man
in Euchromadora, is established for many other genera.
13. Cytolaimian transition-forms exist between the parasitic and free-living
nemas; e.g., Monhystrium.
14. The existence of double-jointed spicula is established for Rhips and Xinema.
15. Nemas are disclosed in which the sperm cells are of extraordinary size; such
species may prove useful in studies in genetics.
16. Rhynchonemas are distributed in various oceans. They are free-living nemas
with beak-like heads, but otherwise normal in form. Presumably, this beak
serves to extract food from receptacles the entrances to which are narrow.
17. There is a marked absence of syngonism in marine forms.
18. The existence is demonstrated of special spermatheca, in the form of special
separate branches of the female sexual organs.
230 ORDER LITINIA
I. Order Litinia
.4 lj.4 28. '-61 88.
1. Litotes minuta n. sp. - 7 " * 5-i 3.2 ~ Cuticle thin, naked.
The mouth opening is almost imperceptibly depressed. The conoid neck carries
a conoid oesophagus. The presence of amphids is indicated by slight, narrow
external markings of a very faint character. In the region of the nerve-ring the
oesophagus is three-fifths as wide as the corresponding portion of the neck, while
finally it is five-sixths as wide as the base of the neck; its lining is indistinct,
its musculature fine and colorless. No oesophageal glands. The intestine
becomes at once three-fourths as wide as the body, is thin-walled, and but few
of its cells are required to complete its girth. The intestinal lumen is distinct.
q>hffl(6) The distinct cardiac collum is two-thirds as wide as the body.
[ I tm ^ ear i^ s beginning the intestine is pressed well to one side by
|jf the renette cell, which is more or less ellipsoidal in form and
oe -P: v x 750 granular in structure. It is about as long as the body is wide
and about half as wide as long, and contains a very indistinct nucleus of medium
size. There are few granules in the cells composing the intestine. The tail
is conoid. Nothing is known concerning the longitudinal fields. The nerve-
ring is medium-sized and accompanied by more or less distinct groups of nerve
cells. The small indistinct vulva is more or less continuous with the ventral
surface of the body. The rather weak, tubular, non-refractive vagina extends
obliquely forward apparently about half way across the body. The ellipsoidal
granular eggs are about three times as long as the body is wide, and nearly one-
third as wide as long. The broad, tapering ovary contains six to eight ova
arranged single file.
Habitat: Algae, near the lighthouse, Bahia, Brazil. Bears some resemblance
to Monhystera and Oxystoma. Differs from Monhystera in having no pharynx
and no distinct amphids; from Oxystoma in the form of the amphids and the form
of the female sexual organs. Sublimate to balsam. Fig. 1.*
2. Nemanema simplex n. sp. Head with faint traces of papillae on the outer
part, indicated by refractions in the cuticle. Possibly the exceedingly minute
/g\ or pharynx contains an acute, forward-pointing projection or tooth, but
] w all details are so exceedingly minute that even under the very highest
" *9J powers of the microscope they are resolvable with difficulty. The
Jimpn oesophagus expands but little until after it passes through the nerve -
\^ x75o ring; thereafter it expands until near its posterior extremity, where
, I 74 it is two-thirds as wide as the base of the neck;
^ .9,17 i. n T8 >2-5 " the posterior extremity of the oesophagus stains
somewhat differently from the rest. Cardia large,
.2 9.i.-H2i. "-* 97-^ ._. conoid, half as wide as the base of the neck. From
the distinct cardiac collum the intestine becomes
at once two-thirds as wide as the body; its cross-section comprises about six
cells. The lateral fields are about half as wide as the body. When viewed dorso-
ventrally the amphids are seen to be connected with refractive, cutinized ducts
which lead inward and backward for a short distance and then become indefinite.
Tail conoid, its terminus three-fifths as wide as its base. The large, elongated,
narrow caudal glands lie tandem on the ventral side in front of the anus, the
foremost being removed from the anus a distance three to six times as great as
the length of the tail. Observations on the ventral gland and excretory pore
Each figure is designated by the number of the genus it illustrates. If two species of the genus
are illustrated, the figures are designated a and ft, respectively.
NEMANEMA, TYCNODORA, SCHISTODERA
231
have not been satisfactory, but it appears as if there is a small, narrow, elongated
ventral gland a short distance behind the cardiac constriction, where the intes-
tine lies a little to one side. Each lateral field contains large ellipsoidal cells,
too large to be placed side by side within its limits; they are placed alternately
to one side and then the other. Their size is such that, in the neck at least,
if they were arranged single file they would make a continuous series a little
more than half as wide as the field and about one-third as wide as the body.
From the raised vulva, the vagina leads half way across the body, where it joins
the single uterus, which extends backward. The ovary reaches about half way
back to the vulva and contains a score or more of developing ova, which are
arranged for the most part single file. Anterior branch rudimentary. The elon-
gated eggs are about four times as long as the body is wide and about one-sixth
as wide as long. The tail of the male is slightly more arcuate than that of his
mate. Opposite the proximal ends of the spiculai, there is a very low, rounded,
ventral elevation. Near the ventral line in front of the anus for a distance two
to three times as great as the length of the tail there are a few minute setae,
about one-eighth as long as the body is wide, and immediately behind the anus
there are one or two similar setae; otherwise there are no indications of special
papillae or setae. Spicula about one and one-half times as long as the anal
body diameter. Their proximal ends lie near the dorsal side of the body.
Habitat: Algae and marine sand at their bases, in surf, Island off Port Royal,
Jamaica. Sublimate to balsam. Fig. 2, p. 230.
3. Tycnodora pachydermata n. sp. -36 i- 2 i-5 i-s .84 " " Cuticle thick,
glassy; near the head more nearly colorless, sometimes smoky, at any rate after
treatment with Flemming's solution; near the middle of the
body, occupying one-sixth the radius; near the spinneret
much thinner than elsewhere; rather suddenly diminishing
in thickness near the nerve-ring. Lining of oesophagus sub-
distinct; the musculature fine and colorless. There is no
cardia. The thin-walled intestine is separated from the
oesophagus by a collum one-fourth as wide as the body. The
lumen of the intestine is faint. From the depressed anus the
inconspicuous rectum extends inward a distance twice as
great as the anal body diameter. Very few granules are to
be seen in the intestinal cells. The contents of the intestine
are finely granular. The more or less arcuate tail is first co-
noid, then cylindroid in the posterior fourth, where it is about
one-fourth as wide as at the anus. The lateral fields are one-
half as wide as the body. From the inconspicuous vulva,
the cutinized vagina extends one-third the way across the
body. The somewhat cylindroid ovaries extend two-fifths
the way back to the vulva and carry twelve to twenty ova
arranged more or less single file.
Habitat: "Seagrass," shoal, two miles off Key West, Fla., U. S. A. Flemming to
glycerine jelly. Resembles Halalaimus, but the female has two reflexed ovaries.
Fig. 3.
<a M !" or
s/a
X750
4. Schistodera exilis n. sp. .1
The naked cuticle is
extremely thin. From the mouth about one-third the way to the anterior mar-
gin of the lateral organs, the lining of the oesophageal tube is a little more mas-
sive than farther back. The amphids are interesting on account of the presence
ORDER LITINIA
in the posterior portion of the cavity of each of a strongly staining body, which
may be assumed to be protoplasmic. The bottoms of the amphids are strongly
cutinized. Oesophagus conoid, finally about half as wide as the base of the
neck; just where it joins the intestine it appears to expand suddenly, although
Ittl (4) or ^ s ex P ans i n could hardly be called a bulb. It is possible that
this expansion indicates the presence of glands about the base
w of the oesophagus. The intestine becomes at once three-fourths
as wide as the body and in cross-section appears to present only
two cells. Little that is definite is known concerning the lateral
fields, but it is presumed that they are well-developed. The
median fields are rather distinct. They contain a series of cells,
I at any rate in the neck; these cells are about half as long as the
neck is wide and are separated from each other by distances
about twice as great as their length. Tail of the male at first
conoid, then cylindroid in the posterior half, where it is about
one-fourth as wide as at the base. The spinneret has a very
minute pore. The caudal glands lie in front of the anus. A
straight refractive piece appears to subtend the arc of the spicula.
These latter are barely cephalated by an almost imperceptible expansion and a
previous constriction. Immediately behind the anus there are two or three
minute submedian setae; similarly, close to the anus, and in front, there is a pair
of subventral setae, all seen with considerable difficulty. The balance of evi-
dence is in favor of the existence of two testes.
Habitat: Algae and sand at their bases, in surf, Island off Port Royal, Jamaica.
Fig. 4.
5. Campylaimus inequalis n. sp. Striae more easily seen along the margin of
the amphids. Wings are indicated by the presence in the lateral fields of two
1.2 7.5 n. ^5?:"....??:. > 7 ,. longitudinal lines
2.1 3.2"" 4.1 4.5 2.9 very close together
and barely resolvable
1.3 9.4 n. "-*t *.. > 6 ,. with high powers.
2. 3.* 3-9 >* ""M-z Like the mouth-open-
ing the cephalic setae are asymmetrically placed.
The mouth is a simple, unarmed, conoid depression
on the ventral side of the head a little behind the
anterior extremity. There are no distinct lips, but
the anterior extremity is modified so as to resemble
a lip-region; it is set off by a minute constriction
and presents a minute depression that takes acid-
carmine stain more strongly than do the adjacent
parts. No doubt this terminal "cap" serves some distinct function, as tactile
or gustatory. The conoid oesophagus finally becomes almost three-fourths as
wide as the base of the neck. There does not appear to be any distinct cardia.
Around the base of the oesophagus there is a circlet of small cells which stain
in the same manner as do the cells of the intestine. This latter becomes at
once about three-fourths as wide as the body. The lateral fields have not been
distinctly seen. Nothing definite is known about the renette and excretory pore.
Tail conoid to the simple terminus, which is set off by a broad, shallow con-
striction. The caudal glands appear to be located in front of the anus, probably
a long distance in front of it. In the male the anus is slightly raised. Spicula
CAMPYLAIMUS, XENNELLA, ALAIMELLA
233
about one and one-half times as long as the anal body diameter, their proximal
ends slightly cephalated by expansion. They are rather markedly arcuate in
their distal two-thirds, but nearly straight in the proximal third. There seems
to be but a single testis.
Habitat: Marine sand and mud, San Pedro, California. Fig. 5.
.17 11. _ 23. "-M 92.
6. Xennella cephalata n. sp. -33 V~ !' 2.3 "^2.2 ! " The cuticle,
which is of medium thickness, is traversed by six to eight longitudinal ribs or
wings on each side. There are at least four cephalic
setae, possibly six; otherwise the cuticle seems to be
naked. The mitriform head is set off by a distinct
constriction. The neck is cylindroid. The some-
what conoid oesophagus is at first one-ninth, near
the nerve-ring one-fifth, and at last two-fifths as
wide as the corresponding portion of the neck. A
final obscure swelling contains one or more nuclei,
which differ from all other nuclei in the organ. The
lining of the oesophagus is indistinct. The intestine
is separated from the oesophagus by a collum one-
fourth as wide as the base of the neck, and becomes
at once two-thirds as wide as the body, and in cross-section presents but few
cells. The anterior part of the intestine for a distance about equal to the length
of the corresponding body-diameter has a
structure different from the portion that fol-
lows. The cells of the intestine contain
numerous very minute granules. The elon-
gated granular renette cell is about as long
as the corresponding body diameter, and lies
a little in front of the cardia. It is not re-
flexed. Apparently the excretory pore is
located near the nerve-ring. This latter is
oblique, distinct, and broad. The spicula
when viewed dorso-ventrally appear to make
an angle of about thirty degrees with each
other. The specimens were molting.
Habitat: "Sea-grass," shoal, two miles off Key West, Florida. Figs. 6a and b.
It is believed only the spinneret was missing fiom the single specimen measured.
2. 106. 219. 4 - 5 M 866.
The actual measurements are, ^ 19 ~ 18 ^ ^^-(?)944..i C r...
la. Alaimella cincta n. sp. Cuticle relatively thick. The secondary elements
of the striae are on the limits of visibility and reach nearly
across the annule. There are probably six, flat, amalgamated
lips. The conoid neck contains an oesophagus which is more
or less clavate at the rear end. Near the mouth it is one-half,
at the nerve-ring two-fifths, and finally three-fifths, as wide as
the corresponding portion of the neck; its lining is indistinct.
There may be a faint, conoid cardia. Intes-
tine at once about three-fourths as wide as the i __ 9 J.*_:_j fi-
body, more or less thin-walled, and present-
ing but few cells in cross-section. The intesti- iy'iTf r~~n 1~f"
nal cells contain numerous, rather uniform
granules, regularly placed. From the continuous anus, the cutinized rectum
234 ORDER LITINIA
is about twice as long as the anal body diameter. Tail conoid. The eggs are
two to three times as long as the body is wide. The ova are arranged more or
less in single file, and the ovary extends two-thirds the way back to the vulva.
The proximal ends of the slender, somewhat tapering, rather frail, subacute spic-
ula lie opposite the body axis. There are two rather frail, simple accessory pieces.
Habitat: Sand-bar, Biscayne Bay, Florida, U. S. A. Flemming to glycer'ne
jelly. Fig. 7a, p. 233.
-_--^._J>5-il_JJL___j-_ >(?)1 . 3 ..
b. Alaimella truncata n. sp. - 6 u ^5 1.5 ~N\ 1.5 This, the type species
of Alaimella, rather closely resembles Alaimella cincta. Secondary markings of
the cuticle faint, if any. Oesophagus as in cincta, except relatively a trifle nar-
rower. Intestine as in cincta, but narrow and displaying only two cells in cross-
section, the cells containing minute inconspicuous granules,
Proximally the slender, uniform, simple, frail and subacute
spicula expand much and suddenly, to form flattish cephala,
located about opposite the body axis. There seem to be two
simple, frail, sub-slender, more or less arcuate accessory
pieces, which are probably joined together at the anus. There
appear to exist throughout the length of the body an unusual x 750 V t i oe
number of nuclei ventrad from the narrow intestine, which keeps well to the
dorsal side. Both before and behind the anus there are some very slender ven-
trally submedian setae half as long as the body is wide. Ejaculatory duct about
one-third as wide as the body. Forward-pointing testes two-fifths as wide
as the body. In the single male examined, which appears to be immature, one
testis ended four tail-lengths from the anus, the other five tail-lengths from the
anus. At one tail-length in front of the anus there occurred one or two glands
(?) with very brilliantly staining nuclei, whose connections remain unknown.
Habitat: Algae, near lighthouse, Bahia, Brazil. Sublimate to balsam. Fig. 7b.
.8 4.5 9.5 12'" 96.
8. Litinium aequale n. sp. 1.3 t-7/ i.s LS 1.7 ' " Oesophagus at first
three-sevenths, near the nerve-ring one-third, and finally three-sevenths, as wide
as the corresponding portion of the neck. Its lining is indistinct. There seems
tt>f nt/fi) i a- tot t/fi} * k e no distinct cardia. The intestine, which
" is separated from the oesophagus by a collum
three-sevenths as wide as the neck, becomes at
once half as wide as the body. Its walls are
thick and its lumen faint. The granules con-
tained in the cells of the intestine are numerous
and more or less uniform. The anus is more or
less continuous, the rectum inconspicuous. The
hemispherical-conoid tail tapers from the anus
to the terminus. There are no caudal setae.
X750 The cau( ial glands are located in front of the
anus. The lateral fields are about one-fourth as wide as the body. The nerve
ring is of medium size and on either side of it are obscure nerve cells. From the
large, depressed, but rather conspicuous vulva, the vagina leads obliquely back-
ward a distance two-thirds as great as the body diameter. Judging from the size
of the ovum just before it leaves the ovary, the eggs are about one and one-half
times as long as the body is wide. In the broad, cylindroid ovary are twenty to
forty ova arranged single file except in the distal half, where they are arranged
irregularly.
Habitat: Sand, Ocean Beach, Miami, Florida, U. S. A. Flemming to glycerine
jelly. Fig. 8.
IONEMA 235
.2 5-9 7.W "'y?'' 92.
9. lonema ocellatum n. 8 p. "*""'"" i-"" i's L' > a " The thin cuticle is
naked except for the cephalic setae. There are no traces of lips. The amphids
are very inconspicuous. The neck is cylindroid posteriorly, and convex-conoid
anteriorly, especially near the head. The eye-spots are light brown in color,
and each has a refractive element in front. In the pigmented portion of each
eye there is a more or less central nucleus with a subsidiary, small companion
object. The cylindroid oesophagus is at first one-third, near the nerve-ring one-
fourth, and finally one-fifth, as wide as the corresponding portion of the body.
Its lining is indistinct. There is no cardia. Owing to the presence of large
somatic glands, observation of the junction of the oesophagus with the intestine
is difficult. The collum appears to be one-fifth as wide as the corresponding
portion of the body. The intestine is two-thirds to three-fourths as wide as
the corresponding portion of the body, and is thick-walled, and has a very faint
lumen. The cells of the intestine, which appear somewhat as if overlapping,
contain more or less uniform, yellowish, scattered granules; they have large,
spherical, granular nuclei with conspicuous nucleoli. The arcuate, conoid tail
tapers from the anus to the unarmed convex-conoid terminus. The conoid spin-
neret is simple in structure. The ellipsoidal caudal glands occur in a loose tan-
dem series in the anterior half of the tail. There are no caudal setae. The lat-
eral fields are two-fifths as wide as the body. The granular, elongated, pyriform
renette is one and one-half times as long as the body is wide, and one-half as wide
as long. It is not reflexed and lies near the middle of the body, a little in front
of the flexure of the front ovary. The nerve-ring is of medium size and is accom-
panied by rather obscure nerve cells. From the small, elevated, more or less
inconspicuous vulva the medium-sized vagina leads inward half m ^
way across the body; it is more or less strongly cutinized. The ;
size, form and covering of the eggs is unknown, but the ripe ova set (4)'
are about as long as the body is wide. The broad, cylindroid
ovaries extend five-sixths the way back to the vulva, and con- " moe
tain about twenty ova, arranged single file in the proximal half, ^
but irregularly in the distal half. The duct of the renette is
necessarily very long and is slender; there is a distinct, elon- oe
gated ampulla, with a very long and very slender duct leading
from it to the pore. This latter duct is about as long as the
body is wide. This genus, of which there are several species, spn
is made very remarkable by the possession of a pair of relatively
huge glands filling most of the body cavity behind the base of X75
the neck and ending two and one-half times as far behind the neck as this latter
is behind the head. The points of exit of these glands appear to be at the head
end. Each gland has a nucleus near its blind end. In the vicinity of the nerve-
ring the glands diminish in size, and half way from this point to the head appear
to come to a narrow, rounded end, strictly lateral in position, and from thence
there appear to be narrow ducts leading toward the lip-region to pores, where
foreign particles are seen to cling, and which are designated in the drawing
as amphids. Near the middle these glands are pressed to one side by two sub-
dorsal cells, apparently nerve cells.
Habitat: Marine algae, Panama. Hot sublimate to balsam. This genus is of
wide occurrence in tropical oceans; specimens from both the East and West
Indies are known to the writer. While specifically different, these forms do
not vary much one from another. Fig. 9.
236 ORDER LITINIA
10. Nemella ocellata n. sp. .* L M i- 2 ~vi-* Except for the ceph-
alic setae, the thin cuticle is naked. At a distance from the anterior extremity
about equal to the width of the head, the striation of the cuticle ceases, so that
the head is set off by an absence of striations, as well as by a slight thickening
of the cuticle. The neck is cylindroid. From the faint amphids, an inner
element can be traced backward to near the base of the head. The two eye-
spots are brownish in color, and each has a colorless lens. The oesophagus, which
has an indistinct lining, is at first one-half, near the nerve-ring also one-half,
and finally three-fifths, as wide as the corresponding portion of the neck. There
is no cardia. The intestine, which is set off from the oesophagus by a collum
one-half as wide as the neck, becomes at once three-fourths as wide as the body.
Its wall is thick, its lumen faint, and it is made up of cells of such a size that prob-
ably only two are required to complete a circumference. These cells are packed
with colorless granules of variable size, the largest of which are about one-
twentieth as wide as the body. The tail is conoid to the convex-conoid spin-
i . .sn*0r nere t, which at its base is one-third as wide as the base of the
- tail, and has somewhat the profile of a swan's head. No setae
were seen on the tail. At their widest part the simple, frail, taper-
ing, subacute spicula are about one-fifth as wide as the corre-
sponding part of the body. Their proximal ends, which are mi-
nutely cephalated by contraction and constriction, appear to lie a
little ventrad from the body axis. They are supported by a simple,
frail, slender, faintly S-shaped accessory, with a tapering apophy-
sis (?) extending backward from the spicula at an angle of about ninety degrees,
and about one-third as long as the anal body-diameter, its proximal end lying
opposite the caudal axis. Whether there is one testis or two remains to be
determined.
Habitat: Eel-grass, Biscayne Bay, Miami, Florida, U. S. A. Flemming to
glycerine jelly. Fig. 10.
11. Porocoma striata n. sp. -V ' J -5 i-J> i-? 1- - The rather thin cuti-
cle appears to be destitute of setae except at the extremities. The body is tra-
versed nearly from end to end by about ten to twelve wings. Between the
wings the transverse striae seem to be resolvable into excessively minute ele-
ments. In addition to the cephalic setae, there is a ventral seta-like organ, oppo-
site the sub-cephalic setae and just behind the excretory pore. This is a little
stouter, longer, and more blunt than the cephalic setae, and seems to have a
special relation to the excretory pore. The mouth is surrounded by relatively
thick, minute lips. It is possible that a more or less vestigial pharynx extends
back to near the cephalic setae, its presence being indicated by a slight difference
in the lining of the canal, and by a break in the musculature. Posteriorly the
neck is cylindroid, anteriorly convex-conoid. No distinct traces of amphids
have been seen, but possibly obscure ones exist opposite the bases of the lateral
setae. The oesophagus is cylindroid, then conoid in its posterior eighth. Near
the head it is one-half, near the nerve-ring two-sevenths, and finally three-
fourths, as wide as the corresponding portion of the neck. Its lining is indis-
tinct. There is a flattish cardia, one-half as wide as the base of the neck. The
thick-walled intestine is separated from the oesophagus by a collum one-half as
wide as the base of the neck and becomes at once two-thirds as wide as the body,
and would present two to three cells in cross-section. Its cells contain scattered
granules of variable size, the largest of which have a diameter about equal
POROCOMA, LITONEMA 237
to the width of two of the adjacent annules; tessellated effect faint. The tail,
which tapers from in front of the anus, is conoid, and then cylindroid in the pos-
terior half, where it is about one-half as wide as at the base Apparently the
ellipsoidal caudal glands are packed in a close tandem in the anterior fourth of
the tail. The lateral fields are one-half as wide as the body. The elongated,
outstretched, granular renette cell lies one to two body-widths
behind the base of the neck. It is two to three times as long as the ,.j
base of the neck is wide and about one-fourth as wide as long. The
broad oblique nerve-ring is accompanied by obscure nerve cells.
While both ovaries are essentially behind the vulva, one of them ~i " ! J M
extends forward a distance about twice as great as the correspond- *TI ':! H3i
ing body diameter, and is then reflexed, and extends backward, so *"
as to lie parallel to the other. The medium-sized, but rather conspicuous vulva
is continuous with the ventral surface. The rather strongly cutinized vagina
extends inward two-fifths the way across the body. It is possible that the nar-
row, cylindroid ovaries are reflexed for a short distance near their blind ends.
Habitat: Biscayne Bay, from sponges and associated material. Flemming to
glycerine jelly. Fig. 11.
II. Order Bolbinia
12. Litonema nudum n. sp. **/ 3 - 5 *?. 4 -9 * -O-- The presence of the
two wings, which begin on the neck and end near the anus, is indicated by two
refractive, longitudinal markings, which occupy a space equal to one-fourth to
one-third the width of the body. The cuticle is entirely naked. There appears
to be a vestigial pharynx nearly as long as the base of the head is wide, simple,
narrow, tubular, obscure. The neck is conoid. Almost on the front of the head,
but near its margin, there are two minute, lateral pores, which may possibly be
amphids. Connected with these pores are inner tubular elements, which may
be followed backward for a considerable distance. The more or less cephaloboid
oesophagus has a very faint, elongated, posterior swelling, one-fourth as wide as
the base of the neck. Near the pharynx the oesophagus is one- /
third, near the nerve-ring one-eighth, and in front of the
cardiac swelling one-seventh, as wide as the corresponding
portion of the neck. The optical expression of the lining of P"
the oesophagus consists of two distinct, refractive lines, hav-
ing a distance apart about equal to one-tenth the width of jnsc
the oesophagus. There is no cardia. The thick-walled intes-
tine presents a faint lumen, and becomes at once five-sixths
as wide as the body. Anus continuous; rectum inconspicu- "
ous. The cells of the intestine are packed with granules
of rather uniform size, the largest of which are one-seventh * 750 i
as wide as the body. The conoid tail tapers from in front of the anus. There
are no caudal glands. The lateral fields are probably one-third as wide as the
body. The excretory pore and the duct leading to it are so refractive as to be
easily visible.
Habitat: About the roots of the lady's slipper, Cypripedium acaule Linn.,
sphagnum swamp, Wisconsin, U. S. A. Flemming to balsam. Fig. 12.
238 ORDER BOLBINIA
-..-..T-.. .. .
13. Hyalaimus brevicollis n. sp. ^ * *j, 5.1 1.7 " The colorless,
naked skin displays irregular markings and a finely crenate contour. The color-
less, transparent, conoid neck ends in a truncate head without setae and having
very flat lips, if any. Six rather conspicuous, sub-marginal, wart-like papillae
occur in a circlet on the front of the head. No amphids are to be seen. The
mouth is a mere depression one-sixth as deep as the head is wide; from it faint
apophyses, of which the ventral is the longest and most conspicuous, extend back-
ward and seem to indicate that the real depth of the pharynx is equal to the
length of the distinct pharyngeal bulb, and accordingly the dimensions are so
given in the above formula. The somewhat phalangiform oesophagus begins
with the bulb just mentioned as filling the head, and which is two-fifths as long
as the neck. Behind this bulb there is a broad, shallow constriction, the remain-
der of the oesophagus being fusiform and in its widest part two-thirds as wide
as the neck. For a short distance the irregular intestine, three-fourths as wide
as the body and separated from the oesophagus by a not very deep constriction,
appears transparent and almost bulbous. The cardiac cavity is small and the
cardia very flat. The large cells composing the intestine are filled with small
granules, displaying no very definite arrangement. The narrow, colorless,
transparent rectum is thrice as long as the anal body-diameter, and has a dis-
tinct lining. The ventral excretory pore is situated as far behind the cardia
as the head is in front of it, the duct in the immediate vicinity being very trans-
parent and distinct, and having a distinct lining. The granular lateral fields
are one-fourth as wide as the body, and from head to tail a finely crenulate,
cuticular wing extends along each lateral line. The tail of the female is conical
to the pointed terminus. The unusually large, flat, elevated vulva is two-
thirds as wide as the body, and from it the vagina extends backward a distance
greater than the body-diameter. The two straight uteri in the only specimen
seen contained six to eight eggs, each a little longer than the body width, and
measuring 56-60 x 132-140 microns. The ovaries extend two-thirds the distance
to the cardia and anus respectively and contain ova arranged single file.
Habitat: Intestine of an earth-worm, Moss Vale, New South Wales, Australia,
April, 1894. It is not certain that this nema may not be con-generic with one
or more of those mentioned by earlier authors under the generic names Anguil-
ula, Nematodum, etc., nemas also found in earth-worms, but insufficiently
described; hence the proposal of a new genus for its reception.
14. Choronema simplex n, sp. L6 2A / 2 -& 2 - 6 1 - 8 ' The thin cuticle is
entirely naked. The wing, which begins near the head and ends on the tail, is
possibly double in structure. There is no cardia. The rather thick-walled
intestine is separated from the oesophagus by an indistinct collum one -half as
wide as the base of the neck, and becomes at once about three-fifths as wide
as the body. It has a faint lumen and presents few cells in cross-section. Anus
subcontinuous; rectum inconspicuous. The cells of the intestine contain scat-
tered colorless granules of variable size, the largest of which are one-fifteenth
as wide as the body. In the specimen examined the tail was destined at the next
molt to become very much shorter, so that the anus would lie at about 90%,
and the tail would therefore be about four times as long as the anal body-
diameter. Two sublateral papillae existed on the tail nearly opposite each
other.
Habitat: Soil about the roots of plants, Arlington Farm, Virginia, opposite
CHORONEMA, IOTALAIMUS
239
M&ato
the city of Washington, U. S. A. Flemming to glycerine jelly. This species, of
which but a single young specimen has been seen, has the general appearance
of being a deteriorated Cephalobus or Diplogaster. The specimen figured was
Mi yung and in process
of molting. In the
left-hand illustration
the excretory pore,
ex p, is shown in its
proper position. Nearly
opposite is shown
the cast-off duct and
pore which has come
into its present posi-
tionbyrotation of
the loose, shed cuticle.
Similarly, in the right-
hand figure the
sloughed anal opening
is shown opposite the
anus, on. The caudal
pores eluded observa-
tion, but that they were
present is shown by the
. two markings at ppl
- m in the cuticle that has
been shed. Probably
the cuticle has length-
ened, as usual, in being
shed, and the pores pre-
JPft sumably occur not far
behind the anus, not-
withstanding the fail-
ure to see them. Ph,
while indicating the
....ttlt (X position of the pharynx,
also indicates an ele-
ment that comes to
the surface ante-
riorly (amphid?). Fig.
X 750 14.
15. lotalaimus striatus n. sp. Cuticle naked; the striae interrupted by well-
developed crenate wings one-fifth as wide as the body. Between the wings is a
straightish refractive line, due to a continuous, cuticular structure. On some
specimens the outer contour of the wings consists of a doubly refractive line.
There appear to be four faint, submedian cephalic papillae. The amphids are
faint. It is possible that there is a vestigial pharynx. The oesophagus is
very faintly cephaloboid in form. The anterior two-fifths is cylindroid and
averages only about half as wide as the corresponding portion of the neck; thence
backward the oesophagus diminishes gradually so that opposite the nerve-
ring it is only about one-fourth as wide as the middle of the neck. It continues
to have this diameter for some distance, but finally begins slowly to expand, so
exp
240
ORDER BOLBINIA
that at last it is about half as wide as the base of the neck. The lining is faint,
and there are no refractive breaks in its structure to indicate the presence of
vestigial bulbs. There is no distinct cardia. The intestine becomes at once
two- to three-fifths as wide as the body. It is composed of cells containing
scattered groups of granules. The distinct "lumen," instead of appearing as
m ?
.93-
3.1
cavity with
refractive
is. _24. "w 9*. lining,
it
.trmd
X750
hmoe
2. $,4 3.5 3-5 -=V3.2 ' usually does
when a distinct feature, seems to have a dif-
ferent structure of about the same general
fllMI a PP earance - From the slightly depressed anus
the conspicuous rectum extends a distance about
w^ one and one-half times as great as the anal
** U ^ J- T J: rt 4- rt T^l-^xx ] n -l- A - n l -C !,!,,
body diameter. The lateral fields are one-third
as wide as the body. It appears as if there is a renette cell opposite the pos-
terior portion of the oesophagus. The tail is conoid to the blunt terminus, which
has a diameter about one-third as great as that of the base of the tail-. There
are no caudal glands. It is possible there is a pair of subventral papillae imme-
diately behind the anus. A trifle behind the middle of the tail, there are two
faint, lateral innervations close together on each side, one in front of the other,
doubtless connected with surface papillae. Ventrad from these, it is possible
there is a third papilla belonging to the same group. There are probably one
or two pairs of subventral papillae near the terminus. The proximal ends of
the tapering, very slightly arcuate spicula are bent in a ventral direction so as
to appear to lie on the ventral side of the body-axis, and
so appear cephalated. The accessory piece is more
strongly refractive than the spicula themselves, the frame-
work of which is not particularly conspicuous.
Habitat: About the roots of Bamboo, Yuma, Arizona,
06 I! ?--- \ iimph U. S. A. Fig. 15, above.
16. Bolbinium brevicolle n. sp. Cuticle of medium
thickness, naked. Posterior half of the neck cylindroid,
anterior half convex-conoid. Amphids unusually large,
with large internal connections that can be followed back-
ward for some distance. The narrow oesophagus contin-
ues to have the same diameter until near the posterior,
pyriform, cardiac swelling, which is one-half as wide as
the base of the neck. Many of the nuclei connected with
the cells of the neck are large and well-developed.
In the dorsal and ventral fields there are strands that
appear to be composed of closely-packed cells. The car-
diac bulb has no distinct valve.
as -mi
1 -* * ^ The spiculum is vestig-
ial. In a variety of ways this nema seems related to the
Mermithidae, for instance, in the structure of the mouth,
the cephalic papillae, the amphids, the internal structure of the tissue of the
neck and of the body, the absence of spinneret, and the short, rounded, broad
tail.
Habitat: Soil, about the roots of citrus plants, Florida, U. S. A. Fig. 16.
ANTOMICRON 241
17. Antomicron pellucidum n. sp. ** 2 -* 2 ~? 2-? ^O 1-1 " Except for the
cephalic setae the cuticle is naked. On the ventral side of the distinctly pro-
jecting wing there is a subordinate line to be seen throughout the greater por-
tion of the length of the body, which is not as conspicuous as the main part of
the wing. Neck conoid. The very minute pharynx (?) is apparently conoid;
whether armed or not is unknown. The lip-region has not been examined with
success on account of deficient material. That portion of the amphid inside the
two ellipses stains more strongly than the tissues elsewhere. The borders of the
two amphids approach each other so closely on the dorsal side that they some-
times almost touch, in fact appear to be connected by a special ^s^g^
cuticular element. Oesophagus cylindroid for some distance back, (^^^'^ ''
and then expanding rather suddenly to form an almost impercep-
tible swelling near the beginning of the middle third of the neck;
thereafter it diminishes almost imperceptibly to near the nerve-
ring, then begins to expand gradually until near the end, where it
rapidly expands to form an obscure, small, elongated, pyriform
cardiac bulb, almost half as wide as the base of the neck. There
is a rounded cardia one-fourth as wide as the base of the neck.
Considering the size of the oesophagus its lining is prominent.
The intestine is separated from the oesophagus by a broad, shallow constriction,
and soon becomes half as wide as the body, and apparently would present only
two or three cells in cross-section. The lateral fields appear to be nearly one-
third as wide as the body. It seems probable that a renette cell occurs at some
distance behind the base of the neck, but no excretory pore has been seen. The
tail of the male is conoid to near the terminus. The caudal glands are located
in an open tandem series in front of and behind the anus. The eight supple-
mentary organs occupy a distance nearly four times as great as the length of the
tail; each is a nearly straight, cutinous tube, half as long as the body is wide,
arranged at an angle of forty-five degrees with the body axis, and having its
distal extremity protruding backward slightly through the cuticle. The organs
taper slightly in the vicinity of the distal end, which is suddenly somewhat
ventrally arcuate at the terminus. They are probably protrusile, though they
have not been seen in a protruded position. These tubes have a diameter approx-
imately equal to the width of one of the adjacent annules of the cuticle, and their
proximal ends show indications of an attachment extending forward. There are
a number of specially-developed setae in the vicinity of the anus; especially
prominent are two submedian setae, one on each side of the anus, one-third as
long as the anal body-diameter. A little in front of these is another pair, one on
each side, of slightly smaller size, and on the tail there are a few similar ven-
trally submedian setae of smaller size. Spicula a little longer than the anal body-
diameter, and tapering to a point in their distal thirds. The accessory piece
surrounds the spicula in their distal fourths, and then extends forward to the
dorsal side of the body from the middle of the spicula at a small angle. The
appearance of the proximal portion of the accessory piece somewhat resembles
that of the proximal ends of the spicula, though it is straighter and more solid.
From its cephalated proximal end a muscular strand joins the body wall on the
dorsal side of the anterior portion of the tail. The posterior testis is the
smaller.
Habitat: Marine; Punta Arenas, Pacific Coast of Costa Rica. Unfortunately
the single specimen examined is of such a character that the details of the
pharynx must be left undetermined. Fig. 17.
242
ORDER BOLBIXIA
nrvr
.9 >.
18. Cyartonema flexile n. sp. Except for the cephalic setae the cuticle is
naked. There appears to be a circlet of six, inconspicuous, minute papillae
.15 5-1 8.4 -47f'
'.ii' 1.3 '/i-i" 2.2
.23 7.4 10.3... "M.
."83 'i.6' /L6 1.7
on the margin of the head.
The form and structure of
the gland at the base of the
narrow oesophagus is remi-
niscent of the salivary
glands in Tylenchus. The
intestine is made up of cells
so arranged that only one
to two are required to build a circumference. The parts of
these cells are so differentiated that the groups of granules char-
acteristic of the cells occur at intervals equal to one to two body-
diameters, and are more or less alternated with finely granular
intestinal elements, or what are suspected to be such (see Figure
18, int.?). The tail, tapering from in front of the anus, is con-
oid then cylindroid in the posterior fifth. Spinneret with min-
ute setae. A single caudal gland was seen near the middle of
the tail. A few very inconspicuous setae were observed on
the tail. Concerning the lateral fields, I was at times uncer-
tain whether the cells marked intf were not in some way con-
r&l \>f!\ '' : \ nected with these fields. From the somewhat elevated vulva,
the relatively large vagina leads inward two-fifths the way
across the body. The eggs are three to four times as long as
the body is wide, and about one-fourth as wide as long. The
broad, more or less cylindroid ovaries suddenly taper near
the blind end. They contain apparently only four to five ova,
* 500 arranged single file. The clavate testis is about two-thirds as
wide as the body.
Habitat: Clean, white sand, in about five feet of water, in a cove near the
entrance to Buzzard's Bay, Mass., U. S. A. Sublimate to balsam. Fig. 18.
set to (6)
19. Stilbonemabrevicollen.sp. Annules
plain, retrorse in the posterior half of
the body, the reverse in the anterior.
Exceedingly short, submedian, slender
setae are found throughout the length
of the body, six to nine annules apart,
those at the extremities being somewhat WA ^^\'^" / '^^JUT tib 1
the longer. Neck cylindroid. Imme-
diately around the mouth there is prob-
ably a row of exceedingly minute papil-
lae. In most of the neck the diameter
of the oesophagus hardly exceeds the J0B...V " *750
thickness of the cuticle; it finally expands to form a pyriform bulb about three-
fifths as wide as the base of the neck. There is no distinct cardia. The very
STILBONEMA, LAXONEMA
243
narrow intestine, joined to a depression in the posterior surface of the cardiac
bulb, becomes at once about one-sixth as wide as the body, and then enlarges
gradually until it is one-fourth as wide. Its
^X 750 cross-section would show two cells. The lat-
eral fields are about one-fourth as wide as
the body, and contain' numerous nuclei.
Nerve-ring oblique. Tail conoid, arcuate.
I. 3 ' * L 5 -M__ 98.
1:2 a; lU" i:5--^iT6 3 - " Spicula slender.
"Acorn-shaped" accessory organs (see fig-
ure) far forward, so that the anterior one is
a little behind the neck. The cup-shaped
part of these organs has slightly different
refractive properties from the "acorn" itself,
which is plainly innervated.
Habitat: Shoal in Kingston Harbor,
Jamaica, in one foot of water. Sublimate to balsam. Fig. 19a, p. 242; Fig. 196.
20. Laxonema majum n. sp. - 6 .7 ^ .s' " Cephalic cuticle radi-
ally striated; the basal part of the cephalic setae penetrate and interrupt the
cuticle. Inside the cephalic setae, as shown in the sketch, other interruptions
occur in the cuticle; possibly in some cases these are the "stumps" of lost setae.
There are two circlets of papillae inside the cephalic setae, one at a distance
from the mouth pore somewhat greater than the thickness of the body cuticle,
and the other twice as far away. Oesophagus nearly cylindroid, finally expand-
ing to form a pyriform cardiac bulb two-thirds as wide as the base of the neck.
There is no cardia. The intestine soon becomes about one-fifth as wide as the
body; at a distance back about twice as great as the body-diameter it expands
and becomes thicker-walled and one-third to one-half as wide as the body. Its
cross-section is composed of about four cells, each with ten to twenty brownish
granules, the largest of pf/f . or ouph set^cph(4)
which have a diameter ^S^'X ^st^^^fc^ j
about one-fourth as great as \\ :\ *^,\\ Wm ^^ /]
the thickness of the cuticle, """* \\^SM^^yifei^^A..^ .
and the smaller one-third
to one-fourth -this size. , ,
Renette unknown. The ^
lateral fields are about one-
fourth as wide as the body,
and contain a double row of
nucleated cells, generally
somewhat rectangular in
form and separated into two
series. The nerve-ring is
probably a little behind the mai
middle of the oesophagus.
The tail of .the male is X 750 hmoe' setcdl spa
arcuate-conoid and ends in a spinneret destitute of striations and having a
length about equal to the sum of the widths of the last eight striae. The tip of
the spinneret is somewhat differentiated, and its core presents minute longi-
tudinal "striations" which end just anterior to the terminal pore. The caudal
244 ORDER BOLBINIA
glands are probably located in front of the anus. No supplementary organs
have been seen. There are no caudal papillae, but both in front of and behind
the anus there are a number of ventrally submedian setae; five or six on each
side of the anterior half of the tail; while an equal number in front of the anus
gradually merge into the scattered setae found all over the body. The proxi-
mal ends of the rather stout acute spicula are somewhat diminished and set
off by a broad and deep constriction. The framework composing the spicula is
relatively massive. The rather straight accessory piece is half as long as the
spicula. The ejaculatory duct is about one-fourth as wide as the body. There
appears to be a single outstretched testis, though there remains a little doubt
on this point.
Habitat: Shoal in Kingston Harbor, Jamaica, in about one foot of water. Fig.
20, p. 243. Sublimate to balsam.
:'. . 2 -. 8 . .5-? . . -*-'. . 96. 22
21. Leptonemella cincta n. sp. '- L - "> w |^"XiJ '" The contour is
more or less serrate, the annules being retrorse posteriorly and the reverse ante-
riorly. In addition to the cephalic setae there are scattered cervical setae
arranged at right angles to the surface and one-third as long as the neck is wide.
No somatic setae have been seen. Apparently at every eight to ten annules
along the lateral lines there are pores, each with its longest diameter arranged
, tat lh transversely. Seemingly there are six, very minute, more
or less amalgamated lips. Posteriorly the neck is cylin-
droid, anteriorly conoid. Amphids are present in the
form of straight transverse slits, one-sixth as long as the
corresponding diameter of the head, and located between
the bases of the submedian cephalic setae. Their presence
and their form is proved by the ribbon-shaped outflow
plainly seen issuing from each amphid. The cylindroid
oesophageal tube ends behind in a broad, pyriform cardiac
bulb, two-thirds as wide as the base of the neck. There
is no cardia. The thick-walled intestine is separated
from the oesophagus by a collum one-tenth as wide as
the neck, and Becomes at once one-fourth as wide as the
* 'ffm" I body. Its lumen is indistinct. Its cells contain fine,
^^ rather numerous granules of more or less uniform size.
set l/Jtt Wjyw g evera i submedian, slender, tapering, cuticular "thorns"
are seen on the tail, each about one-fourth as long as the anal body-diameter.
The lateral fields are one-fourth as wide as the body. The nerve-ring is
accompanied by obscure nerve cells. The tail is more or less conoid from the
anus, but tapers more rapidly in the posterior half. The strong, tapering,
acute, colorless spicula are more or less compound in structure and their extremi-
ties appear to lie somewhat ventrad from the body axis. The single, slender,
rather strong, simple parallel accessory is three-fifths as long as the spicula.
Habitat: Sand, Ocean Beach, Miami, Florida, U. S. A. Flemming to glycerine
jelly. Fig. 21.
.6 4.4 7-5 .-*-. .9*-? >iO..
22. Cinctonema tenue n. sp> -fi*' ' J 1.4-^1.4 Cuticle thin, naked,
its striae not further resolvable. Neck, cylindroid posteriorly, conoid anteri-
orly. In the specimen examined the lip-region was not favorable for observation.
Oesophagus about half as wide as the head and continuing to have this diameter
until after it passes through the nerve-ring, behind which it begins to increase
CINCTONEMA, CEPHALOBELLUS, ANTICYATHUS
245
set (4)
a little, and finally enlarges to form an elongated, pyriform cardiac bulb, three-
fourths as wide as the base of the neck. The intestine is very narrow where
it joins the center of the posterior face of the cardiac bulb, hardly
wider than one of the annules. Very soon, however, it becomes
two-fifths as wide as the body. The lateral fields are about one-
fifth as wide as the body and contain nuclei, two of which placed omphi
side by side would span the field. Tail of the male conoid; on it
there are a few setae in front of the anus. The rather slender/ 75
acute spicula are about one and one-fourth times as long as the anal body-
diameter.
Habitat: Sand and algae near East Drive, east shore of Kingston Harbor,
Jamaica. Sublimate to balsam. Fig. 22.
III. Order Cytolaimia.
23. Cephalobellus papilliger n. sp. * 4 - 7 5. / 6. >L6, ' '" Annules of
the cuticle 2.2 microns wide. Head continuous with the conoid neck. There
are probably six lips, but no labial papillae have been seen. The pharynx resem-
bles that found in the genus Monhystera, being a conoid or more or less
pyramidal depression one-third as wide as the head. Oesophagus cylindroid,
one-fourth as wide as the middle of the neck, joining a pyriform cardiac bulb
two-thirds as wide as the base of the neck and containing a distinct valve.
Lining of the oesophagus rather faint. The rather thick-walled intestine is
three-fifths as wide as the body, and is separated from the neck by a shallow,
cardiac constriction. The ventral renette cell is situated just in front of the
flexure in the testis. From the somewhat elevated anus the tail is conical to
the acute terminus. A pair of tall, conical, sub-ventral papillae are located
opposite the middle of the spiculum. Taken altogether, the papillae are situ-
ated as follows: 1; () 1; 1. Spiculum slender, somewhat irregular, twice as long
as the anal body diameter, placed at angle of forty-five degrees with the body-
axis. The ejaculatory duct was of equal length with the testis, and was con-
nected with it by a tube also of the same length.
Habitat: Intestine of the larva of a lamellicorn beetle, from soil under cow-
dung, Moss Vale, New South Wales, Australia. 1893.
24. Anticyathus tenuicaudatus n. sp. Body wall thick. In addition to ce-
phalic setae there are scattered papilloid cervical setae. Conoid oesophagus at first
set (12)
tTItt two-thirds, near the nerve-ring
four-sevenths, finally four-fifths,
as wide as the corresponding por-
tion of the neck. Oesophageal
lining subdistinct. There is a
somewhat obconoid more or less
"structureless'Mooking anterior
element of the intestine three-
fourths as long as the body is wide; this may be regarded as a cardia one-half as
wide as the neck. The thick-walled intestine, which has a faint lumen, is set off
246 ORDER CYTOLAIMIA
by a collum one-fifth as wide as the base of the neck, and becomes more or less
gradually three-fourths to five-sixths as wide as the body. Its cross-section is
composed of twenty to fifty cells. These cells contain numerous granules of
variable size. The tail tapers from in front of the anus; it is first conoid, then
cylindroid in the posterior fourth, where it becomes one-fifth as wide as at the
anus. There are no caudal glands. Fifteen to twenty almost invisible setae,
as long as the cuticle is thick, occur on each ventrally submedian line on the tail.
The longitudinal fields are one-third as wide as the body. Near the excretory
pore is an ampulla one-sixth as wide as the corresponding portion of the neck.
The nerve-ring is accompanied by obscure nerve-cells. Vulva medium-sized,
more or less elevated; vagina non-cutinized. Near the proximal end, each ovary
presents a double flexure, occupying a distance about equal to one body-width;
thence onward the ovaries are outstretched in opposite directions, at last not
over one-tenth as wide as the body. The eggs occur in the uteri about nine at a
time. They are about one-half to two-thirds as long as the body is wide, though
they are often so crowded together in the uterus that they appear wider than
long. The narrow tapering ovaries contain seventy to eighty ova, arranged
single file. The strong, rather simple, stoutish, tapering, rather blunt spicula
are as long as the anal body-diameter, and are so placed that their proximal ends,
which are cephalated by expansion, appear to lie somewhat dorsad from the body-
axis. At their widest part the spicula are about one-eighth as wide as the corre-
sponding portion of the body; the apophysis is more or less uniform, and one-
fourth as long as the anal body-diameter, so that its proximal extremity appears
to lie opposite to or dorsad from the axis of the tail. The 25 supplementary
organs, hardly more than innervations, are papilloid and of slight elevation,
rather farther apart anteriorly, and occupy a distance five to six times as great as
the corresponding body-diameter. There is a single papilla-like ventral seta
close to the anus.
Habitat: Sand, Coco-plum Beach, Miami, Fla., U. S. A. Flemming to glycer-
ine jelly. Fig. 24, p. 245.
25. Neurella simplex n. sp. Striae resolvable with great difficulty into second-
ary elements. The narrow, sharply-defined wings begin near the head and end
on the tail. The cuticle appears to be naked, except that at the base of the
amphids there are elements of problematical significance and number. The neck
.2 8.7^ ij. ?57.' M. is cylindroid posteri-
.3 1.2 v 1.2 1.7 1.2 1- "" orly, conoid anteriorly,
2 s 3 13. "=n 92. convex-conoid toward
' '.^""i-V^'iz i.i'^i.z 1 ' the head. There seem
to be three lips surrounding the somewhat irregular but
more or less distinct, relatively small pharynx. Oesoph-
U)/ *W,/ agus cylindroid; at first one-half, near the nerve-ring
i@k$jjll one-third, as wide as the corresponding portion of the
V* 1 m neck; its lining is indistinct. The separation between
the oesophagus and the intestine was not very clear-cut. The thick-walled
intestine gradually becomes one-half as wide as the body; its section is made up
of two cells containing scattered granules of variable size, the largest about
one-eighth as wide as the body. Not until near the middle of the body does the
intestine acquire very definite characteristics. Anus more or less elevated.
Tail of the male, as far as seen, conoid; apparently only its tip was missing.
Located well toward the middle of the body there is a long, granular cell empty-
NEURELLA, ZYGONEMELLA . 247
ing forward; probably the renette cell. Excretory pore unknown. Nerve-ring
oblique, accompanied by distinct cells arranged in groups.
Habitat: "Sea-grass," shoal, two miles off,' Key West, Florida, U. S. A. Sub-
limate to balsam. The view of the tail of the female was slightly foreshortened'
the formula must be interpreted accordingly. Fig. 25, p. 246.
^.4_ _ _7_.3_ J3.6 -^t-" _ <&.&_ > 1 2
26. Zygonemella striata n. sp. 3.,i 4.1 4.6" 5.3^3.6 " I n addition to the
cephalic setae, scattered on the anterior part of the neck, there are a consider-
able number of other similar setae, some of which are longer than those near the
margin of the head. Lips three, massive but low, faintly bi-lobed; within these
there is a rather broad inner mouth consisting of three soft, low, flat lobes, which
appear to be extensions of the tissue of the oesophagus. These latter present
faint refractive elements, the expression of minute foldings of the lip tissues,
that make possible the great expansion necessary for the deglutition of the rela-
tively large diatoms constituting the food. In appearance the pharynx closely
resembles the lumen of the oesophagus. It would, in fact, be indefinable, were it
not for the pharyngeal swelling which is half as wide as the head, that is to say,
a very little wider than the remainder of the oesophagus. Immediately behind
the pharyngeal swelling the oesophagus diminishes gradually, so that where it
passes through the nerve-ring it is about set ft (6?) ..
two-fifths as wide as the neck; thence
onward it is cylindroid. The lining of the / lfl} -^ .(
oesophagus is a conspicuous feature
throughout its length. The tubular cardia
is prominent, about one-fourth as wide as
the base of the neck, and about one and
one-half times as wide as long. The intes- X 75(
tine is almost at once fully half as wide as the body and is separated from the
oesophagus by a broad and deep constriction. Its cross-section probably com-
prises only two cells. The cells contain scattered granules of small size and
rather uniform diameter. The lateral fields, about one-fourth as wide as the
body, contain cells packed with fine uniform granules. Renette unknown. The
tail of the male is conoid in such fashion that at the beginning of the final third
it has a diameter about equal to the width of two of the corresponding annules;
thence onward it is very nearly cylindrical. The anus is slightly raised, its
posterior lip elevated. The caudal glands are packed in a tandem series opposite
the anus and occupy a space somewhat longer than the anal body-diameter;
their ducts are narrow. Spicula acute, not quite as long as the anal body-diam-
eter; their width about equal to the width of one of the adjacent annules. They
taper in the distal fourths to slender, acute points. The posterior testis is only
about half as long as the anterior. Ten unicellular glands are a prominent fea-
ture of the anatomy of the male. (1) A pair of clavate glands immediately
behind the blind end of the reflexed posterior testis. Each of these glands has a
length nearly equal to that of the adjacent body-diameter, and empties through
a duct extending backward. The ducts have a width somewhat greater than
that of one of the adjacent annules. (2) Just behind the pair of glands already
mentioned is a second clavate pair of larger size and very similar; these are about
half as wide as the body and somewhat longer than the body is wide, and the
ducts extending backward from them have a width greater than that of two of
the adjacent annules. (3) Behind the second pair of glands there are six small,
pyriform glands, i.e., a set of three on each side of the body, arranged longitudi-
nally close together, but having separate ducts, also extending backward. It
248 ORDER CiTTOLAIMIA
has been impossible to determine with exactitude the entire course of the ducts
of these various glands, but most of them have been seen to be connected with
the rectum, and all are believed to be so connected, though it is possible that
some of them may deliver into a common duct before reaching the rectum. As
to the structure of these glands, the description of one of them will answer fairly
well for all the others. In the fixed specimens, the anterior extremity of each
contains a spherical nucleus with a strongly staining nucleolus : the nucleus lies
in the midst of chromatin matter which stains rather strongly with acid carmine.
The nucleus and chromatin occupy the anterior fourth, or third, of the glandu-
lar cell. The remainder of the contents is of a uniformly fine, granular nature.
This granulation is also characteristic of all the ducts.
Habitat: Punta Arenas, Pacific Coast of Costa Rica. Diatomivorous. Sub-
limate to balsam. Fig. 26, p. 247.
27. Margonema ringens n. sp. Striae unaltered on the lateral fields. Cuticle
apparently naked, but it is possible that through rough handling cephalic setae
fp/Jb may have been broken off, as was the case with some other
, specimens in the same collection. Lips three and double.
Neck cylindroid. Amphids faint. Oesophagus at first two-
subait thirds, near the nerve-ring one-half, and finally two-thirds,
_^ as wide as the corresponding portion of the neck; its lining
indistinct. There is a faint, rather flat cardia about half as
aw son wide as the base of the neck. The cross-section of the thick-
setsm walled intestine is made up of two cells. These transparent,
elongated cells have very distinct nuclei, but few and small
X75 inconspicuous granules. The intestine becomes at once two-
"-6Q- ' 9*- 2 * t 7 thirds as wide as the body, and is separated from
.9 / 1.2 1.2 1.5 i- 2 the oesophagus by a collum two-thirds as wide as
the base of the neck, and has a faint zig-zag lumen.
k. p 12: 'fl ^-^> 1.5. .From the anus, the posterior lip of which is ele-
vated, the prominent rectum extends a distance
about as long as the anal body-diameter. The conoid tail tapers from the anus.
The three ellipsoidal caudal glands lie in a loose tandem in the anterior two-
fifths of the tail. There are no caudal setae. The lateral fields are about
one-third as wide as the body, and contain both small and large nuclei. At a
distance behind the neck equal to twice the width of the body lies the ellip-
soidal renette cell, which is about as long as the body is wide and about half
as wide as long, It empties through an ampulla about as long as the neck is
wide, and about one-fourth as wide as long. This latter is connected with the
excretory pore by a very short duct. The nerve-ring surrounds the oesoph-
agus squarely, and is accompanied by distinct cells apparently not very defi-
nitely arranged. From the somewhat depressed, more or less continuous vulva,
the tubular vagina extends nearly half way across the body. The vagina is
bifurcated, each branch being about half as long as the body is wide. The
uteri are narrow. The eggs are three-fifths as wide as the body, and six times
as long as the body is wide. The narrow ovaries taper but little, and contain
about a dozen ova approximately in single file. At their widest part, the slen-
der, acute spicula are about one-eighth as wide as the corresponding portion of
the body. Their arcuate, cephalic portions, viewed in profile, appear to lie
somewhat ventrad from the body-axis. The subarcuate, rather slender, frail,
simple accessory pieces are joined together at the anus. The separate apophysis
MARGONEMA, LEPTOGASTRELLA
249
is uniform and one-fourth as long as the corresponding body-diameter. There
are thirty to forty low, about equidistant supplementary organs, of such a char-
acter that the ventral contour becomes crenate when the tail end is incurved;
the crenations are then nearly contiguous. There are a few, scattered ventrally
submedian setae on the tail. The acute ends of the spicula are minutely and
sharply curved through an angle of 180 degrees at the very tip. One male speci-
men was seen in which there were two renette cells, each with a separate duct for
some distance.
Habitat: Salavery, Peru. Marine. Sublimate to balsam. Fig. 27, p. 248.
28. Leptogastrella pellucida n. sp. Except for the setae near the head and on
the tail of the male, the cuticle appears to be naked. The neck is cylindroid
posteriorly, becoming faintly convex-conoid toward the rounded head, which
may be set off by an almost imperceptible, broad constriction opposite the base
of the pharynx. The membranous lips, are either six in number, or three and
each two-parted. The oesophagus is cylindroid. There is an elongated cardia,
one-half as long as the body is wide, and about two-thirds as wide as long. The
intestine, separated from the oesophagus by a shallow constriction, becomes
at once two-fifths as wide as the body, and then diminishes slightly so that it has
about one-third the width of the body. Its cross-section would appear to be
made up of not more than two cells. The intestine is so narrow as to give the
nema quite an unusual appearance. It is thick-walled and has an exceedingly
narrow lumen. Its cells are packed with exceedingly minute yellowish granules.
Correspondingly, the body-wall is unusually thick and muscular, and slightly
oblique longitudinal striations due to the refractions of the muscular fibres can
3-3
..9-?.? 1.2..
1.3 9. .... .-. .
'2. 2.5 2.9 3-* " 2-
be seen throughout the length of
the body. The lateral fields
appear to be about one-third as
wide as the body. The renette
has not been seen. Vulva slightly ^
elevated. The outstretched ovary
contains forty or more ova
arranged single file. The blind / cdl
end of the ovary lies not far behind
the nerve-ring. The eggs occur-
ring in the uterus appear to be <K .............
about as long as the body is wide
and one-third to one-fourth as
wide as long. The tail of the
male is conoid to near the termi-
nus, where it has a diameter about
one-fifth as great as at the anus.
Caudal glands are located in the base of the tail. There are no supplementary
organs, nor have any special papillae or setae been seen either in front of the
anus or behind it. The spicula slide in tubular accessory pieces.
Habitat: Marine mud, San Pedro, California, U. S. A. At first glance this
250
ORDER CYTOLAIMIA
nema appears to be a typical Monhystera, but careful examination fails to reveal
any such well-developed amphids as are characteristic of Monhystera. The
spicula are quite different in form from the typical spicula of Monhystera. The
intestine also is highly peculiar. Occurs also at Woods Hole, Mass. Fig. 28, p. 249.
_L 5-_3___-_.._r_8*"_ 'i >m i. ..
29. Dactylaimus aequalis n. sp. ^6 2.2 2.3 2.5 2. Cuticle naked.
Three of the six lips are somewhat more substantial than those alternating with
them. Distal thirds of the lips free, the remaining n/
portions webbed. From the head, the oesophagus con-
tinues to have the same diameter to near the oblique
nerve-ring, but then begins to swell gradually so that fh
finally it is two-thirds as wide as the base of the neck.
There is a small cylindroid cardia. The intestine,
separated from the oesophagus by a deep constriction,
becomes at once about two-thirds as wide as the body. ~^ = ^ f ^- ..^, ..
Its circuit appears to comprise about four cells. The ^
lumen of the intestine presents a refractive and distinct contour. From the
inconspicuous, slightly depressed anus, the rectum is considerably shorter than
the anal body-diameter. The distinct lateral fields are about one-third as wide
as the body and contain numerous cells whose nuclei are arranged in two indis-
tinct rows along the margins of the field, which they fill fairly well. Renette
unknown. The description is derived from a single young female, with the
vulva in process of development. The tail is conoid in such fashion that at a
distance from the anus about five times as great as the length of the anal body-
diameter, where the annules vanish, it has a width about one-sixth as great as
at the anus. An indefinite, but probably not considerable portion of the tail
of the specimen examined was possibly missing. Hence, the above formula may
be only approximately correct. The following formula is in terms of absolute
lengths expressed in microns: }]____ ?*____ w_- *?_ ^niojo.
Habitat: Fine marine mud, San Francisco Bay, California, U. S. A. Sublimate
to balsam. Fig. 29.
1.1 _._ _ Y 72._ 86-' 517
30. Xenolaimus striatus n. sp. !' *' ~ *' ** * ' " Cuticle naked,
and complicated, the annules retrorse posteriorly and the reverse anteriorly.
The twelve longitudinal wings extend to near the spinneret, becoming fewer on
the tail. The thick, somewhat digitate lips are united by a membrane. The
M & Set Jb \ set Sllbm portion of the head containing the pharynx is pro-
trusile and appears as if surrounded by a balustrade
composed of the anterior annules of the cervical
cuticle. The large, simple, regular, conoid phar-
ynx is fully three-fourths as long as the head is
wide. Each of the six lips bears a two-jointed
seta, and appears to be armed internally with a
slender, flexible element considerably longer than
the seta. In the illustration, what appear to rep-
resent two minute setae on the foremost annule of
the neck are probably the optical expression of an
exceedingly tenuous membrane surrounding the
head. Although the oesophagus was not plainly seen, it is evident that it is cyl-
indroid as in Trachynema. The intestine becomes at once three-fourths as wide
as the body. The anus appears continuous. The cells of the intestine con-
XENOLAIMUS, CYTOLAIMIUM
251
tain scattered granules of variable size, the largest of which are one-half as wide
as one of the annules. The conoid tail tapers from in front of the anus and
ends in a spinneret.
Habitat: Marine mud from near the government-dredged cut, Biscayne Bay,
Florida, U. S. A. Sublimate to balsam. Fig. 30, p. 250.
31. Cytolaimium exile n. sp. Cuticle thin, without setae except those on the
head. Lips with thin distal flaps as in Monhystera. The cylindroid oesophagus
is at first three-fifths, near the nerve-ring one-half, and finally three-fifths, as
wide as the corresponding portion of the neck. There is a conoid cardia one-
third as wide as the base of the neck. The thick-walled intestine, which has a
faint lumen, becomes at once three-fourths as wide as the body. Its cells contain
scattered granules of variable size, the largest of which, near the neck, are one-
fifteenth as wide as the corresponding portion of the body, but near the middle
of the nema are one-tenth as wide as the body. The conoid tail tapers rather
regularly from somewhat in front of the anus, but faster near the anus. No
clear evidence of the presence of caudal glands. The lateral fields are about
one-half as wide as the body. The narrow nerve-ring is accompanied by obscure
nerve cells. From the small, continuous, inconspicuous vulva, a small, more or
less weak, non-cutinized vagina extends inward one-third the distance across the
body. In the narrow, tapering ovaries, the ova are arranged single file. Only
one egg at a time occurs in each uterus. The eggs are three times as long as the
body is wide and appear about three-fourths as wide as the body. The tail of
the male is first conoid, then cylindroid in the posterior two-fifths, where it is
one-third as wide as at the base. The somewhat stout, rather blunt spicula are
strong, non-cephalated, and so situated that their proximal ends appear to lie
: --...-V- '-57-' n. ( , opposite the
^*.i body-axis. Ihere
T M w * 95.5 . is u a "fractive
-.- *" ...^....3.5.. short element in
front of the tips
fUbfh of the spicula. Accessory piece slender, appar-
ently strong, one-third as long as the spicula.
The 16 pairs of submedian, equidistant, discoid,
slightly-elevated supplements are not cup-
pli shaped, and are relatively less cutinized than
in well-developed Chromadora supplements.
The posterior pre-anal pair lies opposite the
distal parts of the spicula. Thence, forward,
X 750 placed at intervals about equal to three-fourths
the body-diameter, the organs occupy a space
eight to nine times as long as the anal body-diameter. The post-anal five pairs
occupy the anterior three-fifths of the tail. The discs are about one-fourth as
wide as the body, and one-fourth as wide as high, the distance between them being
about one and one-half times their diameter. There appears to be an innervated
element that projects from near the center of each disc. The ejaculatory duct,
which is co-extensive with the pre-anal supplementary organs, is one-half as wide
as the corresponding portion of the body. The vas deferens is one-half to one-
third as wide as the body. Each testis is at first about one-third as wide as the
body and cylindroid, but afterwards tapers. The anterior testis is much the
longer.
Habitat: Sand-bar opposite Miami River, Biscayne Bay, Fla., U. S. A. Sub-
limate to balsam. Fig. 31.
lit (3)
252
ORDER CYTOLAIMIA
32o. Rhabdocoma americanum n. sp. Type species. Cuticle thin, naked except
for the cephalic setae. Lips three. Wall to the pharyngeal cavity in optical
section showing three somewhat thickened elements, that are possibly minutely
transversely ribbed; these elements, however, are very smallfand difficult of
resolution. Neck somewhat conoid
anteriorly. Oesophagus at the
nerve-ring two-fifths, at the cardia
two-thirds, as wide as the corre-
, spending portion of the neck, and
containing glands, as is indicated
by fine granular matter in branched
dettUtfh . U trm -^ ff W/ X750 cavities. Cardia more or less
spheroidal, one-half as wide as the base of the neck. The rather thick-walled
intestine presents a faint lumen and becomes at once about one-half as wide as
the body; its cross-section presents but few cells. Anus continuous; rectum
about as long as the anal body-diameter. The intestinal cells contain granules
of variable diameter, the largest one-tenth as wide as the body. Doubly refrac-
tive granules occur in all parts of the intestine, but are not numerous; these tend
to have quadrate contours and do not present St. Andrew's crosses. The tail
tapers very gradually throughout, commencing well in front of the anus. Ren-
ette unknown. There is an anterior rudimentary branch to the female sexual
organ, about as long as the body is wide. From the rather large, more or less
depressed vulva the well-developed cutinized vagina extends inward three-fifths
the distance across the body. The elongated eggs are twice as long as the body
is wide. The broad, cylindroid ovary reaches three-fourths the distance back
to the vulva and contains very many ova, those of the two-thirds next the uterus
being arranged single file. The frail spicula are about one and two-thirds times
as long as the anal body diameter and are rather wide apart. Accessory pieces
faint. Supplements papilloid, twelve to sixteen, occupying a distance in front
of the anus ten to twelve times as long as the body-diameter, while a second
series of about eight, occurs on the neck. The members of the anal series are
somewhat farther apart anteriorly; of the cervical series, posteriorly.
Habitat: Sand among mussels, Devil's Island, Woods Hole, Mass. Fig. 32.
6. Rhabdocoma macrurum n. sp. L J -3 i.* %-^i.j " Very closely
resembles the preceding, but differs in the following respects: straight setae,
nearly as long as the head is wide, digitate, with a minute setose mucro; amphids
a trifle farther forward, somewhat elongated; apparently four, submedian, min-
ute, short setae opposite the posterior margin of the amphids; accessory pieces
one-half as long as the spicula and parallel to them.
Habitat: Sulphurous sand, Bay of Naples, toward Vesuvius, 1888.
.35 2.6 7.6 l -44-" 81.
33. Didelta maculatum n. sp. h* L5 J - 8 1>2 * " Cuticle, which is
above medium thickness and naked except for the setae on the head, is charac-
terized by the presence of peculiar transversely-elongated refractive subcuticular
DIDELTA, DASYNEMA
253
markings, reminiscent of the bubbles in defective window glass. The simple,
subregular, somewhat asymmetrical, napiform pharynx is about one-third as wide
as the head. On the dorsal side of the base of the pharynx there is a more or less
glottoid, low, flat elevation, so that the more or less refractive dorsal wall of
the pharynx appears only about half as v^ ~Jt f*\
long as the ventral wall. Posteriorly J ^ t /*
the neck is cylindroid, anteriorly, more
or less conoid. The elliptical amphids
are in reality spirals of about one wind.
They occur on large, somewhat equilat-
erally triangular or deltoid areas on the
sides of the head; hence, the name
Didelta. The oesophagus is at first
about three-fourths, near the nerve-
ring one-half, and finally two-thirds, as
wide as the corresponding part of the
neck. The lining is distinctly indi-
cated by a more or less zig-zag, refrac-
tive line; the musculature is coarse and
colorless. There are no valves, and there is no cardia. The thick-walled intes-
tine, which has a distinct refractive lining, becomes at once three-fourths as
wide as the body; its cross-section being composed of about six cells. It is sep-
arated from the oesophagus by a collum one-third as wide as the base of the neck.
The cells of the intestine are packed with more or less uniform granules, having
a diameter about one-ninetieth that of the body. Arranged in elliptical clusters,
they give rise to a distinct tessellation. The tail, which tapers from the anus,
is first conoid, and then more or less cylindroid in the very narrow posterior
half. It really tapers throughout, but is nearly cylindroid in the setaceous
part. There is no spinneret. The lateral fields are about one-fourth as wide
as the body. The nerve-ring is of medium size, and is accompanied by
obscure nerve cells. From the rather inconspicuous, but somewhat elevated
vulva, the cutinized vagina leads inward two-fifths the distance across the body.
The tapering ovaries were not favorable to detailed observation.
Habitat: "Sea-grass," shoal, two miles off Key West, Florida, U. S. A. Flem-
ming to glycerine jelly. Fig. 33.
setsubcph (6)
X750
18.4
3-7
62.5
14
34. Dasynema sexalineatum n. sp. 3 ' 8 ' 3 :7. *i 2.4 Striae resolv-
able into secondary, elongated elements. Annules retrorse posteriorly, and the
reverse anteriorly. Cuticle naked except for the setae on or near the head.
yl! Lips three, more or less distinct, thin, apparently
acute, possibly conoid, mobile; the appearance is
I that of three segments of the head, each armed at
the summit with a short, inward-pointing, dark,
cutinized apex, having an inward stroke. There
does not appear to be a distinct cardia, but a num-
, lf , } -~^j,. - / r f small cells forming the beginning of the
intestine are manifestly different in structure from
those directly behind. The rather thin-walled intestine, which has a more or
less distinct, refractive lumen, soon becomes two-thirds as wide as the body,
and its cross-section is composed of two to four cells in which there are few or
'xtqAM
setsubcph
mph
254
ORDER CYTOLAIMIA
mr
*375
no granules. From the anus, the posterior lip of which is elevated, the promi-
nent rectum leads inward a distance one and one-half times as great as the
anal body-diameter. The tail is sub-conoid, at first co-
noid, then more or less cylindroid. The elongated caudal
glands appear to lie in the anterior half of the tail.
Habitat: Eel-grass, Woods Hole, Mass., U. S. A. Sub-
limate to balsam. Described from a young specimen.
Fig. 34a, p. 253; Fig. 346.
35. Linhomoella exilis n. sp. The shorter cephalic setae
are differentiated at the extremity, suggesting that they
bear special sensory organs. Cuticle naked except for the
setae on or near the head. Lips apparently confluent.
Possibly there are papillae immediately around the mouth
opening. It sometimes appears as if there is a minute
pharynx like that of Monhystera, but this may be a decep-
tion due to the structure of the front part of the oesopha-
gus; possibly there is no true buccal cavity. Neck cylin-
droid. The more or less cylindroid oesophagus is at first
three-fifths, near the nerve-ring two-fifths, and finally two-
thirds, as wide as the corresponding portion of the neck.
tt It is colorless and has a fine musculature. The cylindroid
cardia is three-fourths as wide as the neck. The intestine, which is separated
from the oesophagus by a collum three-fifths as wide as the base of the neck,
becomes at once three-fourths as wide as the body. Near its anterior end, how-
ever, there is a broad, shallow constriction, in which region its lumen is faint.
Anteriorly the walls are thick, while posteriorly they are thin. A cross-section
of the intestine is probably made up of about three cells. These cells contain
scattered granules of variable size, the largest of which are about one-twelfth
as wide as the body and appear to have the structure of spherical shells. The
arcuate tail tapers from the anus to the terminus, where it is one-fourth as wide
as at the anus. Caudal , It
glands were not seen. : ' " ->3-3
The caudal setae are '
very minute and very : 2 - ^ ''- 1 *.^^.*fci
inconspicuous, five to
six on each ventrally submedian line. From the con-
spicuous, fairly large, elevated vulva the cutinized
vagina extends one-third the distance across the body. w
The slender eggs are ten times as long as the body is
wide, and appear to be about three-fourths as wide W
as the body. The narrow tapering ovaries contain
twenty or more ova arranged single file. The proxi- ompu.
mal extremities of the stoutish, tapering, acute,
rather strong spicula appear to lie ventrad from the x 750
body axis, and are not materially cephalated. The
part of the accessory piece near the spicula is refractive; the apophysis, however,
is faint, and a little more than half as long as the anal body-diameter. As to
supplementary organs, there are almost invisible ventral innervations, equi-
distant and separated from each other by spaces about two-thirds as great as
the body-diameter. The ejaculatory duct and vas deferens are about one-third
as wide as the body. The tapering testes are very narrow.
LINHOMOELLA, NANNOLAIMUS 255
Habitat: Sand-bar, Biscayne Bay, off the mouth of the Miami River, Florida,
U. S. A. Flemming to glycerine jelly. Fig. 35, p. 254. The almost impercep-
tible constriction occurring in the cephalic region, as shown in the illustration,
is somewhat more marked when seen dorso-ventrally; the amphids are located
in the midst of a broad and shallow depression.
...- _____ ..... 1 ..
36. Nannolaimus guttatus n. sp. / 1A U5 l -5 ** *-5 Cuticle of me-
dium thickness, naked except for the cephalic setae, of which there is a circlet of
ten, with a circlet of six immediately preceding it. There are, however, a few,
scattered setae on the neck, one-third as long as the neck is wide, arranged at
right angles to the surface. Lips confluent, very small, thin and minute, prob-
ably six in number. No labial papillae have been seen. Pharynx almost non-
existent, simple, conoid. Neck cylindroid. The oesophagus is at first one-half,
near the nerve-ring two-sevenths, and finally two-thirds, as wide as the corre-
sponding portion of the neck; its lining is subdistinct, wtnJi/fi)
its musculature fine and colorless. There is a hemi- "" --*i*L '
spherical cardia, one-fourth as wide as the base of the
neck. The thick-walled intestine, which is set off by a
collum one-fourth as wide as the base of the neck,
becomes at once two-thirds as wide as the body. Ante-
riorly its lumen is faint, but posteriorly it is distinct, set
The cross-section of the intestine is composed of about
three cells. The granules contained in these cells are
scattered to numerous, and are of variable size, the
largest having a diameter equal to the width of two of the adjacent annules.
They have the appearance of hollow shells, more or less thick-walled. The
conoid tail tapers from the anus to its terminus, which is one-third as wide as
its base. Though the caudal glands were not clearly seen, they appear to be
broadly saccate and to be arranged in a close tandem behind the anus in the ante-
rior half of the tail. There appear to be about three slender, somewhat cylin-
droid, subacute setae on each submedian line on the tail. The lateral fields are
two-fifths as wide as the body. The huge renette cell begins at the cardia and
extends backward a distance equal to the length of the neck. It is two-fifths
as wide as the body, and, of course, is not reflexed. It is granular and possesses
a large nucleus. The elongated ampulla is one-third as wide as the head and emp-
ties through a short duct near the base of the lips. Vulva more or less continu-
ous, small; cutinized vagina of medium size. The thin-shelled, elongated eggs
are probably five to six times as long as the body is wide. According to the con-
dition of the uterus, the broad tapering ovaries reach from three-fifths to the
whole of the distance back to the vulva. They contain about a dozen ova
arranged more or less single file, except near the blind end.
Habitat: Sand, Cape Florida, Biscayne Bay, Florida, U. S. A. Flemming to
glycerine jelly. This genus resembles Cyatholaimus more or less but has no
onchia and the excretory pore is farther forward. The labial features are small-
er and less definite than in Cyatholaimus. It is notable also that no pores are
to be seen in the cuticle. The oesophagus ends behind in an almost impercep-
tible elongated swelling. The color of the ocelli, through oversight, was not
noted. Until the male is known, the affinities will remain doubtful. Fig. 36.
256 ORDER ISOLAIMIA
IV. Order Isolaimia
37. Rhadinema flexile n. sp. -s/ 1-2 1.5 i-3 ' Cephalic setae
3-jointed; cuticle otherwise naked. The thick, small lips confluent. Pharynx
exceedingly minute, two-thirds as deep as the head is wide; wall characterized
by six longitudinal elements of minute size, exactly parallel to the axis of the
head, so that the pharynx appears to be a more or less shallow, cylindroid or
"Xt Ctth (4) P r i sm id CU P> two-thirds as deep as wide. The lining of
the oesophageal canal is more or less modified as far back
^fi/mtphlj) as the base of the amphids. The circumference of the
amphids is almost imperceptibly broken on the dorsal
The somewhat cylindroid oesophagus is almost
imperceptibly swollen in the posterior fifth. At first it
is three-fifths, near the nerve-ring one-half, and finally two-thirds, as wide as
the corresponding portion of the neck. The lining is subdistinct. There is a
more or less hemispherical cardia three-fifths as wide as the base of the neck.
The thick-walled intestine, which has a distinct, refractive, more or less zig-zag
lumen, becomes at once three-fourths as wide as the body. Its cells are packed
with uniform colorless granules of variable size, the largest of which are one-
sixteenth as wide as the body. They do not give rise to more than a faint tessel-
lation. The tail is conoid. The more or less narrow elongated caudal glands
are arranged in a loose tandem behind the anus in the anterior third of the tail.
The elongated renette cell lies at a distance behind the base of the neck equal to
twice the body-diameter; it is one body-width long, about one-third as wide as
long, and contains a rather large nucleus. The rather broad oblique nerve-ring
is accompanied by somewhat obscure nerve cells.
Habitat: Clear, "white" sand, 5 feet of water, cove at the entrance to Buz-
zard's Bay, Mass., U. S. A. Sublimate to balsam. Fig. 37.
4 ?__ __">_} 5. 3'j _ 94. 7_
38. Protrellus aureus n. sp. - 7 **/ 3 -_ ' i-' " Annules as much as
20 microns wide. Striae are visible throughout the length of young specimens,
which also differ from the adults in not having the cuticle inflated on the neck.
No setae or amphids. The conoid neck ends in a truncate head, bearing a
lip-region set off by constriction, and apparently composed of six lips. There
is at least one papilla on each lip. The prismoid pharynx is half as wide as deep.
The major part of the oesophagus is simple and cylindrical, having the same
width as the lip-region, and is separated from the cardiac bulb by a broad con-
striction. The triquetrous lining of the oesophageal tube is easily seen, and
ends in a distinct manner near the base of the pharynx. The intestine is modi-
fied, i.e., enlarged, to form a sort of "stomach," for a distance equal to twice
the width of the body; thereafter its width does not exceed one-fourth that of
the body. The length of the rectum is one and one-half times that of the anal
body-diameter, and it has the peculiarity of lying close to the ventral side of the
body. Region of the ventral excretory pore conspicuously marked by a large
colorless ampulla. The lateral fields are one-third as wide as the body. The
nerve-ring encircles the oesophagus squarely. The anterior fourth of the tail
is somewhat hemispherical, and at the end of this part one-third as wide as at
the anus; thence onward it is conical to the acute terminus. The large, ele-
vated, and very prominent vulva is situated far forward, somewhat in front of
PROTRELLUS, COLPURELLA 257
the cardiac bulb, in fact, and from it the vagina and long single uterus are di-
rected backward, the vagina being highly muscular, and in its contracted condi-
tion thrice as long as the body is wide. The uterus ends and the ovaries begin
near the commencement of the posterior third of the body. There are numerous
fusiform, slightly curved eggs, measuring 50 X 104 microns, the shells of which
acquire a bright yellow color on entering the uterus. In many cases these golden-
shelled eggs give the nemas, when seen with the unaided eye, a bright yellow
appearance. The ovaries extend forward, then backward again; the ova are
arranged single file. The eggs in the proximal part of the ovaries and in the
uterus have the less-pointed end saddled with a peculiar organ. The saddled
end of the egg is directed away from the vulva.
.8 10. 21. M W. _
z.~5 iTv *~6 7.8~-f-TjT ' " On the very much smaller male, the plain,
transverse striae measure 3 microns apart on the neck, and 2 microns on the
body. There is no distinct boundary between the rounded head and the conoid
neck. The lips are very small and connate. Small, low, refractive papillae
occur near the margin of the head. The somewhat irregular pharynx is half as
deep as the head is wide, and about two-thirds as wide as deep. The anterior
three-fifths of the oesophagus is a tube two-fifths as wide as the middle of the
neck, the remaining two-fifths being flask-shaped, the neck of the flask being
somewhat narrower than the anterior tube, and the ovoid bulb being two-thirds
as wide as the neck. Cardiac collum, though shallow, distinct. The thin-
walled intestine is at first at least two-thirds as wide as the body. The nerve-
ring encircles the oesophagus squarely. The tail diminishes rapidly behind the
anus, until only one-third as wide as at the anus. There are three pairs of papil-
lae, all sub-ventral : one pair of conical papillae, the largest of all, just in front
of the anus; a second smaller pair somewhat behind the anus; and a third pair
near the middle of the tail. The single linear, acute spiculum makes an angle
of 45 with the axis of the body; its length equal to that of the narrow part of the
tail. Testis-flexure such that the cardia lies half way between it and the nerve-ring.
Habitat: Rectum of the cock-roach, Polyzostaria melanaria Erich., Moss Vale,
New South Wales, Australia, August 17, 1894. Examined in water.
(.6)7.6 . *>. '=* 98. 1( .
39. Colpurella fontinalis n. sp. UJ l - 9 " 2 ' 2 Cuticle thick,
naked. No labial papillae. Pharynx very long and tubular.
Neck cylindroid posteriorly. The oesophagus is at first three-
fifths, near the nerve-ring two-fifths, and finally two-thirds, as
wide as the base of the pharynx. It is a little narrower through
the middle, so that one may detect a faint posterior swelling.
No cardia. The thick-walled intestine, which has a faint
lumen, is separated from the oesophagus by a collum one-fourth
as wide as the neck, and becomes at once one-half as wide as the
body. Numerous, minute, uniform granules occur in the cells X 750
of the intestine. Renette unknown. Female unknown. Five
somewhat equidistant, papillate supplementary organs, one-
third as high as the cuticle is thick, occupy a distance equal to
two and one-half times the length of the body-diameter. The
posterior supplement is near the proximal part of the spicula.
The organs are wider apart anteriorly. Oblique copulatory IfOl.
muscles coextensive with the supplements. Exact form of the testes unknown.
Habitat: Spring, at Country Club, Washington, D. C., U. S. A. Sublimate to
balsam. Fig. 39. n, designates a caudal pocket, and not the anus, which is
farther forward.
258 ORDER ISOLAIMIA
40. Pycnolaimus pygmaeus n. sp. *? 6 - TJ 7.7 4.9 ' " Cuticle thin
naked. Near the middle of the body the very narrow, exceedingly minutely
crenate wings occupy a space about equal to the width of two annules of the
cuticle. Neck conoid. From the amphids an internal element extends inward
and backward a distance twice as great as the width of the corresponding portion
of the neck. Lip-region difficult to decipher. Cephalic cuticle very thick, espe-
cially near the base of the lips. When the head is viewed in profile and in optical
section there are seen connected with this thickened portion of the labial cuticle
elements that extend forward over the vestibule. At first sight these extensions
appear to be thin, cutinized flaps, that are very minutely transversely striated.
A careful examination, however, appears to indicate that they may have some-
what the structure of odontia, inasmuch as a short distance behind the apices,
which are decidedly sharp, the inner contours curve in toward the axis of the
head, and the longitudinal section of the elements, including the bases, above
described, appear claw-shaped. The dorsal and ventral elements, thus viewed,
are very much alike. Concentrating attention on either lateral surface of the
head one finds, opposite the axis, two elements which extend forward parallel
to each other and then bend toward the axis, arching inward to meet the dorsal
and ventral elements already described, and appear to be the median elements
of lateral labial organs. These elements are not so finely striated as the labial
elements first mentioned, and appear to be slightly darker. The napiform
vestibule leads to the pharynx, the entrance to which seems to be nearly closed
mnd by a very slight curvature on the anterior part of one of the cutin-
ous elements marking its contour. The oesophagus diminishes
, . slightly in diameter as it passes backward, so that its middle part
1 is hardly two-fifths as wide as the corresponding portion of the
neck. It then diminishes more rapidly, so that just in front of the
aw Jw?S"* cardiac bulb it is only about one-third as wide as the corresponding
spn jfeJ x75o portion of the neck. There is no vestige of a median bulb. Cardiac
bulb somewhat pear-shaped, or sub-spherical, three-fifths as wide as the base of
the neck, and containing a rather complex central valve half as wide as the bulb
itself. Two small, refractive elements occur one in front of the other in the midst
of the valve. There is a sub-spherical cardia one-third as wide as the base of
the neck. The intestine becomes at once three-fourths as wide as the body;
its cross-section presents apparently only two cells. These cells contain granules
of various sizes and kinds; the largest and clearest are spherical, and have a
width two to three times that of one of the annules of the cuticle. The smaller
and darker granules are not distinctly spherical and vary in size down to those
of very minute size. From the inconspicuous but very slightly raised anus, the
refractive rectum extends inward a distance a little greater than the anal body-
diameter. The tail is conoid from the anus, but is convex-conoid at the termi-
nus. The description is derived from a specimen much too young to give any
indication as to the position and form of the sexual organs. The measurements
must be correspondingly interpreted.
Habitat: From green-house soil, Ann Arbor, Mich., U. S. A. Fixed in Flem-
ming; examined in water. Fig. 40.
41. Isolaimium papillatum n. sp. Cuticle rather thin, naked. Neck convex-
conoid anteriorly. Cuticle with surface innervations along the edges of the
lateral field. Nerve-ring oblique. Pharynx tubular, one-sixth as wide as the
head measured opposite its base. Tail of the male conoid, slightly arcuate, a
ISOLAIMIUM, COINONEMA 259
little longer than the anal body-diameter, blunt, its ventral contour nearly
straight, its dorsal contour arcuate. The rather simple, blunt, uniform, more or
.**. A 5 . ."'. 53 !". .9-. 3.9.. less slender, arcuate
LZ w ''* spicula are about as
.5-. 2 . A 6 . . r*r. .** , 8 long as the anal body-
diameter. Their non-
cephalated proximal ends lie ventrad from the body-
axis. The frail, slender, arcuate accessory piece is
parallel to the spicula and one-third as long; at its prox-
imal end it has a very small, backward-pointing apoph-
ysis from which muscular strands pass forward to the
dorsally submedian lines and backward to the ventral
subait field near the middle of the tail. The six papilloid or
mammiform, sub-equidistant supplements occupy a
X 750 space about three times as great as the anal body-diam-
eter. Each comprises about six annules of the cuticle
and has the same slightly crenate contour as the ventral surface. The tail bears
four pairs of flattish, conoid papillae, a little behind its middle; one dorsally
submedian, one lateral, one ventrally submedian and one subventral.
Habitat: Soil, Plummer's Island, Potomac River, Virginia, U. S. A. Flem-
ming to glycerine jelly. Fig. 41.
42. Coinonema punctatum n. sp. Lips thick. Neck conoid. Eye-spots two,
far apart, brown to yellow, solid, with backward connections. The cylindroid
oesophagus is at first one-half, at the nerve-ring one-third, and finally also one-
third, as wide as the corresponding portion of the neck ; lining subdistinct. There
is a cylindroid cardia one-fourth as wide as the base of the neck. The intestine,
set off by a collum one-fifth as wide as the base of the neck, becomes at once
three-fourths as wide as the body. Anteriorly it is thick-walled, posteriorly
thin-walled. Its cross-section is composed of four to five cells. These cells
contain numerous granules packed together in such a way as to give rise to a
faint tessellation. The granules are of variable size, the largest set subm \ Ib / ytqih
being one-tenth to one-sixteenthjas wide as the body. The anus
is continuous, the rectum three-fourths as long as the anal
body-diameter. The conoid tail tapers from the anus to the
rather minute spinneret. The three, broadly-saccate caudal pw Lfe
glands lie hi a close tandem in the anterior third of the tail. ' .,
The ellipsoidal renette cell stretches along behind the base of (f^llfe
the neck for a distance equal to 1 9 M > 52 i 87 jfe^lr^^t
twice the width of the body; it 14; H IT? M aTT* 1 ' " #/j V//.'
is two-thirds as wide as long. ^ 13 5 _^ ^
From the continuous, rather i.2/ 2.3 2.4 2.7"~^2.2 ?1-
inconspicuous vulva, the rather weak, non-cutinized, medium-sized vagina leads
inward one-third the way across the body. The eggs occur one at a time in each
uterus, and are one and one-half times as long as the body is wide. They appear
elongated in form and are deposited after segmentation begins. In the medium-
sized, tapering ovaries are ten to twelve ova arranged single file. The acute
spicula are rather frail and slender. Their proximal ends appear to lie ventrad
from the body-axis. A refractive "chord" appears to subtend the arc of the
spicula. The rather frail, somewhat slender, arcuate accessory pieces have an
260 ORDER ISOLAIMIA
applied part one-third as long as the spicula, and projecting at right angles to
this is a uniform, blunt apophysis, one-half as long as the anal body-diameter
having its proximal end opposite the axis of the tail. The testes are wide and
more or less tapering.
Habitat: Key West and Biscayne Bay, U. S. A., on algae. Flemming to glyc-
erine jelly. Fig. 42, p. 259.
43. Rhynchonema cinctum n. sp. Annules of the cuticle retrorse posteriorly,
the reverse anteriorly. Neck cylindroid, very rapidly narrowing just behind the
head, and thence nearly cylindroid, so that the entire head
qJlsetUOl forms a kind of flexible beak. There are no eye-spots. Co-
tstibcph n id oesophagus at the nerve-ring two-fifths, and finally one-
half, as wide as the corresponding part of the neck; it has a
(" fine colorless musculature with no indication of glands. The
lining is indistinct. There is no cardia. The intestine, set
off by a collum one-fifth as wide as the neck, becomes at once
three-fourths as wide as the body. It has a distinct refrac-
5) 7 3 16 25. '-72 89. tive lumen and is thick-walled; its cross-section
'(.8)'i.V "i5' : "3-V " '3.4 '2:9 presents two to three cells. From the continu-
(.5) 7.4 16. 26. *-M 87. > 5 us anus, the rather inconspicuous though
'(.9) 'i.V ' 3-3' '3.'?' ' ' j.j'f^M cutinized rectum is three-fourths as long as the
anal body-diameter. Only the first few cells of the intestine show granulation.
The conoid, sub-arcuate tail tapers from the anus to the non-striated spin-
neret, whose width is about equal to that of three of the caudal annules. At
the base of the spinneret there are always about three minute nuclei that stain
strongly. The ellipsoidal caudal glands form a close tandem in the anterior
two-fifths of the tail. The lateral fields are about one-third as wide as the
body, but are more or less indistinct. Renette unknown. In the vicinity
of the vulva about eight of the annules present simply a crenate, instead of
a serrate contour. The broadly elevated vulva is rather conspicuous, particu-
larly in front. Vagina small. A mass of small sperm cells has been noted near
the vulva. The eggs are about eight times as long as the body is wide and one-
twelfth as wide as long. They are granular ^and have a prominent central
nucleus. The narrow cylindroid ovaries contain ova arranged single file. The
spicula of the male, about as wide as one of the adjacent annules, are slender,
rather frail, and sub-acute, and when seen in profile appear to have their proxi-
mal ends about opposite, or a little dorsad from, the body-axis. There is a
slender, frail accessory piece. The three minute papilloid supplementary organs
occupy a space three times as great as the body-diameter, and are about one
body-width apart; the posterior member is about two body-widths in front of
the anus. They hardly more than accentuate the annules on which they occur,
but are rendered visible by carmine stains. The ejaculatory duct is one-fourth
as wide as the corresponding portion of the body, the cylindroid testis one-half
as wide.
Habitat: Salaverry, Peru, near low tide mark; marine. Rhynchonema is com-
posed of a considerable number of species occurring in at least the Atlantic and
Pacific Oceans. With low powers it is difficult to distinguish the head end from
the tail end. The flexible, narrow head suggests the functions of a beak. One
may imagine it to probe the depths of some receptacle containing food, for
instance the neck of an algal oogonium. However, nothing is known with cer-
tainty concerning the food habits. Fig. 43.
LAIMELLA, ILLIUM
261
1.3 5-4 9.2 "-3?-". . .70.. . 1
44. Laimella longicauda n. sp Li" 'i.j/ ' to ..... i* 1-7 ' " Striae difficult to
detect, but resolvable into almost invisible dots. Cuticle naked. Labial papil-
lae obscure. Pharynx closed, inconspicuous, but undoubtedly present. There
is a slight thickening or extra-refractiveness at one portion of the pharyngeal
wall that suggests the presence of an extremely minute onchium. The cylindroid
oesophagus near the nerve-ring is two-fifths as wide as the neck, and ends in an
ellipsoidal valveless bulb three-fourths as wide as the base of the neck. The
oesophagus has a fine colorless musculature. Hemispherical cardia, two-sevenths
as wide as the base of the neck. The thick-walled intes-
tine, set off by a cardiac collum one-fifth as wide as the
neck, becomes gradually five-sixths as wide as the body,
its cross-section presenting about six cells. From the
somewhat depressed anus, the rather prominent cutin-
ized rectum extends inward a distance equal to the anal
body-diameter. The colorless, scattered to numerous
intestinal granules are of variable size, the largest of
them at first only twice as wide as one of the annules, but
near the middle of the body six to eight times as wide.
Tail setaceous, but conoid for a distance six times as
great as the anal body-diameter, at which distance it is one-fifth as wide as at
the base; thence it tapers very gradually to the terminus. It is very doubtful
if there is a spinneret. There are elements in the base of the tail, simulating
caudal glands, but no definite ducts have been seen, and the terminus seems
too fine to afford space for a spinneret. About six very slender caudal setae,
each about two-thirds as long as the anal body-diameter, occur on each of the
four submedian lines. Similar setae occur throughout the body. The lateral
fields are two-fifths as wide as the body. The large, non-granular, elongated
renette cell lies just behind the base of the neck, and empties through an ellip-
soidal ampulla, one-third as wide as the neck. The broad, oblique nerve-ring
is accompanied by rather obscure nerve cells. From the small, more or less
continuous vulva, the moderate-sized, conoid, cutinized vagina extends three-
fifths the distance across the body. The elongated eggs are one to one and one-
half times as long as the body is wide. The ellipsoidal sperm cells in the uterus
are granular and about half as long as the body is wide. The cylindroid ovaries
contain at least ten ova, arranged single file.
Habitat: Algae, Key West; also mud-flat, Biscayne Bay, Florida, U. S. A.
Flemming to glycerine jelly. Fig. 44. Terminus, trm, shown foreshortened.
* 750
45. Illium exile n. sp. - 4 -^ i- 1-1 .e >2 ' 5 " Cuticle naked. Neck co-
noid. Oesophagus conoid, finally about three-fourths as wide as the base of the
neck. Cardia elongated, half as wide as the base of the neck. The intestine
amoh \arna becomes at once about two-thirds to three-fourths as
I \ wide as the body. Its cross-section appears to be
\j/spn made up of about six cells. The posterior lip of the
anus is slightly elevated. From it there extends
inward the rather strongly cutinized rectum, which
is about as long as the anal body-diameter. The lateral fields are a little more
than one-third as wide as the body. The ventral gland is a much elongated
cell, lying at a distance behind the base of the neck equal to about three to four
body-diameters, and having a width about one-fourth as great as that of the
corresponding portion of the body. There is a distinct ellipsoidal ampulla
262
ORDER ISOLAIMIA
one-third as wide as the middle of the neck, connected with the excretory pore
by a short, rather sharply curved, minute duct. The caudal glands are located
in a tandem series a considerable distance in front of the anus, that which is
farthest forward being somewhat farther from the anus than is the spinneret.
The tail is conoid in the anterior three-fifths in such a fashion that at the begin-
ning of the fourth fifth it has a diameter about one-fourth as great as at the anus;
thence onward the tail is cylindroid to the terminus which bears a slightly oblique
spinneret. From the inconspicuous vulva the rather strongly cutinized vagina
leads inward more than half way across the body. The ovaries reach about two-
thirds the distance back to the vulva, at any rate in the only specimen so far
examined, which was a rather immature female. Nothing is known concerning
the number, size and structure of the eggs.
Habitat: Green algae, Carlisle Bay, Jamaica. Fig. 45, p. 261.
46. Cynura uniformis n. sp. ' 9
" The rather thick cuticle
is naked. The two wings, occupying a space one-third as wide as the body,
begin near the head and end on the tail. Pharynx very strongly reminiscent
of that of Plectus; is continued by a longer posterior
part, whose presence is indicated mainly by alterations
in the lining. This part, however, is rather easily dis-
tinguished from the oesophagus proper. Neck cylin-
droid posteriorly, convex-conoid anteriorly. The cylin-
droid oesophagus near the nerve-ring is three-sevenths,
finally three-fifths, as wide as the corresponding
portion of the neck. The radial oesophageal tissue con-
. I i\i\\ tinues to the middle of the anterior chamber of the
pharynx, but is narrower there. There is the faintest
/.' ;; feIHi 5g2sL lV possible break in the lining of the oesophagus near the
oe nerve-ring, possibly the vestige of a bulb. There is a
large cylindroid cardia, three-fifths as wide as the neck.
The thick-walled intestine becomes at once two-thirds
as wide as the body; while its lumen is faint anteriorly,
it is very pronounced posteriorly. From the elevated
anus, the strongly-built, prominent rectum, the lining
of which is somewhat cutinized, extends a distance
three-fourths as great as the anal body-diameter. The
cells of the intestine are packed with granules of variable
size, the largest of which have a width equal to that of
X 750 one of the annules. The tail is cylindroid, then conoid
in the posterior three-sevenths. The blunt, conoid terminus is strengthened by
a large, obliquely-truncate cap, the several component plates of which are mi-
nutely punctate. The caudal glands probably lie in front of the anus; they end
in the terminus in three simple, prominent ampullae. There are no caudal setae.
The lateral fields appear to be about one-third as wide as the body. The granular
ellipsoidal renette cell, two-thirds as long as the body is wide, and half as wide
as long, lies about two body-widths behind the base of the neck. The medium-
sized nerve-ring is accompanied by obscure nerve cells. From the medium-
sized, more or less elevated, refractive and therefore conspicuous vulva, the
vagina leads inward half way across the body. The inner wall of the vagina
is also cutinized. The short, broad, cylindroid ovaries contain about fifteen
ova arranged somewhat irregularly. Ellipsoidal granular spermatozoa, seen in
the uteri, are one-eighth to one-tenth as wide as the body of the female.
CYNURA, XINEMA
263
Habitat: Seaweed, washed up at Ocean Beach, Miami, Fla., U. S. A., after a
storm. Flemming to glycerine jelly. Only a single specimen seen. Fig. 46, p. 262.
47. Xinema perfectum n. sp. Neck conoid. Somatic setae papilloid, or nearly
so; cuticle becoming much thinner in the region of the lateral organs, thickening
again in front of them and becoming again as thick as ever on the front of the
head. The oesophagus continues to have the same diameter until after it passes
through the nerve-ring, when it begins to expand gradually, until finally it is
nearly three-fourths as wide as the base of the neck. The two ventrally sub-
median sectors of the oesophagus appear to contain glands, at least in each there
extends from near the posterior end of the oesophagus forward a minute duct,
which stains distinctly with carmine. This duct can be traced at least as far
as the nerve- .4 .4.5 : 8.7 "-&-" 94.3 y23
ring. There does """>''""" .s Of* '
not appear to be .3 4.4. s.s> -M-" 94. ^ 24
any very distinct W*"xi/":i i'.ir^U
cardia. The intestine gradually becomes three-
fourths as wide as the body. In cross-section
it is composed of six to eight cells, containing
relatively large nuclei and numerous small, uni-
form granules. The renette cell, nearly as long
as the body is wide and about one-third as wide #"
as long, is located just behind the base of the neck. Its ampulla, about one-
fourth as wide as the corresponding portion of the neck, is connected with the
excretory pore by means of a very short duct. The lateral fields are about one-
third as wide as the body. The nerve-ring surrounds the oesophagus squarely.
The tail tapers from considerably in front of the anus, being convex-conoid in
such a fashion that at the beginning of the final fifth it has a diameter about
one-fifth as great as at the anus, or even less; thence onward, the tail expands
a little. The caudal glands are located near the anus. From the depressed
vulva, the vagina leads inward more than half way across the body, where it
joins the two symmetrically-placed uteri; its internal walls are distinctly cutin-
ized. The ovaries contain twelve to fifteen ova arranged single file. Occasion-
ally the tips of the ovaries are reflexed. Apparently the females possess a pair of
spermatheca, which when filled reach to near the bases of the ovaries. The sper-
matozoa appear to be elongated. The elongated eggs are about twice as long
as the body is wide and a little less than half as wide as long; they have been
seen in the uteri one at a time. Tail of the male a little more bulky than that of
the female and a little narrower in the posterior part, which instead of constitut-
ing one-fourth of the tail, constitutes about one-third. No supplements or
special setae. Spicula consisting of two, equal segments, one in front of the
other. The muscular tunic enclosing the spicula is continuous at the elbow.
While the spicula and their sheaths tend to stain in acid carmine, the accessory
pieces do not do so, but retain a slight yellowish color of their own. The caudal
glands are located alongside the accessory pieces, both in front of the anus and
behind it. The ejaculatory duct is about one-fourth as wide as the body, the
vas deferens about one-third.
Habitat: Marine mud, San Pedro, California, U. S. A. Specimens of this
species appear to have a tendency, when killed with hot sublimate, to twist and
present a dorsoventral view of the head instead of a lateral. Fig. 47.
264 ORDER ISOLAIM1A
.?. ..S-Jrr ..-... 1 . 1 '*'!'... 9-. .>!.!..
48. Ceramonema attenuatum n. sp. l - 2 - 4 2 - 8 3 - 1>9 Each annule
of the thick, transparent, naked cuticle is made up of eight elements so fitted
together as to be reminiscent of the arrangement of corrugated roof-tiles; hence,
the name "Ceramonema" (see an, Fig. 48). Neck cylindroid, with minute,
somewhat forward-pointing setae one-fourth as long as the annules are wide.
The setae occur in longitudinal rows, one on each annule, but whether on each
of the longitudinal lines is problematical. Lips amalgamated. It is probable
that there are minute papillae a little in front of the anterior row of cephalic
setae. The very narrow pharynx joins the oesophageal lumen with little alter-
ation. The oesophagus gradually narrows to near its posterior part, becoming at
its narrowest point about one-fourth as wide as the neck; thence onward, how-
ever, it expands so that where it joins the intestine it is about half as wide as the
base of the neck. There is no distinct cardia. The thin-walled intestine
becomes at once two-thirds as wide as the body. Possibly its cross-section is
v>t rnh Ifil f Ih com P ose d of as few as three or four cells. Anus
inconspicuous; rectum fully twice as long as anal
$ body-diameter. Salivary glands unknown. The
renette appears to be a unicellular gland located
fflpfi immediately behind the cardiac constriction ; it is
about half as long as the body is wide, and, as usual,
~y tapers anteriorly to join the narrow excretory tube.
The excretory pore is perhaps just to the rear of the
wph nerve - rin g- ^ is ver y difficult to observe the longi-
tudinal fields, owing to the highly refractive nature
of the elements composing the cuticle. These latter
join each other in such fashion as to give rise to eight
longitudinal lines, two of which are, of course, sub-
lateral and span a distance equal to about one-third
the width of the body. The nerve-ring surrounds
the oesophagus near where it is narrowest. Tail
conoid; terminus having a diameter about half as great as that of the base of
the tail. The final caudal segment of the cuticle is more than twice as long as
the penultimate, though it seems also to be compound in its structure. The
caudal glands appear to be located in front of the anus, near the place where the
intestine joins the rectum. From the depressed and inconspicuous vulva the
vagina leads inward nearly half way across the body. The reflexed portions of
the ovaries reach well back toward the vulva. The eggs are long and narrow,
though no specimens have been seen containing well-matured eggs.
Habitat: Mud among marine algae, shores of Kingston Harbor, Jamaica. Sub-
limate to balsam. The male of another undescribed species has stoutish, taper-
ing, subacute, rather frail spicula, accompanied by a more or less arcuate, rather
slender, frail, simple accessory piece half as long. There are no supplementary
organs. This undescribed species is so similar to C. attenuatum that it is believed
the male of attenuatum will be found to present similar features. Fig. 48.
.4 4.8 . 7.8 "<4<> 1S 92.
49. Bolbonema brevicolle n. sp. i-*' ' '*$'' ' V? U* 1 ' 3 " Neck conoid.
The walls of the pharynx are a little more strongly cutinized than those of the
oesophagus, especially toward the minute mouth opening. The cylindroid
oesophagus is about three-fifths as wide as the base of the head, but expands
finally to form the pyriform cardiac bulb, which is about four-fifths as wide
as the base of the neck. This bulb has no distinct valve, though the cutinous
BOLBONEMA, OMICHONEMA 265
lining is more strongly developed in the bulb than it is elsewhere. There appears
to be an elongated cardia, perhaps one-third as long as the neck is wide. The
intestine begins as a narrow tube only about one-fourth as wide as the base of the
neck, and enlarges gradually so that near the middle of the nema it is about one-
half as wide as the corresponding portion of the body. For a distance behind
the bulb as great as the body-diameter, the cells of the set (4)
intestine contain nuclei which stain more strongly with
carmine than do their neighbors. Thence onward the
cells contain granules of variable size, the largest being
larger than any of the nuclei in any of the adjacent ,
cells. The intestine shows about four cells in cross- "'..
section; their contents are so disposed that there is .a \jjl
distinct tessellated effect. Anus slightly raised; the -?Hy : ^ : = : rg3\ X750
rectum as long as the anal body-diameter. There appears to be no doubt about
the existence of a unicellular renette cell just behind the neck, but the position
of the excretory pore is unknown. Lateral fields about one-third as wide as the
body. Tail conoid. From the slightly raised vulva, the vagina leads inward
fully one-third the distance across the body. The eggs appear to occur one at a
time in each uterus. They are fully twice as long as the body is wide, and con-
siderably less than half as wide as long. It seems probable that segmentation
sets in before the eggs are deposited.
Habitat: Mud, shallows of Kingston harbor, Jamaica. Sublimate to balsam.
Fig. 49.
1.1 8.8 . 19- -85. _
50. Omicronema litorium n. sp. 1.5 "*. : i-9 *-i 1-6 " " Cuticle rather
thin, naked, its striae more easily resolvable into rows of longitudinal markings
near the extremities. Wings faint. No labial papillae. Amphids yellowish.
Oesophagus at the nerve-ring one-half as wide as the middle of the neck; there-
after it expands somewhat, so that finally it is about two-thirds as wide as the base
of the neck. The oesophagus has a somewhat wavy lining. There is a narrow,
elongated cardia, nearly half as long as the body is wide. The intestine, set off
by a deep and broad constriction, becomes at once about three-fourths as wide
as the body. The lateral fields appear to be about one-fourth as wide as the body.
The female has a single outstretched ovary extending forward. From the more or
less conspicuous, depressed vulva, the rather weak, more or less cutinized vagina
connects with the straight uterus, which contains elongated eggs, twice as long
as the body is wide and about one-eighth as wide as long. The narrow ovary is
first cylindroid, then tapering. The larger ova are arranged single file; toward
the blind end, however, the ova are arranged irregularly.
The conoid, arcuate tail tapers from the anus, or from /
somewhat in front of it. The three ellipsoidal caudal ph ..^jflf^- Ml/r ^
glands lie in a loose tandem in the anterior half of the tail.
M 1.5-1.7 1.7 -11 i.T The tail of the male is W
arcuate and conoid to the spinneret, which is one-sixth
as wide as the base of the tail. No supplements, though
there are inconspicuous setae on the submedian lines, both behind and in front
of the anus. The dark rather slender spicula attain their greatest width at
their bent middle parts. Accessory piece nearly as long as the anal body-
diameter. Near the bends of the spicula the accessory piece takes on a sigmoid
contour, and this portion is connected with the body wall both anteriorly and
posteriorly by strands of muscle. The ejaculatory duct is about one-third as
wide as the body.
266 ORDER ISOLAIMIA
Habitat: Ocean beach-sand, vicinity of Los Angeles, Calif., U. S. A., near loi
tide mark. Fig. 50, p. 265.
1. 6. 14. 18-" 66.
51. Halanonchus macrurus n. sp. * *- i-9 2.1 i.
cuticle is very finely and somewhat irregularly reticulated upon the head. Outer
row of cephalic setae stout, two-jointed. Lips probably distinct and six in num-
ber, thin, flap-like. Pharynx somewhat deeper than the base of the head is wide.
The pharynx has a faint triquetrous framework, the three, slender, longitudinal
elements of which are split behind (and also less conspicuously in front), the
.,*,. <_;, tfttfi) branches thus made bowing round together; this imparts
W to the wall of the pharynx, opposite the beginning of the
P sterior f ourt h> a junction-like effect. As a whole the
pharynx is much like an elongated and naked and weakened
Oncholaimus pharynx destitute of onchia. The cylindroid
to conoid oesophagus near the nerve-ring is three-fifths,
and finally two-thirds, as wide as the neck. The distinct
re f rac tive lining appears to be composed of two to three
faint elements, occupying a space three-fifths as wide as
the oesophagus; the musculature is coarse. Probably
glands are present in the oesophageal tissues. There is a
X 750 mor e or less hemispherical cardia, one-third as wide as the
neck. The thick-walled intestine is set off by a constriction one-third as wide
as the base of the neck, and becomes at once two-thirds as wide as the body. In
cross-section it is composed of about twelve cells. The rather inconspicuous
rectum is as long as the anal body-diameter. The cells of the intestine contain
scattered, colorless granules, of variable size, the largest of which are one-twen-
tieth as wide as the body. The larger granules darken in Flemming's solution.
The tail is first conoid, and then cylindroid in the posterior two-thirds, where
it is one-third as wide as at the base. It tapers from in front of the anus to the
terminus, which is apparently devoid of spinneret. The lateral fields are three-
fifths as wide as the body; their margins are rather distinctly indicated by the
abrupt beginning of the longitudinal musculature. Renette unknown. Nerve-
ring accompanied by obscure nerve cells. From the large, conspicuous, some-
what elevated vulva the large, tubular to conoid, non-cutinized vagina extends
obliquely backward a distance equal to the body-diameter. The uterus is twice
as long as the body is wide, and contains four to seven eggs, which are probably
deposited after segmentation begins. The narrow ovary tapers but little, and
contains about thirty ova arranged single file. The sub-arcuate, rather simple,
frail, blunt spicula are one-eighth as wide as the body; viewed in profile their
non-cephalated proximal ends appear to lie dorsad from the body-axis. The
single, more or less straight, very slender, frail, simple, parallel accessory piece
is one-third as long as the spicula. The fifteen to eighteen very inconspicuous,
sub-equidistant, papilloid, ventral supplementary organs occupy a space in front
of the anus seven times as long as the body-diameter; the posterior one lies
opposite the middle of the spicula. The distance between these organs is about
one-fourth of one body-diameter. For each supplement there is a "pore" in
the cuticle, and to this comes a "nerve-ending" that appears to project more or
less. The sperm cells are long and cylindroid.
Habitat: Sand inside government cut, Biscayne Bay, Florida, U. S. A. Flem-
ming to glycerine jelly. Fig. 51.
HALINEMA
267
52. Halinema spinosum n. sp. There are a few, very inconspicuous cervical
setae, one-third as long as the neck iswide. Cephalic setae three-jointed (Fig.
1, 2, 3). Lips three, possibly double. Neck more or less cylindroid. Oesophagus
cylindroid, with an almost imperceptible cardiac swelling; at the nerve-ring
four-sevenths, and finally three-fourths as wide as the corresponding portion of
the neck. The sub-distinct lining of the oesophagus is optically expressed by
refractive lines occupying a space two-sevenths as wide as the organ itself. The
colorless musculature is rather coarse. No cardia has been noted, but the intestine
is at first more refractive in its lining, and otherwise altered. The thick walled
intestine is set off by a collum one-fourth as wide as the neck, and has a faint,
but somewhat refractive lining. It soon becomes two-thirds as wide as the body,
and in cross-section is composed of few cells. From the anus, the posterior lip
of which is elevated, the rather inconspicuous rectum leads inward a distance
three-fourths as long as the anal body diameter. The intestinal cells contain
scattered granules of variable size, the largest of which are about one-tenth as
wide as the body; they darken on treatment with Flemming's solution, and are
strongly refractive in glycerine jelly. The conoid tail tapers from the anus.
The broadly saccate caudal glands, three in number and relatively small, form
a close tandem in the anterior eighth of the tail. The posterior half of the tail
bears eight pairs of ventrally submedian stiff setae. The rather fusiform, non-
granular renette cell lies on the ventral side of the body a little behind the base
of the neck; it empties through a rather conspicuous ampulla one-third to one-
fourth as wide as the corresponding portion of the neck. The nerve-ring is of
medium size and . 7 3 . 2 6 . 8 "_ 5? .> ?3 ^^
is accompanied * J -V i-3 i-'' ' "i. '
by obscure nerve .4 2.3 4.3 -H-<" 90. ?26
cells. The fe- ' 8 ' V V ' ' '"'**"
male sexual apparatus presents a vestigial pos-
terior branch. Vulva rather large, somewhat
elevated; vagina more or less cutinized. The
eggs are five times as long as the body is wide,
and evidently occur in the uterus one at a time.
The narrow tapering ovaries contain few ova
arranged single file. The spicula are rather
strong, somewhat slender, tapering and acute.
Their expanded proximal ends appear to lie ven-
trad from the body-axis. The applied parts of j^
the two rather frail accessory pieces are one-
fourth as long as the spicula. They have taper-
ing apophyses, one-third as long as the anal
body diameter, whose proximal ends lie ventrad from the body-axis. Papilloid
sub-equidistant supplementary organs on the ventral line occupy a space five to
six times as long as the body diameter, the distance between them being about
equal to three-fourths the corresponding body diameter. Of these almost imper-
ceptible innervations, the posterior one lies opposite the distal portions of the
spicula. Ejaculatory duct two-fifths as wide as the body. There seem to be
two narrow, tapering testes, but there is a little uncertainty about the posterior
one.
Habitat: Sand bar, opposite the mouth of the Miami River, Biscayne Bay,
Florida, U. S. A. Flemming to glycerine jelly. Fig. 52.
268
ORDER ISOLAIMIA
4.8 10.2.... 16. "-54-" 86. g __
53a. Pseudolella cephalata n. sp. !> 8 i*"" 5j '3.V 2.7 '' " Cuticle naked;
wings optically expressed in the form of closely approximated, indistinct longi-
tudinal lines. The unusually long amphids are of such a character as to be
mistaken at first for wings. Behind the neck the amphids gradually narrow, so
that somewhat in front of the middle of the body, where they end, their width
is only about one-third as great as opposite the base of the pharynx. Neck
conoid. Cuticula much thinner on the head. Lips thick ; six, or three and two-
SSt(J)h(4)
parted. Internally the lips are armed with six very minute
odontia (?), apparently having an outward stroke. From
the expanded base of the pharynx muscular fibres are seen
passing to the front, clearly indicating that the entire struc-
ture can be moved forward; such movement would be
entirely in accord with the structure of the labial region.
The oesophagus maintains the same diameter until after it
passes through the nerve-ring; it then expands rather rap-
idly so as to form the pyriform cardiac bulb nearly two-thirds
as wide as the base of the neck. There is a flattish-conoid
cardia, one-third as wide as the base of the neck. The front
end of the intestine is pressed to one side by the strongly
developed renette cell, but behind this cell it becomes about
two-thirds to three-fourths as wide as the body; its cross-
section probably is composed of six or more cells. These
cells contain scattered yellowish to brownish granules of small but variable size.
The anus is rather inconspicuous. The rectum is about as long as the anal body
diameter. The tail is at first conoid, so that at a distance from the anus equal
to five times the anal body diameter, its diameter is not over one-sixth as great
as at the base. The remainder of the tail, probably a short part only, is missing.
Caudal glands probably located in the base of the tail. The renette cell, half
as wide as the body and about twice as long as it is wide, is located behind the
base of the neck a distance equal to two body diameters. From the slightly
elevated vulva the rather massive vagina leads inward fully half way across the
body. About eight ova are arranged single file in each ovary. The eggs are
two to three times as long as the body is wide, and a little less than one-third as
wide as long. The spermatozoa seen in the uterus are about one-sixth as wide
as the body, and are finely granular and have their chromatin in an ellipsoidal
form surrounded by a clear area.
Habitat: Punta Arenas, Pacific Coast of Costa Rica. The following are the
actual measurements in microns: n ?s._ m. '"-4ior"' 658 Fig. 53o.
./ *^ :: '.- ;.'".' M'* 900 - .....
b. Pseudolella granulifera n. sp. Type species. Cuticle as in P. cephalata,
but without wings. Neck convex-conoid anteriorly ; especially at the head, which
is somewhat bluntly pointed. Cephalic setae four, arcuate, spreading, and one-
third as long as the corresponding diameter of the head, arranged about one-
fourth of the distance back to the beginning of the tubular portion of the pharynx.
Lips confluent, obscure, probably three in number. No labial papillae seen.
Amphids long, slender; beginning some distance behind the pharynx and extend-
ing forward in the form of a band or groove about half as wide as the pharynx,
and having refractive cutinized edges. This band extends to very near the lips,
then suddenly narrows and turns back on itself and ends indefinitely in front of
PSEUDOLELLA
269
the middle of the pharynx. At its widest, i.e., toward the front, the amphid is
a little narrower than the pharynx. Lips relatively thick, closing to form an
exceedingly narrow, cutinized vestibule. Pharynx and all parts of the alimentary
canal like those of P. cephalata. Pharynx sub-uniform, about one-sixth as wide
as the base of the head. A little behind the lips the lining of the pharynx is
discontinuous and the cavity bends slightly toward the ventral side, and there
appears to be a pair of very small, ventrally submedian onchia of equilateral
profile. It is difficult to make out the details sufficiently well to state positively
that these refractive, cutinous elements are homologous with ordinary onchia.
Opposite the onchia on the dorsal side the cutinized, pharyngeal elements are
discontinuous, two or three in number, but not very variable in character. The
onchia and the elements opposite them and in front 'of them are fully as robust
as the walls of the pharynx, of which the ventral side supporting the "onchia"
is considerably thicker than the dorsal. The cross-section of the intestine
appears to be made up of few cells, perhaps only two or three. The granules in
the intestinal cells, the largest of which are half as wide as the nucleus of the
renette cell, are a very conspicuous feature and give rise to a very indistinct
tessellated effect. In its anterior half the tail is conoid from the anus, and at the
middle is one-fifth as wide as at the base. Thence onward, it tapers but little
and ends in a somewhat rounded, unarmed spinneret. There are no caudal setae.
Caudal glands occur in the anterior part of the tail. Lateral fields indistinct,
apparently one-third as wide" as the body. Both before and behind the renette
cell there are bodies of unknown significance that stain with carmine. Nucleus
of the renette cell distinct, slung in a conspicuous protoplasmic network. Behind
the renette cell is a spindle-shaped, distinctly nucleated cell fully one-third as
wide as the body and about twice as long as wide. Still further back, after a
.HI .'
4.1 7- 12.7 4 M- 86.
2y?' "% * *ij" " " 3.8 '^N- 2.9
considerable interval, there is
another similar cell of larger
size; these two latter cells seem
connected by a narrow process,
and the anterior smaller cell
presents a narrow process
extending forward. Spicula uni-
form, arcuate, one and one-half
s~--- '
times as long as the anal body
diameter; their proximal ends rather prominently and obliquely cephalated by
expansion. Proximal ends a little dorsad from the body-axis. The spicula
taper to a fairly acute point in the distal fourths and their cutinized framework
is duplex; at their widest part, the middle part, the spicula are about one-sixth
as wide as the corresponding portion of the body. Two accessory pieces adjoin-
ing the distal fourths of the spicula; extending backward at right angles to the
spicula are the blunt apophyses three-fifths as long as the anal body diameter.
The number and the structure of the testes is uncertain, but apparently there
are two, of which the anterior is reflexed and the posterior outstretched. The
sexual cells are of unusually large size and their walls appear to divide up the
testes in an irregular geometric fashion.
Habitat: Marine mud and sand, Noumea, New Caledonia. Fig 536.
270
ORDER POLYLAIMIA
V. Order Polylaimia
This order cannot at present be so satisfactorily defined as most of the others
herein represented. There probably can be removed from it sooner or later a
number of groups of ordinal rank, but the time seems hardly yet ripe for such
a removal. For the present, therefore, the genera and families ranged under
this name are of a more heterogeneous character than under most of the other
twelve orders here presented. Some slight effort has been made, here as else-
where, to place these new genera in the order of their family relationships. In
general, the genera that are first mentioned in an ordinal group, and the genera
placed at the end of the group, as here presented, exhibit more or less manifest
relationships to genera included in other orders. (See p. 217.)
54. Cephalobium microbivorum n. sp. The wing begins near
the head and ends near the terminus. Its optical expression is
either a pair of lines, or a single line, in the middle of a field one-
twelfth as wide as the body. The contour of the body may
become crenate in the anal region. There are about thirteen
lateral organs in each lateral field connected with pores in
cuticle (see org. lat., Fig. 54). Base of the pharynx containing
a large, complicated and peculiar dorsal glottoid organ. No
amphids. The rather thin-walled intestine is set off by a collum
one-eighth as wide as the neck, and has a rather distinct lumen.
It becomes at once five-sixths as wide as the body, and in cross-
section presents two to four cells. From the somewhat depressed
anus, the narrow, cutinized rectum extends inward a distance
one and one-fourth tunes as great as the anal body diameter.
Scattered yellowish granules of variable size occur in the cells
of the intestine, the largest being one-twenty-fifth as wide as
the body. In addition, there are numerous very small granules.
; The subarcuate, conoid tail tapers from in front of the anus to
the acute fine terminus. There is no spinneret. From the ele-
vated vulva, the rather small, somewhat weak vagina extends
inward one-fourth the way across the body. Along the middle
half of the body the two equal uteri contain ellipsoidal eggs
two-thirds as long as the body is wide, which are deposited after
segmentation begins. No embryos were seen in these eggs,
only blastulas. For the most part the ova are arranged irregu-
larly in the somewhat tapering ovaries. The rather strong,
slender, tapering, subacute spicula, when seen in profile, have
their proximal ends nearly opposite the body-axis. Toward
_J-.___l (l !i3-=i?-'___'l' > _'l-__ 8 *-_- their distal ends four slender
stiffening pieces are apparent.
i.z w. _!?. 74 -* *>. There is a strong, and rather
i3TVf " solidj s t ra ight accessory piece,
bending back from the spicula at an angle of about 90 degrees, so that its proxi-
mal end lies opposite the body-axis. Near the beginning of the second quarter
of the tail there is a pair of lateral pores (?) similar to those on the female.
On the female these pores have been shown by intra vitam staining to be homol-
ogous with those mentioned above, and shown in the illustration at por lat.
Pairs of papillae on the tail of the male flattish-conoid, plainly innervated, rather
ayJai
CEPHALOBIUM, BLATTOPHILA, CATANEMA
271
inconspicuous, occupying the anterior two-thirds of the tail, thus: 1()1; 111; 1.
The members of the posterior four pairs are not located exactly opposite each
other, the right hand member
each pair being slightly behind the
left hand member. Spicula con-
spicuous, rather close together; at
the widest part about one-eighth
wide as the corresponding portion
of the body, ending in minute "bi
tons." The lateral pores on the
tail are the final members of the
xayg/at, alfit taoe segmmr.
series of lateral organs.
Habitat: Intestine of field cricket, Gryllus neglectus Scudd.
Fig. 54a and b.
77.
55. Blattophila sphaerolaima n. sp.
Cuticle
marked with plain transverse striae, 3 microns apart on the head and 24 microns
apart on the body, where they are much less plainly to be seen, though they cause
a slight crenation of contour. No amphids or setae of any sort. The head is
somewhat hemispherical, bearing very small lips almost in the form of an annular
elevation about the mouth. The pharynx and its apophyses are contained in a
small spherical pharyngeal bulb, hence the specific name. When closed, the
pharynx is a prismoid cavity one-fourth as deep as the head is wide and about
half as wide as deep, and backward from its base spring apophyses, a dorsal one
dominating. The mouth can probably be turned partially inside out. The ante-
rior three-fourths of the oesophagus is clavate, averaging one-third as wide as
the corresponding part of the neck; this anterior part is connected by a narrow
and very short tube with an oblate cardiac bulb one-half as wide as the base of
the neck. The intestine, which appears to be only one-third as wide as the body,
is set off by a broad and very deep constriction. The rectum is one and one-half
times as long as the anal body-diameter. The renette plexus is quadruple.
The nerve-ring encircles the oesophagus obliquely. The acute, conoid tail tapers
rapidly near the anus, where there is a somewhat indistinct constriction. The
anterior lip of the anus projects. The vulva is not very prominent. The num-
erous elongated ellipsoidal eggs measure 40-48 X 88-104 microns, and may seg-
ment before deposition.
.4 7.7 15- K 82.
i._ 3. 4.5 / 5.4 ^3.1 Of the papillae on the male two are pre-anal,
being large submedian ones adjoining the anus and having a truncate-conoid
form with a mucro; there are also two post-anal papillae similar to the foregoing
but smaller, and removed from the anus a distance equal to one-third of the body
diameter. The spicula appear to be represented by a mere rudimentary point,
no longer than the larger papillae, conical in form and projecting with the
anus when the nema is killed with osmic acid. The single testis is reflexed at a
point somewhat farther behind the cardia than the latter is behind the head.
Habitat: Intestine of Panesthia brevicollis Sauss., the common spiny-legged
wild cockroach ; Moss Vale, New South Wales, Australia. 1889. Osmic to water ?
56. Catanema exile n. sp. '- L 1- ~~ Nr1 -? The mouth opening is
closed by three or six very minute, slightly refractive structures. About oppo-
site the bases of the cephalic setae there are exceedingly minute onchia (?),
possibly six, difficult to see in profile; impossible to count because of their
272
ORDER POLYLAIMIA
small size and their overlapping. Amphids forward-pointing, minute, difficult
to see. The oesophagus becomes slightly narrower where it passes through the
nerve-ring; posterior bulb napiform, three-fourths as wide as the base of the
neck. There is no distinct cardia. The thick-walled intestine becomes at once
about two-thirds as wide as the body, and its cross-section is made up of about
Wj?
four cells, which are
packed with granules
of uniform size. The
lateral fields are about
one-third as wide as the
body, and contain a
series of cells of large
size. The nerve-ring
surrounds the oesoph-
agus obliquely. There
is a single, small, elon-
spn gated, very inconspic-
uous ventral supple-
mentary organ of the
ordinary kind opposite
the posterior part of
the spicula, and in
; front of it a number of
minute ventral setae.
Seven pairs of sub-
ventral tubular sup-
y 7 cft plements occur on the
tail. The ejaculatory
duct is about two-fifths as wide as the body. The caudal glands are evidently
located in front of the tail, but their exact position has not been made out.
Habitat: Marine sand about the bases of algae, in surf, Island off Port Royal,
Jamaica. This genus resembles Laxonema in many respects, and also resembles
Laxus but differs in the form of the lateral organs and in other ways. Sublimate
to balsam. Fig. 56.
57. Zalonema nudum n. sp. Cuticle naked. The face view of the striae gives
the impression of a series of narrow, contiguous hoops. The cuticle becomes
thicker on the neck, and much thicker on the head. Lips, thick, small, plain.
On the male there are very distinct and prominent wings, beginning about three
times as far in front of the anus as the terminus is behind it. Each wing extends
backward and ends opposite the proximal ends of the spicula. The width of
this wing is about equal to the corresponding thickness of the dorsal or ventral
cuticle as seen in optical section. None of the irregularities in the wall of the
pharynx are suggestive of the ordinary pharyngeal organs, and yet they are very
distinct features. Two of them are rather prominent, one on the dorsal side,
opposite the anterior portion of the cephalic thickening, and the other on the
ventral side opposite the middle or posterior portion of the cephalic thickening.
The oesophagus continues with the same diameter until it expands to form the
very broadly pyriform or napiform cardiac bulb, which is three-fourths as wide
as the base of the neck. The lining of the oesophagus occupies nearly one-third
of the optical section. The oesophageal lumen continues through the bulb.
ZALONEMA, PSEUDONCHUS
273
The intestine joins the middle of the posterior surface of the cardiac bulb, and
at this point the collum is nearly one-third as wide as the base of the neck. The
rather thin-walled intestine becomes at once about two-thirds as wide as the
body. From the nearly continuous anus, the tail is arcuate and conoid. There
are no supple- fi
mentary or- j^' '^
gans. The
moderately V?. . , 5 .^ . . ?-. 7 . .
stout spicula 1-
taper to a blunt point in their distal halves.
At their widest part they are about one-fifth
to one-sixth as wide as the corresponding
part of the body; they are accompanied by X750
accessory pieces half as long. The distal ends of the accessory pieces are applied
closely to the spicula, but the proximal ends curve away slightly and then recurve.
The ejaculatory duct is about one-third as wide as the body. Apparently there
is but a single testis.
Habitat. Marine mud and sand, Noumea, New Caledonia. Sublimate to bal-
58. Psendcmc/ms rotundicephalus n. sp. i^ i-5 i_J> '- 8 In most
portions of the body longitudinal striations have been observed, apparently
connected with the cuticle rather than with the musculature. Neck cylindroid.
Lips two, each lateral. See Fig. 58. The mouth is very difficult to see in the
lateral view. In the dorso-ventral view it is easily seen, and is found to be a
dorso-ventral opening running across the head. Each lip has about six very
minute, refractive, double, cutinous markings, each presenting two blunt-edged
"teeth" directed toward the base of the pharynx. It appears that these repre-
sent foldings in the closed lips. In any case they represent, when viewed later-
ally, the roof of the pharynx, located opposite the bases of the anterior cephalic
setae. The elements in the pharynx opposite the anterior borders of the amphids,
which, at first sight, appear to be onchia, prove on careful examination to be
ridges, (see pseudon, in the illustrations). The pharynx is unusual in structure
and rather difficult to understand. The amphids of the female occur in about
the same position as those of the male, but instead of appearing spiral appear
wind. The narrow oesoph-
agus has the same diameter
unt il it expands to form the
somewhat obscurely pyri-
form bulb, which is three-
fourths as wide as the base
x750 mm W yn of the neck. There is a
flattish cardia, about one-third as wide as the base of the neck. The intestine is
set off by a constriction about one-half as wide as the body, and in cross-section
presents about half a dozen cells. There appear to be faint indications of the
presence of wings. Renette unknown. Lateral fields are about one-fourth as
wide as the body. Nerve-ring oblique. The tail is convex-conoid to the termi-
274 ORDER POLYLAIMIA
nus, where the conoid spinneret has a diameter about one-fifth as great as that
of the base of the tail. From the slightly elevated vulva the vagina leads inward
half way across the body, where it joins the two, symmetrically placed uteri.
The ovaries reach about half way back to the vulva, at least in specimens in
which the uteri are empty. There are eight to ten ova in each ovary, arranged
single file.
1.1 3-3 5-8 "-K 95-9 >, 6
tj 1.3 M 1.4^1.4 The spinneret of the male is about one-third as
wide as the base of the tail. No supplements or special setae or papillae have
been observed either in front of the anus or behind it. The spicula are rather
uniform and taper to an acute point in their distal thirds; in profile their proxi-
mal ends are seen to lie near the ventral surface of the body. The ejaculatory
duct is about half as wide as the body.
Habitat: Mud, tide pool, Portsmouth, N. H., U. S. A. Sublimate to balsam.
Fig. 58, p. 273.
1.5 6.3 . 10. "*41" 85.
59. Polylaimium exile n. sp. > L ' 1,2 1.2 i. >lb " Striae of the thin
cuticle minute. It seems very likely that four cephalic setae have been lost
from the specimen from which the description and illustration are drawn. Lips
three, and double, (or possibly six), with six minute labial papillae. Cuticle
naked. Neck convex-conoid, especially toward the head. The oesophagus at
the nerve-ring is one-half, just in front of the cardiac swelling one-half, and
finally two-thirds, as wide as the corresponding portion of the neck. The elon-
Ib(6) aJ (6) gate( * to Pyrifp 1 cardiac bulb is very small. The lining of the
""/56k oesophagus is quite distinct and at first is indicated by two refrac-
ph ml . /^ tive lines, occupying a space one-sixth as wide as that of the
, 1 1 k oesophagus. There appear to be no glands in its fine colorless
ifr l musculature. There is an indistinct cardia. The thick-walled
ejf |n .. fjj intestine is set off by a collum one-third as wide as the base of the
I I ] I Yf neck; it has a faint lumen and becomes at once two-thirds as
. 50 .M 1 w wide as the body. In cross-section it is made up of two to three
cells. Anus more or less continuous; rectum somewhat cutinized, equal in
length to the anal body-diameter. The granules contained in the intestinal
cells are numerous, uniform and colorless. The tail is conoid from the anus,
and then cylindroid in the posterior half, where it is two-thirds as wide as at the
base. It is probable that the caudal glands are small and located near the anus.
There are no caudal setae. Renette present; excretory pore probably located
near the nerve-ring. Full-grown ova are twice as long as the body is wide,
and nearly one-half as wide as long. The reflexed parts of the ovaries reach
about three to four body-widths back toward the vulva.
Habitat: Sand below low-tide mark, Belmar, New Jersey, U. S. A. Sublimate
to balsam. Apparently the species is syngonic. Up to the present time
extremely few free-living marine nemas have been observed to be syngonic.
A similar species with four setae occurs at Woods Hole, Mass, U. S. A. Fig. 59.
60. Myolaimus heterurus n. sp. Cuticle thin, naked; striae fine. Lips thin,
low, flat, confluent; six, or three and two-parted. Amphids faint, in the form
of transverse slits. That portion of the pharynx in front of the amphids is
about half as wide as the lip region; this chamber is continued by a narrower
tubular portion, nearly one-third as long as the neck and surrounded by a pecul-
iar radial musculature, differing from that of the oesophagus proper. Nearly as
far behind the amphids as these latter are behind the anterior extremity, there
is a prominent infolding in the wall of the pharynx. The amphids are difficult
MYOLAIMUS
275
to detect with the nema in profile, more easily when viewed dorso-ventrally.
Behind the anterior chamber of the pharynx, which in many respects resembles
that of Diplogaster, there is a muscular portion closely resembling the oesophagus
in size and structure, but which seems undoubtedly pharyngeal. This is indi-
cated in two ways; first, the lining is different from that of the portion of the
oesophagus immediately following it, and second, it behaves differently with
staining material, indicating that its muscular wall also is considerably different
in nature from that of the oesophagus. The dimensions given in the formulae
relate to the anterior or labial chamber. At the base of the anterior pharyngeal
chamber there appear to
13.7 25.2
A 3.9
(Sflpft/m
be minute cutinous pro-
cesses which perhaps may
function as onchia. It
would appear possible
that all that portion of the pharynx in front of the folds '
in its lining are capable of being opened out or everted.
From the pharynx the oesophagus is cylindrical to near'
the nerve-ring, where it diminishes rather suddenly in
diameter near the very faint vestiges (?) of a median
structure. The vestiges consist in internal modifications
of the oesophagus only. From the nerve-ring onward the
oesophageal tube is about two-fifths as wide as the corre-
sponding portion of the neck. It finally expands to form the elongated-ellip-
soidal cardiac bulb, which bears a more or less distinct cardia, and is separated
from the intestine by a shallow constriction. The cardiac valvular apparatus
appears to be comparatively simple. The intestine becomes at once four-fifths
as wide as the body. The intestinal walls are rather thick, and the cells are
packed with minute granules. The rectum is about twice as long as the anal
body diameter. The lateral fields appear to be half as wide as the body.
The tail of the female is conical to the acute terminus and presents the peculiarity
of diminishing in diameter very suddenly immediately behind the anus, the dimi-
nution taking place on the ventral side. The anal region is, therefore, conspic-
uous on this account, as well as on account of the fact that it is slightly depressed,
and again on account of the refractive nature of the lining of the comparatively
long and large rectum. The salient lips of the vulva are conspicuous, a property
that is increased by the refractive nature of the lining of the vagina, which extends
inward two-fifths the distance across the body. Tail of the male very different
from that of the female. There is a bursal membrane connected with the digi-
tate organs shown in Fig. 60. The specimens seen were molting, so that the exact
nature of the membrane, which is believed to connect these organs one with
another, has not been deciphered. It seems also certain, however, that the ante-
rior four are joined together by means of a ventrally submedian membrane
somewhat as in the case of the bursa in Rhabditis. The spicula are very weak
and poorly developed in the specimens thus far seen. They appear to be as
long as the tail, and are probably cephalated at their proximal ends by constric-
tion; but they are very difficult to discern, and it is possible that the appearances
are deceptive and that they are altogether absent. The testis extends forward
to near the posterior end of the neck and appears to be reflexed for a short dis-
tance, but this is somewhat uncertain.
Habitat: Loamy soil, El Paso, Texas, U. S. A. Flemming to glycerine jelly.
Fig. 60.
276 ORDER POLYLAIMIA
9-5 13. 16-6 <45; 83.
61. Myctolaimus pellucidus n. sp.
traces of a very fine transverse striation. No amphids or setae of any sort to
be seen. Head continuous. Six relatively large, obtusely conical lips, each
supplied with an obscure papilla, surround the mouth. The cuticle at the base
of the lips, and at the beginning of the pharyngeal tube, is somewhat thickened,
and this gives rise to obscure rings at the base of the lip-region. The unusually
long pharynx is divided into two very distinct parts of about equal length,
together occupying nearly two-thirds the length of the neck. The anterior part
is a simple, narrow, straight strongly cutinized tube, having a lumen one-third as
wide as the lip-region. The succeeding second part of the pharynx is a cylindroid
bulb, rounded at both ends, and two-thirds as wide as the corresponding part of
the neck. Its lumen is triangular and of about the same width as that of the
anterior part of the pharynx, from which it is separated by a distinct break in
the continuity of the cutinous lining. From this elongated bulb a tube one-sixth
as wide as the corresponding part of the neck passes backward and gradually
expands into a valveless bulb half as wide as the base of the neck, thus complet-
ing the oesophagus. The intestine, which at first is colorless and transparent and
only one-fourth as wide as the body, gradually expands and becomes half as wide
as the body and distinctly granular. The refractive lining of the intestine is a
prominent feature. The cardia is unusually long and narrow, and opens into a
small cardiac cavity. The cells composing the intestine are relatively large.
The length of the well-cutinized rectum is about one and one-half times that of
the anal body diameter. Renettte unknown. The width of the lateral fields is
one-third that of the body. The nerve-ring is small and narrow. The acute
tail is almost exactly conical. The vulva is very slightly elevated. The ovaries
extend back as far as the vulva, and are often there again reflexed. Each uterus
contains one to two eggs, measuring 32 X 56 microns. Segmentation takes place
in the uterus, and proceeds to at least the gastrula stage, probably beyond it.
4.9 3j 3-2 5.7 "">- 2.5 1 The tail of the male instead of being conical is
convex-conoid in the anterior half, tapering in this part in such a fashion that
the middle of the tail is one-fourth as wide as the base; thence onward the tail is
cylindroid to the acute terminus. While the anterior part of the tail is ventrally
arcuate, the remainder is dorsally arcuate. No ventral supplements or bursa.
Nine pairs of papillae, mostly finger-shaped, are arranged as follows: 1; 1(1)1, 1;
1, 3. The linear, tapering, rather blunt spicula somewhat exceed the anal body
diameter in length. The spicula are supported by sigmoid accessory pieces half
as long as they themselves. The reflexed part of the testis is nearly equal to the
neck in length; it can be seen to contain small glassy, globular spermatocytes,
which reach their full growth near the middle of the body, becoming as long as
the body is wide and two-thirds as wide as long. At this stage they are granular,
with a large central nucleus containing a prominent nucleolus. By division these
large cells give rise to the granular spermatozoa, an elongated parcel of a dozen
or more of which is usually to be seen in each uterus of the female.
Habitat: Sheep-dung, Moss Vale, New South Wales, September 2, 1894. It
will be seen that this genus is similar to Cephalobus. It is equally clear that it
is generically distinct. It is unfortunate that no specimens of this species were
preserved, and hence no drawings can be presented. This is all the more to be
regretted because the genus is evidently closely related not only to Cephalobus
but to one or two others of similar character.
APODONTIUM, IRONELLA
277
VI. Order Apodontia
i.'5"\(i.*'* 2-3 "" Striae resolv-
.7 5. 9.4
62. Apodontium pacificum n. sp. '.?"/" Y.z""i.'3
able into dot-like elements. Neck cylindroid posteriorly, convex-conoid ante-
riorly. The cylindroid oesophagus ends in an inconspicuous, flattish-conoid
cardia one-third as wide as the base of the neck. The thin-walled intestine is
set off by a collum two-thirds as wide as the base of the neck, has a somewhat
distinct lumen, becomes at once two-thirds as wide as the body, and in cross-
~^.mn(l(6l section presents three to four cells containing granules of
, uniform size. From the somewhat elevated anus the prom-
" inent rectum extends inward a distance equal to the anal
tsubcph body diameter. Tail conoid from the anus. The conspicu-
ous, more or less elongated caudal glands are packed in a
close tandem behind the anus in the anterior half of the
Wt&il. There are about eight ventrally submedian and two
dorsally submedian setae on each side of the tail. These
stoutish, tapering setae are about one-fourth as long as the
X750 anal body diameter. The large granular, ellipsoidal renette
cell, two-thirds as long as the body is wide, and two-thirds as wide as long, lies
a short distance behind the base of the neck, and empties through an ellipsoidal,
thin-walled ampulla. The nerve-ring is accompanied by obscure nerve cells.
The yellowish spicula are slender and subacute. Their proximal ends appear
to lie somewhat dorsad from the body-axis. There are two separate, strong,
rather stout, simple accessory pieces. They are one-half to two-thirds as long
as the anal body diameter, and their proximal ends lie near the dorsal body
wall. There are no supplementary organs, special setae, or papillae on the tail
of the male. The ejaculatory duct is one-third, the vas deferens one-third, and
the testis one-half, as wide as the body. The testis tapers and is at last narrow.
Habitat: Marine; Mollendo and Salaverry, coast of Peru, S. A. Sublimate to
balsam. Fig. 62.
8.7 1 20. '= 9*. y . ln
63. Ironella prismatolaima n. sp. /u* i i-9 2. -T-*. 1.1 ' Lateral wings
very faint. Body naked. Lips six, very tenuous, revolute, forming a short
tube one-fourth as wide as the lip-region.
There are six obscure, flat, conical, labial
papillae, not shown in the illustration.
Labial setae minutely "furcated" at the
extremity. Each of the three odontia is
duplex, the two parts of the submedian
ones being of unequal size. The odontia
are contained in a somewhat napiform
cavity. Odontia acute, with an outward
stroke; when at rest somewhat outward-
pointing, and blocking the entrance to the
pharynx. Posterior part of the napiform
cavity apparently lined with exceedingly
minute denticles . Neck cylindroid.
Amphids faint, apparently consisting of
an almost imperceptible transverse groove / j
partially encircling the head. The cylin-
droid oesophagus is at the nerve-ring four-sevenths, and finally three-fifths, as wide
as the corresponding portion of the neck; its lining is prominent, occupying one-
third the diameter of the organ. In the coarse, colorless musculature there are
iP^O^i^r In
f 1 l| I
278
ORDER APODONTIA, ORDER SYNODOXTIA
three glands which empty at the mouth. There is a cylindroid cardia two-
sevenths as wide as the base of the neck. The thick-walled intestine is set off by
a collum one-third as wide as the base of the neck, and becomes at once one-half
to three-fifths as wide as the body. Its cross-section is composed of four to six
cells. It has a faint zig-zag lumen. Very fine, colorless, more or less polyhedral
granules of variable size are found scattered in the intestinal cells. The largest
of these are one-twenty-fifth as wide as the body. They give rise to no more
than a faint tessellation. The more or less arcuate tail of the male tapers from
in front of the anus, and is first conoid then cylindroid and two-fifths as wide as
at the anus. The caudal glands are probably preanal. There are no caudal
setae. The lateral fields are one-fourth as wide as the body, and faintly granular.
The very frail, straight, slender, subacute spicula become arcuate near the tips,
and are faintly cephalated by expansion. Their proximal extremities appear to
lie dorsad from the body-axis. The frail, simple, arcuate, slender accessory piece
lies parallel to, and is two-fifths as long as, the spicula. There is a single supple-
mentary organ opposite the posterior part of the spicula. The internal part is
refractive and more or less irregularly cylindrical, and bent back parallel to the
ventral surface. It is one-half as long as the body is wide, and one-fourth to
one-fifth as wide as long, and is probably protrusile through the small, short,
cylindrical element at the ventral surface, where there is also a single, strongly
curved seta, of considerable size. The ejaculatory duct is one-third as wide as
the body. The testes are characterized by the presence of numerous, elongated
elements, which constitute one phase in the development of the sperm. These
elements are apparently two-thirds as long as the body is wide and one-fifth to
one-eighth as wide as long, and are rounded at the end. From the living nema.
Habitat: Sand, Nobsca Beach, Woods Hole, below low tide. Fig. 63.
VH. Order Synodontia
.8 12.7 20.2 "'58 93.6
Chambersiellarodensn.sp.i-9 }./ 3j 5.7 3.1
radictr Only the external walls of the six odontia
are cutinized and this portion, but not the
interior, stains very strongly in acid-car-
* mine. The odontia are used to nibble the
mycelium of the fungi constituting the food.
cut The cells of the vas deferens are packed with
transparent, homogeneous, ellipsoidal gran-
ules, whose maximum diameter is about one-
third as great as that of the spermatozoa; the
cells of the ejaculatory duct are packed with
similar granules having about half as great a
diameter. The junction of the ejaculatory
duct and the vas deferens is distinctly marked
set hi by the change in the size of the granules con-
tained in these cells composing their walls.
The lateral pores on the tail of Chambersiella
\- w rodens connect with elongated, clavate cells
\\ located opposite the anus in a lateral position.
\\ The nuclei of these cells usually lie a trifle
X2000 behind the anal region. From the elevated
KM-nore and conspicuous vulva, the somewhat cutin-
cfearly the mandibles and the setae. ized large vagina leads inward and obliquely
forward. The eggs are elongated, apparently more or less long and slender.
The gently tapering ovary contains 50-100 ova; reflexed to near anus.
team
cirtiM
set Ib
CHAMBERSIELLA
279
.6 14. 20.8 5 *OI 94.1
1.7 1.7, 3^1 *.8-pi. 5 . The males are less common than
Habitat: Bark of a great variety of trees set cph ht set cph suta ad
in many parts of the eastern United States;
on "Spanish Moss," Miami, Florida. Flem- .^ ^
ming's solution to glycerine jelly. This
genus comprises a considerable number of ^
species, all with a hooked caudal extremity.
The species vary considerably in the labial ,
accessories. The present species has the ^
strongest mandibles so far known in the
genus. These nemas are highly resistant w
to drought and cold, and may be kept on
dried bark for several years and then be ' m ^
fully revived by soaking the bark in water.
They may be repeatedly frozen in and
thawed out without injury. Recently
revived specimens are mostly immature d nm
and seem to present an empty intestinal
canal, suggesting that on the approach of gj an
untoward conditions, they evacuate the
canal. Not infrequently, the lip-region of
revived specimens appears to exhibit a
ndarlat . . ndmsc
alhil
6ppl
VKtsecadS)
spinet seaid0
tnatst .-- 'spaictprm a/1
pluglike accession, seen also in the mouth opening of similarly revived Cepha-
lobi. The opening is protected during "suspended animation" by means of this
dried-up evacuation from the oesophagus. Fig. 64a, p. 278; Fig. 646.
The name of this remarkable genus, the abundant species of which are widely
distributed on trees, commemorates the classic work in this field of Mr. W. E.
Chambers, through whose untimely death science has lost one of its greatest
graphic interpreters.
280 ORDER SYNODONTIA
65. Synodontium fecundum n. sp. About forty setae occur on the neck; those
on the anterior part are about one-half, while those on the posterior part are one-
fourth, as long as the corresponding portion of the neck is wide. There are six
subdistinct lips, each with a somewhat forward-pointing, innervated, conoid
papilla. The pharynx is fairly well cutinized, and bears probably twelve closely
approximated odontia, forming a distinct circlet opposite the bases of the ceph-
alic setae; only their points are easily visible. The conoid neck becomes more
decidedly conoid near the head. At first sight the oesophagus appears as if com-
posed mainly of glands, which extend backward to the cardia. These glands are,
however, outside the oesophagus and empty near the bases of the odontia by
means of three or four ducts. At the nerve-ring the oesophagus is three-sevenths,
and finally one-half, as wide as the corresponding part of the neck, and ends pos-
teriorly in a faint, elongated, pyrif orm, valveless bulb. The lining of the oesoph-
agus is narrow; its musculature fine. The thin-walled intestine has a faint lumen
and is set off by a collum two-fifths as wide as the base of the neck and becomes
at once one-half as wide as the body. In cross-section it presents four to five
at aulm I Ib set (kl sulm ,. fcj ,., 15 _" 9i . cells. The scat-
Is/ '1.8 ' 1.9 ' ' 't.6 ' Y* 2-4 "tered granules
(impll contained in the
L . , 6 ' 9 . . 10 : 7*7 . ' 3 "-7 a.?- intestinal cells
i./ 1.6 1.6 2. 7^ Sr1 - 7 are of variable
size, the largest being one-fifteenth as wide as
.fa ph the body. The nuclei of the intestinal cells are
one-seventh to one-eighth as wide as the body
at the base of the neck. Tail conoid from the
anus, but tapering faster near the anus. The
end of the spinneret is in the form of a hemi-
spherical button, the three sectors of which are
- ] !/ L op * * 750 (S "* > SIHI eversible. so that the organ may appear three-
lobed. The ducts of the caudal glands are sep-
arate, practically to the spinneret pore. There are about fifteen ventrally sub-
median, and about ten dorsally submedian, slender, flexible, tapering setae on
each side of the tail of the male. There is a much smaller number of setae on the
tail of the female. The lateral fields are one-third as wide as the body. The
granular, ellipsoidal renette cell, two-thirds as long as the body is wide and two-
thirds as wide as long, is located at a distance behind the neck equal to the body
diameter. The obscure, rather broad nerve-ring is accompanied by distinct
and numerous nerve cells of large size, extending back to the base of the neck.
The large, elevated, conspicuous vulva leads to a conoid, rather muscular, cutin-
ized vagina accompanied by small, ellpisoidal glands. There is a small anterior
branch to the female sexual organs, about as long as the body is wide. The uterus
extends back to near the middle of the body. The eggs are one and one-half to
two times as long as the body is wide and one-fourth to one-third as wide as
long. Numerous, granular, spherical sperm cells, one-fifteenth as wide as the
body, are abundant near the middle of the body, disarranging the chain of eggs
in such a way as to suggest the presence of a spermatheca. The broad ovary
tapers gradually, and contains twenty to thirty ova arranged single file. The
egg, just before deposition, lies opposite the vulva, one-half of it being in the
small anterior branch of the uterus. The spicula are strong, somewhat slender,
sub-uniform, and rather blunt. Their proximal ends appear to lie ventrad from
the body-axis. The two strong, well-separated accessory pieces are one-fourth
SYNODONTIUM. DAPTONEMA
281
as long as the spicula. Their uniform, blunt apophyses extend backward at an
angle of ninety degrees with the spicula, and are one-half as long as the anal
body diameter. Fifty to seventy equidistant supplementary organs, in the form
of a series of slight undulations, extend forward in front of the anus a distance
three to four times as great as the length of the tail. The undulations are sepa-
rated from each other by a space about equal to one-fourth the body diameter,
though they become gradually a little farther apart anteriorly. Thejr eleva-
tion is slight, and every other undulation is opposite a granular, saccate gland,
about one-third as wide as the body. These glands form a contiguous series
and seem to empty ventrally. There is no bursa. The ejaculatory duct is one-
third, and the testes are one-half, as wide as the body, these latter gradually
tapering so that they are narrow at the extremities.
Habitat: Sand, below Bathing Beach, Woods Hole, Mass., U. S. A. Also
beach-sand, Squibnocket, Martha's Vineyard, Mass., U. S. A. Flemming to
glycerine jelly. Fig. 65, p. 280.
66. Daptonemafissidensn. sp. w 2 - 8 3 - ? Type species. The
contour of the moderately thick cuticle is crenate, the annules being separated
by refractive lines. Toward the head end the $ cp/f (/2)
annules diminish in width until they elude detec-
tion. Neck conoid; head rounded. Here and
there on the neck occur long, slender hairs, as
long as those on the head, but colorless and very
much more slender. Each of the six lips is
strengthened by three, dark-brown, or blackish,
strongly arcuate, incurved, slender, acute, cutin-
ized ribs or teeth. Lips capable of being
turned over into the pharynx so as to form a
flattish, centrally indented dome. From the
head backward the oesophagus narrows a little,
becoming two-thirds as wide as the correspond-
ing portion of the neck. There is no very dis-
tinct cardia. The rather thick-walled intestine
becomes at once about half as wide as the body,
and in cross-section presents about four cells.
The cells contain scattered brownish granules,
of variable size, the largest of which are nearly
as wide as one of the annules of the cuticle. The
lumen of the intestine is quite narrow, and its
lining somewhat refractive. Renette unknown.
The tail of the male is conoid from the anus to
the somewhat blunt terminus, which has a plain,
rather blunt spinneret, armed with two setae
considerably longer than the diameter of the ^
terminus. The caudal glands appear to be
located in front of the anus. The brownish
spicula have been seen only in dorso-ventral
view. The accessory pieces are curved distally ase m
in the same way as the spicula, and end in minute points. The ejaculatory duct
is about one-third, the vas deferens about one-half, as wide as the body.
Habitat: Larat, East Indies; marine. In the general form of the neck and
pharynx these nemas closely resemble Monhystera, but the food habits are
Illl
282
ORDER SYNOUONTIA
hmoe.
The
probably different, and the structure of the male differs materially from the
structure of the male of Monhystera, dark-colored, punctate, out-bending spic-
ula; and two g ,. seHfh(/2\ i tf to (6) \ Jb\(6)
testes. A very IT"~i8-~i9 5.1" " 3.2 V
similar marine 1% !.__ ""im. 1260.
species occurs * 2 -~ *
in the harbor at Portsmouth, N. H., and at / a 13X6)
Woods Hole, Mass., U. S. A., namely Dapto-
nema fimbriatum, n. sp. of which the formulae
and the figure of the head end are given on
this page. The head of Daptonema fissidens
differs but slightly from that of D. fimbriatum.
Daptonema is manifestly an offshoot of Monhystera. Probably
the eighteen refractive labial elements are ribs attached to a
thin membrane. They sometimes appear, however, as if free at
the extremities, and if so, would function as combs in securing
the food, which is probably combed or scraped from the surface
of algae and other submarine objects. Fig. 660. p. 281 (fissidens) ;
Fig. 666 (fimbriatum).
.6 2.6 4.3 -70."
67. Crystallonema fuscacephalum n. sp. /l- ' 1- 14
longer, cephalic setae are two-jointed. The scattered, inconspicuous cervical
setae are one-tenth as long as the neck is wide. Opposite the pharynx the head
contains dark brownish gray pigment. The consistency of the labial palps (?)
remains undetermined, that is to say, it is uncertain whether they are apodontia
with an inward stroke and capable of executing a firm grip, or whether they are
more or less flabby palps. Neck somewhat cylindroid, expanding a little toward
the head. Amphid with a pore near the posterior margin, from which there
set Cph(4] \ pip Jb set U) (6 I ^ ea ds inward and backward a narrow duct
with granular contents. There is a faint,
elongated, more or less pyriform cardiac
swelling. Near the nerve-ring the oesoph-
agus is one-half, just in front of the cardiac
swelling three-fifths, and finally two-thirds,
as wide as the corresponding portion of the
neck. The musculature of the oesophagus
is rather coarse and colorless. Cardiac col-
lum two-fifths as wide as the body. The
intestine begins with a specially modified
segment, two-thirds as long as the corre-
Itrm s P on ding body diameter. The intestine,
rhicli has a somewhat irregular lumen,
1 75Q gradually becomes one-half to two-thirds
as wide as the body. The colorless gran-
ules in the intestinal cells are scattered in groups and -are of variable size, the
largest granules being about as wide as one of the annules on the neck. The
nema is strongly characterized by the presence of more or less angular, doubly
refractive crystalline masses, having about the same diameter in every direction,
and being about one-sixth as wide as the body. The crystalline bodies are one-
half to one body-width apart and seem to lie in the longitudinal fields. The
conoid tail tapers from the anus, but at last for a short distance is more or less
hanoe
CRYSTALLONEMA, ZANEMA
283
cylindroid and one-fifth as wide as at the anus. There are no caudal setae.
The ellipsoidal to prolate renette cell lies close behind the neck, and is one-half
as long as the body is wide and five-sixths as wide as long. The large, continuous
vulva is inconspicuous. The medium-sized vagina extends two-fifths the way
across the body. There is a posterior rudimen-
tary branch to the sexual organs, three times as
long as the corresponding body diameter. The
uterus is four times as long as the body is wide, and
one-sixth to one-fifth as wide as long. The elon-
gated eggs are three times as long as the body is
wide. The relatively very small ovary contains
twelve ova, which diminish rapidly in size toward
the blind end, and are arranged single file. The
finely-granular, ripe ova are three times as long
as the body is wide, and three-fourths as wide as
long.
Habitat: Sand, below Bathing Beach, Woods
Hole, Mass., U. S. A. Flemming to water. The
males of this species, C. fvscacephalum, are
unknown, but the males of two other species are
known to the writer. As these two are structu-
rally closely related to C. fuscacephalum, it may be
assumed that the spicula of C. fuscacephalum are
similar to those of these others, one of which is
Crystallonema simile n. sp., Miami, Fla., the anal
region of the male of which is shown in the adjac-
ent illustration, together with the dimensions of
both sexes. Besides being smaller, C. simile differs in lacking pigment at the
head end; in having relatively slightly longer and more nearly equal cephalic
setae; in having amphids relatively larger, three-sevenths as wide as the head;
in having the posterior oesophageal swelling almost indistinguishable; in having
the preliminary segment of the intestine as long as the body is wide, and the
intestine itself relatively a little wider, three-fourths as wide as the body.
Fig. 67a, p. 282, C. fuscacephalum; Fig. 676, C. simile, n. sp., type species.
dnm
X750
..?:?... .*.?.
1.2 1.3
"-69
i.3
-M"
"1.5"
68. Zanema acanthurum n.
Neck cylindroid.
Cuticle naked.
It is possible that very small or broken
(lui
I members of the submedian group of cephalic setae have
//ph escaped notice, and that there are really three submedian
<-/4) setae on each lip. There appear to be six lips, but this
' number is assumed largely on the basis of the six labial
^P" appendages, shown in the illustration. The lips are rela-
amph tively rather thick, and are arched together over the
somewhat spheroidal pharynx. Oesophagus cylindroid.
The intestine becomes at once three-fourths as wide as
the body, and appears to be made up of cells of large
size, so that perhaps only two appear in the cross-section.
The posterior lip of the anus is slightly raised; rectum
about as long as the anal body diameter. The tail tapers from a little in front
of the anus and soon is reduced to a diameter about half as great as at the base.
Thence onward it tapers gently, so that near the terminus it has a diameter about
seta//
284 ORDER SYNODONTIA
one-fourth as great as at the anus. Posterior two-fifths of the tail armed with
short, backward-pointing, arcuate, acute thorn-like setae to the number of ten
on each ventrally submedian line. No caudal glands. The lateral fields appear
to be fully one-third as wide as the body. The excretory pore appears to be con-
nected with a large, ellipsoidal ampulla, nearly half as wide as the neck. The
position of the renette cell has not been determined. From the depressed vulva
the vagina leads slightly forward. Beyond this fact little is known concerning
the internal organs. As no traces of ova have been seen behind the vulva it is
assumed that the organs are asymmetrical.
Habitat: Mud, tide pool, low tide, Portsmouth, N. H., U. S. A. The single
specimen examined contained numerous yellowish, spherical/^crystalline bodies,
arranged in an obscurely double series, beginning at the base of the neck and
ending at the anus. Whether these are natural or have been induced by the
method of preservation remains to be determined. The peculiarities of the spe-
cies justifying the establishment of a new genus are as follows : (1) the formation
of the pharynx and of the lips with their distinct forward-pointing appendages;
(2) the unusual size and form of the amphids; (3) the absence of caudal glands;
and (4) the peculiar thorn-like setae on the tail. These, combined with the very
slender form, make it difficult to refer this specimen to any known genus. Fig.
68, p. 283.
69a. Monhystrium transitans n. sp. Type species. Cuticle naked, except for
the setae on the head. Lips three, more or less confluent, thick and mobile.
Pharynx double; the closed lips forming a narrow vestibule reaching one-third
the way to the base of the pharynx. Anterior chamber of the pharynx pyramidal,
the posterior more of less napiform. The lips come to a sharp edge, and are
stiffened by several refractive "plates," whose direction is radial but indefinite,
as if due to the folding of a cutinized membrane. Oesophagus cylindroid, end-
ing posteriorly in a pyriform cardiac bulb five-sixths as wide as the base of the
neck. Its lining finds expression in three longitudinal lines, occupying a space
equal to two-sevenths the width of the whole organ. Its musculature is rather
coarse. There is no cardia. The thick-walled intestine, which has a distinct,
refractive lumen, is set off from the oesophagus by a constriction one-fourth as
wide as the base of the neck, and becomes at once three-fourths as wide as the
body. Its cross-section shows two cells. In contour, it is more or less crenate,
at least in alcoholic specimens, because of the pronounced nature of the intestinal
cells. These latter contain numerous granules of rather uniform size. The
walls of the intestinal cells are refractive. The tail is at first conoid, then cylin-
droid in the posterior two-fifths. It tapers from in front of the anus to the almost
imperceptibly swollen, more or less apiculate, unarmed, symmetrical terminus,
which presents a profile similar to that of a swan's head. It bears a simple,
unarmed, blunt spinneret. Only two caudal glands are to be seen; these are
broadly saccate cells, forming a close tandem in the anterior third of the tail.
The more or less finely granular longitudinal fields are one-third as wide as the
body. The post-cervical renette cell empties through the excretory pore a little
in front of the nerve-ring by means of a more or less spherical ampulla, and final
slender duct one-half as long as the body is wide, leading therefrom to the
excretory pore. The vulva is large and more or less elevated. The ellipsoidal
eggs are three-fourths as long as the body is wide and are deposited after seg-
mentation; it is probable that the species is viviparous, or ovoviviparous. The
small posterior branch of the sexual organ is one-half as long as the body is wide.
MONHYSTRIUM
285
rpt
msuM
axjlaind
mnldsl
The tapering ovary is at first broad, and contains numerous ova arranged for the
most part single file. At its blind end, it is one-eighth as wide as the base of the
neck. At their widest part, that is, near the middle, the spicula are one-sixth as
wide as the corresponding portion of the body. They taper to a rather blunt point,
and present a faint, stiffening element. These ^int a mnh wfsn/m
colorless, rather frail spicula appear to have
their proximal ends somewhat dorsad from the
body-axis. There is a faint, frail, slender,
arcuate accessory piece, lying parallel to the
spicula, probably consisting merely of a differ- or "" ' " /////.'///
entiation of the lining of the cloaca. Obscure
papillae occur on the middle part of the tail, msc silbm .:
near the place where it suddenly diminishes a
little in diameter. These are probably as fol-
lows: one ventrally submedian pair opposite
the middle of the spicula; three ventrally sub-
median pairs, one of them nearly anal, the
other two at the beginning of the middle third,
and occurring one in front of the other; one
dorsally submedian pair. The large spermato-
cytes in the testes are three-fourths to two-
thirds as wide as the body. That portion of
the testis, containing them is correspondingly
wide, but the testis tapers so as finally to be
only about one-fourth as wide as the body.
Habitat: Gill-chambers of the Land Crab,
G. ruricola, Jamaica. Coll., Dr. C. B. Wilson,
Westfield, Mass. Described from more or
less shrunken alcoholic specimens, mounted in
balsam and in glycerine jelly. May be looked lumoe ,
upon as a transitional form between a free- 1.4 10.6 20. **-& 90. < ) . 9
living and parasitic state. Hence, the specific 3 ' 5 /4 ' J
name transitans. While much reduced and 11 "J M ^_ ^ > 83 ..
flabby, the cephalic setae still exist. Very
few parasitic nemas possess cephalic setae. Fig. 69a.
b. Monhystrium wilsoni (Baylis). Very narrow wings extend from the base
of the neck to near the anus. Each wing is expressed as a double line. Eight
to twelve longitudinal striations occur on each submedian field. The longi-
tudinal striae do not anastomose, and seem to be in the outer cuticle. Lips con-
fluent, elastic, closing to a small central pore. Pharynx of two chambers; the
anterior, pyramidal, the posterior appearing roughly napiform in profile, but
really three-sided as shown in the illustration. The distinct, refractive lining
becomes rapidly thicker in the posterior half of the second chamber. About
eighteen duplex radial refractive ribs of small size occur in the anterior chamber,
somewhat as in Cyatholaimus; i.e., there are about six refractive radial markings
on each of the three lips. These have a rather definite duplex outer end, or con-
tour, but are not so definite as the "rods" of Cyatholaimus, being more like
folds. Neck conoid; head convex-conoid. The cylindroid oesophagus near the
nerve-ring is two-fifths, just in front of the pyriform cardiac swelling two-thirds,
X1000
286 ORDER SYNODONTIA
finally two-thirds, as wide as the corresponding part of the neck. There are no
oesophageal bulbs, but there is a pyriform anterior segment of the intestine,
set off on both sides by a distinct constriction, in some ways resembling a cardiac
bulb. This pseudo-bulb is three-fourths as wide as the corresponding portion of
the body, as measured in alcoholic specimens. The lining of the oesophagus is
a prominent feature, and its optical expression consists in three refractive lines,
occupying a space one-fourth as wide as the entire organ. The oesophageal
musculature is coarse. At the cardiac constriction there are three elements,
questionably glands, each one-third as wide as the corresponding portion of the
body. There is no cardia. The thick-walled intestine has a very distinct refrac-
tive lumen and soon becomes five-sixths as wide as the body. The cells compos-
ing the intestine are about twice as long as he body is wide, and are so
arranged that each cross-section presents practically only two of them. These
cells are packed with exceedingly fine granules of more or less uniform size. The
tail is first conoid, then cylindroid in the posterior half. It tapers from in front
of the anus; the terminus has a contour more or less resembling that of a swan's
head. The simple, unarmed, symmetrical, blunt spinneret is half as wide as the
terminus. The three, broadly saccate caudal glands form a close tandem in the
anterior fourth of the tail. Their ducts and ampullae are distinct. There are
no caudal setae. The tail, like the body, is naked. The elongated renette cell
lies two to four body-widths behind the neck, and empties through a wide duct
separated from the ampulla by a constriction; the ampulla is one-fourth as wide
as the corresponding portion of the neck, and empties through a pore located
half-way back to the nerve-ring. The nerve-ring is accompanied by distinct
nerve-cells arranged in groups. From the somewhat large, more or less conspicu-
ous vulva, the large, rather muscular, cutinized vagina leads half-way across the
body. The straight uterus is about fourteen times as long as the body is wide,
and contains ellipsoidal eggs, each about as long as the body is wide, which are
deposited after segmentation begins, in fact, the species may be viviparous.
Fully-formed embryos occur in the eggs near the vulva. Spermatozoa, half as
wide as the body of the female, and with strong refractive nuclei, occur in the
uterus. There is a rather narrow, ventral posterior rudimentary part to the
female sexual organ, about one and one-half times as long as the corresponding
portion of the body is wide. The ovary is nearly cylindroid, but tapers slightly,
and contains numerous ova arranged single file. Toward its blind end, it sud-
denly narrows, and is reflexed, or thrown into an "S" form, in a space one to two
times as long as the body is wide; here it is only one-sixth as wide as the body.
The rather frail, somewhat simple, rather slender, subacute spicula are one and
one-half times as long as the anal body diameter. At their widest part near the
middle, they are about one-sixth as wide as the corresponding portion of the body.
Their proximal ends appear to lie dorsad from the body-axis. The single, frail,
very slender, more or less arcuate, accessory piece is somewhat removed from the
spicula, at least from the refractive part. Its proximal extremity lies dorsad
from the body-axis. There are no supplementary organs. About ten pairs of
papillae occur on the tail of the male. These are very inconspicuous and are
arranged as follows: one ventral, single, and two submedian pairs just in- front
of the anus; third, fourth, fifth and sixth pairs behind the anus, opposite the two
anterior caudal glands; seventh and eighth, lateral, opposite the posterior caudal
gland; ninth and tenth farther back, not so close together, averaging about twice
as far from the anus, as the seventh and eighth. There is a rudimentary bursa;
i.e., there are submedian longitudinal elevations of considerable magnitude
MONHYSTRIUM, ASYMMETBELLA
287
beginning some distance in front of the anus and extending on to the tail to a
point opposite the posterior caudal gland. Most of the papillae described occur
on the ventral surface of these welt-like elevations. A cross-section taken near
the anus clearly discloses these well-developed organs. The ejaculatory duct is
one-fourth, the vas deferens one-fourth, the testis two-thirds, as wide as the
corresponding portion of the body. Toward its blind end, however, the testis
tapers so as to be only one-eighth as wide as the corresponding portion of the
body. Spermatocytes, occupying a considerable portion of the length of the
testis, are one-half to two-thirds as wide as the body, so that the testis bears
considerable resemblance to an ovary. The/inset hblbsubm pfllb set lot setsdm
deceptive appearance created by these large
spermatocytes might easily lead to the con-nrpffl/
elusion that the males are hermaphrodites.
Habitat: Found with the preceding.
One is inclined to suggest that this Mon- ..
hystrium also represents a transitional form
from a free-living to a parasitic condition.
A careful study of such forms is destined to
throw much light on the relationship between
the Laimia and Alaimia.
Although bearing considerable resemblance
to Monhystera, this species and its close rela-
tive just described seem to make a new genus
desirable for their reception. The distin-
guishing differences may be listed as follows:
(1) In Monhystrium, the pharynx is a double
chamber; moreover, the anterior chamber
has a distinctly radiated structure, more eas-
ily seen if the specimen is viewed slightly
obliquely instead of laterally, as shown in the
illustration. These radial elements are stiff-
ening factors enabling the lips to bite more
efficiently. The margins of the lips are sharp-
cutting edges, as is clearly shown in the profile
view in the illustration. Further study is necessary to determine whether these
organs are odontia or onchia. (2) The pseudo-bulb, which is not common in
Monhystera. (3) Monhystrium is ovoviviparous or viviparous. (4) There is
a pronounced renette. (5) There are no cephalic setae or the setae are very
weakly developed. (6) The species is presumably carnivorous; the more typical
Monhysteras, perhaps all, are vegetarian.
Larvae removed fron the uterus of alcoholic specimens present differences
from the adults as follows: (1) The amphids are farther back. (2) The pharynx
is tubular, and not in two parts. (3) The head is more tapering. (4) The spin-
neret is not so well defined. (5) No wings were seen. (6) The pseudo-bulb is
less conspicuous. Fig. 696, on this page. Syn. Monhystera wilsoni Baylis.
1.3 14. 27. '"'62'" 95- >2
70. Asymmetrella glabra n. sp. U4 *- 6 E - 3 1 - 8 '' ' " Lips three, dis-
tinct, unequal, flat, thin. Pharynx with a peculiar dorsal onchium, bent inward
at right angles at the apex. Oesophagus surrounding the posterior two-fifths of
the pharynx in the form of three, somewhat finger-shaped processes. Wall of
the pharynx fairly well cutinized, especially near the lips on the dorsal side,
288 ORDER SYNODONTIA, ORDER SYNONCHIA
where it bends inward and forms an elbowed lip, giving to the front of the head
an asymmetrical appearance; hence, the generic name. Neck cylindroid posteri-
orly, convex-conoid anteriorly. Amphids faint. At the base of the pharynx
there are three spherical collections of black, loosely-placed granules (ocelli?),
one collection dorsal and two submedian, the dorsal collection being the least
pronounced. The cylindroid oesophagus at the nerve-ring is one-third, and fi-
nally is one-half, as wide as the corresponding portion of the neck; it has an indis-
tinct lining, and a fine, colorless musculature. There is a more or less hemi-
spherical cardia, three-fifths as wide as the base of the neck. The thick-walled
intestine, which is set off by a constriction one-half as wide as the base of the
neck, becomes at once three-fourths as wide as the body. It has a faint lumen,
and its cross-section exhibits about four cells. In all parts of the intestine the
cell walls are rather distinct and optically give rise to a network
effect. From the more or less continuous anus the prominent,
cutinized rectum extends inward a distance three-fourths as great
as the anal body diameter. The rather numerous, more or less
yellowish granules contained in the cells of the intestine are of
Invariable size, the .largest being about one-thirty-fifth as wide as
the body. They are so arranged as to give rise to a more or
less distinct tessellation. The lateral fields are one-fourth
as wide as the body. The tail tapers from the anus, and is at first conoid, and
then convex-conoid in the posterior eighth. It is arcuate to the unarmed, more
or less symmetrical terminus. There is a conoid, symmetrical spinneret. In it
a compound ampulla is apparent. Renette unknown. The female sexual organs
are probably double and symmetrically placed.
Habitat: Marine tap water, laboratory, Woods Hole, Mass., U. S. A. Flem-
ming to glycerine jelly. Fig. 70.
VIII. Order Synonchia
71. Tripylium carcinicolum (Baylis). Cuticle naked. Cephalic setae papil-
loid. Wall of the pharynx fairly thick and refractive, and curved inward on the
inner surface of each pair of lips so as to form three 120 biting organs, which
close together as shown in the illustration. Pharynx cylindroid. Neck cylin-
droid posteriorly, conoid anteriorly. Oesophagus cylindroid, its lining a trifle
stronger behind the pharynx for a distance equal to the length of the pharynx.
The anterior portion of the intestine is altered so as to produce the effect
of a pyriform bulb three-fourths as wide as the base of the neck, set off on
both sides by a constriction. At the nerve-ring, the oesophagus is two-thirds,
and finally three-fifths, as wide as the corresponding part of the neck. The lin-
ing of the oesophagus finds optical expression in three refractive lines, occupying
two-fifths of the width of the organ. There is no cardia. What appear to be
glandular cells occur opposite the cardiac constriction, two, one on each side,
each ellipsoidal and half as wide as the neck, finely granular and with a promi-
nent nucleus. The thick-walled intestine has a distinct, refractive, more or less
zig-zag lumen, and becomes at once three-fourths as wide as the body; in cross-
section it presents two cells. The cardiac collum is one-fourth as wide as the
neck. From the more or less continuous anus, the cutinized rectum extends a
distance equal to the length of the anal body diameter. Fine uniform granules
pack the cells of the intestine; there is a faint tessellated effect due to the refrac-
tive nature of the cell walls. From in front of the anus, the straight tail is first
TRIPYLIUM, XYALA
289
xtaim
conoid, then cylindroid in the posterior two-fifths, where it is one-eighth as
wide as at the base. Terminus apiculate, bearing a simple, symmetrical spin-
neret. The three broadly-saccate caudal glands are packed into the anterior
two-fifths of the tail, and empty by means of separate ducts. Three pairs of
conoid, subacute, ventrally submedian papilloid setae occur on the tail of the
female, one pair near the anus, one near the middle of the tail and one at the begin-
ning of the posterior fourth. Midway on the tail there is a dorsally submedian
pair of setae. The finely-granular lateral fields are half as wide as the body.
There appears to be an elongated renette cell one body-diameter behind the
neck; it is one-fifth as wide as the body. From
the large, conspicuous, elevated vulva, the
vagina, also large, extends inward half way across j^y^
the body. Its wall is cutinized. There is no
posterior vestigial portion to the sexual organ.
The straight uterus contains twelve or more
already liberated embryos. Ova are arranged
single file. The simple, rather frail, slender,
uniform, acute spicula are arcuate distally.
They are three-fourths as long as the tail, and at
their widest, about one-tenth as wide as the cor- .>.
responding portion of the body. Their proximal
ends seem to lie more or less dorsad from the
body-axis. The simple, frail, very slender, arcu-
ate accessory piece is more or less obscure in alco-
holic specimens. It lies parallel to the spicula
and its proximal end appears to be dorsad from
the body-axis. There are three pairs of very flat,
conoid, innervated, inconspicuous, nearly ven-
tral papillae on the tail, one at the beginning of
the fourth fifth, and two at equal distances
between it and the anus. The ejaculatory duct
is one-third, the testis two-thirds, as wide as
the body. Only the narrow blind end of the
testis, for a distance equal to one body-diameter, \-^ j^ ^ ~li ^frf"* 1-1 "
is reflexed. In one specimen, the spicula were
more or less compound. jj| ^3 TT~~ ^i Tz~ > 0-9
Habitat: Found in the gills of the Land Crabs,
Gecarcinus ruricola and Cardisoma guanhumi, Jamaica. Collected by Dr. Chas.
B. Wilson, Westfield, Mass. This genus differs from Monhystera as follows: (1)
Male has caudal papillae; (2) Has a cardiac bulb or pseudo-bulb; (3) Is vivip-
arous; (4) Is parasitic in crabs; (5) Has three biting edges to the segments of
the pharynx. Fig. 71. Syn. Monhystera carcinicola Baylis.
72. Xyala striata n. sp. Cuticle with numerous wings, especially anteriorly,
where there are sixteen, increasing to about thirty-two on the head; behind the
vulva the number is twelve, at the terminus four. Contour dentate. There are
a few cervical setae, about as long as the body is wide, occurring in groups of
four; no somatic setae. Lips thick, armed with three, mandible-like odontia,
or onchia, somewhat flap-shaped, and apparently very mobile. Pharynx simple,
regular, more or less conoid, large and long, three-fourths as wide as the head,
having the form of a deep cup. There is a distinct, transverse, cutinized raised
290
ORDER SYNONCHIA
circle on the inner wall of the pharynx, dividing it into two more or less distinct
parts; nevertheless, the inner contour of the pharynx is rather regular on the
whole. Neck cylindroid. Oesophagus plain, except that there is a pyriform
bulb surrounding the pharynx, tapering gradually into the oesophagus, which is
at first two-thirds, at the nerve-ring one-half, and finally two-fifths, as wide as
the corresponding portion of the neck. There is a more or less cylindroid cardia
one-third as wide as the base of the neck. The thick-walled intestine has a
distinct lumen, and becomes at once two-thirds as wide as the body. Cardiac
k collum one-half as wide as the body. The scattered, rather uniform yellow
seHphestrW mnd \lat setcphJntr(6> -'f--^ ---^| - -^ _->i.4.. granules,
found in the
LI v-A25. _ -*-' __.9i. ?18 intestinal
1-4 ll7 1-8 2 ' 2 ~* 1>6 cells, are less
than half as wide as one of the annules.
From the continuous anus the more or
less cutinized rectum extends inward a
distance hardly as great as the anal body
diameter. The conoid tail tapers from
the anus, near which, in the anterior third
of the tail, the three ellipsoidal, caudal
glands lie in a close tandem. There are
very few, inconspicuous, slender, taper-
ing, acute, dorsally submedian caudal
setae. Renette unknown. The nerve-
ring surrounds the oesophagus obliquely and is accompanied by obscure nerve
cells. From the large, conspicuous vulva, the large, tubular, muscular, cutin-
ized vagina extends forward a distance equal to the width of the body, where it
joins the straight uterus, which is six times as long as the body is wide and con-
tains eggs two and one-half times as long as the body is wide, and one-third as
wide as long, if one may judge the size of the eggs from that of a full-grown
ovum. There is a spermatheca extending forward a distance five to six times
greater than the body diameter, the extent of which is plainly indicated by the
definite contour of its blind end. The rather narrow, tapering ovary contains
about twenty ova arranged single file. The spicula are slender, uniform, and
acute. Their spherical proximal ends appear to lie dorsad from the body-axis.
The two, separate, slender, acute, strong accessory pieces have proximal parts
that appear to envelop the spicula. There are no pre-anal ventral supplemen-
tary organs, or special papillae. The ejaculatory duct is one-third as wide as the
body. The narrow, cylindroid testes finally taper to a width two-fifths as great
as that of the body.
Habitat: Eel-grass, Woods Hole, Mass.; also Belmar, New Jersey, U. S. A.
Sublimate to balsam. Fig. 72.
X750
97.2
> 1.3 .,
There
7-5 . 15- 61
............... -
73. Synonchium obtusum n. sp. ^ 3>5 ' 3 - 6 Tere are no
wings. On the lateral fields, which are about one-fourth as wide as the body,
the secondary elements of the annules become scattered and coarser, and oval
or elongated in contour. There are two laterally submedian, irregular rows of
pores, one to two times as wide as the annules, lying along the margins of the lat-
eral fields, and separated from each other transversely by a distance about equal
to one-fourth the width of the body; measured in a longitudinal direction, the
distances between the pores are about the same, but somewhat irregular. These
pores have a special arrangement on the tail. (See illustration.) Neck cylin-
SYNONCHIUM. GAMMANEMA
291
droid; oesophagus somewhat cylindroid, but presenting a more or less spheroidal
bulb about the mandibles. At the base of the neck, the oesophagus is two-thirds
as wide as the corresponding portion of the body. Its lining is more or less dis-
tinct; its musculature colorless. The rather thick-walled intestine has a faint
lumen, and becomes at once five-sixths as wide as the body. Throughout the
X750
body under the cuticle, there are coarsely granular, spherical organs one-fourth
to one-third as wide as the body, located in the lateral fields, and separated
from each other longitudinally by a distance about equal to the body diameter.
It is probable that the female organs are double, and symmetrically reflexed.
.
2.7 3.1 : s.i 3.1 "^a-s Apparently there are only two small supple-
mentary organs in front of the anus. (See illustration, sup.) Resembles Eno-
plus, from which it is distinguishable, however, by the form of the spicula, and
other organs of the male, as well as by the form of the amphids.
Habitat: Seaweed, drifted ashore, Ocean Beach, Miami, Florida, U. S. A.
Fig. 73.
74. Gammanema ferox n. sp. Neck cylindroid. Cuticle naked, except for the
setae on the head. Lips joined by a membrane,
ii' ' 3?i'=' ' ii ..... 3.2 ' ' ' 2/5' >2 ' 5 "* variously armed as shown in the illustration.
Probably the twelve "spatulate" appendages are
Ii' ' Vg''' ''I''!' ' ' '~3'1' =- ; -4^'9' > ' 2 - 5 " sensor y organs, if one may judge by their form
and position. The pharyngeal bulb contains
three "apophyses," each carrying near its summit an inward-pointing, acute
onchium, or perhaps it would be better to say, each of the three strong ribs of
292
ORDER SYNONCHIA
the posterior portion of the pharynx bears one of these onchia. The oesophagus
gradually diminishes so that at no great distance behind the head it is but little
more than half as wide as the neck, and continues thus throughout. There is a some-
what small, hemispherical cardia about one-third as wide as the base of the neck.
The intestine becomes at once about three-fourths as wide as the body. In cross-
section it presents four to six cells, manifestly of two different kinds, one of which,
a minority, is much more distinctly granular than the other and is more numer-
ous in the anterior portion of the intestine than in the posterior. The limits of
each cell, of whichever kind, are rather clearly marked on account of the refrac-
tive nature of the cell-walls. The cells are packed with a multitude of fine,
nearly colorless granules. The anus is prominently raised; the rectum is as long
as the anal body diameter. The tail is conoid to the convex-conoid terminus,
which forms a convex-conoid, somewhat truncate spinneret of large size, in which
is the group of large ampullae of the caudal glands, which nearly fills the terminus,
its diameter being about half as great as that of the base of the tail. The large
caudal glands are located in a close tandem just behind the anus, in the anterior
two-thirds of the tail. The lateral fields are fully one-third as wide as the body,
and contain cells of unusual size, of such a width as to reach nearly across the
fields themselves. These cells are not contiguous, and there are found with
them in the lateral field cells of small size. Renette unknown. From the ele-
vated vulva the vagina leads inward half way across the body, where it joins the
single uterus, which extends backward. The ovary reaches about half way back
to the vulva and contains
six to twelve developing
ova, of which the larger
ph are arranged single file.
The eggs appear to be
elongated, somewhat
murph longer than the body is
wide and about one-third
as wide as long. The anus
of the male is prominently
raised. In front of it there
is a ventral series of sup-
plementary organs occu-
pying a space equal to six
to eight body-diameters.
The hindermost of these
organs is located opposite
750 the posterior part of the
spicula, and the penultimate opposite the middle of the spicula, and the third
from the last nearly opposite the proximal ends of the spicula; the series contin-
ues along the ventral line with a somewhat equidistant arrangement, the total
number of supplements being at least sixteen. Each supplement is a somewhat
narrow cutinized structure of small size, extending outward and backward, and
its distal extremity is capable of being exserted. These organs are not very con-
spicuous. A few submedian setae are seen near the anus, one pair opposite the
distal parts of the spicula, and one or two on the bulky portion of the tail. The
slender, uniform spicula have their proximal ends located opposite the body-
axis. The width of the spicula is not much greater than that of the surrounding
nuclei, in other words, the spicula are quite slender. They are accompanied
GAMMANEMA, TROGOLAIMUS
293
by obscure accessory pieces. The ejaculatory duct is about one-third as wide as
the body, the vas deferens about half. The testes are unusually short and broad,
only about four to six body-diameters long, and are, at their broadest, two-
thirds as wide as the body; they taper rapidly to the blind ends, which are only
about one-fourth as wide as the body.
Habitat: Marine; coral sand. New Hebrides. Sublimate to balsam. Fig. 74
p. 292.
lb(6)
ndm
75. Trogolaimus uniformis n. sp. '^ M : ^ ' i~~f^~~i~ ' Lip-region
divided into twelve parts, readily distinguishable, though not cutinized. The
broadly cup-shaped anterior por-
tion of the pharynx is that part
referred to in the formula. From
its rather flattish base three
apophyses extend backward close
together, near the axis of the '
head, a distance about equal to
the depth of the open portion of asc -
the pharynx, thus adding a second
chamber. Each of these apophy- -
ses has a small, inward-pointing
onchium at its apex. These &$
onchia meet together and cross at the middle of the floor of the anterior portion
of the pharynx. As usual, the apophyses serve for the attachment of muscles,
and all that portion of the pharyngeal bulb in front of the bases of the apophyses
is different in character from the wall of the oesophagus, being more completely
fibrous and destitute of the large nuclei that occur in the oesophageal muscula-
ture. The oesophagus continues with the same diameter until after it passes
through the nerve ring, when it begins to expand gradually, so that finally it
is more than half as wide as the base of the neck. In optical section the lining
of the oesophagus appears wavy. There is no distinct cardia. The intest ne,
which is separated from the oesophagus by a deep constriction, becomes at once
about three-fourths as wide as the body. Its cross-section probably presents
two to four cells. These contain a multitude of minute, evenly distributed
granules. The walls of the cells are refractive. The lateral fields are about two-
fifths as wide as the body, and appear to be composed of two rows of cells.
Renette unknown. The tail of the male is conoid from the prominently raised
anus. It diminishes in diameter rather slowly until near the end. The diam-
eter of the base of the spinneret is about one-sixth to one-eighth as great as that
of the base of the tail. The caudal glands appear to be located in front of the
anus. In Cyatholaimus, with which Trogolaimus may be compared, it is usually
easy to discover the ventral gland and excretory pore. So far these have not been
seen in the present species. The following is a description of the tail of a young
female : The posterior lip of the anus is distinctly raised and rather broad. The
rectum is somewhat longer than the anal body-diameter. The tail is cylindrical
to the rounded or conoid-hemispherical terminus, which ends in a somewhat
cylindrical spinneret, having a diameter about one-sixth as great as that of
the base of the tail. The length of the tail is about two and one-half times as
great as that of the anal body-diameter. This description is derived from a
specimen in which the sexual organs are represented by an oval body consisting
mainly of two cells. Supplements twenty-one, slightly elevated, flat, similar
to those frequently seen on the males of Chromadora. These organs occupy a
294 ORDER SYNONCHIA, ORDER MESONCHIA
distance about three times as great as the length of the tail; the posterior ones
are a little nearer together than the anterior ones. The two hindermost are
opposite the anterior halves of the spicula, while the antepenultimate is a little in
front of the proximal ends of the spicula. The average distance between the
organs is one and one-half to two times as great as their diameter. No special
setae or papillae have been seen on the tail either in front of the anus or behind
it. The strongly developed spicula taper at both ends. The proximal ends are
slightly hooked toward the ventral side of the body, and also slightly enlarged,
so that they are distinctly cephalated. The main portion of the framework of
each spiculum consists of four refractive elements arranged in two pairs, one
dorsal, the other ventral. The slightly curved accessory piece leaves the surface
of the spicula somewhat and then recurves so as to touch them again. The ejacu-
latory duct is half as wide as the body.
Habitat: Mud, tide pool, low tide, Portsmouth, N. H., U. S. A. At first sight
this species appears to be a Cyatholaimus but examination shows a number of
important differences. The pharynx is not striated in the same way as that of
Cyatholaimus, nor is there a dorsal onchium. The examination has not revealed
the pores frequently to be seen along the borders of the lateral fields in Cyatho-
laimus. Most Cyatholaimi have a single testis. This genus also bears a con-
siderable resemblance to Halichoanolaimus, but differs in that the numerous,
minute pharyngeal denticles of Halichoanolaimus are lacking. Alternating with
each pair of the twelve amalgamated lips there are papillae which extend an
exceedingly short distance beyond the margin of the lips. Fig. 75, p. 293.
IX. Order Mesonchia.
76. Mesonchium poriferum n. sp. The thickish, colorless cuticle has on the
females three rows of round cuticular elements on the lateral fields, on the males,
two; similar markings arranged irregularly occur on the ventral surface. Setae,
half as long as the corresponding part of the body is wide, are found scattered on
the neck. None are seen on the body. Rows of pores occur on the lateral fields,
one row on each side just outside the longitudinal rows of lateral markings. The
diameter of these pores is about equal to the width of two annules; the distances
%tcph(4)\w(3) pplOl (6+6) * *^^J2*t!Ljfe_, M separating them longi-
^ --.\A__J>- j L2 2 " 2 - 7 -s 2.i /2 - 4 " tudmally are about
equal to the diameter
' 5 " of the pores. Lips
confluent, rounded, thick. Each onchium
appears to be the apex of a plate which
forms one of the three faces of the pharyn-
geal cavity. These plates are thickened at
the anterior end of the pharynx. Pharynx
ward in a direction parallel to the axis of the head. Neck conoid. Oesophagus
conoid, with a faint cardiac swelling, hardly to be called a bulb. Near the
nerve-ring, the oesophagus is one-half, and finally three-fifths, as wide as the
corresponding portion of the neck. The lining of the oesophagus finds optical
expression in three parallel, refractive lines. Its musculature is rather coarse.
There is a more or less hemispherical cardia, one-fourth as wide as the base of
the neck. The intestine becomes at once three-fourths as wide as the body, its
MESONCHIUM, PEPSONEMA 295
cells containing numerous granules of rather uniform size, and of about the same
diameter as the dot-like lateral, cuticular elements. The conoid tail tapers from
in front of the anus and becomes cylindroid in the posterior third, where it is
one-seventh as wide as at the base. The elongated caudal glands, which empty
by separate ducts, are packed in the anterior half of the tail. Slender, rather
tapering setae, to the number of twelve occur on each ventrally submedian line
in front of the anus; about seven setae occur on each of the submedian lines on
the tail. The pre-anal setae are scattered through a distance about equal to the
length of the tail, and are mostly very inconspicuous, especially anteriorly. The
lateral fields are two-sevenths as wide as the body. The non-granular, ellipsoidal
renette cell occurs near the cardia, and is one-third as wide as the base of the neck.
The large, rather conspicuous, elevated vulva leads into a large, conoid, muscu-
lar, more or less cutinized vagina, which extends inward half way across the body.
It is probable that the prolate eggs are about as long as the body is wide, but there
is some uncertainty about this. An unusual feature is that the ovaries are
reflexed only near their blind ends. Each contains about twenty ova, arranged
more or less single file. The tail of the male is cylindroid in the posterior two-
fifths, where, at its widest, it is only one-tenth as wide as at the anus. The rather
long, slender, uniform, more or less acute, colorless spicula are straight to near
the middle, but are arcuate distally. Their proximal ends appear to lie more or
less ventrad from the body-axis. The rather strong, slender accessory piece has
an applied part one-fourth to one-third as long as the spicula; its uniform, more
or less blunt, rather slender apophysis bends and extends backward parallel to
the body-axis. The proximal extremity of the apophysis lies dorsad from the
body-axis. To be seen along the posterior half of the region occupied by the
oblique copulatory muscles, is a pre-anal series of almost invisible ventral inner-
vations, the distances between which are about equal to one-third the body-diam-
eter. The space occupied by the oblique copulatory muscles is about two and
one-half times as long as the tail.
Habitat: Marine algae, Key West, Fla., U. S. A. Flemming to glycerine jelly.
Fig. 76, p. 294.
77. Pepsonema pellucidum n. sp. Cuticle of medium thickness. Anteriorly
the number of the longitudinal rows of "beads" appears fewer than near the tail,
where there are sometimes six
or possibly eight rows. Forma-
tion of the cuticula like that
found in the genus Spilophora.
Somatic setae very minute. , ,
Lips six, or three and two-
parted. Mouth-opening about
one-fourth as wide as the front
of the head, and leading into a
minute vestibule, which is X 750
nearly twice as wide as the mouth opening and very shallow. The pointed,
cutinized apices of three inner lips come together in this vestibule; they are of
nearly equal size, the dorsal being only slightly larger than the two submedian
ones. It may possibly be questionable whether this genus should not be placed
in the Anaxonchia. At the base of the pharynx, there are one or two minute,
onchium-like processes, which are so small as to be easily overlooked. The
oesophagus continues to have the same width, or to decrease slightly, until it
296 ORDER MESONCHIA
passes through the nerve-ring. Thence onward it increases rather regularly,
though finally there is a tendency to form a much elongated bulb two-thirds to
three-fourths as wide as the base of the neck. There is a distinct though small
cardia. The intestine begins as a tube one-half to one-third as wide as the body,
but soon expands so as to become two-thirds as wide as the body. It presents
i.s 5.4 T- 12- "-*?~V ? 2 -. >2.?-. the very interesting peculiarity of containing in
'ij 2.5^ 3- its anterior part about a score of cells whose
1.4 6.7 T*-H. .-*-. ?!-. ?2. .. staining properties indicate that a different phys-
ij z.y 2-8 3-7 *. iological function is discharged in this portion of
the intestine, possibly some gastric function. This is in line with other anatomi-
cal observations, indicating that the anterior portion of the nema intestine
possesses functions differing from those of the middle and posterior portions.
Opposite the cardiac constriction, there are two or three bodies closely resembling
those usually seen in this position in the genus Trilobus. The nature of these
organs still remains problematical. From the slightly depressed anus, the rec-
tum, which is somewhat shorter than the anal body-diameter, extends inward
almost at right angles to the ventral surface. Owing to the strong development
of the somatic muscles, the intestine is only about one-half as wide as the body.
The tissues of the oesophagus evidently contain glands, of which the dorsal is
much the more highly developed; from its structure, it would be easy to suppose
that the gland in the dorsal sector empties at the pharynx, but no conclusive
proof of this has been obtained. In a similar way, it may be surmised that the
glands in the submedian sectors empty into the lumen of the oesophagus in the
vicinity of the nerve-ring. The tail is at first convex-conoid in such fashion that
at the middle it is only about one-sixth as wide as at the anus; from the middle
onward it is cylindroid, expanding slightly to form the rather rounded spinneret.
The ovaries may be reflexed for a short distance near their blind ends. The tail
of the male is rather strongly ventrally arcuate. For a distance in front of the
anus equal to about five-body-diameters, there is found a ventral row of sub-
equidistant innervations probably amounting, in fact, to a series of supple-
ments. These begin near the anus, where they are only one-third as far apart
as at the front end of the series. These very inconspicuous organs are nearly
co-extensive with the series of oblique copulatory muscles. There are two lat-
eral and two ventrally submedian rows of setae on the tail, the lateral rows
lying close to the outside lateral rows of beads. Of these lateral pairs there
are eight or nine. Each of the two sub-ventral rows has about twelve to fourteen
setae. There are a few other setae scattered irregularly on the ventral side of
the tail, as well as in the dorsally submedian positions. Spicula much elongated,
narrow, acute; guided by accessory pieces about as long as the anal body-diam-
eter, which have, projecting backward from their middle parts, processes nearly
as long as they themselves are. The distal ends of the spicula are obscurely
retrorsely barbed. The caudal glands seem to be located in the tail. It appears
that sometimes the distal extremity of the anterior testis may be reflexed for a
short distance. The posterior testis is considerably smaller than the anterior.
Habitat: Mud in the shallow portions of the harbor of Kingston, Jamaica. The
name Pepsonema is suggested by the interesting cells found in the anterior
portion of the intestinal wall. Such specially differentiated cells are now known
for all parts of the nema intestine. In general the specialized cells of the pos-
terior part of the intestine are histologically different from the specialized cells
of the anterior portion. Fig. 77, p. 295.
TRISSONCHULUS
297
m(3J.....lb(6)
X. Order Aponchia.
78. Trissonchulus oceanus n. sp. Cuticle naked, practically without marks of
any kind. Onchia refractive, in contour roughly equilateral, slightly curved,
apparently with an outward stroke. When the mouth is slightly open, the apices
of the teeth are on a level with the surface of the head. Neck slightly conoid,
convex-conoid at the head. Amphids very faint. Inner surface of each of the
six lips armed with scores of exceedingly minute, closely set denticles. Oesoph-
agus cylindroid, then conoid in the posterior fourth, where there is a faint cardiac
swelling, which can hardly be called a bulb. At the nerve-ring the oesophagus is
one-half, and finally three-fifths, as wide as the corresponding part of the neck.
The indistinct lining is expressed by three parallel
lines occupying a space two-sevenths as wide as
the oesophagus. There is a conoid cardia one-half
as wide as the base of the neck. The thin-walled
intestine becomes at once three-fourths as wide as
the body, at least when gorged. Its cross-section
is probably made up of eight to ten cells. These
cells contain scattered colorless granules of vari-
able size, the largest of which are one-fortieth as
wide as the body. Tail sub-cylindroid in the ante-
rior three-fourths. The spinneret presents the
peculiarity of being on the ventral surface of the
tail some distance from the tip. (See illustra-
tion.) The elongated-ellipsoidal caudal glands,
as long as the body is wide and one-third as wide
as long, are located in front of the copulatory mus-
cles. They form a loose tandem, and empty
through distinct ducts and ampullae, the latter
being large and filling the tail. There are no cau-
dal setae. The lateral fields are one-third as wide
as the body and contain large, ellipsoidal cells
nearly as wide as the fields themselves, occurring
at intervals of one to three body-widths; these are
apparently glandular, and connect with the sur-
face by means of pores on the lateral line. The
excretory pore is at the lips and is directed for-
ward. The renette cell, one neck-length behind
the cardia, and as long as the neck, is granular and
contains a large nucleus; its duct is about as wide \ *1 H '"' fe -^'* > 3.6
as the cuticle is thick, and being coarsely granular,
is rather easily followed. There is an anterior rudimentary part to the female
sexual organs two to three body-widths long. From the continuous vulva, the
medium-sized, more or less tubular vagina leads inward two-fifths the distance
across the body. The broad, cylindroid ovary contains about thirty ova,
arranged single file proximally, but irregularly distally. Tail of the male smaller
and more arcuate than that of the female, and more nearly conoid. The proximal
ends of the stoutish, tapering, rather blunt spicula appear to lie opposite the
body-axis. There is a rather frail, slender accessory piece. There is a low and
more or less obscure ventral pre-anal elevation at the anterior portion of the
region occupied by the copulatory muscles. This may perhaps partake of the
nature of a supplementary organ. On each side, in front of the anus, there are
X750
298 ORDER APONCHIA
three, and behind the anus four, ventrally submedian papillae, the former sepa-
rated by spaces about one and one-half times as great as the width of the body.
Of those on the tail two are in front of the spinneret pore and two behind. Of the
two testes the anterior one is much the longer; both are narrow. The ejaculatory
duct is one-half as wide as the body, the vas deferens one-fifth to one-third.
The copulatory muscles occupy a space five times as long as the tail. The sperma-
tozoa are more or less ellipsoidal, and one-fifteenth to one-tenth as wide as the
body of the female. In the male, at a distance in front of the anus four to eight
times the length of the tail there are seven clavate, long glands connecting back-
ward with the ejaculatory duct. These glands darken in Flemming's solution. In
front of these glands, for a distance equal to four to five times the body-diameter,
there are about seventeen spherical glands not darkening in Flemming. These
also seem to connect with the ejaculatory duct.
Habitat: Seaweed that drifted ashore after a storm at Ocean Beach, Miami,
Florida, U. S. A. Also found in beach sand at Ocean Beach. Flemming to
glycerine jelly. Fig. 78, p. 297.
79. Aponchium cylindricolle n. sp. When the lips are closed the three onchia
almost completely fill the pharyngeal cavity. Extending backward and slightly
outward from the bases of the teeth are refractive
i?^ ^L_ 2L_ >1 . 9 _. markings in the pharynx, indicating folds,
evidence that the cavity containing the teeth can
1.8 6. 10. "''M 93.5 > 1 9 .. be everted. The pharyngeal cavity seems tc
merge gradually into the lumen of the oesoph-
agus; it probably extends backward a distance equal to the diameter of the head.
Onchia of very slightly unequal size; the dorsal perhaps smallest, the submed-
ian ones equal. The oesophagus continues to have the same diameter until after
it passes through the nerve-ring, when it expands to form the elongated, pyri-
form, posterior bulb or swelling, three-fourths as wide as the base of the neck.
There is a distinct, somewhat cylindroid cardia, about one-third as long as the
neck is wide. The thick-walled intestine, which is separated from the oesophagus
by a broad and deep constriction, soon becomes three-fourths as wide as the body.
Its cross-section would display six to eight cells. The cells of the anterior por-
tion of the intestine for a distance twice as great as the corresponding body-
diameter appear to be of a slightly different character from those farther back,
as they almost invariably stain somewhat differently. The preliminary cells of
the intestine, namely, a transverse series of about six cells, are undoubtedly of
a larger size than those immediately following, and stain in a different manner;
they fail to take acid carmine stain, when the cells immediately following stain
well. These cells are packed with granules of rather uniform size. The succeed-
ing intestinal cells contain numerous yellowish granules of variable size, which
are rather irregularly disposed. A notable feature of the intestine is the lining,
which is unusually thick, and consists of two elements; an interior thin, refrac-
tive membrane surrounded by a non-staining layer nearly as thick as that portion
of the intestine containing the granules, already mentioned. In many parts of
the intestine this lining, composed of the two above-mentioned elements, occu-
pies fully half the optical longitudinal section. Anus raised, rectum somewhat
shorter than the anal body-diameter. The tail begins to taper slowly from some
little distance in front of the anus. Behind the anus it tapers somewhat more
rapidly, and is conoid to the terminus. The three saccate caudal glands form a
close tandem series in the anterior half of the tail. The nuclei of these cells
APONCHIUM
299
are slung in a rather fine net-work of protoplasm. The lateral fields are fully
one-third as wide as the body. The renette cell is not yet fully understood.
There is a series of rather prominent cells a short distance behind the base of the
neck on the ventral side of the intestine which undoubtedly constitutes the
X750
renette. In one typical specimen these cells were arranged as follows: First,
an elongated-ellipsoidal cell, which failed to take the carmine stain, but con-
tained a distinctly stained nucleolus in its nucleus. This, was followed by a cell
which stained rather strongly, which in turn was followed by a pair of cells which
did not stain, except in their nuclei; these two cells were arranged side by side,
and were the largest of the series, being nearly half as wide as the body, and
nearly twice as long as wide. Behind this pair of cells there was a single cell
300
ORDER APONCHIA, ORDER TRIPLONCH1A
resembling the first member of the series, and behind this one or two others
arranged tandem. This entire series occupies a distance equal to the length of
the neck. From the raised vulva the vagina extends inward and forward. The
outstretched ovary contains fifty or more developing ova arranged in double
file, except near the blind end, which is located near the middle of the body.
The eggs are of large size, elongated, about one and one-half times as long as the
body is wide and about two-fifths as wide as long. In all those thus far seen the
spherical nucleus is of unusually large size. There is no posterior rudimentary
branch to the sexual organs. Well-developed accessory pieces surround the dis-
tal ends of the spicula. With them a median piece extends along the spicula
and appears to end opposite the body-axis, near the base of the apophysis. The
karyokinesis of the sperm atocytes shows the arrangement of the chromosomes
in spireme threads, something very uncommon in nemas.
Habitat: Larat, East Indies. Marine Fig. 79, p. 299.
XI. Order Triplonchia.
80. Triplonchium cylindricum n. sp. Cuticle naked as in the case of nearly
6.9 13. "'541" 98. a ^ Triplonchs.
, 3.i 37a T IT 1-2 " Cylindroid neck
7.6 15. "-M 97. ending in a con-
*ni' in "nm '"X ^ HUB 'Bfliu /m - 3 ' 4 4 ~ 4 ' 2 ~' 7 ' " vex - conoid head -
*jy \\ Amphids more or less protrusile, projecting con-
mnd siderably in all specimens killed with Flemming's
solution. (See illustration.) In some respects
the amphids are reminiscent of those of certain
Mermithidae. Oesophagus mainly cylindroid,
but finally expanding to form a pyriform bulb
nearly two-thirds as wide as the base of the neck,
and having a rather indistinct valve one-sixth as
wide as itself. The lining of the oesophagus is
lot a very distinct feature. There is no very
distinct cardia. The intestine becomes at once
about two-thirds as wide as the body. The cells
contain numerous refractive spherical granules, the largest of which are about
one-sixth as wide as the body, the smallest of which are very much smaller.
These granules are packed so closely together as to obscure the details of the
histological structure of the intestine. Anus continuous; rectum slightly refrac-
tive. The lateral fields have not been clearly seen, but appear to be about one-
fourth as wide as the body. Renette unknown. The nerve-ring surrounds the
oesophagus squarely, and there are numerous nerve cells close together, both in
front of the nerve-ring and behind it, filling the greater part of the cavity of the
neck. From the slightly raised vulva the distinctly cutinized vagina leads back-
ward a distance nearly equal to half the corresponding body diameter; it then
joins the single uterus, which extends first backward, then forward. This latter,
when empty, appears to be about two-fifths as wide as the body. The end of
the posterior ovary lies about one to two body-widths behind the vulva. Noth-
ing is known concerning the size and form of the eggs. There is a cell located
about as far behind the base of the neck as this latter is behind the anterior
extremity, which attracts attention on account of its somewhat peculiar appear-
ance. It presses the intestine to one side, and has a distinct nucleus, with a
TRIPLONCHIUM, APHELENCHULTJS
301
refractive nucleolus. Possibly this cell is the renette cell. The tail of the male
is a little more strongly developed than that of his mate. No pre-anal supple-
ments, though there appear to be one or two obscure papillae just in front of the
anus. There are very obscure, straight accessory pieces; these may be little
more than thickenings of the wall of the cloaca. The ejaculatory duct is two-
fifths, the vas deferens about two-thirds, as wide as the body. In glycerine speci-
mens the spermatocytes are distinctly refractive, ellipsoidal bodies, about one-
sixth as long as the body is wide. The dorso-ventral view of the amphids is very
instructive. As seen in glycerine preparations fixed with Flemming's solution,
the external amphids appear as tubular protrusile organs, arcuate in form, and
three to four times as long as wide. They may be protruded for at least half
their length. Their outer surface is of a refractive character, and there appears
to be a slightly refractive core. At the extremity they are almost imperceptibly
expanded, somewhat hemispherical in form, with the terminal surface much
thinner and less refractive than the lateral. They appear to slide in an inner tube
located in the head, which is also cutinized. This tube extends inward and back-
ward, and ends opposite the base of the pharynx, and is therefore arcuate like
the amphid itself. Tubes leading back from the external amphid may be traced
at least half way to the nerve-ring. The inner elements of the tube are refrac-
tive, and are seen to lie more or less parallel to the body-axis, but as yet have not
been connected up with any internal cellular structure. There are comparatively
few ova in the ovary, perhaps about a dozen in all, arranged somewhat irregularly.
Habitat: Humus, Plummer's Island, Potomac River, near the District of Colum-
bia, U. S. A. Fig. 80, p. 300.
81. Aphelenchulus mollis n. sp. Cuticle thin, naked; the wings, extending from
the neck to near the terminus and bearing about twelve, j-
very fine, longitudinal striae, are hardly raised at all. Con-
tour, very minutely crenate. The head, which is more or
less rounded in the adult, is sub-truncate in the young, and tib (HI-
the region is sometimes set off by an almost imperceptible
broad, shallow constriction. The spear is nearly vestigial,
probably nearly functionless, and may act merely as a tube
through which the food passes. It is not clear what the
motive force in deglutition is, as the usual oesophageal
bulbous pump is absent. Oesophagus cylindroid or faintly
cephaloboid. In the larvae opposite the excretory pore are '/'*
to be seen two successive breaks in the lining of the oesoph-
agus, which are probably vestiges of a bulb. At first, the
oesophagus is two-fifths, near the nerve- ring one-half, and
finally one-fourth, as wide as the corresponding portion of
the neck; the lining is subdistinct, the musculature fine and
colorless. There is no car- 1.1 8.9 _u. Y 93.2 x ^
dia. The oesophagus ' 9 / 1-8 2-1
changes gradually into the
intestine, as in Aphelen-
chus. In the larvae, the
.1 / 1.8 2. 2. 2
Upper Fig Adult male.
ina
Lower Figs. Adult female.
thick-walled intestine gradually becomes three-fifths as wide as the body.
Its lining is refractive and in cross-section, it presents one to two cells only,
which alternate with each other as in some Rhabdites. The anus is con-
302
ORDER TRIPLONCHIA
arm
tinuous, the rectum inconspicuous and about as long as the anal body diameter.
The nuclei of the intestinal cells are clear, and have twice the diameter of the
largest intestinal granules, and present a nucleolus. The cells of the intestine
are usually packed with granules of variable size, the largest of which are one-
ninth as wide as the body and are so arranged as to give rise to a more or less
distinct tessellated effect. Tail of the adult, as shown in the illustration. The
tail of a larva is more or less cylindroid, but slightly conoid and at the end bluntly
rounded and almost imperceptibly apiculate. There are no caudal glands.
i ^PP site the base of the oesophagus,
..... there are two to three nuclei similar to
those often found in the genera Tylen-
.CUt chus and Aphelenchus, and probably hav-
ing the same function, namely, that of
salivary glands. The long renette, which
LSImUt appears to be sometimes on the right,
sometimes on the left, extends back along
the lateral field a long distance; it has
been followed for three-fourths the length
of the body. The nerve-ring is accom-
dl panied by rather obscure nerve cells.
Only the blind end of the tapering ovary
^ - is reflexed. The vulva is large and con-
spicuous, and is somewhat elevated, espe-
cially in front. The straight uterus contains ellipsoidal to elongated eggs, which
are about as long as the body is wide, measuring forty by twenty-five microns.
They begin segmenting before deposition.
Habitat: Found at Falls Church. Va., U. S. A., parasitic in a wood-boring
beetle, determined by Mr. F. C. Craighead as Cyllene picta Drury. Sixteen
thousand larvae and a few adult females were found in one beetle. Both male
and female beetle are infested, usually with only a few female parasites ; at least
such is the condition in the month of May. Of fourteen female insects, three
were infested; of twelve males, seven were infested. As a rule, only a few adult
females of Aphelenchulus mollis occur in one host, about one to eight. Two
living adult males of Aphelenchulus mollis were found in the castings of beetles
taken from infested logs. These are the only adult males so far seen. This
finding may indicate that the females are fertilized before entering the host.
The parasites are found in the thorax of the beetle, as well as the abdomen. Fig.
81a, p. 301; Fig. 816.
.4 . 14. -88. 92.
gmm
82. lotonchium imperfectum (Butschli) nom. nov. t- 6 '* 'A, '!' 2 -5
Striae fine; contour entire. Head abruptly truncate, set off by expansion. Spear
exceedingly minute, eight microns long, about one-fourth to one-fifth as long as
the head is wide, simple, plain, apparently not bulbed; in the male, the spear is
difficult to see, being reduced to a mere point. Neck conoid; amphids?. Intes-
tine very transparent; anus indistinct. Tail of the female conical from the vulva,
acute. Excretory duct single, much coiled. Ovary outstretched forward; eggs
somewhat longer than body is wide, half as wide as long, deposited after segmen-
tation. Spicula L-form, tapering, cephalated by constriction, considerably
longer than the anal body-diameter; accessory pieces none; bursa well-developed,
springing from considerably in front of the spicula and extending somewhat
beyond the terminus.
Habitat: In rotting fungi, Germany. Syn. Tylenchus imperfeclus Btsli.
ONCHIUM, DORYLLTUM
303
XII.
83. Onchium ocellatum n. sp.
Order Axonchia
.27 7.2 19. Y? 52 t
1.8 1.2' " " Cuticle thin, the
transverse striae almost impossible of resolution. Except for the cephalic setae,
the cuticle is naked. Spear hollow, brownish, very thin-walled. Though the
yellowish, solid, refractive eye-spots are sublateral in position, they are rather
near together. The specimens thus far examined do not enable one to make a
clear distinction between the oesophagus and the intestine. Connected with
the posterior part of the oesoph- set (ph (4-l\^ QMph ^&_
agus are large glandular cells, (^^C\ // A
probably three in number, judg- "\vv^H%
ing by the number of nuclei. These w aHHm \VW m
structures seem to be homologous
with those found in a similar posi- ^
tion in Tylenchus and Aphelen-
chus, but their actual connection
with the lumen of the oesophagus * 750
is problematical, as no connecting duct has been seen. The fl(X
best interpretation seems to be to consider these structures
as a part of the oesophagus, but it is entirely possible that ^ p
the oesophagus ends just in front of these glands. The thick-
walled intestine, which has a very distinct, refractive zig- ,,
zag lumen, becomes almost at once three-fourths as wide as
the body. From the elevated anus, the prominent, cutinized , /a
rectum extends inward a distance equal to the anal body- >
diameter. The cells of the intestine contain numerous some-
what variable yellowish granules, the largest of which are OCt /W.
one-sixteenth as wide as the body. The conoid tail is arcuate.
Caudal glands have not been clearly deciphered, but they ff/
probably lie behind the anus in the anterior half of the tail
in a loose tandem. They are narrow and elongated. The (fa[ rffl
elongated, granular renette cell, twice as long as the body
is wide, and about one-third as wide as long, is located // ,./
six to eight body-widths behind the neck. The single,
reflexed sexual organ extends forward; the accompanying
formula, correct for the larvae, does not pretend to indi- lMlnt..
cate the true form of the developed organ. Males unknown.
Habitat: Clean "white" marine sand, in five feet of water, x 500
from a cove near the entrance to Buzzard's Bay, Mass., U. S. A., Also from
"sea-grass," Key West, Florida. Fig. 83.
84. Doryllium uniforme n. sp. Cuticle naked, very minutely transversely stri-
ated. Neck conoid. Spear minute, dorylaimoid, but with a distinct, somewhat
refractive posterior swollen part. The oesophagus continues with slight vari-
ations until it joins the pineapple-shaped cardiac bulb, which is two-thirds as
wide as the base of the neck and is separated from the preceding portion of the
oesophageal tube by a constriction. This bulb contains, among other things,
a spherical nucleus with a distinct nucleolus, presumably indicating the exis-
tence here of glands like those of Dorylaimus. The narrow intestine joins the
middle of the posterior surface of the bulb, and becomes at once about two-fifths
304
ORDER AXONCHIA
X750
ndtm
as wide as the body; its cross-section would present only about two cells. These
cells contain scattered yellowish granules of uniform size. From the incon-
spicuous anus the rectum extends a distance longer than the anal body-diaineter.
The pre-rectum is about four times as long as the corresponding body-diameter,
rmJb K *rm V* JftJfr^V* -4 9.5 19. '-si." 97. and is readily distin-
X ^ " g U i s hed from the rest of
.4 12. 19. -x- 1 96. gz the intestine by differ-
l - 2 - 4 '^ 2-~rx,i. "ences in structure; it
appears more transparent and more nearly colorless.
Renette unknown. There seem to be very faint indi-
cations of the presence of a lateral wing. The lateral
fields are about one-fifth to one-fourth as wide as the
body. From the rather inconspicuous vulva, the
vagina, which is well cutinized, extends inward and
'backward half way across the body, where it joins the
single uterus which extends backward. The reflexed
'ovary reaches half way back to the vulva, and con-
tains ten to twenty ova arranged for the most part single file. There is an ante-
rior rudimentary branch to the uterus which is a little longer than the corre-
sponding body-diameter. Eggs unknown; judging from the full-grown ova they
are about as long as the body is wide and about half as wide as long. Single male
supplement two body-diameters in front of the anus, four times as far away as
the anal pair.
Habitat: Brackish soil on the banks of a marine estuary, Los Patos, California,
U. S. A. Differs from Dorylaimus in the form of the spear, and the oesophagus.
Most species of Dorylaimus have two ovaries. Differs also in the reduced num-
ber of supplementary organs; outside the anal pair, there is only one. Differs
in material respects also from Tylencholaimus. to which it may be compared.
Fig. 84.
.7 7.2 ; 20. "'??'" 99-
85. Leptonchus granulosus n. sp. L -~ 2 ; 5 J - 3 ' 4 2 -^ " Cuticle naked,
its transverse striae resolvable with difficulty into exceedingly minute dots.
One of the inner striae seems to correspond to about four of the outer. Cuticle
also possessed of inconspicuous longitudinal striae. Neck
conoid. Amphids broad, faint, somewhat stirrup-shaped, fP
their anterior contours opposite the labial constriction. The
oesophagus begins as a tube about one-fourth as wide as the
base of the head, and continues to have this diameter until
it finally expands to form the clavate or elongated pyriform
cardiac swelling, which is about one-half as wide as the base
of the neck. There is an inconspicuous conoid cardia about
one-third as wide as the body. The oesophagus is therefore
essentially tubular throughout most of its length. It is, or.
however, a trifle wider near the middle, in the neighborhood
of the nerve-ring, usually behind it, and at this point there
appears to be a slight alteration in the lining, suggesting in the faintest possible
manner vestiges of a median bulb ; at its widest part, however, the slender part
of the oesophageal tube is not more than one-fourth to one-fifth as wide as the
corresponding portion of the neck. At its narrowest part, just in front of the
cardiac swelling, it is about half as wide as it is at its widest part. The lining
of the oesophagus is not a conspicuous feature. The intestine, which becomes
at once fully three-fourths as wide as the body, is made up of cells of such a size
LEPTONCHUS, AXONCHIUM
305
that its cross-section presents but two of them. These cells are packed with
granules of variable size, the largest having a diameter one-eighth as great as
that of the body, while the smallest are very minute. The tail begins to taper
from some distance in front of the anus. There are a few inconspicuous papillae
near the posterior extremity of the tail of the female. The pre-rectum is of
most unusual length, extending to a little beyond the flexure of the anterior
ovary, and hence occupying about half the length of the body. It is set off from
the front portion of the intestinal tube by a distinct constriction, and differs also
in structure. The lateral fields are about one-third as wide as the body. The
ventral fields appear to be wider than the lateral, nearly half as wide as the body,
at least appearances half way between the vulva and the anus give rise to this
measurement. The traces of the excretory pore are difficult to observe, but they
are uniform in the different specimens, and as no other similar "break" in the
cuticle is to be deciphered it seems impossible that the single "break" opposite
the nerve-ring can be anything but an excretory pore. No indications are seen
of the existence of an internal structure connecting with this
pore, but the neck, especially the posterior portion of it in front
of the cardiac swelling, is occupied by elongated structures,
which may be of a glandular nature and connected with the
aforesaid "pore." The slightly elevated vulva is a trans-
verse slit about one-fourth as long as the body is wide. Radi-
ating from its ends are four muscles passing to the submedian
fields. The vagina leads about halfway across the body. The
reflexed ovaries reach about three-fourths the distance back to
the vulva, and contain a dozen or more developing ova,
arranged somewhat irregularly. The elongated eggs are three
to four times as long as the body is wide, and about one-fourth
to one-fifth as wide as long.
Habitat: Soil about willow trees, Arlington Farm, Va., oppo-
site the city of Washington, D. C., U. S. A. Fig. 85, p. 304.
.2 6.7 34. 55'" 98.8 9 9
86. Axonchium amplicollen. sp. ' 6 (7) / 1 ' 9 2 ' 8
Cuticle naked. The two portions of the ]b(6)
oesophagus are separated by a constriction,
as shown in the figure; both parts cylindri-
cal. Lining of the oesophagus well-devel- aai P"
oped, but more or less obscured by the
well marked, rather coarse, colorless muscu-
lature in the posterior part. Salivary glands
in the posterior part of the oesophagus as in
Dorylaimus, one gland emptying into the
lumen near the anterior portion of the
larger cylindroid half of the oesophagus,
the others farther back. Anus subcon-
tinuous; the rectum prominent and cutin-
ized, and one and one-third times as long
as the anal body-diameter. The anal mus- x750
cles are clearly disclosed. The pre-rectum is five times as long as the anal body-
diameter, and set off by a definite but faint constriction. The cells of the intes-
tine contain numerous, colorless granules of variable size, the largest of which
are one-twenty-fifth as wide as the body. Tail of the adult female as shown in
the illustration. In the youngest larvae, however, the tail is cylindroid in the
pplWIS)
mscon
air mi
ml
mar
as-
306 ORDER AXONCHIA
posterior half, and in this part, about one-third as wide as at the anus, the ter-
minus being rounded. The coarsely granular lateral fields are one-fourth to
one-sixth as wide as the body. Renette problematical. From the small, incon-
spicuous, faintly elevated vulva, the rather weak, non-cutinized vagina leads
inward two-fifths the distance across the body. The elongated eggs are three
times as long as wide and twice as long as the body is wide. The tapering ovary
reaches about half way back to the vulva, and contains about twenty ova. the
largest of which are arranged single file, while the others are arranged irregularly.
Habitat: Soil about the roots of Luca da Persia, Brazil. The part of Brazil
from which the plants came is unknown. The soil examined was removed from
the roots after they were imported into the United States. It is probable that
the species is syngonic. Another tropical species, originally described by the
writer under the name of Dorylaimus longicollis, from about banana roots, Fiji,
possibly also belongs to this genus. Fig. 86. p. 305.
87. Onchulella ocellata n. sp. 1.2 i.* 1.6 1.7 1.3 " Cuticle naked.
Striae almost impossible of resolution. Spear solid, refractive and apparently
"structureless" throughout. The two yellowish ocelli are wide apart, their
lenses colorless. The oesophagus is at first about one-half, near the nerve ring
two-fifths, and finally five-sixths, as wide as the corresponding portion of the
neck; the anterior part is cylindroid, the posterior part more or less obscure.
The oesophageal region seems to be largely filled with a series of elongated,
clavate glands, some granular and some not, and hence of two kinds. The hind-
ermost of these is the largest, and with reference to the oesophagus lies in much
the same way as the larger salivary gland of Tylenchus. There
is also a large spherical nucleus in this gland, as in Tylenchus.
This is the only one of the granular cells having a large conspicu-
ous nucleus. The non-granular cells are smaller; two or three
of them present nuclei. The measurements given in the formula
for the base of the oesophagus really refer to the posterior limits
of these glands. Just in front of the ocelli there are two lateral,
external, elliptical, cuticular elements, two-thirds as long as
the corresponding diameter of the neck, and one-third as wide
as long. These connect backward by means of ducts, and it
seems probable that they are connected with one of the two kinds of glandular
cells contained in the neck. The lining of the oesophagus is indistinct, its mus-
culature fine and colorless. No cardia has been seen. The thick-walled intes-
tine, which has a distinct, refractive, ziz-zag lining, becomes at once five-sixths
as wide as the body. The anterior lip of the anus is more or less elevated. The
inconspicuous rectum is about three-fourths as long as the anal body-diameter;
anal muscles are dimly to be seen. The cells of the intestine, of which only two
to three would be presented in cross-section, are packed with colorless granules
of variable size, the largest of which are one-fifteenth as wide as the body. The
arcuate tail tapers from the anus to the terminus, and presents a spinneret
about one-sixth as wide as its base. Caudal glands tandem in front half of tail.
No caudal setae. Renette unknown. From the somewhat depressed vulva, the
more or less cutinized vagina extends inward three-fifths the distance across the
body. An ovum, apparently full-grown and about to enter the uterus, is twice
as long as the body is wide, and one-third as wide as long.
Habitat: Eel-grass, Biscayne Bay, Miami, Florida, U. S. A. Flemming to
glycerine jelly. Only one specimen that, a shrunken one seen. Fig. 87.
CAMPYDORA 307
XIII. Order Anaxonchia
.6 12.2 33. "56 85.
88. Campydora demonstrans
Eight longitudinal striations exist throughout the length of the body. In cer-
tain parts, especially along the neck, the longitudinal striae are more marked
than elsewhere, attaining almost the magnitude of wings. There appear to be
four such "wings," but an exact count has not yet been made. Neck conoid.
There are six rounded, somewhat flat, partly confluent lips, bearing two circlets
of labial papillae, as shown in the illustration. These are plainly innervated,
and are of the sort commonly seen in Dorylaimus. The inner circlet has six
members; the outer circlet twelve, i.e., six pairs. The six slender structures
extending forward around the mouth, the inner circlet, may also end in organs
having the nature of papillae, but if so, they are of a different character
from the outer papillae. Base of the solid onchium axial, m
or nearly so, the apex however, bent considerably to the dorsal
side. The onchium may be protruded by means of longitudi-
nal muscles composing the pharyngeal bulb. Lining of the
posterior portion of the pharynx considerably less refractive.
The oesophagus has about the same relative diameter until it
finally expands suddenly to form the somewhat elongated, msc
cylindroid cardiac bulb, which is fully five-sixths as wide as
the corresponding portion of the neck, and contains a rather
faint, elongated, three-parted valve occupying about half XTSO
the optical longitudinal section. This cardiac bulb has a peculiar formation in
that the valve extends very nearly from end to end of the bulb and is manifestly
triquetrous, so that by the contraction of the radial muscles, the bulb can be
thrown into the form of a chamber. Lining of the oesophagus unusually distinct.
The central oesophageal tube, when seen in optical section presents each of its
walls with a double contour, and the lumen has about the same width as the
thickness of the walls. The entire width of this tube is considerably greater
than the thickness of the cuticle, and is about equal to 'one- twelfth the diam-
eter of the middle of the neck. The intestine becomes at once about five-sixths
as wide as the body. There is a comparatively distinct, broad, low cardia.
The walls of the intestine are comparatively thick. Its cross-section would
probably present two to four cells. These cells contain doubly-refractive,
spherical, scattered granules of variable size, the largest of which have a diam-
eter one-tenth as great as that of the body, the smallest being very much smaller.
When seen with crossed Nicols, these granules show a prominent St. Andrew's
cross. All the granules appear to be of the same character; their walls, seen in
optical section, present a double contour. Behind the base of the neck for
a distance about equal to one body-diameter, the granules are few in number
and small in size. Elsewhere, they are about equally distributed, or perhaps a
little less abundant toward the posterior end. The tail is conoid from near
the anus, and the cuticle becomes thicker on the posterior extremity and more
strongly striated. In young specimens it expands laterally to form wings,
which appear quite distinctly striated when viewed dorso-ventrally. From
the conspicuous, depressed anus, the strongly refractive, cutinized rectum
is considerably longer than the anal body-diameter. Excretory pore depressed
and rather conspicuous. From it, the cutinized duct can be distinctly seen
leading inward. From the depressed somewhat circular vulva, the cutinized
ORDER ANAXONCHIA
3 >2 ' 2 " Naked cuti-
vagina leads inward nearly half way across the body, where it joins the single
uterus, which apparently extends forward. The ovary extends backward past
the vulva. Nothing is known concerning the size and form of the eggs.
Habitat: About the roots of citrus trees, Corfu, Greece. Fig. 88, p. 304.
(1.1)15. 12. 22. "5S. 1 '
89. Catalaimusacuminatus n.sp- <-9)/i.9 i.s 1.9 z-4
cle traversed by exceedingly fine transverse striae. Lips when closed exhibiting
about a dozen folds which
are barely visible with the
, highest powers. Onchium
arcuate, slender, long,
spear-like. Eye-spots
two, lateral, refractive,
, colorless, glistening.
| set CTT Near the beginning of the
pharyngeal tube, each of
' x 75 the three sectors of the
oesophagus presents longitudinal lines of yellowish pigment.
From some little distance behind the nerve-ring, the oesoph-
agus continues to have the same diameter throughout the
remainder of its length. There is a flattish conoid cardia,
about one-third as wide as the base of the neck. Lining of the oesophagus appar-
ently wavy, occupying one-third of the optical section. The intestine, which
becomes at once three-fourths as wide as the body, is made up of cells of large
size, at least some of the cells are of very large size, of such a size that probably
two only would be required to build a circumference. Whether there are other
smaller cells scattered among these larger cells remains to be determined. The
large cells are packed with nearly colorless granules of rather uniform size, hav-
ing a width about half as great as the thickness of the body wall. While the anus
is depressed, its posterior lip is slightly raised. Rectum about as long as the
anal body-diameter. The nema tapers gradually from a considerable distance
in front of the anus. Near the anus, it begins to taper more rapidly, so that at
the middle of the tail, the diameter is only about half as great as at the anus;
thence onward, the tail is nearly cylindroid and ends in an elongated spinneret.
No distinct traces of caudal glands are to be seen in the base of the tail; hence
it is assumed that they are located in front of the anus. Obscure indications
have been seen of their presence half as far in front of the anus as the terminus
is behind it. The lateral fields have not been distinctly seen. The location of
the renette cell remains undetermined. This description is derived from a
young female, and all that can be said is that the ovaries are probably double
and reflexed.
Habitat: Marine mud and sand, Noumea, New Caledonia, and Biscayne Bay,
Fla., U. SL A. Other species of this genus occur in the Indian Ocean and in the
Mediterranean Sea. Fig. 89.
90. Bolbella tenuidens n. sp. Transverse striae excessively fine, more readily
seen in the subcuticle with high powers under fav-
orable conditions. Longitudinal striations are >2.9 ..
present throughout the length of the body. Body >3 '
wall massive, occupying one-third the radius. As - ; 9 - 19 - '*' 22.7 -
compared with related species the anterior cham- ' 4
ber of the pharynx is somewhat more foreshortened. There are two to three
BOLBELLA
309
dozen very long and very slender cervical setae, those toward the head end
being nearly twice as long as the cephalic setae, more of them than are shown
in the illustration. Glandular tissue exists in the oesophagus, the granular
branches of which may be seen more particularly between the oesophageal bulbs:
a duct appears to lead to the pharynx. A cross-section of the intestine would
present four to six cells. In the female, from the more or less continuous anus,
of which, however, the posterior lip is slightly elevated, the inconspicuous rec-
tum extends inward a distance equal to the anal body-diameter. A narrow ren-
ette cell exists two to three body widths behind the cardia on the ventral side.
The slightly elevated vulva is of medium size, and leads to a large tubular vagina,
at first at right angles to the ventral surface and then leading obliquely forward.
The wall of the vagina is well cutinized. Each branch of the two-horned uterus
is about one and one-half times as long as the body is wide. Two eggs have
been seen in a uterus at one time, each about twice as long as the body is wide.
The spherical spermatozoa existing in the uterus are about one-sixteenth as wide
as the body. The broad, more or less cylindroid ovaries extend two-fifths the
way back to the vulva, and contain eight to ten countable ova arranged for the
most part irregularly. The two supplementary organs of Bolbella, like the simi-
lar organs of Eurystoma, are connected with large glands, one to each supple-
ment. One of these glands is very well shown in the illustration at gl sup cf.
ait lumoe
FIG. 90. Bolbella tenuidens.
Details of the pharynx are
shown X 1500 on the following
There are other species
of Bolbella.
dctm
x225
dctq
mi copmsc thtglsup
The gland is long and unicellular and its nucleus is shown at ncl gl. A natural
supposition is that these two supplements are cup-shaped organs attachable by
suction. The supposition appears, at first thought, to find support in the exis-
tence of the "anchors," which are manipulated by special muscles. It is rather
difficult to harmonize this theory with the existence of such large glands, so
much so that one feels inclined to give up all idea that suction plays any part
in the functioning of these organs. The so-called cups of the supplements are
310 ORDER ANAXONCHIA
to a considerable extent protrusile, just as in Eurystoma. The males of Bol-
MqthllOl bella seem to be considerably less common than
the females.
Habitat: Sand, Bathing Beach, Woods Hole,
Mass., U. S. A. Flemming to glycerine jelly.
. Sublimate to balsam. Resembles Symplocos-
toma Bastian, but differs materially in the
structure of the posterior part of the oesoph-
agus, as well as in the absence of eye-spots.
The males of Symplocostoma have no sup-
plements.
The strongly tapering neck of Bolbella results
in a head of small size. Notwithstanding its
small size, one is immediately struck by its
strong resemblance to the head of Eurystoma.
The following differences, however, are to be
^m siilm dxt noted. The amphid is smaller and of a differ-
ent form, though here also, as in Eurystoma,
/V/ located on the dorsal side of the lateral lines.
While the pharynx is divided into two more or
xlSOO less distinct chambers, the division line is not
marked by transverse rows of denticles. Fig. 90a, p. 309; Fig. 906.
91. Thoonchus ferox n. sp. Striae resolvable with difficulty. The thin, color-
less lips are arched over the pharynx as in Oncholaimus, but the minute flaps
often seen on the tips of the lips of Oncholaimus
appear to be absent in this species, or at any ^ ^ '-^ 5^_ >2 .2..
rate, much reduced. Labial papillae located in
the midst of shallow depressions. Amphids faint. ii| -| ^ """ 6 7 ^ 9 ^>2.i..
Pharynx denticulate. The oesophagus has the
same diameter throughout its anterior half, after which it begins slowly to expand
and finally is two-thirds as wide as the base of the neck. There is a distinct,
bluntly convex-conoid cardia, nearly half as wide as the base of the neck. The
intestine, which is separated from the oesophagus by a deep constriction, becomes
at once three-fourths as wide as the body. It is rather thin walled and in cross
section presents about six cells. These cells contain scattered, yellowish gran-
ules of variable sizes, so arranged as to give rise to an obscure tessellated effect.
The largest granules have a diameter nearly equal to the thickness of the body
wall. Posterior lip of the anus strongly elevated. Rectum equal in length to
the anal body-diameter. Renette elongated, located a little distance behind
the cardia. The lateral fields appear to be rather narrow; they are character-
ized by the presence in them of numerous, rather scattered, yellowish granules,
which are more numerous toward the edges of the field, and which, therefore,
define the fields more distinctly than is usually the case. At the base of the
head, the fields are seen to widen out and terminate in a rounded contour; the
margin of this contour marks the position of the amphids. The granules found
along the lateral fields appear also in longitudinal rows outside these fields.
Thus, on either side of the lateral fields, there is a single distinct row of these
granules; on the submedian line, another very distinct assemblage of granules,
consisting of several irregular rows. Then comes another scattered faint row;
then a ventral or sub-ventral assemblage consisting of several rows. There is
thus produced on the neck as well as elsewhere quite a distinct longitudinal
THOONCHUS
311
"striping" whose presence is indicated mainly by the arrangement of these
minute yellowish granules. The stout tail diminishes rapidly from the posterior
lip of the anus, so that at the middle it has a diameter about two-thirds as great
as at the base; thence onward it is nearly cylindroid to the rounded terminus.
The caudal glands are located in a tandem series considerably in front of the
anus; the hindermost being about four times as far from the anus as the termi-
nus. The two anterior glands are close together and are nearly as far in front
of the hindermost as this latter is in front of the anus. From the elevated vulva,
the vagina extends inward half way across the body. The ovaries reach about
one-third the distance back to the vulva in specimens that contain three eggs
in the uterus. Eggs elongated, about twice as long as the body is wide and about
one-third as wide as' long. Each of the twc uteri may contain three eggs at one
time. Tail of the male more strongly arcuate than that of his mate. Clavate
caudal glands about as long as the body is wide and about one-third as wide as
long, arranged some distance apart in a tandem series. When the body of the
male is closely coiled, the ventral surface toward the posterior end becomes
corrugated in a definite way for some distance in front of the anus, suggesting
that this area may be systematically innervated and serve the purpose of a ven-
tral series of about two dozen subequidistant supplementary organs. These
corrugations are apparently innervated, but no distinct corresponding breaks
or openings have been seen in the cuticle. On the ventral side at a distance
in front of the anus three times as great as the length of the tail, there is an
elevated supplementary organ in the form of a transverse ridge. This occurs
in the midst of the corrugations just described, at least, it appears that the
corrugations extend beyond it, although they are not quite so close together
or so marked in this region. This supplementary organ begins near the sub-
median lines and extends across the ventral region. Its internal structure has
not been satisfactorily elucidated. It appears probable that the cuticle on
the ventral line ^ mSllIm(txt\setCph(JOi dd CBBBte^^^ *SE S*
is interrupted,
but even this is
not clearly es- "
tablished. This
swelling has two
to three times
the width of the
corrugations and
occurs at the
same position on
three different
male specimens,
X750
extn
so there can be
no doubt about its being a distinct supplementary structure. Opposite the
middle of the spicula, also, there is a pair of subventral supplementary papillae,
accompanied by slender subventral setae in the rear. There are a few short
delicate setae on the tail, especially on the submedian lines, but also in front of
the anus for some distance, where they are longer, more nearly the size of
those on the anterior extremity. About a dozen pairs of copulatory muscles
occur in the ventrally submedian region, in a space four to five times as long as
the tail. Testes relatively small.
Habitat: Open-ocean beach-sand, South California. Bay City, Huntington
Beach U. S. A. Fig. 91.
312 ORDER ANAXOXCHIA
92. Trilepta guttata n. sp. -J. -5 -5 .5 ~~N . 4 >(?!5 - 4 " Cuticle naked except
for the cephalic and cervical setae. Lips probably three, and double, rather thick
and well-developed. When closed the pharynx appears as if longitudinally
ribbed. This appearance, however, may be due to the folding of the rather
massive lips, which close together and form a vestibule nearly one-half as long
as the remainder of the pharynx. Neck cylindroid. The cylindroid oesophagus
near the nerve-ring is one-half, and also finally one-half, as wide as the base of
the neck; its musculature is fine and its lining indistinct. There is an indistinct
cardia one-third as wide as the base of the neck. The thick-walled intestine,
set off by a collum two-fifths as wide as the neck, and presenting a faint lumen,
becomes at once two-thirds as wide as the body, and in cross-section is made
up of but few cells containing scattered to numerous, small, more or less uniform,
yellowish granules. Neither spinneret nor caudal glands have been distinctly
seen. The lateral fields are one-fourth as wide as the body. Renette unknown.
From the raised anus the tail diminishes rather suddenly, then tapers gently to
the middle, where it is about one-half as wide as at the base; thence onward it is
cylindroid to the terminus, which is one-third as wide as the base of the tail.
The two simple, slender, rather frail and more or less tapering, acute to sub-acute
spicula are arcuate or somewhat bent, and are one and one-half times as long
set Ib set Jot as the anal body-diameter. Viewed in profile their
proximal ends appear to lie dorsad from the body-
axis. The inconspicuous accessory piece lies paral-
lel to the spicula. There are no supplementary
organs. The ejaculatory duct is one-third, the vas
deferens one-half, as wide as the body. The cyl-
indroid testis is one-half as wide as the body, even
at its rounded, blind end. Oblong, fusiform, chro-
matin masses are to be seen in the sperm cells.
IIM OP Habitat: Sand, below low-tide mark Bathing
Beach, Woods Hole, Mass., U. S. A. Sublimate to balsam. Fig. 92.
93. Anoncholaimus mobilis n. sp. l -V ^ l - 6 *"* l - z "The cuticle is
so very thin that it wrinkles on the inside of the curve when the body bends.
Though there are no true wings, there is a faint, clear wing-space about one-eighth
as wide as the body. The thin, flat lips resemble those of Oncholaimus. There
is a vestigial dorsal onchium opposite the bases of the cephalic setae, faintly
shown in the illustration. The neck is cylindroid. In the oesophagus near the
base of the pharynx there are scattered yellowish granules. The oesophagus is a
little wider at both ends than elsewhere. Near the pharynx it is two-thirds, at
the nerve-ring two-fifths, and finally three-fifths, as wide as the corresponding
portion of the neck. It has a distinct, refractive, apparently corrugated lining;
among its radial muscles there is more or less of yellow pigmented matter, which
occurs in straightish radial lines. There are at least two submedian glands in
the tissues of the oesophagus, emptying at the pharynx. The thick-walled intes-
tine is set off by a constriction half as wide as the neck, and has a faint ziz-zag
lumen; it becomes at once two-thirds as wide as the body, and in cross-section
presents about ten to twelve cells. There are numerous yellow granules of vari-
able size in the cells of the intestine, the largest being one-thirtieth as wide as
the body; owing to their arrangement there is a faint tessellated effect. From
the anus, the posterior lip of which is elevated, the rather prominent rectum
extends a distance one and one-fourth times as great as the anal body-diameter.
ANONCHOLAIMUS, ONCHULUS
313
The convex-conoid tail tapers from the anus to the spinneret, which is armed
with submedian setae. The caudal glands lie in front of the anus. There are
practically no caudal setae. The lateral fields are
two-fifths as wide as the body and contain large
ain/)/l ce ^ u l ar elements. Anoncholaimus has eight cervi-
cal glands, six emptying into the anterior part of
the pharynx opposite the bases of the setae and two
smaller, a little farther back, on the dorsally sub-
lateral lines. The granular contents of the ducts
of these glands, increased slightly in volume, form
move back and forth during the various movements
of the head. Hence the specific name "mobilis."
The cervical glands lie behind the nerve-ring, since
their ducts have been followed backward to behind the nerve-ring. There are
also ducts of glands to be seen in the ventrally submedian sectors of the oesoph-
agus. The pyriform renette cell, which lies a very short distance behind the
base of the neck, empties through a rather distinct ampulla twice as far back as
the base of the pharynx. The narrow nerve-ring is accompanied by large distinct
nerve cells arranged in groups. From the rather large and conspicuous, more or
less elevated vulva, the large muscular, non-cutinized vagina leads inward to
the two straight uteri. The eggs are twice as long as the body is wide, and two
and one-half times as long as wide. Judging by their size when empty, the uteri
are adapted to receive one egg at a time, possibly two. The posterior ovary is
a little the smaller; both are more or less cylindroid, finally tapering, of medium
size, and reach three-fourths the distance back to the vulva. The ova in them
are arranged single file. An ovum about to enter the oviduct is two to three
times as long as the body is wide, and about one-fourth as wide as long.
Habitat: Sea-weed, Squibnocket, Martha's Vineyard, Mass., U. S. A.; Bathing
Beach, Wood's Hole, Mass., U. S. A.; not common. Examined living, in water.
Fig. 93.
94. Onchulus longicaudatus n. sp. 1.6
" 1 " Cuticle naked
1.7 2.3 2-
except for the setae on the head; its striae very difficult of resolution. Whether
the onchium is hollow and perforated remains uncertain,
but seems probable. Neck subcylindroid. The cylin-
droid oesophagus is at the nerve-ring three-fifths, and
finally three-fourths, as wide as the corresponding por-
tioh of the neck. Throughout its length, the colorless,
coarse musculature is interspersed with granular, gland-
ular tissues, as in Oncholaimus, making it seem probable
that the pharyngeal outlets are similar, but no duct has
been definitely established in the dorsal onchium. There
is a cylindroid cardia, about one-third as wide as the oe
base of the neck. Scattered setae having a length equal
to the breadth of two annules occur on the tail. There
are no caudal glands. The description is derived from a single young specimen
in which the vulva was not yet developed. The immature ovaries reached two-
thirds the way back to the location of the future vulva.
Habitat: Soil about the roots of living plants imported from Brazil into the
United States. Flemming to glycerine jelly. Fig. 94.
314 ORDER ANAXONCHIA
1-. .. .<-.. .1?-. . .'.'5.1'.'.. .?. >2 . 4 ..
95. Digitonchus uniformis n. sp. l - 5 1 - 9 * ** 5 Possibly the
transverse striae are resolvable into exceedingly minute markings. Cuticle
naked except for the cephalic setae. Lips three, possibly very faintly double.
Onchium spear-like, solid. Anteriorly, the neck is convex-
conoid. The oesophagus has not been well seen but
appears to bo more or less cylindroid; its diameter at
the base is about half as great as that of the base of the
neck. Its lining is subdistinct, its colorless musculature
fine in texture. The more or less thick-walled intestine,
fuNe " x750 which has a faint lumen, becomes at once half as wide as
the body. Cardiac collum one-third as wide as the base of the neck. From the
more or less elevated anus, the prominent, cutinized rqctum is about as long as
the anal body-diameter. The conoid, arcuate tail tapers from the anus to the
rather simple spinneret. The rather broadly saccate caudal glands are packed
behind the anus in the anterior third of the tail; they empty by separate ducts.
The lateral fields are one-third as wide as the body. Renette unknown. The
nerve-ring is accompanied by obscure nerve cells. From the more or less con-
tinuous, inconspicuous vulva, the vagina extends inward three-fifths the
distance across the body. It is muscular and more or less cutinized. The
medium-sized, tapering ovaries reach half way back to the vulva.
Habitat: Beach sand, Squibnocket, Martha's Vineyard, Mass., U. S. A. Flem-
ming to glycerine jelly. Fig. 95.
. .
96. Ypsilon exile n. sp. -1 V %i i6 L6 There are
cervical setae about half as long as the neck is wide. Three flat,
minute, confluent lips bear a circlet of six forward-pointing or
somewhat spreading papillae around the mouth opening. Though
there are six nerves, one to each papilla, they are not precisely
equidistant, but seem to be arranged in three, somewhat distinct
pairs. Pharynx relatively strongly cutinized. In optical con-
tour, the anterior end of the onchium is more or less crescent-
shaped; this cup-shaped head is fixed obliquely on the strong,
straight element that forms the main portion of the dorsal wall x750
of the pharynx. The head of the onchium is yellowish in color. The neck is
cylindroid posteriorly, convex-conoid anteriorly. The oesophagus, narrow and
more or less cephaloboid in form, ends in a somewhat cylindroid cardiac swelling,
two-sevenths as long as the neck, and three-fifths as wide as the base of the
neck. At the nerve-ring, the oesophagus is one-third, just in front of the cardiac
swelling also one-third, as wide as the corresponding portion of the neck. The
lining of the oesophagus is rather prominent. The colorless musculature of the
oesophagus is of fine texture; in it, traces of oesophageal glands have been seen.
There is a distinct, refractive, cylindroid cardia, two-sevenths as wide as the
base of the neck. The intestine, which is thick-walled and has a faint, zig-zag
lumen, gradually becomes three-fourths as wide as the body. The cardiac col-
lum is one-third as wide as the body. The anus is elevated, and the rectum
is one and one-fourth times as long as the anal body-diameter. The intestinal
cells are packed with pearly granules, such as are often seen in Aphelenchus;
the largest of these are one-eighth as wide as the body. These granules tend to
be larger posteriorly than anteriorly, and sometimes appear to be polyhedral.
The posterior part of the body tapers from in front of the anus, is at first conoid
then convex-conoid, and ends in a spinneret one-sixth as wide as the base of
YPSILON, GONIONCHUS 315
the tail. The ellipsoidal to broadly saccate caudal glands are packed in a close
tandem behind and opposite to the anus in the anterior three-fifths of the tail.
Their large, distinct ampullae are two-sevenths as long as the tail. There are
one or two slender setae at the middle of the tail, and near the terminus. The
lateral fields are about one-fourth as wide as the body. The much elongated
renette cell lies about one body-width behind the neck. The frail, strongly arcu-
ate, rather slender, tapering, subacute spicula are cephalated by a constriction
on the ventral side in such fashion that the proximal ends appear to be more or
less barbed. The simple, frail, very slender, arcuate accessory piece is one-third
as long as the spicula and presents a faint apophysis; its proximal end, like those
of the spicula, lies dorsad from the body-axis. At first it is parallel to the spicula,
then recedes and bends away at an angle of ninety degrees. There are three
faint and minute supplementary organs in front of the anus, occupying a space
one and one-half times as long as the body-diameter, little more than innerva-
tions. The posterior of these is opposite the distal ends of the spicula. The
distance between the first and second is equal to two-thirds, that between the
second and third, to one-half, the body-diameter. At the posterior end of the
middle fifth of the tail there is a somewhat raised small area supplied with two
subventral nerve endings.
Habitat: Coarse sand, Beach, Devil's Island, Woods Hole, Mass, U. S. A. The
sexual organs are difficult to decipher on account of the granules in the intestine.
It does not seem advisable to refer this species to Acmaeolaimus Filipjev. The
following differences may be noted: (1) The cuticle is coarsely striated.
(2) The cephalic setae are in one circlet only. (3) The amphids are not "split."
(4) The pharynx is not open. (5) The dorsal organ is "Y "-shaped. Possibly
the Filipjevian specimen might have been referred to Camacolaimus de Man.
Fig. 96, p. 314.
97. Gonionchus villosus n. sp. Annules separated by strongly refractive lines.
Neck conoid in the anterior half. About twice as far from the anterior extremity
as the amphids are four submedian groups of hairs, which are longer than the
cephalic setae. These groups consist of three each, arranged one in front of the
other, the members being separated by a distance equal to the width of one of
the annules. Similar submedian long and slender hairs occur throughout the
length of the body and are so numerous as to con- setqihdOJ H)(6l
stitute a very striking feature. The amphids at
first appear "O "-shaped; in reality, however,
they are spiral. The terminal flaps are hinged to
the lips, and the anterior portion of each lip appar-
ently is hinged to the main portion of the wall of (Ufa |jppsgj_. 00
the head, which is itself unusually thin. Onchia
apparently more or less plate-like. The oesoph- Mslficph(4)^iSk ' X 750
agus continues to have the same diameter until
after it passes through the nerve-ring; thereafter,
it expands very little so that finally it is about j. 1 3._iq.4___24.____'_ -76_ ??.>, J4 ..
two-thirds as wide as the base of the neck. There l6 */> M""'~
is a distinct conoid cardia, having a base about i..,___9.5___2_ 2 -- .-A-". .._*.>,, ,..
one-third as wide as the base of the neck. The " ^ '" 2 J 2 - 4 "^ 2 -
intestine becomes at once about two-thirds as wide as the body. It is rather
thick-walled, and its cross-section would present about four to six cells.
The lining of the intestine is refractive, so that the lumen is readily fol-
lowed; in fact it is a rather striking feature. The cells contain scattered yel-
316 ORDER ANAXONCHIA
lowish granules of variable size, arranged irregularly. The posterior lip of the
anus is slightly raised. Rectum only about two-thirds as long as the anal body-
diameter. The tail is conoid in such fashion that, at a distance from the anus
equal to eight times the anal body-diameter, it has a diameter about one-fourth
as great as at the anus. The remainder of the tail has been lost from the speci-
men from which the description was drawn and is therefore of unknown form;
hence the dimensions given in the formula must be interpreted accordingly. The
tail is just as distinctly striated as the body. -The lateral fields are about one-
third as wide as the body. It is probable that the renette is located at a distance
behind the base of the neck about equal to two body-diameters. At this point
there is an elongated structure somewhat longer than the body is wide and about
one-fifth as wide as it is long, which bears a general resemblance to a renette
cell. From the slightly elevated vulva, the vagina extends inward and forward.
The tapering ovary ends somewhat in front of the cardia where it is about one-
fourth as wide as the corresponding portion of the neck. The eggs are about
three times as long as the body is wide, and about one-fourth as wide as long.
There is a small posterior rudimentary branch to the sexual organs, extending
back from the vulva a distance equal to two to three body-diameters. This
has been seen to contain spermatozoa and may function as a spermatheca. The
presence of caudal glands remains problematical. Unfortunately, also, in the
case of the only male specimen available, the tail is broken, but that portion of
it remaining is about two-thirds as long as the neck. It tapers a little more
rapidly at first than it does farther back, in fact, toward the terminus, it must
be very nearly cylindroid. It seems probable that caudal glands are present,
but there is some doubt about this. There are no special supplements, papillae
or setae on the male. The long and slender hairs found on the body occur also
on the tail, and are there equally long and slender so far as observed. The
proximal ends of the acute, slender spicula present the peculiarity of being
separated from the remainder of the spicula by straight shafts, having a length
somewhat greater than that of the cephalic portions. The cephalic portion,
together with this shaft constitutes about one-fourth of the spiculum; the remain-
ing portion of the spiculum is uniformly arcuate, and tapers regularly to the sub-
acute terminus. The proximal ends of the spicula lie toward the dorsal side of
the body. There are inconspicuous accessory pieces arranged parallel to and
close by the spicula, and which are about half as long as these latter. The ejacu-
latory duct is one-third, and the vas deferens about one-half, as wide as the body.
Development of the spermatozoa in the two testes presents rather marked con-
trasts. From the blind end of the anterior testis, lying near the base of the neck,
the spermatozoa develop regularly and form spermatocytes half as wide as the
body, which develop into spermatozoa with nuclei that stain prominently. The
blind end of the posterior testis contains spermatocytes which, for a short dist-
ance, resemble those already described, but they do not form large spermato-
cytes. They nevertheless develop into spermatozoa having the character just
described. At a distance in front of the anus about equal to the length of the
tail, there are three glands on each side of the body, arranged tandem. These
glands are accessory to the male organs. Each is more or less homogeneous ante-
riorly, and granular posteriorly, the granules not retaining carmine stain, as do
the nucleus and the anterior parts. The ducts of these glands lead backward to
the cloaca.
Habitat: Mud, tide pool, near low tide mark, Portsmouth, New Hampshire,
U. S. A. Fig. 97, p. 315.
XANTHODORA 317
98. Xanthodora nuda n. sp. The striae of the yellow, naked cuticle have the
appearance of a series of hoops that are considerably wider on the neck, espe-
cially toward the head. The anterior half of the neck is convex-conoid, the
convexity increasing steadily toward the head. From the point where the
striae cease on the head, the cuticle diminishes
i'|- '" -^Y ''^V y 8 -> 2 -2- very rapidly in thickness, so that opposite the
dorsal tooth, it is not more than one-third as
I'.l ' ' 3*5 ' 'Ts " " ?j >' 9 ->2- " thick as a little farther back; thence onward, it
is thin to a point half way between the circlet of
setae and the axis of the mouth opening. At this point, the hard cuticle ceases
and there is a very minute, faint groove encircling the lip-region. The lips come
together so as to form a vestibule having a width about one-third as great as the
diameter of the circlet of setae. The tissues of the lips apparently reach back a
little farther than the apex of the dorsal tooth, and their limits are rather easily
noted on account of the fact that they attract carmine stain more than the
surrounding tissues do. The lip-region appears to be longitudinally striated
internally, and probably to consist of about a dozen elements folded together.
When the mouth is open and the onchium thrust forward, the labial region is
seen to be practically continuous and entire on its anterior margin, from which
it follows that any striations appearing when the mouth is closed are due to
foldings of the lip-region. When the mouth is open and the lips expanded, the
amphids become more nearly circular. When the lips are closed, the vestibule
widens out but little in front of the dorsal tooth, whose apex lies in the axis of
the vestibule. The pharynx is surrounded by muscles which appertain particu-
larly to it, as is indicated by the fact that they are separated from the oesoph-
agus by a broad but fairly distinct constriction. The oesophagus continues to
have the same diameter until near the nerve-ring, where it diminishes somewhat
in diameter. Very soon after passing through the nerve-ring, it enlarges, some-
times rather suddenly, to form the elongated posterior three-fifths of the organ.
This enlarged part averages to be about
three-fifths as wide as the corresponding por-
tion of the neck, and contains a massive lin-
ing, which, when viewed in optical section,
occupies one-fifth of the diameter. This
enlarged portion of the oesophagus is divided
into three regions by breaks in its radial mus-
culature, of which one region comprises
nearly the whole of the anterior half. The
other two parts are of subequal size. Though
the lining of the oesophagus is quite distinct .
in the narrow portion, it is considerably less
so in the wider portion, and ceases a short
distance in front of the posterior end of the P
oesophagus. Cardiac collum less than one-
third as wide as the base of the neck. For a $?
short distance, the intestine is composed of small cells differing from those which
make up its main part. These cells stain more strongly with carmine and con-
tain nuclei of relatively larger size. This region probably may be regarded as a
sort of cardia. The intestine becomes almost at once two-fifths as wide as the
body. Its cross-section would present about eight cells. The cells are packed
318 ORDER ANAXONCHIA
with numerous yellowish granules. In the body cavity at the cardiac collura,
there are three ellipsoidal groups of cells, two dorsally submedian and one ven-
tral or nearly so. These groups contain eight to ten nuclei, and one of them is
seen to be connected to a distinct, refractive strand, extending forward along
the surface of the oesophagus. These groups of cells have their nuclei close
together and seem to have a general membrane covering them. In addition to
these groups of cells, there are two other granular bodies, ventrally submedian,
each containing a single, strongly staining nucleus, and a second body which
does not stain so strongly. The structure of these latter is suggestive of that of
the ordinary renette cell, but their connections have not been made out. Rec-
tum somewhat longer than the anal body diameter. The three caudal glands
are arranged in a close tandem in front of, opposite to and behind the anus.
Each is a large cell with a protoplasmic network, in the midst of which the single
nucleus is slung. The lateral fields are about one fourth as wide as the body and
are composed of two ranges of cells with a space between them, in which lie
nuclei belonging to cells of a different group. Renette unknown. From the
slightly raised anus, the arcuate tail is conoid to the terminus, which has a
diameter about one third to one half as great as that of the base of the tail.
From the very slightly elevated vulva, the well cutinized vagina extends fully
half way across the body. The ovaries reach half way back to the vulva and
contain ten to fifteen ova arranged, for the most part, single file. The moder-
ately thin-shelled eggs are twice as long as the body is wide and one-third as
wide as long. They occur in the uteri one at a time. The spermatozoa in the
uterus are one-seventh as wide as the body. The conoid, arcuate tail of the
male begins to taper from a short distance in front of the anus. The six sup-
plementary organs occupy a distance equal to the length of the tail. The pos-
terior supplement is nearly opposite the posterior thirds of the spicula; the
second, third and fourth succeed each other without intervening spaces, in
such a way that the third and fourth are pretty nearly opposite the proximal
ends of the spicula. The fifth is separated by a greater space from the fourth,
and the sixth is about as far from the fifth as the fifth is from the fourth. The
fifth and sixth are of smaller size than the others, the inconspicuous sixth being
the smallest of all. Their apices are more transparent than the other portions.
An unusual feature is the presence of nerve endings between the organs. It
is possible that nearer the anus still than any described, there is another incon-
spicuous organ of somewhat the same character. The strongly arcuate, some-
what acute, yellowish spicula are about twice as long as the anal body-diam-
eter. They appear to be widest in the middle and to taper both ways. The
cephalated portion of the spicula are cut off obliquely. The proximal ends lie
a little to the dorsal side of the body-axis. The accessory pieces are for the
main portion of their length not very conspicuous. Surrounding the distal
ends of the spicula, however, there is a rather prominent portion which must
be reckoned a portion of the accessory apparatus. Oblique copulatory mus-
cles are present for a distance twice as great as the space occupied by the sup-
plementary organs. The ejaculatory duct is about one-third, and the vas
deferens a little more than one-third, as wide as the body. It remains uncer-
tain whether there is one testis or two, but the evidence seems to favor the
supposition that there is one only, and that its blind end lies about as far behind
the base of the neck as the nerve-ring is in front of it.
Habitat: Larat, East Indies. Marine. Fig. 98, p. 317.
ANAXONCHIUM, BOLBOLAIMUS
319
1.6 7.6 17.1 . . .'*. . . 90.. ?11 ..
99. Anaxonchiwn liiorium n. sp. Li ' Vi-' 2.3 ' ' 2.47^*1.9 ' Cuticle thin,
but considerably thicker near the head. Striae resolvable with difficulty into
dot-like elements, which are close together on the body, more distant on the
head. The striae are altered on the lateral fields so as to give rise to a ladder-like
pattern, with the "rungs" very close together. Cephalic setae two-jointed. No
pores are seen in the cuticle; nevertheless, they may have been present and escaped
notice. The lips are thick and double. In the single male specimen examined,
the conical branches of the lips end in minute setae, each about as long as the
labial setae, and terminating in a "blob, " this latter hardly an artefact. Dor-
sal onchium opposed on the ventral side by several irregularly arranged, small
denticles, among which probably two submedian ones dominate. Apparently
somewhat similar denticles occur
setlb(6)
trm
behind and above the dorsal
onchium. Amphids peculiar, large,
faint. The plain oesophagus, near on
the nerve-ring is one-half, and fin-
ally three-fourths, as wide as the
corresponding portion of the neck.
Its lining appears corrugated; its
colorless musculature is more or less
coarse, but there seem to be no indi-
cations of the presence of glands,
and there is no distinct cardia. The
thin-walled intestine, which has a
rather faint, though distinctly visi-
ble lumen, becomes at once half as *750
wide as the body, and in cross-section would present four to six cells. Cardiac
collum one-half as wide as the neck. The cells of the intestine contain scattered
yellow granules of variable size, having a diameter about equal to the width of
two annules of the cuticle. The tail tapers from the anus, and is at first conoid
then cylindroid in the posterior third, where it is about one-fourth as wide as at
the anus. A few, rather small, tapering, subacute setae occur on the tail. The
lateral fields are about one- third as wide as the body. The non-granular ellip-
soidal renette cell lies only a short distance behind the neck, and is three-fourths
as long as the body is wide, and one-third as wide as long. The rather pronounced
clavate ampulla empties through the distinct pore lying close to its anterior end.
The nerve-ring is accompanied by obscure nerve cells. The yellowish spicula
are guided by two separate, strong, rather wide, more or less arcuate, somewhat
shoe-shaped pieces near the anus, with a single median piece between and behind
them. Ejaculatory duct one-fourth, testis two-thirds, as wide as the correspond-
ing portion of the body.
Habitat: Marine; Belmar, N. J., U. S. A., below low tide mark in beach sand.
Female unknown. Anaxonchium bears considerable resemblance to Cyatho-
laimus, but differs, among other ways, in the almost obsolete amphid (?), the
reflexed testis, and in the large number of small supplementary organs. Fig. 99.
lOOa. Bolbolaimus pellucidus n. sp. Type species. Naked except for the setae
on the head; possibly there are very inconspicuous wings. Lips subdistinct, the
region elastic and finely subdivided. Margin of the lip-region serrated by the
forward projection of about fifteen papillae (?) with minute bristles outside the
serrations. The appearance is as if each papilla is armed with a pair of minute
320 ORDER ANAXONCHTA
bristles very difficult to see. Onchium capable of being protruded past the lips.
Opposite the onchium is a pseudo-onchium, somewhat smaller, and more dis-
tinctly visible in some attitudes of the pharynx than in others. Amphids exceed-
ingly inconspicuous, nearly circular, a little the wider transversely, apparently
circular but really consisting of spirals of one wind slightly open behind. At
the nerve-ring, the oesophagus is three-fifths, just in front of the cardiac bulb
one-half, and finally five-sixths, as wide as the base of the neck. This latter
measurement is that of the elongated, ellipsoidal cardiac bulb. The rather
prominent, apparently corrugated lining of the oesophagus is distinctly visible.
sefMfSfi.9 6.6 u.9 -46.6- , The musculature
> 1.2,, becomes coarse near
the cardiac bulb.
7.2 M.7 "-M 91.6 ^ ^ ^ There is a transverse
z.4/ 2^s_ . 2.5 -fNM division of the muscu-
lature of the .cardiac bulb near the middle. The
wall of the intestine is of variable thickness; the
lumen is distinct. Gradually the intestine becomes
two-thirds to three-fourths as wide as the body ; its
spa ^rncoe^ nd'. * 750 cross-section would present five to six cells. Often
the lumen of the intestine presents the appearance of having certain cells bulging
inward. Cardiac collum one-sixth as wide as the neck. From the more or
less elevated anus, the cutinized rectum extends inward for a distance five-
sixths as great as the body-diameter. From the anus, the tail is conoid to the
rather blunt terminus. The long, simple spinneret is in its basal part one-
third as wide as the base of the tail. The broadly saccate caudal glands form
a loose tandem behind the anus in the anterior half of the tail; they empty
through separate ducts and ampullae, the latter elongated. The lateral fields
are one-third to two-fifths as wide as the body. The ellipsoidal, non-granular
renette cell lies close behind the neck, and is two-thirds as long as the body
is wide and two-thirds as wide as long. The ampulla is one-third as long as
the neck is wide, and three-fourths as wide as long. The nerve-ring is accom-
panied by obscure nerve cells. From the small, inconspicuous, rather contin-
uous vulva, the small tubular vagina extends inward one-third the distance across
the body. Its inner wall is cutinized, so that its rectangular furcation is plainly
to be seen. The ellipsoidal eggs are one and one-half times as long as the body
is wide and appear to begin segmentation before being deposited. One or two
at a time occur in the uteri, which are five times as long as the body is wide.
The somewhat narrow, tapering ovaries contain about a dozen ova arranged
single file for the most part, but irregularly near the blind end. The faint,
acute, tapering, stoutish spicula are colorless and one and one-half times as long
as the anal body-diameter. They are so located that their proximal ends appear
to be opposite the body-axis. The simple, strong, separate accessory pieces
are somewhat slender. They are yellow and quite as conspicuous as the spic-
ula. Their applied parts are two-thirds as long as the spicula, from which they
recede a little. Their proximal ends appear to lie dorsad from the body-axis.
The six, very small and inconspicuous, equidistant supplementary organs occupy
a distance somewhat less than the length of the tail. The last is opposite the
proximal parts of the spicula. The spaces between them are about equal to
half the body-diameter. They hardly disturb the ventral contour of the body.
Possibly there is also one near the anus. They are papilloid and have but slight
elevation. The ejaculatory duct is one-half, the vas deferens one-half, and
BOLBOLAIMUS, ACANTHONCHUS 321
the testes two-thirds, as wide as the corresponding portion of the body, but the
testes taper so that at their blind ends they are only one-half as wide as the body.
The various regions of the male sexual organs are separated from each other by
narrower channels. After synapsis, the spermatozoa grow and become granular.
Habitat: Sand, below low tide mark, Belmar, N. J., U. S. A. Sublimate to
balsam. Fig. lOOa, p.. 320.
b. Bolbolaimus punctatus n. sp. r6~~~2."8/"" ; ~lT~ j~3 XJ* 1 *" Striae resolvable
into rows of dots, of which about every third row is a trifle coarser, thus indi-
cating the real width of the annules. Labial papillae six, setose, about one-third
as long as the cephalic setae. Around the mouth, there are fine, longitudinal
striations due to foldings in the vestibule. The punctate walls of the pharynx
are well-cutinized. There are two very small ventrally submedian projecting
onchia opposite the dorsal onchium. The oesophagus near the nerve-ring is
two-fifths, just in front of the cardiac bulb a little more than two-fifths, and
finally three-fourths, as wide as the base of the neck. This latter measurement
is the diameter of the somewhat elongated cardiac bulb, which is two-sevenths
as long as the neck. There is an obscure, elongated, two-parted valve in the car-
diac swelling, one-third as wide as the swelling m>[
itself. The cardiac valve is divided into three
parts, corresponding to breaks in the muscula- on SU/ml
ture, the anterior part inconspicuous, the other
two each occupying nearly one-half the length n
of the bulb. The thick-walled intestine becomes
at once three-fifths as wide as the body. Its ^
cross-section would present three to four cells,
containing scattered granules of variable size, /
the largest of which are about one-twenty-fifth
as wide as the body. Cardiac collum one-fourth
as wide as the base of the neck. From the con- $
tinuous, inconspicuous anus, the rectum extends inward a distance two-thirds
as great as the anal body-diameter. The conoid tail tapers from the anus to the
blunt, conoid, symmetrical, unarmed spinneret. The broadly saccate caudal
glands lie behind and opposite the anus in the anterior half of the tail. Meas-
ured near the neck, the lateral fields are one-fourth as wide 'as the body.
The ellipsoidal, non-granular renette cell, one body-width behind the neck, is
one-half as long as the body is wide and five-sixths as wide as long. From the
small, inconspicuous, continuous vulva, the rather weak vagina extends inward
two-fifths the distance across the body. The elongated eggs are as long as the
body is wide and three-fourths as wide as long, and are packed three to five in
each uterus at once. The tapering ovaries contain about twenty ova arranged
single file.
Habitat: Marine sand, Nobsca Beach, Woods Hole, Mass., U. S. A. Flemming
to glycerine jelly. Fig. 1006.
101. Acanthonchus viviparus n. sp. There are distinct wings, whose presence
is indicated by about four to six longitudinal striations, resolvable, at least the
outer ones, into rows of dots. The wings extend from near the head to near
the tail. Neck conoid. Setae two- (or three-) jointed. The lip-region appears
to be divided into twelve parts, or into six parts, each of which is double. The
mouth cavity is cyathiform and shallow when the lips are closed and is entered
322 ORDER ANAXONCHIA
through a narrow vestibule. The cavity itself is very small, and a good deal
wider than it is high when the lips are closed. In fact, when the lips are closed
they appear to form a depression on the front of the head, so that their interior
margins actually rest on the dorsal tooth and on the base of the pharynx. The
pharynx actually continues to twice the depth indicated in the formula, though
when the mouth is closed this posterior portion appears to be very similar to
the lumen of the oesophagus. The oesophagus swells a little in the anterior
third, then diminishes almost imperceptibly, and finally swells toward the pos-
terior extremity where it is two-thirds as wide as the base of the neck. The
thick-walled intestine becomes at once two-thirds as wide as the body, and
expands so as soon to be three-fourths to four-fifths as wide as the body. Its
cross-section would probably present about eight cells. The elongated ventral
7.4+ 15. "W" 92.3 >16 gland lies im-
'%J '*"'' i;i 2 ' 6 ' ' " mediately be-
8.1.^15. "-M 91.9 y . , hind the cardiac
'&'*"* W^iV ' - constriction.
The lateral fields are about one-third as wide
as the body, and are composed mainly of a
double row of very prominent ellipsoidal cells,
which in the females at least, may be most
clearly seen in the region of the neck. From
X750 the slightly raised vulva, the vagina leads
inward about half way across the body. The uteri are generally about one and
one-half times as long as the neck, and contain numerous developing eggs or
embryos. The ovaries are reflexed for a distance about twice as great as the
body-diameter, and contain a dozen or more ova arranged in several series. This
species is viviparous. Tail of the male is very much like that of the female, but
more arcuate. Its terminus has a diameter one-fifth as great as the diameter
of the base of the tail. The equidistant supplements are of unequal size, those
more distant from the anus being much the larger. The first is opposite the prox-
imal ends of the spicula and is very minute. It is visible mainly on account of
the refractive nature of the material of which it is composed. The second is
about twice as far from the anus as the first and of about the same size. The
third, which is three times as far from the anus as the first, is very much larger,
having a length half as great as the body-diameter; its internal walls are brown
and strongly lined and refractive. It is somewhat curved and passes inward
and forward; its proximal portion is slightly cephalated. The fourth of these
organs is more than four times as far from the anus as the first, and is more than
twice as long as the third, having a length approximately equal to the body-
diameter. Its internal walls are strongly cutinized, and it is a very prominent
feature, almost as much so as the spicula. Where it passes through the cuticle,
its point is curved backward; thence inward, it is somewhat sigmoid, enlarging
all the time, so that its proximal portion is about one-fifth as wide as the cor-
responding portion of the body. The slightly arcuate, rather uniform spicula
are somewhat longer than the anal body-diameter. Their proximal ends are not
distinctly cephalated. Parallel to the spicula, and extending inward from the
prominently raised anus for a distance three-fourths the length of the spicula,
are the accessory pieces, whose distal extremities are two to three times as wide
as the spicula, but which decrease in size internally. They are considerably
more prominent than the spicula. The ejaculatory duct is about half as wide
as the body.
ACANTHONCHUS, XENONEMA 323
Habitat: Marine mud, San Pedro, California. Possibly another species exists
at Woods Hole, Mass., U. S. A. Sublimate to balsam. Fig. 101, p. 322.
- 1 jl--!-- 6 -t_ 1 ?-A___l 6 ?l -5 > .95 ..
102. Xenonema obesum n. &p. \I~(.> 2 -9~ V M " 7.T" T. " Striae resolvable
with high powers into rows of dots or elongated markings which are altered some-
what on the lateral field, where there is a wing extending from near the base of
the neck to the base of the tail. There are setae on all parts of the body, but
they do not appear to be very numerous. Pharynx apparently consisting of a
cavity whose walls are folded and which is capable of being opened outward.
The oesophagus continues to have the same diameter until near the posterior
end, where it contracts slightly and then expands to form the pyriform cardiac
bulb, four-fifths to five-sixths as wide as the base of the neck. There is no car-
dia. The intestine at first is only one-fourth as wide as the oesophageal bulb.
Its cross-section presents about four or five cells; that those next the oesophagus
are physiologically different from those following is shown by the way in which
they stain. The intestine soon enlarges so that its maximum diameter is twice
as great as that presented near the bulb, but nowhere does the intestine become
more than about half as wide as the body. Its cells contain a few yellowish or
brownish granules of variable size, the largest of which have a diameter about
equal to the distance between two striae of the cuticle, the smallest being not
more than one-tenth as wide; otherwise, the cells of the intestine are very trans-
parent so that their nuclei can readily be seen. These latter are of large size
and each presents a distinct nucleolus; the average diameter of one of these nuclei
is rather more than double the distance between two successive striations. The
anus is elevated; the rectum is two and one-half to three times as long as the anal
body-diameter. Immediately behind the anus, the tail diminishes abruptly in
diameter, and in this region for a short distance near the anus on the ventral sur-
face, the striations of the cuticle are much less conspicuous. The location of
the excretory pore and the ventral gland remains uncertain, but it appears pos-
sible that the latter lies a short distance in front of the cardiac bulb. The
lateral fields are about one-fourth as wide as the body, corresponding approxi-
mately in width, at least in the anterior part of the body, with the alterations
in the transverse striae which exist along the sides of the body. The tail is
conical from a short distance behind the anus. Behind ^ ^m^^ (imph
the anus, the tail diminishes so rapidly in diameter, espe-
cially on the ventral side, that it becomes almost at once
only about two-thirds as wide as at the anus; thence am.
onward, it is conical. The three caudal glands are located
in a tandem series in front of the anus. From the enor- ^
mously developed vulva, the vagina leads inward and forward at an angle of
forty-five degrees with the body-axis a distance equal to the span of eight to
ten striae. The walls of the vagina are brownish, thick, and highly refractive.
There is a single uterus connected with two short ovaries, each containing three
to four ova. This entire system of organs is clustered near the vulva and occu-
pies a distance about five times as great as the average body-diameter. The
size and nature of the eggs remains to be discovered. Overhanging the vulva is
a flap-like expansion of the cuticle which adds much to the ventral prominence.
Tissues of the body-wall are contained also in the cavity of this peculiar expan-
sion of the cuticle. Owing to the peculiar development in this region, the
diameter of the body here is more than twice the average body-diameter. In fact
324 ORDER ANAXONCHIA
these structures are so very peculiar as to suggest abnormality, but as there is
no evidence of any disease or malformation in the single, very transparent
specimen examined, it seems best to regard it as the normal form of a very
exceptional species.
Habitat: Salt River, Jamaica, in six inches of water. Fig. 102, p. 323.
1.8 10. 16. Y 88.
......... .^ .g
103. Amphispira rotundicephala n. sp. * *? 1i? *? 5- Contour
plain, or exceedingly finely crenate. Apparently there are very faint subce-
phalic setae near the base of the "cuirasse." At the mouth opening of the single
specimen examined there are three punctate spherical elements, as shown in the
illustration. The significance of these remains problematical; while they may
possibly be fixation products, such a supposition is doubtful. Neck conoid.
The oesophagus retains the same diameter until it expands to form the flattish-
pyriform cardiac bulb, which has a faint valve one-third as wide as itself. There
appears to be an almost imperceptible break in the musculature near the middle
of the oesophagus, and a corresponding very slight swelling. The thick-walled
intestine has a faint lumen and soon becomes one-half as wide as the correspond-
jj ing portion of the body. Its cross-section pre-
sents few cells. From the apparently contin-
uous anus the prominent rectum extends a
distance equal to the anal body-diameter. The
scattered to rather numerous, spherical gran-
ules found in the cells of the intestine are of
variable size, the largest being one-thirty-
sixth as wide as the body. Tail arcuate, co-
X 750 noid, ending in a spinneret one-third as wide as
its base. The broadly truncate caudal glands are located opposite to and behind
the anus in the anterior third of the tail. The lateral fields are one-third as
wide as the body. What appears to be the renette cell is located about three
body-widths behind the neck; it is one-third as long as the body is wide and one-
half as wide as long. The location of the excretory pore remains unknown.
Nerve-ring oblique. From the location of the rudimentary sexual organs in the
single young specimen seen it seems probable that they will develop to be double
and symmetrically reflexed.
Habitat: Soil, Arlington Farm, opposite the District of Columbia, U. S. A.
Flemming to glycerine jelly. This species almost seems out of place in the
habitat in which it was discovered, as it is most closely related to marine forms.
.Fig. 103.
104. Micromicron cephalatum n. sp. 2 - 8 3-7 %7 3.8 '"> V ' " Neck short,
cylindroid. There seems little doubt that the mouth cavity is armed with a
single, dorsal tooth, which can be placed so closely against the dorsal wall of the
pharynx as to be difficult of detection, although the tooth itself is of considerable
magnitude. It appears to have an acute apex, located opposite to or a little
behind the labial constriction. Oesophagus cylindroid, ending behind in a pro-
late or pyriform cardiac bulb four-fifths as wide as the base of the neck. Cardia
faint. The intestine, which joins the middle of the posterior surface of the
cardiac bulb, is at first about one-third as wide as the neck. It widens out grad-
ually so as to become about half as wide as the body, and its cross-section would
appear to be composed of about six to eight cells containing yellowish granules
of rather uniform size. The lateral fields are about one-fourth as wide as the
MICROMICRON, MESODORUS 325
body. Just behind the base of the neck, there are cells which stain a little more
strongly than the adjacent structures, possibly renette cells. The tail of the
male is conoid to the terminus, where it has a width one-fourth as great as at
its base. The caudal glands seem to be located in the base-of the tail. The pres-
ence of a series of ventral supplementary organs is indicated by corrugations
occurring in the cuticle on the ventral surface when the posterior extremity is
incurved. This series extends from the anus forward a distance about equal
to twice the length of the tail, and must be composed of about
twenty elements. Each probably consists of an inconspicuous
modification of the ordinary cuticle, in the midst of which there
is a nerve ending. In front of the anus on the ventrally sub-
median lines there are series of setae, each seta being nearly one-
third as long as the body is wide. There is one of these setae
in front of the anus on each side, a second pair nearly opposite
the proximal ends of the spicula, and so on. Similar setae occur on the anterior
two-thirds of the tail on the submedian lines. When seen in profile, the spicula
appear at the middle to be about one-third as wide as the body. They taper
rapidly to the acute distal extremities. The proximal ends are slightly arcuate
in a ventral direction. Near the proximal extremities there is a break in the
framework on the ventral side. The framework of the spicula is rather frail,
considering the size of the spicula themselves. Muscular fibers appear to pass
from the inner free end of the accessory piece backward to the ventral surface
of the anterior portion of the tail.
Habitat: Punta Arenas, Pacific Coast of Costa Rica. The intestine contained
a considerable number of diatoms. Sublimate to balsam. Fig. 104.
105. Mesodorus cylindricollis n. sp. ^ ] - 7 ^ 1.9^1.7 '" Naked cuticle
traversed by exceedingly fine, plain transverse striae. Neck cylindroid. In
certain aspects, the amphids appear to consist of one circlet within another,
but are in reality true spirals. No doubt the papillae surrounding the mouth
opening correspond with folds in the lip-region; these, however, are so very mi-
nute as to be difficult of resolution. From the base of the onchium backward, the
pharynx is narrow and tapering, and joins the lumen of the oesophagus in an
indefinite way at a point distant from the anterior extremity nearly equal to the
diameter of the front of the head. From behind the pharyngeal swelling, the
oesophagus continues with about the same diameter until it expands to form the
rather obscurely pyriform cardiac bulb, which is fully three-fourths as wide as
the base of the neck, and contains a relatively large s^cph(14) Mj^ se(J6f6)
though rather simple valvular apparatus, having a diam-
eter half as great as that of the bulb itself. This valve
is about twice as long as wide. The relatively narrow . ^ (
intestine joins the middle of the posterior surface of the M fljJaHBH^ 1 ~ 'j m ^
cardiac bulb and soon enlarges so as to be two-fifths as _^
wide as the body. There is no distinct cardia. In cross- Sftwcph *750 9"
section, the intestine presents six to eight cells. The lateral fields are about
one-fourth as wide as the body. Nothing is known concerning the renette or
the excretory pore. The nerve-ring surrounds the oesophagus squarely. The
tail of the male is strongly arcuate and conoid from the prominently raised anus.
The terminus is blunt and bears a simple spinneret. The caudal glands are
packed together in the anterior third of the tail, extending a little in front of the
ORDER ANAXOXCHIA
anus. The twenty-five supplements are rather simple and when the body is
curved, take on the form of semi-cylindroid, transverse elevations, the distance
between them increasing anteriorly. There are two opposite the spicula and a
third a short distance in front of the proximal ends of the spicula; and then for
a distance equal to four times the length of the tail, the organs are separated by
spaces not greater than their own width. Thence forward, the organs are sepa-
rated by wider spaces, and occasionally one of the series appears to be missing.
The two anterior ones are separated by a distance about twice as great as the
width of one of the organs. The entire series occupies a distance about eight
times as long as the tail. No special papillae or setae have been seen on the
tail end, either in front of the anus or behind it. The proximal ends of the strongly
arcuate, slender-looking spicula appear to lie nearly opposite the body-axis.
Apparently connecting the cephalic expansions with the anus are slightly curved,
refractive lines, indicating that the spicula may be broader than would appear
from an examination of only the more striking portions of the framework. Acces-
sories parallel to, and two-fifths as long as the spicula. Ejaculatory duct one-
third as wide as the body. The blind end of the testis is about half as wide as
the body.
Habitat: Mud, tide pool, Portsmouth, N. H., U. S. A., near low tide mark.
This genus resembles Onyx. Fig. 105, p. 325.
106. Polysigma uniforme n. sp. Cuticle, if striated at all, very finely so.
Body naked except for the setae on the head. Lips minute, more or less conflu-
ent, relatively thick, six and double, or possibly twelve. Near the nerve-ring
and just in front of the cardiac bulb, the oesophagus is one-half, and finally
three-fourths, as wide as the corresponding portion of the neck, this latter figure
being the measurement of the pyriform cardiac bulb. The refractive lining is
one-twentieth as wide as the oesophagus. In the posterior half of the oesoph-
agus, there are pigment granules in
the fine-textured musculature. The
two elongated masses of brown pig-
ment granules begin suddenly at the
middle of the cardiac bulb and end
suddenly near the middle of the neck.
There are quite prominent, pigmented
submedian glands in the oseophagus,
but apparently no dorsal one. The
thick-walled intestine, which has a
faint lumen, becomes at once half as
wide as the body, and in cross-section
would present three to four cells.
Very minute, but distinct, yellowish
granules of uniform size are scattered
in the intestinal cells. The cardiac
collum is two-fifths as wide as the
X 750 neck. The medium-sized nerve-ring
is accompanied by distinct nerve cells, not very definitely grouped. From the
more or less elevated vulva, the fairly-well cutinized vagina extends inward half
POLYSIGMA, ALAIMONEMA
327
way across the body. The eggs are probably about three times as long as the
body is wide. The broad, tapering ovaries, which contain about ten ova arranged
mostly in single file, but
irregularly near the blind
end, reach about half
way back to the vulva. m w
The tail of the male is
conoid to the spinneret, Off <M
which is nearly one-third
as wide as the base of the
tail itself. The slightly
yellowish, rather strong,
mph
subslender, rather acute
X750
cmm
nn(3)
spicula appear to have their slightly expanded proximal extremities nearly oppo-
site the body-axis. There are seventy-six yellowish, refractive supplementary
organs in two subventral rows of thirty-eight each. They are subequidistant,
but somewhat wider apart anteriorly. They appear to be more or less protrusile.
Ejaculatory duct one-third to two-fifths, the testis one-half, as wide as the
body. The testis is cylindroid, but tapers near its blind end.
Habitat: Marine mud, twenty-five fathoms deep, Woods Hole, Mass., U. S. A.
Fig. 106a, p. 326; Fig. 1066.
.5. _2.7 s 5.7 "-H 95. j 21- .
107. Alaimonema multicinctum n. sp. i'.^ i.5" ! "iVi" i.'i'^'i.'.* '"" Striae over
1500 to the millimeter, resolvable with difficulty into very exceedingly fine dot-
like elements. Cephalic and subcephalic setae sixteen, in four sets of four.
Cervical setae scattered, the first four to eight larger than the cephalic setae, the
others smaller. Somatic setae scattered, inconspicuous, about one-sixth as long
as the body is wide. In two series on the borders of the lateral fields, every
amph t set sibcph twenty to thirty annules throughout the nema,
there are round, pore-like markings, twice as wide
as the annules. The two rows of pores opposite
^ ne l a t era l ne lds are removed from each other by
a Distance about equal to three-fifths the body-
diameter. There are no lips. The simple, more or
j egg triquetrous pharynx is so small as to be very
easily overlooked. The three very small onchia are more or less equal in size.
Their forward-pointing, acute apices are about opposite the anterior borders of
the amphids. The oesophagus is at first three-fifths, near the nerve-ring and in
front of the cardiac bulb two-sevenths, and finally three-fourths, as wide as the
corresponding portion of the neck. The pyriform cardiac bulb contains a more or
less spheroidal, simple valve, two-sevenths as wide as the bulb itself. The oeso-
phagus has a subdistinct, narrow lining, and a fine musculature. The intestine,
which has a more or less thick wall and a faint lumen, soon becomes half as wide
as the body. In cross-section it presents but few cells. The cardiac collum is one-
fourth as wide as the base of the neck. The widest of the variable, colorless gran-
ules found scattered in the intestinal cells are twice as wide as one of the annules.
The longitudinal fields are three-fifths as wide as the body. The tail is conoid from
the rather prominently raised anus. The large, rather frail, tapering, somewhat
blunt spicula, at their widest parts, near the proximal ends, are one-fourth as
wide as the corresponding portion of the body. There is a rather frail, slender
accessory piece. The elevated, "campanulate," subequidistant supplementary
organs begin opposite the proximal parts of the spicula and are stationed at a
328 ORDER ANAXONCHIA
distance from each other varying from one-sixth of one, to one, entire body-
diameter. The organs are nearly as high as they are wide, and are more or less
asymmetrical. Each is connected with an internal, refractive piece, a little
farther forward. They somewhat resemble the well-developed supplementary
organs of Chromadora. The ejaculatory duct is one-half, the vas deferens three-
fifths, as wide as the body. A considerable portion of the male sexual organs is
filled with spherical granular spermatocytes, one-third as wide as the body, and
having a distinct ectosarc.
Habitat: Beach sand, Bathing Beach, Woods Hole, Mass., U. S. A. Flemming
to water. Fig. 107, p. 327.
.6 10.5 tf- -*-*' 95. > . 6
108. Cophonchus ocellatus n. sp. i._/ 1.9 * 3- T^i-9 ' Transverse
striae exceedingly minute; the cuticle is also longitudinally striated. The some-
on what cylindroid neck is almost imperceptibly convex-
conoid in its anterior part. Cuticle relatively thicker
on the head. A few short setae occur here and there on
the neck. There appear to be three somewhat confluent
lips with papillae on their outer margins, probably to
the number of six. There are two dark-brown dorsally
\~aiSC su bmedian eye-spots and opposite them in the ventral
portion of the oesophagus a linear collection of pig-
^ mented granules, from which there also extends backward
a line of scattered granules. Similar granules occur
1 ^throughout the oesophagus in groups of a score or more.
Spear-like onchium very slightly sigmoid. It is probable that the pharynx
extends back to opposite the row of cephalic setae. The cuticle on the anterior
surface of the head, as far back as the cephalic setae or a little farther, reminds
one of the covering on the head in Thoracostoma, but the thickening is less pro-
nounced, and the cuticle here is not materially different in color or texture from
that elsewhere on the body. Where the cuticle reaches its maximum thickness,
near the lips, it is three to four times as thick as elsewhere on the body. From
this point backward to near the base of the head, it gradually grows thinner.
The oesophagus continues to have the same diameter until after it passes through
the nerve-ring; there it begins to enlarge, so that finally it is two-fifths as wide
as the base of the neck. The intestine, set off by a deep constriction, becomes
at once about two-thirds as wide as the body. Its cross-section would present
four to six cells packed with minute granules. The conoid cardia is one-fourth
as wide as the corresponding portion of the body. The renette cell is about
half as wide as the body, and is located on the ventral side just in front of the
cardia; its pyriform ampulla is one- fifth as wide as the corresponding portion of
the neck. The lateral fields appear to be about one-third as wide as the body,
and to contain numerous, rather small, scattered nuclei. The nerve-ring sur-
rounds the oesophagus squarely. Tail of the male conoid in the anterior four-
fifths; thence cylindroid for a short distance to the almost imperceptibly swollen
terminus. The caudal glands are apparently located opposite to and a little
behind the anus, and present the peculiarity that one of them, the one on the
ventral side, has a separate duct leading to the separate smaller ampulla in the
slightly enlarged spinneret, while the other two have their ducts parallel and
close together and appear to join in a single, much larger ampulla opposite the
smaller one. From these ampullae, minute ducts lead backward to the pore
of the spinneret, which presents a minute, conoid depression on the terminus.
Supplementary organ tubular, of about the same diameter as the spicula, extend-
COPHONCHUS, ISONEMELLA 329
ing first inward, then directly forward. It is about one-third as long as the cor-
responding body-diameter. Its outlet is opposite the middle of the spicula.
There appear to be some obscure papillae on the tail, evidenced by almost imper-
ceptible ventral elevations. Mention may be made of one of these near the
beginning of the middle third, and another near the beginning of the posterior
third. Spicula slender, uniform, acute, one and one-half times as long as the
tail, and five to six times as long as the anal body-diameter. Their proximal
ends are cephalated by expansion. They are accompanied, both in front and
behind, at their distal extremities, by accessory pieces two-thirds as long as the
anal body-diameter. The ejaculatory duct is one-fourth as wide as the body,
and extends forward to near the middle of the body, where it joins the testes.
Habitat: Shoal in Kingston Harbor, Jamaica, in about one foot of water. This
genus bears a very considerable resemblance to Digitonchus. Fig. 108, p. 328.
109. Isonemella acuta n. sp. ' 7 / Body-wall thick
and muscular; in the middle of the single specimen seen it takes up about three-
fifths of the radius. There are a few exceedingly minute setae to be seen on
the tail; otherwise than these, and those shown in the illustration, no others are
known. There appear to be three lips, but they are so small and so thoroughly
amalgamated that it is very difficult to decide on their structure, and it is possible
that there is no division of the margin of the mouth into lips. The mouth opening
is nearly as wide as the front end of the head. Between the thin lips there is a
very short vestibule, whose limits are marked by the presence of an internal
refractive structure on the inner wall of the pharynx very near the margin of the
lips. It is impossible to say from the observations so far made whether this
refractive marking is a circular affair or whether it is dis- setl/ffl
continuous and represents special thickenings on the inner ^
surface of the three components of the lip-region. The
result of this thickening is a sudden, but very slight nar- am P"
rowing of the vestibule. The very short vestibule, there- DC .
fore, begins nearly as wide as the front of the head, widens ^
out posteriorly and then soon suddenly narrows to the
beginning of the pharynx proper. At its base this lat- *"
ter tapers to join the lumen of the oesophagus. At
first sight it appears that, with the exception of the above-
mentioned, excessively minute, cutinized processes at the
base of the vestibule, the pharynx does not present any
feature suggestive of a particular armature, but there is spn x750
nevertheless a minute, forward-pointing ventral (?) onchium of small size. The
walls of the pharynx, though distinctly outlined by the refractive nature of
the cuticle, are very thin throughout. The lip-region stains more strongly
than any of the succeeding tissues of the head, or of the anterior part of the
neck. All that portion of the lip-region in front of the middle of the pharynx
takes part in this staining, and the posterior contour of the stained portion
extends outward and backward from the front part of the pharynx. Behind
this stained portion, indicated in the illustration, there are two elongated "cavi-
ties," beginning opposite the middle of the pharynx and ending a little behind
the eye-spots, one dorsal and one ventral, and the outer contour of the head
opposite these "cavities" is very slightly elevated, in the single specimen so far
examined. When viewed in profile these "cavities" have a size and contour
330 ORDER ANAXONCHIA
somewhat similar to that of the pharynx. The amphids, difficult to observe,
have a somewhat elongated, inward, refractive extension, as shown in the illus-
tration. Eye-spots colorless or slightly yellow. There are rather inconspicu-
ous collections of golden brown pigment granules in the anterior portion of the
oesophagus. This latter continues with much the same diameter for some dis-
tance, but gradually enlarges. After it passes through the nerve-ring it is two-
fifths as wide a's the corresponding portion of the neck, and it finally becomes
three-fifths as wide as the base of the neck. Its radial musculature is very
strongly marked in the posterior half, reminding one to some extent of the oesoph-
agus in Bolbella. The nerve cells both before and behind the nerve-ring are an
unusually prominent feature. A little more than half way from the head to the
nerve-ring the foremost of these cells occur as two lateral ellipsoidal granular
cells half as wide as long, and having a length one-third as great as the corre-
sponding width of the neck. Almost on a level with these is a ventral cell, and
immediately behind them are other lateral cells of somewhat smaller size, and
thence onward the neck is packed with cells of the same character, which gradu-
ally become globular and continue behind the nerve-ring and cease about half
way between the nerve-ring and the cardia. There is a collection of similar cells
in front of and behind the anus. The cardia is convex-conoid and about one-
third as wide as the corresponding portion of the body. The intestine becomes
at once about two- to three-fifths as wide as the body. The anus is almost
continuous, though the posterior lip is very slightly raised. The refractive,
narrow rectum is about one and one-half times as long as the anal body-diameter.
The tail begins to taper from a little in front of the anus, and tapers at much the
same rate behind the anus, in such a fashion that at its middle the diameter is
about one-third as great as at its base; thence onward, it tapers but little and
ends in a terminus about one-fourth as wide as its base. Caudal glands appear
to be located in the base of the tail. The renette cell is located just behind the
base of the neck. The lateral fields appear to be about one-half as wide as the
body, and are characterized by a succession of groups of cells, which are larger
than usually seen in these regions. These groups contain dozens of nuclei packed
rather closely together. The groups do not seem to be very regularly arranged,
but succeed each other with intervals between them that are shorter than the
length of the groups. The groups are of rather uneven size, and are most con-
spicuous between the neck and the anus.
Habitat: Larat, East Indies. Marine. Fig. 109, p. 329.
.7 5.6 9. S-W. .7
110. Synonema braziliense n. sp. 1.3 / i.5 ij l - s J - 2 Cuticle naked
except for the setae at the anterior end. Mouth depressed. Lips subdistinct,
flat, rather thin, fairly developed, flap-like; lip-region apparently twelve-ribbed,
closing nearly together over the rather small pharynx, which may be reckoned
to extend at least a short distance behind the base of the dorsal onchium. The
oesophagus near the nerve-ring is one-half, just in front of the cardiac bulb one-
half, and finally three-fourths, as wide as the base of the neck. This latter
measurement represents the diameter of the valveless, pyriform cardiac bulb.
The musculature of the oesophagus is colorless, with no indication of the pres-
ence of glands. There is a cylindroid cardia one-third to two-fifths as wide as
the base of the neck, and two-thirds as long as the body is wide. The thick-walled
intestine, which has a distinct, refractive lining, becomes at once three-fourths
as wide as the body, and in cross-section would present about four cells. Cardiac
collum one-half as wide as the neck. From the more or less depressed anus, the
SYNONEMA, ANTIC YCLUS 331
prominent cutinized rectum extends inward a distance equal to the anal body-
diameter. Anal muscles are dimly to be seen. The intestinal cells have conspic-
uous nuclei, and as there is an almost entire absence of granules, the intestine
is very transparent. Tail arcuate, conoid. The three saccate caudal glands
form a close tandem in the anterior half of the tail; they
empty through separate ducts and ampullae. No caudal
setae are to be seen. The lateral fields have not been
clearly seen; they are probably one-third as wide as the
body and composed mainly of two rows of cells. The
granular renette cell is three times as long as the body is
wide and one-sixth as wide as long. It is placed from two
to six body-widths behind the neck, and seems to be com-
posed of about six ellipsoidal, granular cells, arranged more or less in pairs.
The excretory pore is two-fifths the way back to the nerve-ring; there is no
ampulla. The nerve-ring is accompanied by distinct nerve cells arranged in
groups. The following description of the sexual organs is derived from an
immature specimen: The tubular, muscular, more or less cutinized vagina
extends obliquely forward two-thirds the distance across the body, where it
joins the straight uterus, which is about twice as long as the body is wide. Ova
prolate; the maturest six to eight being arranged single file, the others irregu-
larly, about thirty in all. Ovary medium-sized and tapering. Male unknown.
Habitat: Algae, near lighthouse, Bahia, Brazil. Sublimate to balsam. The
multicellular renette is highly peculiar. Fig. 110.
111. Anticyclus exilis n. sp. Cephalic setae sixteen, subcephalic four; cuticle
otherwise naked. The rather thin lips, apparently six in number, arch together
over the pharynx, somewhat as in Oncholaimus. According to the state of the
muscular contraction in the lips, the head is
_J ti ^1 -i|_ 55^ > 2.2- slightly convex on the front surface, or slightly
70 concave. Margins of the amphids strongly refrac-
jj* |;^ H Tsu-vts* 2 - 9 " tive > so that their contours are exceedingly dis-
tinct. At first, the oesophagus has a diameter
fully two-thirds as great as that of the corresponding portion of the neck, and
it retains this diameter until after it passes through the nerve-ring; about half
way between the nerve-ring and the intestine, it begins to expand, and continues
to do so very gradually, so that finally it is about three-fourths as wide as the
base of the neck. The anterior cells of the intestine are more transparent and
otherwise different in appearance from those which succeed, and it not infre-
quently happens that they present a strong resemblance to the oesophagus,
so that the real position of the cardiac constriction is likely to be mistaken.
The intestine is at first about two-thirds as wide as the body. It soon, how-
ever, becomes three-fourths to four-fifths as wide as the body, and is composed
of rather massive cells, so that the lumen is narrow. Its cross-section prob-
ably presents about six cells. These contain numerous granules, rather uni-
form in size and so arranged as to give rise to an indistinct tessellation. From
the inconspicuous anus, the rectum, which has about the same length as the
anal body-diameter, extends inward and forward. The lateral fields are one-
third as wide as the body. Renette unknown; it is possible that the renette cell
is unusually small and located near the cardiac constriction. The tail of the
female is supposed to be like that of the male described below, but there is
332 ORDER ANAXONCHIA
uncertainty on this point, as all the female specimens so far examined have
lacked the posterior portion of the tail; the portion present has the same form
as the corresponding portion of the tail of the male. From the inconspicuous
vulva, the vagina leads inward and probably slightly forward. The eggs are
about three to four times as long as the body is wide and about one-fourth as wide
as long. The tail of the male is conoid in the anterior fourth in such fashion
that at the beginning of the second fourth, its diameter is about one-third as great
as at the anus; thence onward, it tapers much less rapidly, and in the posterior
half hardly tapers at all, the diameter for a considerable distance in front of the
terminus being no greater than that of the thickness of the body-wall. There
is present behind the anus a collection of cells which bear some resemblance
to caudal glands, but whether they really are caudal glands and empty through
a spinneret at the terminus remains uncertain. The seventeen equidistant
supplementary organs are rounded, low, conoid papillae separated by distances
about equal to their own diameters, and occupy a distance from two to three
times as great as the corresponding body-diameter. These organs appear to be
innervated, but they at times closely resemble mere transverse corrugations
of the cuticle. Behind the anus, at least when the tail is incurved, there are
folds in the cuticle that present a very similar appearance to those just described
as supplementary organs, occurring in front of the anus; these are confined to
the wide and muscular portion of the tail, and do not extend, as a rule, as far
backward as the corresponding appearances in front of the anus extend forward.
Spicula somewhat longer than the anal body-diameter,
more strongly arcuate toward their proximal extremities
than near the anus. They extend about two-thirds the
distance across the body and then curve around toward
body-axis. There extend from the proximal ends
toward the anus nearly straight refractive elements that
'^fofii pill 06 mav possibly indicate that the spicula are much wider
V-^^ffil *^ e m iddle than at either extremity. The spicula are
accompanied by accessory pieces which extend inward
f 7"tt4ifx IdWluin 06 from the anus pretty nearly at right angles and end near
the body-axis. The ejaculatory duct is two-fifths as wide as the body. Pos-
terior testis much the smaller.
Habitat: Bath Tub Springs, Jamaica, near Salt River. These are salt springs
having about body temperature. Fig. 111.
_1._6 _ _5.3_ jqa _ _^'_61t^ _ J5 9 ^
112. Croconema cinctum n. sp. 2.3 2.6 /( ,, 2.6 3.6 i.s 72 " " Cuticle thick
transparent, yellow, composed of about 500 annules imparting to the contour
of the body throughout a distinctly crenate appearance, and bearing numerous
short, stiff, slightly curved bristles, having a length somewhat greater than its
own thickness. The cuticle of the head seems to consist of a single, somewhat
hemispherical helmet-like piece. In all, there must be at least six irregular longi-
tudinal rows of setae on the "helmet," but it seems impossible to pick out any
single circlet of these setae that particularly merit the term cephalic setae.
The spreading setae on the neck curve backward. Both here and toward the
tail end, these setae are shorter than near the middle of the body where they
are tapering, acute, nearly twice as long as the cuticle is thick and have a base
one-fourth as wide as the distance between two successive annules of the cuticle.
When the mouth is closed, the tips of the lips are bunched at the middle of the
front of the head. There appear to be about twelve of these tips. The pharynx
CROCONEMA
333
is about one-eighth as wide as the base of the head and is fairly well filled by
the apices of the teeth. Two of these onchia (?) have been distinctly seen,
a dorsal one which extends to the base of the lips and has a subacute, conical,
refractive apex, and whose base is about one-eighth as wide as the corresponding
diameter of the head, and a larger submedian one with a conical, refractive
apex, and having a base somewhat wider than that of the dorsal one. This
latter has a length somewhat greater than the width of the amphids, and its base
lies near the center of the head and rather behind the middle of the pharyngeal
bulb. The pharynx is strongly aaipli on f Ib setqih
cutinized, and manifestly extends
backward through the greater part
of the region surrounded by the
"helmet." The rather obscure
change from pharynx to oesoph-
agus takes place suddenly along
two loci which extend obliquely
outward and forward from the
lumen of the oesophagus. The
oesophagus retains the same diam-
eter until after it passes through
the nerve-ring; soon after that it
begins to enlarge gradually in
diameter, so that finally it is three-
fourths as wide as the base of the X 750
neck. The intestine is at first very narrow, about one-fifth as wide as the body,
and for a short distance has a different structure from the portion that follows.
Possibly this first part should be considered a cardia. In this cardiac portion,
there are no cells containing granules. Immediately behind the "cardiac"
portion, the intestine is half as wide as the body and would present eight to
ten cells in cross-section. The cells contain brownish granules of uniform size,
so arranged as to give rise to a distinct tessellation. The intestine is moder-
ately thick-walled. From the raised anus, the strongly cutinized rectum, which
is somewhat longer than the anal body-diameter, extends inward and then
almost directly forward, so that it joins the intestine considerably ventrad from
the body-axis. The tail is arcuate-conoid, and presents the peculiarity that
the annules of the cuticle cease in front of the middle; thence onward, the cuticle
is considerably thicker and is traversed by radial markings, which pass out-
ward and a little backward and give to the surface of this portion of the tail
a distinctly punctate appearance, which, however, is less marked than the
similar appearance on the head. The caudal glands are arranged tandem imme-
diately in front of the anus, extending from the end of the intestine proper to
a little behind the anus. There is apparently a small renette cell imme-
diately behind the oesophagus. The nerve-ring surrounds the oesophagus
obliquely. From the slightly elevated, rather inconspicuous vulva the vagina
extends nearly half way across the body. The ovaries reach more than half
way back to the vulva, and contain a dozen to twenty developing ova, arranged
irregularly.
Habitat: Sand and marine algae, in surf, shore of small island off Port Eoyal,
Jamaica. Fig. 112.
334 ORDER ANAXONCHIA
113. Nudora lineata n. sp. Cuticle two to three times as thick at the head
end as elsewhere; more or less like that of Desmodora, but with longitudinal
striae somewhat like those of Monoposthia. The annules increase in width,
and are more accentuated, toward the head. Each of the ten longitudinal wings
appears to comprise a series of "V"-like markings on the anterior portion of
the body, which are reversed on the posterior. Following the serrate contour
of the head it is discovered that this reversal takes place not far behind the
neck. There seem to be twelve, subdistinct, more or less conoid, minute, blunt
labial elements. The labial papillae are more or less setose, one seta between
each pair of labial elements. Limits of the pharynx rendered very definite on
account of the elongated pharyngeal swelling. Anterior part of the pharynx
cyathiform, posterior triquetrous-tubular. Posterior part of the neck cylin-
setqM4) J-l-l-W 13 ---:? 9 ?2l" >i. 7 6.. droid, anterior convex-co-
lh\\ ; V\ktf*^^ "I/A '" noid. The amphids appear
1 J-l _ 1-^t. _ _ _* y >: 48 to be oylindroid depressions
E.2 2.9 3.2 3.4 r^Z.? , ,, ,. ,
about as deep as the cuticle
is thick. In front of the wide annule bearing the amphids,
there is another about as wide as those on the neck,
which, however, does not thin out on its anterior edge,
X756 "^^strJongity spn as do the regular annules. Following this annule comes
the lip-region, which in contra-distinction takes a carmine stain. The elon-
gated, pharyngeal bulb, one-half as wide as the neck, is set off from the remainder
of the oesophagus by a constriction. The oesophagus is at first one-third, near
the nerve-ring one-third, preceding the cardiac bulb one-third, and finally five-
sixths, as wide as the corresponding portion of the neck. The cardiac bulb is
cylindroid and makes up one-third of the oesophagus. Its musculature is coarse
and colorless. The oesophageal tube expands suddenly to form the cardiac
bulb, which is divided into two main parts by a break in its musculature. There
are smaller breaks, also, near each end. The lining of the oesophagus appears
to occupy one-sixth of its width. The rather thin-walled, narrow intestine
becomes at once one-fifth as wide as the body. At the cardiac constriction the
intestine joins the center of the posterior surface of the oesophageal bulb.
Minute granules are scattered in the intestinal cells. The conoid tail, on which
there are obscure longitudinal striae, tapers from the anus to the non-striated,
simple, symmetrical spinneret. The broadly saccate caudal glands form a close
tandem in the anterior half of the tail. Slender caudal setae occur on the tail
end, both preanal and postanal, three to four ventrally submedian, and three to
four dorsally submedian. just in front of as well as behind the anus, about one
and one-half body-widths apart, and shorter on the male than on the female.
The rather broad ovary tapers near its blind end. The flattish ova are arranged
for the most part single file. The spicula are frail, very slender, mostly uniform,
but finally tapering and acute. Their proximal ends appear to lie about opposite
the body-axis. The yellow accessory pieces are somewhat longer than the
spicula. They are arcuate and stoutish, and their proximal ends appear to lie
somewhat dorsad from the body-axis. There are two obscure supplementary
organs, the anterior of which is located at a distance in front of the anus equal
to one and one-half body-diameters, the posterior being opposite the middle of
the spicula. These consist of slight elevations further accentuated by small
alterations in about three consecutive annules.
Habitat: Sand, below low tide mark, Hull, Massachusetts, U. S. A. Fig. 113.
RHINEMA 335
114. Rhinema retrorsum n. sp. Cuticle thick, interrupted at twelve places so
as to form exceedingly distinct longitudinal wings, which when brought into
focus give a somewhat "fishbone "-like effect. The annules and their modifica-
tions give a retrorse appearance to the entire cuticle, but in reality the striae
are retrorse in the posterior part of the body, and the reverse in the anterior part.
Some of the cuticular markings cease in front of the anus on the male and are
not continued on the tail, so that the tail has a somewhat unusual appearance.
There are submedian longitudinal striations extending to the middle of the
tail. Neck for the most part cylindroid. Opposite the dorsal tooth there
is a distinct junction with the cuticle of the lip-region indicated by an almost
imperceptible constriction encircling the head. In front of this constriction
there are two others, close together, connected with the lip-region. Lips with
outward-curved api- j. _io. ___. l''5?'l*_ J>i-*
ces, surrounding a ^ 2 ' 8 3 "
cyathiform cavity J-L _ M^J?^ r^n _ _?Ai- >" 12 ,.
having a diameter 2 '- 9 3 ' 5 ^ ~* JUKSJH* , *,*
about three-fifths as great as that of the front of J^Wlj/jj|| iH^JrifQfflfc
the head, and a depth not more than half that
amount. Into the midst of this shallow cavity the
dorsal onchium projects. Sometimes, however, this p/L.
cavity is deeper, namely, when the dorsal tooth is
withdrawn to a greater extent. Then the cavity
is about half as wide as the head, and about as deep 75 * lmlte 'apndal^Lpspn
as wide, and the lip-region is manifestly more closely folded. Onchium faintly
spear-like. Muscles of the pharynx of an entirely different character from
those of the oesophagus, which begins as a tube about half as wide as the cor-
responding portion of the neck, and continues to have this diameter until after
it passes through the nerve-ring, thereafter expanding gradually, but finally
somewhat faster, so that at the end it becomes two-thirds as wide as the base
of the neck. The posterior swelling is of such a character that one might speak
of it as a bulb. There is no very distinct cardia. Renette unknown. Vagina
reaching half way across the body. Mature ova at the flexure, ready to enter
the uterus, are one and one-half times as long as the body is wide and about half
as wide as long, with nuclei one-third as broad as themselves. The narrow ova-
ries are more or less cylindroid and contain comparatively few ova, apparently
arranged more or less single file. Anus of the male distinctly raised. Tail
arcuate and conoid to the naked terminus, which has a length about equal to
that of five of the preceding annules. Position of the caudal glands doubtful,
but it seems quite possible that they are located in the base of the tail. There
are a few inconspicuous hairs on the smooth terminus that are not shown in the
illustration, of which two have been seen in the ventrally submedian position,
having a length about two-thirds as great as the corresponding diameter of the
terminus. No supplements or special papillae or setae have been seen, though
it is possible that very small setae may have escaped observation. The slender,
slightly arcuate, rather uniform spicula have their proximal ends almost imper-
ceptibly cephalated by expansion. The uniform proximal three-fourths of the
spicula, when viewed in profile appear to have approximately the width of one
of the adjacent annules. In the distal fourths the spicula taper to an acute
point. There is a single, nearly straight but slightly "S "-shaped accessory
piece, two-thirds as long as the spicula, which is acute at its distal extremity
and capable of protrusion to a certain extent. It is fully as wide as the spicula.
336 ORDER ANAXONCHIA
Its proximal half curves away from the spicula and then recurves, and is con-
nected with the ventral part of the body-wall a short distance behind the anus
by means of oblique muscles.
Habitat: Coral sand, New Hebrides. This genus differs from Chromadora,
Spilophora and Euchromadora in the possession of distinct circular amphids,
and also in the possession of twelve longitudinal cuticular costae. In this latter
respect it resembles Monoposthia, but here the spicula are double, and there
are no supplementary organs or swellings. The lip-region and pharynx also pre-
sent contrasts with any of the above genera. The striking differences are: (1)
The continuation of the pharynx in its narrow part as a definite well lined pos-
terior chamber, ending definitely opposite the point where the pharyngeal bulb
is separated from the oesophagus by a distinct constriction. (2) By the form of
the lips, which, instead of being soft and internally folded so as to give rise to
about twelve refractive ribs, or folds, are more strongly built, cutinized and out-
wardly recurved, and are only six in number. (3) -M-Fig. 114, p. 335.
A-.5. . . 9.7 .;. i6 : 6 ...'*-* aq. . 4> 4 _
115. lotadorus punctulatus n. sp.mj* 5-* : 5J 6.5 "* 5.9 ' Striae of the
naked cuticle resolvable into rows of dots, which are modified a little on the
lateral fields, where there are distinguishable two longitudinal rows of markings
close together on each side of the lateral line, at least toward the anterior extrem-
ity and on the neck. The neck is cylindroid. There are probably four or six
short and inconspicuous cephalic setae in the midst of the labial constriction.
There are twelve lips of the character usually found in the genus Cyatholaimus,
but smaller, and in such a position in the specimen examined that it is impos-
sible to make out the details, except that when the mouth is open about twelve
papilla-like lips of small size are to be seen toward the margin of the head.
Behind the pharyngeal bulb the oesophagus is about one-half as wide as the
base of the head. It continues to have this diameter until after it passes through
Ub _ M Hi the nerve-ring, when it expands to form the pyriform cardiac
bulb, which contains a distinct but simple valvular apparatus.
The intestine joins the middle of the posterior surface of the
3~~fjgK3r / cardiac bulb, and is at that point only about one-fourth as wide
g|l Qg as the base of the neck; it gradually widens out so as to become
half as wide as the body. It would present few cells in cross-
750 section, perhaps only two. The renette cell is about one-third
as wide as the body, and fully twice as long as wide, and lies a short distance
behind the base of the neck. The tail of the male is conoid in the anterior three-
fourths; thence onward it tapers more rapidly to the minute spinneret. The
posterior fourth of the tail is more finely striated than the remainder. Caudal
setae few, minute, and scattered. The proximal ends of the uniform spicula are
bent over toward the ventral side of the body. The spicula are of very peculiar
form, the proximal halves being much more strongly arcuate than the distal
halves. At the distal extremity each spiculum is bifurcated, one fork, the
anterior, being rudimentary, while the other, the posterior, is somewhat S-shaped
and acute distally. The finger-shaped apophysis of the accessory extends back-
ward nearly parallel to the body-axis. The apophysis is nearly as strongly cutin-
ized as the spicula themselves, and has a length nearly equal to that of the anal
body-diameter. The apophysis is nearly twice as wide as the spicula, which
have a width about equal to that of three of the adjacent annules of the cuticle.
Ejaculatory duct about one-third as wide as the body; vas deferens about half.
Habitat: Punta Arenas, Pacific coast of Costa Rica. Marine. Fig. 115.
PTYCHOLAIMELLTJS 337
116. Ptycholaimellus carinatus n. sp. Cuticle rather thin and naked, resolvable
near the anterior extremity into elements which are interrupted on the lateral
fields. Near the middle of the body, the division line between the annules is
resolvable into dotlike elements; these are interrupted by two prominent lateral
wings. These wings begin near the head and end behind the middle of the tail,
and near the middle of the body occupy a space about equal to the width of one
of the annules. l-9__8^ j.5.5 "'49." 90.
Neck conoid ; A 3 ^ ' ~ ~ ~ *-3~ " ~2l > L
.? Td #-^V-3S~- . . . .^;.:.-,
connected with the anterior margin of the cer-
vical cuticle by a thin, flexible membrane.
When the mouth is closed, it is surrounded by
twelve folds in the lip-region, which come
together and form a striated, somewhat tubu-
lar vestibule, having a length about equal to
the width of two of the adjacent annules of the
cuticle. The lip-region stains strongly with
carmine, and is a very striking feature in
stained specimens. The lips arch together V 1 ^ :; - :m ' f: n X 750
over the somewhat spheroidal anterior portion of the pharynx, which is about
one-third as wide as the front of the head and contains the strongly cutinized
apex of the massive dorsal onchium, which has, passing backward from it, dis-
tinct refractive extensions that gradually merge into the structures of the oesoph-
agus. The narrow portion of the pharynx merges gradually into the lumen of
the oesophagus. The pharyngeal swelling contains special muscles for the oper-
ation of the lips and dorsal onchium; these are much more strongly developed
on the dorsal side, and the pharyngeal swelling presents the peculiarity of being
widest near its anterior part, and tapering gradually nearly half way to the nerve-
ring, where the diameter has been so reduced as to be one-third that of the
corresponding portion of the neck. The oesophagus continues to have this width
until after it passes through the nerve-ring, where it enlarges rather gradually
for a short distance, and then more rapidly to form the clavate, or elongated-
pyriform, strongly developed cardiac bulb, which occupies the posterior three-
sevenths of the neck, and becomes three-fourths as wide as the base of the neck.
This bulb is divided into two approximately equal parts by a transverse division
of the musculature and its valvular apparatus is correspondingly divided. This
latter consists essentially in a plain expansion of the lining of the oesophagus,
which is in its widest part, about one-third as wide as the bulb. There is no dis-
tinct cardia. The intestine joins the middle of the posterior surface of the car-
diac bulb, and at this point is only one-fifth as wide as the neck. It gradually
widens out so as to become half as wide as the body and then diminishes again
to give place to the enormously developed renette cell, behind which it again
becomes about half as wide as the body. The intestine is rather thin-walled, its
cross-section presenting about four to six cells containing scattered yellowish
granules of variable size, the largest of which have a diameter nearly as great as
the width of one of the adjacent annules of the cuticle. From the slightly raised
anus, the rectum extends inward a distance equal to the anal body diameter.
The lateral fields are fully one-third as wide as the body. The renette cell, two-
thirds to three-fourths as long as the neck, is clavate, and at its widest part half
338 ORDER ANAXONCHIA
as wide as the body. It contains a single nucleus, which is swung centrally in
the protoplasmic network. The renette cell has two spherical ellipsoidal com-
panion cells in the rear. The excretory pore lies at the base of the lips, and is
connected with the elongated, fusiform ampulla by means of a duct which extends
from the base of the lips to nearly opposite the base of the pharynx. Some-
times the ampulla is much elongated, and one-fourth as wide as the corresponding
portion of the neck, reaching nearly to the nerve-ring. The tail begins to taper
from far in front of the anus, and tapers at about the same rate for some little
distance behind the anus, then tapers more rapidly for a short distance, and
then finally tapers gradually to the terminus. The caudal glands are located
in the base of the tail. The vulva is massive and yet does not project much
beyond the main ventral contour. It is prominent on account of a depression
which surrounds it. From the vulva the large vagina leads inward half way
across the body. The tapering, reflexed ovaries reach half way back to the vulva
and contain upwards of ten ova arranged single file. The prolate eggs are nearly
as long as the body is wide and have been seen in the uterus one at a time. The
distance between the wings on the cuticle, near the anus of the male, is about
equal to the width of two of the annules. The tapering, yellowish spicula are
more strongly arcuate in their proximal halves than elsewhere. At their widest
part they are about one-sixth as wide as the corresponding portion of the body.
Their proximal ends, when viewed laterally, appear to lie opposite the body-
axis. An indistinct refractive line passes from the proximal ends of the spicula
to the distal ends, indicating that the spicula may be wider than would be judged
by a consideration of only the main portion of their framework. The accessory
pieces are one-half as long as the spicula and in the main parallel to them and
are arranged in comparatively close contact. Near the anus, however, the frame-
work of the accessory pieces bends away from the spicula. Each accessory piece
ends in an acute protrusile point, which is rather suddenly and rather markedly
bent forward. The spicula present the same arcuate appearances at their tips
as do the accessory pieces. Both the ejaculatory duct and vas deferens are about
one-third as wide as the corresponding portion of the body.
Habitat: Larat, East Indies. Marine; apparently very common. Sublimate
to balsam. Fig. 116, p. 337. An examination of sloughed cuticle of the head
gave equally satisfactory evidence of the existence of joints in the setae.
117. Actinonema pachydermatum n. sp. Cuticle naked, very thick, occupying
one-half the radius as measured at the base of the neck. Annules alike except
-35 8.6 -it__ _V 1 L_?i'_> 83 . tnat tney grow narrower toward
T8~~ir~3Tj 4. 2-5 ' "" the extremities, especially the head
.35 9.z _i6. -x 85. end; resolvable with difficulty into
T.~~i.l~7.7 M^S,*!" * S " rod-like markings, with less diffi-
culty on the anterior half of the body. The prominent wings, begin-
ning on the neck, end near the middle of the tail. As there are deep,
narrow grooves between the annules, the contour of the body is irreg-
ularly crenate. Head set off by contraction and a deep constric-
tion, subtruncate ; mouth more or less depressed. The lip-region is one-half as high
as wide, and appears to be composed of three fairly well developed, rounded, sub-
distinct lips, which are set off by constriction. This lip-region appears as if
protruding from within the thick cuticle, and stains in carmine while the cuticle
remains quite colorless. On the lips there are no obvious signs of a cuticle. The
ACTINONEMA, RHIPS 339
pharynx is very small and inconspicuous, or even absent apparently. There seems
to exist, however, a minute, more or less arcuate dorsal onchium, to be seen in
balsam specimens only when -exserted. The neck is conoid, the head convex-
conoid. Amphids nearly straight transverse slits, four-fifths as long as the
corresponding diameter of the head, and apparently eight times as long as wide.
One of the foremost annules appears to be more or less dislocated; that is to
say, the regular succession of the fore-most annules is somewhat disturbed by
X?50 \>\ SP ^ ne P resence f the amphids, which are otherwise almost
invisible. Oesophagus more or less conoid, but decidedly
clavate posteriorly. Near the head it is two-fifths, near
the nerve-ring about one-fourth, and finally one-half, as
wide as the corresponding portion of the neck. There is
no distinct cardia. The rather thin-walled intestine, which
becomes at once two-fifths as wide as the body, has a dis-
tinct lumen. Its cross-section presents four to six cells.
Cardiac collum one-fifth as wide as the body. From the
depressed anus the prominent cutinized rectum is one and
one-fourth times as long as the anal body-diameter. The
cells of the intestine contain numerous, very fine, colorless granules. The co-
noid, subarcuate tail tapers from in front of the anus to the simple, unarmed, con-
vex-conoid, rather blunt spinneret. The ellipsoidal caudal glands are small
and inconspicuous, more or less unsymmetrical, and apparently lie in a close tan-
dem opposite the anus. The elongated to fusiform, granular renette cell lies
behind the neck a distance equal to one and one-half body-diameters; it is as
long as the body is wide and one-fifth as wide as long. Female sexual organs
double. The tapering ovaries are of moderate size and extend half way back to
the vulva. They contain few ova arranged for the most part single file. The
simple, strong, tapering, rather stout spicula are at their widest part about one-
sixth as wide as long. Their proximal ends appear to lie more or less opposite
the body-axis. The simple, rather frail, slender accessory piece is about two-
thirds as long as the spicula. There are no supplements or special papillae.
Habitat: "Seagrass," shoal, two miles off Key West, Florida, U. S. A. Fig. 117.
118. Rhips ornata n. sp. 1.3 i.i/~ 2~._6. 3- 1.9 ' " Cuticle thick, contour
more or less crenate. Striae resolvable into rod-like markings, ygf//n/ ._ ppl(l)l
changing so as to produce a basketwork-like effect on the neck.
On the posterior half of the body on each lateral field each
annule presents two forward-pointing, "V "-shaped marks of
unequal size, the ventral being the larger; these are inconspicu-
ous, but are less so posteriorly. These markings occur also on
the anterior half of the body, but are there reversed. On a par
with the celphalic setae, and just in front of the ends of the
amphids, there are four sublateral, special scales, or short,
more or less conical horns, about half as long as the setae, (ppl Fig. 118a.)-
What function is associated with these peculiar appendages is unknown. Lips
very minute, apparently six and double. The neck has the peculiarity of dimin-
ishing more rapidly from the middle forward for a short distance. The dorsal
onchium is opposed by one or two very minute ventrally submedian ones. The
oesophagus is conoid, though there is a more or less pronounced clavate cardiac
swelling. At the nerve-ring, the oesophagus is one-half, and finally three-fourths,
340
ORDER AXAXOXCHIA
as wide as the corresponding portion of the neck. The rather prominent lining
of the oesophagus finds expression in about three parallel refractive lines, occu-
pying a space equal to two-fifths its width. The
fine musculature is more or less pigmented. There
is a decided thickening of the lining in the cardiac
swelling. There is no cardia. The thin-walled
intestine presents a faint lumen, and becomes at
once three-fifths as wide as the body. Cardiac col-
lum one-fourth as wide as the neck. From the
more or less continuous anus, the inconspicuous
rectum leads inward a distance one and one-fourth
times as great as the anal body-diameter. The
postanal region has the appearance of lacking one
of the regular striae. Colorless granules of vari-
able size are scattered in the intestinal cells. The
largest of them are about half as wide as one of the
annules. The conoid, subarcuate tail tapers from
in front of the anus to the convex-conoid spinneret.
Apparently, the caudal glands lie in the anterior
third of the tail. Though the renette has not been
clearly seen, it appears to lie two body-widths
behind the neck, to be elongated and twice as long
as the body is wide. The large, elevated, conspic-
uous vulva, occupying twenty-five to thirty annules
sutait
X7
of the cuticle, leads to a medium-sized vagina. The female sexual organs are
double and symmetrically reflexed. The eggs are probably rather large, since
an ovum which has not yet entered the uterus, but appears to be mature, is
three times as long as the body is wide. Spherical, granular spermatozoa,
.9 7-5 . i*. _ -x" 90. one-half as wide as the
-1:2"- ."T"i:- " body, were seen in the
uterus. Spicula two-jointed, as shown in the illus-
tration. A mature specimen was seen in which the
spicula were lacking, suggesting that possibly they
are Tost at the time of copulation. See adjacent illustra-
tion. Accessory pieces, two in front of the spicula and
two behind, with an additional median one behind,
that is to say, five in all. The ventral, longitudinal opti-
cal section, about twenty-five annules in front of the
anus, is such that the subcuticle appears more or less as
if retrorsely serrate. This alteration in the annules is
co-extensive with the oblique copulatory muscles, so that no doubt these struc-
tures must be regarded as indicating the presence of supplementary organs.
Habitat: Marine mud, Ocean Beach, Florida, U. S. A. Fig. 118a, p. 339;
Figs. 1186 and c.
X750
ABBREVIATIONS USED IN ILLUSTRATIONS
Frequently the abbreviations are combined, thus: set trm, seta terminalis, terminal hair; set vph
dxt subl, seta cephalicadextra. sublateralis, right sublateral cephalic seta.
Ac, accessory
af, afferent
al, wing
fr, front, frontal
frt, fertile, fertilized
furc, furcation, forked
post, posterior
pp, ppl, papilla, papillate
prerct, prerectum
amp, ampulla
prm, primary, first
amph, amphid
an, anus, anal
anak, anakinesis, anaphase
Gam, gamete
gl, gland, glandular
glot, glottis, glottoid
prok, prokinesis, prophase
prtph, protophyte
prtz, protozoon
ann, annule
gub, gubernaculum, guide, ac-
prx, proxima, proximal
ant, anterior
cessory piece
pseudon, pseudonchium
anus, anus
gnd, gonad
punct, point, bead, dot
apic, apiculum
gng, ganglion
pyl, pylorus, pyloric
apnd, appendage
apph, apophysis
or, area, field
grn, granule, granular
Tm, immature
Rack, rachis, axial strand
rcpt, receptacle, sack
asp, aspect, view
^- ing, ingested
ret, rectum, rectal
ast, aster
int, intestine, intestinal
red, reduction, reduced
axil, axil, axillary
intnl, internal, inner
reg, region
ax, axis, axis
intr, interior
rem, lost, discarded
ren, renette, ventral gland
1>as, base
O birefr, birefringent
bib, bulb, bulbous
Tnc, junction, junctional
res, resv, reservoir
ret, reticulum, reticular
brs, bursa, bursal
Kar, karyokinetic figure
rtr, retrorse, reversed
fal, lime, calcareous
*-* cav, cavity
rtrct, retractor, retracting
rud, rudiment, rudimentary
cd, cdl, tail, caudal
cer, ceratin, ceratinous
*-* lac, lacuna, pit, depression
lam, lamina, plate, laminate
Sal, saliva, salivary
sb, sub
cere, cervical
chrm, color, chromatio
chrmt, chromatin
chrsm, chromosome
chrt, chromatin
cir, cirrus, cirri *
cl, cell, cellular
clc, cloaca, cloacal
dv, cleavage, cleft
lat, lateral, laterad
Ib, lip, labial
Ins, lens (of eye)
lob, lobe, lobate
longt, longitudinal
In, larva, larval
Ingt sec, longitudinal section
lum, lumen, luminal
sc, scale, scaly
sec, section, cross-section
secnd, second, secondary
se(7, segment, segmented
sem, semen, seminal
set, seta, setaceous
snst, left, left-hand
som, soma, body, somatio
cntr, centrosome
col, collum, constriction
com, commissure
comp, companion
constr, constriction
cop, copulatory
corp, body, thing, corpus
cost, costa, rib, costal
cph, cephalum, cephalic
cpl, hair, capillary
crd, cardia, cardiac
crib, sieve, mesh
crp, corpus, body, thing
en, neck, cervical .
cryst, crystal, crystalline
Ma/, major, the larger
mat, mature
marg, margin, edge, marginal
md, middle, median
mesok, mesokinesis, mesophase
metak, metakinesis, metaphase
micrph, microphyte
micrz, microzoon
min, minor, the lesser
mit, mitosis, mitosis-figure
mnd, mandible, jaw, mandibula
monast, monaster
msc, muscle, muscular
mur, wall, mural
sp, spiculum, spicula
sphnc, sphincter
spir, spireme, spiral
spm, sperm, spermatozoa
spmct, spermatocyte
spmtd, spermatid
spn, spinneret
spndl, spindle
spthc, spermatheca
sq, scale, squamule
st, stoma, mouth, pore
str, stria, striated
sub. sub, nearly, almost
subd. subdorsal
subl, sublateral
subm, submedian
cut, cuticle, cuticular
cutn, cutin, cutinous
cytp, cytoplasm
N nerve
ncl, nucleus, nuclear
nema, nema, nematode
n r, nerve-ring
subst, substance, matter
subv, subventral
sup, supplement, supplementary
sut, suture
T-|C<, duct
"-* dep, deposit, deposited
nud, naked
rpfc, tube, tubular
diast, diaster
* teg, shell, tegument
dir, directrix, guide
dnt, tooth, dental
f\c, eye, ocular
" oe, oesophagus, oesophageal
telek, telekinesis, telephase
tesl, tessellation
dntcl, denticle, little tooth
dsc, disc, discoid
on, onchium, tooth, spear
onch, onchium, spear, onchial
trans, transverse
trm, end, blind end, terminal
dsl, dorsal, dorsad
ocyt, oocyte
ttrd, tetrad, four-fold
dst, distal, far, farther
or, mouth, oral
turn, tumor, swelling, swollen
dxt, right, right-hand
org, organ
orgf, organ in doubt, doubtful
Ut, uterus, uterine
IT 1 /, efferent
os, ostium
*-' elast, elastic spring, springy
or, ovum, egg
elev, elevation
our, ovary, ovarian
V vessel
elmt, element, component
emb, embryo, embryonic
Ppor, pore
' vag, vagina, vaginal
valv, valve, valvular
eg, equator, equatorial
ex, excreta, excretory
ex p, excretory pore
par, parasite, parasitic
pet, pectoral
pclr, peculiar, remarkable
DOS, vessel
ras def, v def, vas deferens
vesic, vesicle, vesicular
extn, extension, extended
pgm, pigment, pigmented
vlv, vulva
extnl, external
ph, pharynx, pharyngeal
vnt, ventral, ventrad
extr, exterior, outer
phs, phase, state, condition
pigm, pigment, pigmented
vst, vestige, vestigial
nstbl, vestibule, vestibular
"CVjfe, fb, framework
pip, palp
vstg, vestige, vestigial
" fasc, fascicle
plr, polar
fibr, fibre, fibrous
pnct, point, dot, punctate
Zon, zone, zonal
fix, flexure
par, pore
341
INDEX
Acanthonchus
page
... 321
cephalata
Pseudolella
page
... 268
fissidens
Daptonema
page
acanthurum
Zanema
Actinonema
... 283
... 338
Xennella
cephalatum
Micromicron
Cephalobellus
... 233
... 324
flexile
Cyartonema
Rhadinema
fontinalis
. 242
. 256
245
Colpurella
257
... 308
acuta
329
microbivorum
... 270
Crystallonema
. 282
i
264
Gammanema
... 234
Chambersiella
ferox
. 291
aequalis
250
rodens
... 278
glabra
Asymmetrella
. 287
Alaimella
simplex
...238
Gonionchus
315
cincta
234
Alaimella
233
granulifera
Leptonemella
...244
Pseudolella
. 268
multicinctum
americanum
... 327
252
Cinctonema
tenue
... 244
granulosus
Leptonchus
guttata
. 304
Amphispira
rotundicephala
amplicolle
... 324
... 305
Croconema
Rhynchonema
Coinonema
... 332
... 260
... 259
Trilepta
guttatus
Nannolaimus
. 312
. 255
Anaxonchium
. 319
Colpurella
fontinalis
257
macrurus
. 266
Anoncholaimus
mobilis
Anticyatbus
... 312
245
Cophonchus
ocellatus
Croconema
...328
332
spinosum
heterurus
Myolaimus
. 267
. 274
Anticyclus
exilis.
...331
Crystallonema
fuscacephalum
... 282
... 283
Hyalaimus
brevicollis
. 238
241
exile
261
flexile
. 242
mollis.
...301
cylindricolle
... 298
lotonchium
. 302
... 277
cylindricollis
r^mnvlaimus
232
Aponchium
..298
Mesodorus
... 325
lonema
235
Asymmetrella
glabra
... 287
Triplonchium
... SCO
lotadorus
336
i if is
262
T t 1 '
Cpramonema
264
P t 1 'miiiTn
lotaiaiinus
239
251
s triatus
Protrellus
Axonchium
... 256
305
"rvactylaimus
JLJ aequalis
250
imperfectum (Butschli)
Ironella
. 302
277
-plattophila
Daptonema
fimbriatum
fissidens
... 282
... 281
Isolaimium
papillatum
. 258
*-* sphaerolaima
Bolbella
.... 271
308
Dasynema
sexalineatum
... 253
acuta
. 329
Bolbinium
brevicolle
Bolbolaimus
.... 240
demonstrans
Campydora
Didelta
... 307
longicauda
Laxonema
. 261
?43
... 319
maj i
punctatus
.... 321
314
pellucfda
. 249
Bolbonema
.... 264
Dorylaimus Dujardin
Leptonchus
304
braziliense
Synonema
brevicolle
.... 330
...240
Doryllium
uniforme
... 303
Leptonemella
cincta
lineata
.. 244
334
Bolbonema
Stilbonema
.... 264
.... 242
Catanema
... 271
251
Linhomoella
exilis
254
brevicollis
' Illium
... 261
Litinium
Polylaimium
Ypsilon
... 274
... 314
aequale
Litonema
237
^ demonstrans
Campylaimus
.... 307
232
Anticyclus
Linhomoella
Schistodera
...331
... 254
231
litorium
Anaxonchium
Omicronema
,. 319
carcinicolum (Baylis)
Tripylium
carinatus
Ptycholaimellus
.... 288
.... 337
.fecundum
1 Synodontium
ferox
... 280
Litotes
minuta
longicauda
Laimella
.. 230
.. 261
Catalaimus
acuminatus
Catanema
exile...
.... 308
... 271
Gammanema
Thoonchus
fimbriatum
Daptonema
... 291
... 310
... 282
longicaudatus
Onchulus
longicollis
Dorylaimus Dujardin. .
. 313
.. 306
342
INDEX
343
ryiacrurum
Rhabdocoma....
page
252
pacificum
Apodontium
papillatum
page
277
258
spinosum
page
macrurus
Halanonchus
maculatum
Didelta
266
252
Stilbonema
brevicolle
striata
... 242
papilliger
Cephalobellus
pellucida
245
249
majutn
Laxonema
Margonema
ringens
243
248
Xyala
... 289
... 247
Zygonemella
striatus
pellucidum
Antomicron
Pepsonema
pellucidus
Bolbolaimus
Myctolaimus
Pepsonema
pellucidum
perfectum
Xinema
Polylaimium
exile
241
295
319
276
295
263
274
Mesodorus
cylindricollis
Mesonchium
325
294
... 250
. . . 280
... 290
...330
Synodontium
fecundum
Synonchium
obtusum
Synonema
braziliense
microbivorum
Cephalobium
270
minuta
Litotes
mobilis
230
312
4-enue
L Cinctonema
tenuicaudatus
Anticyathus
tenuidens
Bolbella
Thoonchus
f erox
transitans
Monhystrium
Trilepta
guttata
cylindricum
Tripylium
carcinicolum (Baylis) . ,
Trissonchulus
oceanus
Trogolaimus
uniformis
truncata
Alaimella
Tycnodora
... 244
. . . 245
... 308
... 310
...284
...312
...300
. . 288
... 297
... 293
... 234
231
Polysigma
326
mollis
Aphelenchulus
Monhystrium
transitans
wilsoni
multicinctum
Alaimonema
Myctolaimus
pellucidus
301
... 284
285
327
276
poriferum
Mesonchium
Porocoma
striata
..... 294
236
prismatolaima
Ironella
Protrellus
277
256
Pseudolella
cephalata
granulifera
Pseudonchus
rotundicephalus
Ptycholaimellus
carinatus
punctatum
Coinonema
punctatus
Bolbolaimus
punctulatus
lotadorus
Pycnolaimus
pygmaeus
pygmaeus
Pycnolaimus
petrorsum
Rhinema
Rhabdocoma
... 268
268
273
337
259
321
336
258
258
335
252
Myolaimus
heterurus
Nannolaimus
guttatus
Nemanema
simplex
Nemella
ocellata
Neurella '
simplex
nuda
274
255
230
236
246
317
iiniforme
Doryllium
... 303
... 326
... 262
... 314
... 293
... 315
... 321
... 285
... 317
233
Nudora
lineata
nudum
Litonema
Zalonema
Obesum
Xenonema
obtusum
Synonchium
oceanus
Trissonchulus
ocellata
Nemella
Onchulella
ocellatum
Onchium
ocellatus
Cophonchus
Omicronema
litorium
Onchium
ocellatum
Onchulella
ocellata
Onchulus
longicaudatus
ornata
Rhips
334
... 237
272
323
290
297
..... 236
. . . 306
235
303
328
265
303
306
313
339
uniformis
Cynura
Digitonchus
Trogolaimus
Villosus
Gomonchus
viviparus
Acanthonchus
Wilsoni
Monhystrium. . . .
Xanthodora
nuda
Xennella
macrurum
Rhadinema
flexile
252
256
Rhinema
retrorsum
Rhips
335
339
Rhynchonema
cinctum
ringens
Margonema
rodens
Chambersiella
rotundicephala
Amphispira
rotundicephalus
Pseudonchus
Schistodera
exilis
sexalineatum
Dasynema
simile
Crystallonema
simplex
Choronema
Nemanema
Neurella
sphaerolaima
Blattophila
260
248
278
324
273
231
253
283
238
230
246
271
Xenolaimus
striatus
Xenonema
obesum
Xinema
perfectum
Xyala
...250
... 323
... 263
289
Vpsilon
i exile
.. 314
. 272
283
^alonema
t* nudum
Zanema
rjachydermata
" Tycnodora
pachydermatum
Actinonema
231
338
Zygonemella
striata
.. 247
HOWARDULA BENIGNA
A nemic parasite of the Cucumber-beetle, (Diabrotica)
CONTRIBUTIONS TO A SCIENCE OF NEMATOLOGY X
BY N. A. COBB
Howardula Cobb, '21. Characters of Tylenchus Bastian, 1865, but without
oesophageal bulb and with a non-bulbous onchium and much reflexed ovary.
Female finally a flaccid, cylindroid sack, without distinct alimentary canal, and
otherwise very much deteriorated. Amphigonic; male, free-living. Howardula
is probably related to Bradynema zur Strassen 1892. The latter however is
anonchial, and even lacks a mouth opening.
Howardula benigna Cobb, '21. i:i (?) ^ .... (?) <98 - (?)99 - 3 5 c BB
2.5 ,4.0'" 4.7 4.1 L9
Anus none or vestigial; vulva sometimes terminal; uterus nearly filling the
body-cavity, posteriorly packed with larvae and ante-
riorly with segmenting eggs, near the head in the vicinity
of the small spermatheca narrowed and reflexed to the
middle of the body, whence the narrow ovary turns for-
ward and ends blind near the head; onchium of adult
obscure but the minute mouth opening still persisting.
Inert, viviparous, usually all of about the same stage of
development in any individual host-insect, each when
mature containing about two thousand embryos and seg-
menting eggs; the larvae, of two kinds, sometimes ten
to twenty thousand of them, proceeding from the mother
nemas into the body-cavity, and thence into the sexual
apparatus, of the host, and so becoming deposited with
the eggs of the latter. See Figs. 3, 6 and 7.
2. 16. (?)24. -95. (?)97. n =
Larval formula : 0.5-
2. 4 X 5. 4. 2.6
These are the measurements of the larvae as they issue
from the vulva. Those within the mother nema and in
the anterior part of the uterus are considerably shorter. F H g itl
Anus none or vestigial; tail conoid, straight, broadly ture and
rounded or subtruncate at the terminus. After deposi-
tion along with the beetle eggs, the young nemas moult ^^J^ actual length of
with little increase in size; after mating, the female
drills into the body-cavity of even very young beetle larvae of both sexes,
sometimes to the number of thirty, but more often five or six. The following
Waverlv Press. Baltimore, Md.. June 9. 1928. Revised and continued from Nematology X, Aug. 8.
1921, Waverly Press. See Science, Dec. 30, 1921.
346
DISTRIBUTION OF HOWARDULA
are the dimensions and other details of these young but already spermatized
individuals, as found both in the soil and in very young beetle-larvae, which
in the body-cavity of the host reach the above seven to ten times longer, mature
3.4 (?)12. 28. -91. (?-)94.8
form: 7 ::::: 7 7 ^ ^~7 0.54
3.7
2.8
Fig. 2. Map showing distribution of the nema
Howardula benigna as disclosed by examinations in
1921 The aim was to examine at least 100 cucumber-
beetles from each locality. This aim was achieved
in most cases. The map-figures give the percentage
of beetles found infested by Howardula. The figures
for different localities a few miles apart in any given
region usually were in substantial agreement, but the
figures for different regions varied much. Where the
percentage of infestation was highest, the nematism
was highest. The presence of the nema does not
exclude other internal parasites, such as other insects
and gregarines. Only one other nemic parasite was
observed, represented by a single Nova Scotian speci-
men. About 1500 D. tittata were examined. Below
are the addresses of those who kindly contribut J
insects for examination.
Balduf, W. V. Marietta, O.
Campbell, R. Alhambra, Cal.
Hall, Dr. M. C. Chevy Chase, Md. Ross, W. A. Vineland Sta., Ont.
Harned, R. W. Agr. College, Miss. Smith, C. E. Baton Rouge, La.
Thomas, W. A. Chadbourn, N. C.
Walters, M. J. New London, Ct.
Cobb, Dr. F. Ann Arbor, Mich. High, M. M. Kingsville, Texas.
Cobb, V. Whitman, Mass. Kelsall, A. Annapolis Royal, N. S.
Centner, L. Lansing, Mich.
, .
Raps, E. M. Oakton, Va.
Watson, J. R. Birmingham, Al.
Habitat: Common in the body-cavity (abdomen, thorax and even head) of
all stages of Diabrotica vittata, trivittata, and 12-punctata, especially the two for-
mer, infesting the two sexes about equally.
My attention was called to this nema by Mr. W. V. Balduf, Assistant Ento-
mologist, Ohio Agricultural Experiment Station, Marietta, Ohio, where he dis-
covered the larvae in the course of experiments on Diabrotica. Owing to the
economic aspect of the subject, beetles sent me by Mr. Balduf were exhibited,
dissected, at the Washington Helminthological Society's meeting, March 17,
1921. Examination revealed the adult female form, which is so flaccid and
otherwise deceptive as to cause it rather easily to be confused with the internal
organs of the host by one not already versed in both insect and nemic anatomy.
With the aid of Dr. F. H. Chittenden and colleagues, Federal Bureau of
Entomology, and others, the geographical distribution of the nema was
studied with results shown on the accompanying map, which indicates that the
distribution in the spring and summer of 1921 was probably nearly coextensive
with that of the main hosts, Diabrotica vittata Fab. and trivittata Mann. The
nematism is often high and affects on the average about 20% (0%-70%) of the
insects. Beetles from a locality where they are not nematized are larger, brighter,
more vigorous. Thus twenty-five beetles from an uninfested lot were much
INTENSITY AND EFFECT OF THE NEMATISM 347
larger and averaged seventy per cent heavier than a similarly chosen twenty-five
from a fifty per cent infested lot. Anatomical evidence shows the infested female
beetles to be less fertile than the non-infested, doubt as to diminished fecundity
vanishing where the female host harbors a dozen or more adult nemas. In such
cases the mere relative volume of the parasites is convincing evidence of handi-
cap. See Fig. 1. Mr. Balduf in a letter speaks of beetles, many of which "died
of nemas." I have no rigid proof of such deaths, but believe them very probable
and at times numerous. Among the grubs the mortality may be heavy.
In none of the numerous lots of beetles examined was the rate of infesta-
tion by any other zoo parasite as high as by Howardula, with the single excep-
tion of a forty-three per cent dipterous infestation; but no note was made of
degrees of phyto-infestation (cucumber-wilt organism, etc.).
As many as thirteen thousand nemic larvae, by count, have been removed
from the body-cavity of a single Diabrotica vittata, and no doubt the number
may go much higher. On several occasions twenty or more adult Howardulas
were taken from a single beetle. Theoretically these should produce some forty
thousand larvae or more. The older female beetles, when nematized, deposit
from a few to upwards of fifty nemic larvae with each egg. See Fig. 3. These
soon mature on the eggs or in the soil (where they can live several weeks), moult
and copulate, the female developing a more perfect spear, and by its aid drilling
into the body-cavity of the beetle grubs soon after the latter hatch out. See Figs. 3
and 4. That it is most improbable the nemas enter the host by way of the
mouth and alimentary canal is well illustrated in Fig. 8. The active young beetle
larvae are armed with sharp-toothed, well developed mandibles. That the
fragile young nemas could, in any considerable numbers, pass so relatively small
a throat and mouth, armed as the latter is, one hesitates to believe.
In plant-infesting triplonchs I have shown the devel-
opment of the so-called salivary glands to be greatest
in species noted for their efficiency in destroying the
tissues of the host, e.g., Tylenchus dipsaci, Caconema
radicicola, and suggested that these glands aid in dis-
solving the host tissues and thus supplement the mechani-
cal action of the spear or onchium, which therefore should
then act also as a spewing channel. In light of this, it
may not be without significance that the salivary glands
of Howardula benigna, at the time of entering its host,
appear better developed than in some of its nearest known
relatives. Conceivably this secretion is also antiseptic.
Nemas of very many kinds make their way through the Fig.3. Egg of a c
tissues of their hosts without causing fatal infections. ^
For instance, I have observed the most important abdomi-
nal and thoracic organs, heart excepted, of Dasyurus
literally sewn through and through by long and slender nemas without apparent
infection. The existence of an antiseptic nemic secretion or excretion might ex-
plain this. In the case of Diabrotica, there is no known trace left of the relative-
ly large breach made by the parasite (see Fig. 4), a benignant result perhaps
facilitated by the parasite itself in the way indicated.
348
ANATOMY OF ADULT HOWARDULA
THE SOIL-INHABITING MALE AND FEMALE HOWARDULA, FIG. 4.
Female. X 3. : '- "iS " ' '^8 ' ' ' "III - 57 m The colorless
cuticle is traversed by plain transverse striae, all alike, 1.3 microns apart, some-
what difficult of resolution except with the highest powers. Very slightly oblique
longitudinal striae, due to the attachment of the musculature, are
visible in most regions of the body. Xo series of pores have been
seen in the cuticle. The lips are amalgamated; the lip region has
no apparent framework. Xo labial papillae have been seen. Be-
hind the pharynx the oesophagus is about one-fourth, at the nerve-
ring about one-fifth, as wide as the corresponding part of the neck.
The beginning of the intestine is somewhat indefinite; but proba-
bly is indicated by the anterior limits of the minute, elongate bire-
fringents, grn bif, Fig. 4. A dorsal oesophageal gland empties
through a duct and ampulla near the base of the spear. Two large
coarser glands empty a trifle farther back. These glands, Fig. 4,
Fig. 4. Profile view of the soil-inhabiting male and
female of Howardula benigna. The female has a well
developed spear; the male none. The female has three
strongly developed cesophageal glands; the male none.
As in some mermithids, and in some triplonchs, the
oesophageal glands are of two kinds, the dorsal gland
differing in structure from the two submedian ones.
See gl sal dsl and gl sal subm. This difference in struc-
ture suggests a double function. The abbreviations
are self explanatory.
The different zones
in the vas deferens
tsl mvmm
generations of sperma-
tidia, somewhat
as in Spirina. on
xst, vestigial onchium
of the male.
J
X400
are reminiscent of those in the neck of mermithidae (e.g. Agamermis larvae) and
of Tylenchus and Heterodera. The striking difference in the composition of the
DEVELOPING PARASITIC FEMALE
349
glandular secretions sug-
gests two functions ; e .g. , (1 )
solvent action on the chitin
of the host at the time the
nema drills into the host,
and (2) an aseptic effect to
aid in healing the wound
thus inflicted on the host.
Small, irregularly poly-
hedral birefringents occur
among the spherical gran-
ules of the intestine. Very
small amphids are believed
to occur. There are no
eyespots. Sometimes the
terminus of the female is
marked by the presence of
one or two small, back-
ward-pointing, short, trun-
cate, cylindroid mucronea,
about one micron long and
about equally wide. The
blind end of the gonad, half
as wide as the body, lies
near the middle of the
nema and is directed for-
ward. Passing backward
two body widths, the gonad
becomes one-third as wide
as the body; five body
widths back it is only
about one-fifth as wide as nrt rnt
the body. It then expands
a little, and is separated
from the large sperm recep-
tacle comprising the rest of
the gonad, by a rather dis-
tinct constriction. Begin-
ning narrow near the head,
the lateral chords widen
regularly until they reach
their full width, about
one-third that of the body,
a little behind the nerve-
ring. Here, at intervals
equalling the body diam-
eter, the lateral chords
carry broad ellipsoid cells
about one-fourth as wide
as the body, containing
'Iff
Fig. 5. Quarter grown
Howardula benigna removed
from the body cavity of the
cucumber beetle, Diabrotica
vittata. The striations of
the cuticle are much too
fine to be shown in a figure
of this magnification; the
features shown at ruga are
folds in the cuticle depend-
ent on the attitude of the
nema. The narrow, imma-
ture sexual organ is shown
dark. The spermatheca,
spthc, with its excessively
minute sperm elements, is
shown overlaid by the much
coarser tissues of the body
wall. A few sperms occur
near the vulva. The uterus
ultimately enlarges so as
nearly to fill the body cav-
ity; the ovary, ovr, mean-
time, is shoved forward into
the front end of the body,
trm ovr, present position of
blind end of ovary.
X320
350
ANATOMY OF THE MALE HOWARDULA
spherical nuclei two-thirds as wide as the cells themselves; and these nuclei
carry spherical nucleoli half as wide as the nuclei themselves. The inter-
spaces in the chord are nearly filled by granules of variable size, the largest one-
sixth as wide as the nema. The chords narrow in the tail to near the terminus.
Possibly there are faint refractive elements in the inconspicuous lining of the
oesophagus indicating the presence of a vestigial bulbous body. In the specimen
under examination the cells near the blind end of the gonad have considerable size,
being about one-fourth as wide as the body.
Male: *J ^ -Z- *J ^ ?J O .G1 Striae, 1.2 mi-
crons apart, rather readily resolvable with high powers. As in the female, there is
no perceptible framework to the lip re-
v gion, but six very flat lips can be faintly
M seen. No papillae have been distin-
guished on the lips. The tail presents a
terminal dimple. There is very little
vestige of a spear in the pharynx (Fig.
4) but the limits of the pharynx usually
can be made out, its length being a
little greater than the width of the base
of the head. Behind the pharynx, the
OfT oesophagus can be seen to be about one-
third as wide as the base of the head,
and it continues at first more or less nor-
mal, but becomes indefinite. There is
no distinct O3sophageal swelling, nor has
any vestige of such been seen. At the
nerve-ring, the oesophagus is probably
'IKflKI less than one-third as wide as the corre-
sponding portion of the neck. The
cesophagus is indefinite behind, but
spherical granules, such as are charac-
teristic of the intestinal cells, occur
about one body width behind the nerve-
ring. However, it seems likely that, as
in the female, the first appearance of
birefringents probably indicates the be-
ginning of the vestigial intestine. The
blind end of the testis, about one-third
as wide as the body, is indistinct, and a
little more than twice as far from the
' anterior extremity as the nerve-ring.
For about two to three body widths the
X18
Fig. 6. Gonads of the female cucumber beetle,
Diabrotica tittata, previous to egg-laying, when the
nemic larvae swarm into the ovaries.
testis increases in diameter, becoming
half as wide as the body, this portion
being rather coarsely and irregularly
granular. The anal region is very slightly raised. There are two, nearly straight,
tapering, blunt spicula, nearly as long as the anal body diameter. These are
INFESTED MALE CUCUMBER BEETLES
351
vaguely cephalated, and at their cephalated ends are a little wider than anywhere
else. They taper rather regularly to the blunt distal ends. There is a short, sim-
ple, narrow, refractive gubernaculum, about one-third as long as the spicula. No
definite ribs or special papillae have been seen on the tail, or in front of the anus.
The wings project sufficiently so that the cross section of the nema in the vicinity
of the anus must be thrown out of dorso-ventral symmetry considerably. The pos-
terior extremity of the male is more or less helical, and, oppo-
site the anus, the somewhat raised wing occupies nearly one-
fourth the corresponding width of the body. The contour of
the wing is almost imperceptibly and very finely crenate, the
corresponding annules of the cuticle here averaging about one
micron.
Habitat: Garden soils near cucurbits, and especially near
eggs and very young larvae of D. vittata; widespread. The
spherical and refractive intestinal granules hinder an examina-
tion of other anatomical and histological features.
Possible transfer of nemas by beetles in copula.
Males and females of D. vittata were gathered and examined
for their nematization with H. benigna. Of 15 females, 7 were
infested; 8 not infested. Of 29 males, 17 were infested; 12 not
infested. Roughly speaking, therefore, there was a 50 per cent
nematization, of which each sex had about half its individuals
nematized. This seemed a suitable case to scrutinize with re-
gard to the transfer of larval Howardulas from the male beetle
to his mate.
Of 19 infested males, 7 had nemas in the genitalia, the
number of nemas varying from 1 to 14. The nemas seemed to
tend to gather in the distal end of the genitalia, though found
in all parts.
Following up this observation, beetles in copula were gath-
ered and the females examined. If the female was infested in malTcucumb7rl:>eetle*
the body cavity, she was not further examined; if not infested tst, testis; gl, glands,
in the body cavity, then her more external genitalia were scru- Note nemas in cavity
,..,., , u-T-Tr j uu j j. f genitalia, genit
tinized for larval nemas, which, if found, could be assumed to ( w hite) and ros
have been placed there by the males with which these females (black)'. Nemas seem
were known to have copulated. less abundant in male
Examination of 13 such non-nematized females disclosed no ge
larvae of Howardula in the distal genitalia. This might seem to indicate that
such transfer of Howardula larvae from male beetle to female was improbable.
On the other hand, no sperms were found in these females, although they were pres-
ent in all the males examined. The fact that no sperms were transferred to the fe-
males seems to indicate that the copulation was a mere gesture, which did not
result in fertilization. The females were not yet at the egg-laying stage, as was
indicated by the condition of their ovaries. In only one female examined dur-
ing the whole of these examinations was an egg found lower down than the
ovaries. This egg was in an infested female and had two or three nemas on its
surface; the egg was in the oviduct. This experiment should be repeated.
nan
Fig. 7. Gonads of
352
GUIDE ECOLOGY TO FAVOR AGRICULTURE
The present investigations suggest how far we are from appreciating the
abundance and importance of insect parasites and how backward in attempting
their control. Howardula is, beyond any reasonable question, ages old, for
on no other supposition can the remarkable relationship of host and parasite
be explained. It is only one of a consider-
able number of parasites of the same destruc-
tive insect that have much to do with the
welfare of the host. Intelligently increasing
the incidence of the parasite will decrease
the ravages of the host. When we come to
understand these relationships, these "bal-
ances" between host and parasites, doubtless
we can do much toward inclining the "bal-
ance" in our favor. We hear more or less of
organisms introduced to new areas without
their enemies and parasites, and in conse-
quence becoming frightful pests; and we have,
very painfully and slowly it seems to some of
us, learned that searching for and introduc-
ing these same enemies and parasites affords
relief. Marked successes of this kind at last
place it beyond doubt that this portion of
the field of economic parasitology will be Jjf e 8 gru e * d d of *^^
Carefully explored. But there is another entering the grub. The sharp active man-
very important part of the field of which we Jgft?g n ^ u a ld ' eemtaberatherim P ass -
hear little if anything, and that is the com-
prehension and watchful control of what may be termed indigenous or long-
established "balances."
The cucumber-beetle affords good enough example of these latter to justify
an appeal, on the basis of it, to economic biologists to scrutinize more carefully
the ever changing "balances" between pests and their parasites and other ene-
mies, including pests of long standing, with a view to keeping the "balance"
always inclined in our favor. I believe any well trained, experienced and
thoughtful biologist will agree that such a course is bound finally to result in
notable economies. A case in point is the existence of localities, among those
here tested, in which the total zoo-parasitism of the beetles reached only about
two per cent. At the same time not very far away there was a nemic infesta-
tion exceeding fifty per cent and a dipterous infestation exceeding forty per cent.
The investigation showed that the transference by post of the two parasites
mentioned from highly infested areas to low or non-infested areas was easily
feasible at small cost. Beetles simply posted in a ventilated box containing
cucurbit leaves survived a two to four days' journey; turned loose at night
they lived.
MARIONELLA 1
(Eurystoma Marion, 1870);
an emendation, with notes on a new birefringent substance,
mariohellin, found in the intestinal cells.
CONTRIBUTIONS TO A SCIENCE OF NEMATOLOGY XI
BY N. A. COBB
United States Department of Agriculture
Marionella, 2 nom. nov.
Eurystoma Marion, Ann. Sci. Nat. Zool. V. 13: 19. 1870. Not Eurystoma
Raf. 1818.
Cuticle and setae. The thin layers of the transparent, colorless cuticle are
traversed by transverse striae so exceedingly fine that they are very difficult
to see even with highest powers of the microscope. Occasionally oblique striae
also are to be seen in the cuticle of the lips, running in the direction of a
left-handed screw. There are no lateral wings to the cuticle, and the striae
are not altered on the lateral fields. There are no longitudinal striae
in the cuticle itself, but the attachments of the somatic muscles give
rise to longitudinal markings of a character somewhat resembling true
striae. The contour of the body is always plain.
The cephalic setae, which are one-third to two-thirds as long as the lip-
region is wide, are six or ten in number. Even when at first sight there ap-
pear to be only six, it is frequently found that in reality there are ten,
each of the four submedian setae having a very short and very inconspicuous
companion hugging its base. The setae, two lateral and four or eight sub--
median, are usually slightly curved, of medium size to very slender, taper-
ing, and somewhat acute, and have innervations that are most clearly visible
near their bases; they are of medium stiffness to flexible, and spread out-
ward from the lateral surface of the head opposite the apex of the onchium.
Occasionally the larger setae can be seen to be about three- jointed. There
are no special subcephalic setae. On the anterior portion of the neck in
the vicinity of the head there are always to be found a few small, slender
setae, one-sixth to one-eighth as long as the corresponding body diameter;
these usually project at right angles to the neck or incline forward at an angle
of sometimes as much as forty -five degrees. Not infrequently among the
cervical setae there is one, a dorsal one, two to three times as far back as
1 This paper was published in the Journal of the Washington Academy of Sciences,
vol. 11, no. 21, pp. 504-509 (issued January 9, 1922). It is reprinted with changed pagina-
tion but without change of page content.
2 The name Eurystoma, applied by Marion in 1870 to a new genus of free living
marine nemas discovered by him near Marseilles, France, was preempted, having been
applied by Rafinesque in 1818 to a genus of molluscs. Naturally, investigations made
during the last half century enable one, at the present time, to emend Marion's original
description. Having examined as many more new, and as yet unpublished, species of the
genus as have been already published, I venture to make this emendation, based on a
study of about twenty-five species, and to propose for the genus the new name Marionella,
in commemoration of its original author.
354 MARIONELLA
the base of the head, which is more prominent than the others. The somatic
setae appear always to be reduced to innervations. There are no conspic-
uous pores on the surface of the body, but the ellipsoidal glandular cells of
considerable size invariably found in the lateral fields are connected with
the exterior by means of very small and inconspicuous pores.
Head and pharynx. The somewhat rounded to subtruncate head is us-
ually continuous with the neck, but is sometimes set off by a slight contrac-
tion, or by a very slight, broad, shallow constriction. The lip-region, on
the other hand, is nearly always set off by a very slight, narrow and shallow,
but usually distinctly visible constriction. The membranous lips are them-
selves thin and confluent, and apparently close by virtue of their elasticity.
Their margins are very finely striated and possibly sometimes fimbriate.
The lips are supplied externally with six forward-pointing papillae (or six
sets of papillae), arranged in a single circlet having a diameter about one-
half as great as that of the lip-region. These papillae are so exceedingly
small as usually to escape observation. Their innervations are also exceed-
ingly inconspicuous. Usually it is only when the papillae happen to project
forward a little in exact profile that they come into view.
At first sight the pharynx appears to have the form of that of Oncholaimus.
It is, however, nearly always divided into two distinct chambers of more or
less equal length, the anterior of which is somewhat the wider and the more
symmetrical. This regular anterior chamber is nearly always a napiform
cavity one-half to two-thirds or even three-fourths as wide as the correspond-
ing portion of the head. The posterior chamber is of smaller size, usually
only about three-fourths as wide as the anterior chamber, and more or less
irregularlv spheroidal in form. The refractive walls of the pharynx are
well-developed, but not very thick. The pharynx is usually armed with a
single well-developed, forward-pointing onchinm, but there may be one or two
additional smaller onchia in exceptional cases. The apex of the main, and
usually only, onchium, always occupying the right ventral submedian posi-
tion, extends forward sometimes as far as the lips. The convex-conoid,
enlarged base of the onchium fills the posterior chamber of the pharynx
comparatively full. This enlarged portion of the onchium is continued in
the front chamber by a narrower, more slowly tapering, convex-conoid,
more or less acute summit. This organ is perforated and so serves as the
outlet of a large oesophageal gland. The posterior pharyngeal chamber is
separated from the anterior by a constriction, marked in its most pronounced
form by the presence of narrow and refractive, transverse, arcuate elements
or thickenings, placed end to end in a circle. Adjacent to this circle, usually
in front of it and close together, there are one to three transverse rows of
denticles, each consisting of either about thirty-two, or about sixty-four
to eighty, somewhat forward-pointing units. These more or less inward
pointing denticles are rather acute, cylindroid-conoid, uniform in size, and
are usually so minute as to be barely resolvable with high powers of the
microscope.
When viewed from in front, the pharynx is seen to be very nearly round.
The margin of the lip-region is so thin and filmy that oftentimes it is difficult
to delimit. An exact count of the denticles in a specimen of an unpublished
but typical species, gave the following figures: anterior series of denticles
62 ; second series 62 ; back series of larger denticles 20 ; this decreased number
in the back row being due not only to the fact that the denticles are larger
MARIONELLA 355
and farther apart, but also to the fact that one-third of the circumference
is destitute of denticles, namely that part of the circumference opposite
the large onchium. In this particular region, however, the'interior walls
of the pharynx are very finely longitudinally striated. The back row of
denticles, it should be pointed out, is on the wall of thfe posterior half of the
pharynx.
The neck is conoid, or occasionally subcylindroid, and ends in a cylindroid
or, more often, a rather decidedly convex-conoid head.
Amphids and eye-spots. Though the amphids are well-developed, they
are rarely plainly to be seen. Their exterior expression consists of two dor-
sally sub-lateral concavities two to three times as wide as long, impinging on
the bases of the lateral setae. Though the peripheries of the amphids may
seem to be closed, they are, in fact, nearly always found to be open on the
posterior margin near the lateral fields. As a rule their contours are almost
invisible, so that their form and extent are mainly indicated by the apparent
absence in them of the fine structural elements to be seen elsewhere in the
cuticle of the head. When clearly defined, their contours are found to be
reniform with the convex side forward. They are located on or near the
base of the lip-region, and more or less opposite to the rows of denticles.
They are usually one-third to two -fifths as wide as the corresponding diameter
of the lip-region and two to three times as wide as long.
More often than not two eye-spots are present. These take the form of sphe-
roidal, compact collections of about one hundred brownish granules, each
collection lateral in position and lying between the oesophagus and body-
wall, being about one-fourth as wide as the corresponding portion of the
neck, and removed from the anterior extremity by a distance two to four
times as great as the width of the head. Anteriorly, these ocelli often present
a spherical cavity in which there is at least the suggestion of a spherical
lens.
Oesophagus. The simple conoid oesophagus is destitute of bulbs and
receives the base of the pharynx in its anterior extremity, where it is usually
about half as wide as the base of the head. Near the nerve-ring it is usually
about one-half, and posteriorly usually about three-fifths, as wide as the
corresponding part of the neck. It is always separated from the intestine
by a distinct cardiac collum about one-third as wide as the base of the neck.
While not conspicuous, the lining of the oesophagus is a distinct feature
throughout its length. Though the oesophageal musculature is usually
fine, the structure is occasionally coarse in the posterior part. Rarely,
yellowish spherical granules are found in the tissues of the oesophagus.
The oesophageal glands are well-developed, or at least one of them is; as
before stated, they empty into the pharynx through pores in the onchia.
The right submedian gland is without exception the largest. There is us-
ually a well-developed conoid or hemispherical cardia one-third to one-half
as wide as the corresponding portion of the neck.
Intestine. The intestine becomes at once one-half to two-thirds as wide
as the body, and is made up of cells of such a size that few are required to
build a circumference. Its walls are thick, and its lumen faint. Its cells
invariably contain fine spherical granules of more or less variable size, the
largest of them being one-fortieth to one-twentieth as wide as the body.
The granules are scattered, or sometimes numerous, in the cells, and may
be so arranged as to give rise to a faint tessellated effect, though this is unusual.
356 MARIONELLA
Doubly refractive granules (Marionellin} in the intestinal cells. In the
single layer of cells composing the intestine, an undescribed species of Mari-
onella presented about twenty scattered special cells, more numerous and
closer together anteriorly, each packed with doubly refractive granules
(marionellin) mostly of very small size. Marionellin occurs in other species
of Marionella.
These special intestinal cells were not distributed along a definite longi-
tudinal line as in Ironus, where there is a decided dorsb-ventral symmetry
to the intestine due to the dorsal cells having a different character from
the ventral. The interspaces between these special cells in this species of
Marionella increased rather regularly from front to rear.
The discovery of these special intestinal cells is an additional observation
indicating differentiation among the cells of the nema intestine. Such differ-
entiated cells are now known to the writer in the following genera, among
others: Enoplus, Bathylaimus, Ironus, Mononchus, Eurystoma (all carniv-
orous). It seems very reasonable to suppose that these differentiated cells
may have functions similar to those of the glands accessory to the intestine
of other and larger animals. Assuming that digestion in nemas has a general
similarity to that of the higher animals, it would seem that gastric, hepatic,
renal and other functions must exist in some form in the nema; thus far,
however, very few of these functions can be assigned to special organs, as
few or no such special organs exist. Instead of each cell of the intestine
carrying out all of these distinct functions, in view of the above observations
there is now morphological evidence of "division of labor," and when these
differentiated cells have been adequately investigated, we shall probably be able
to assign to them definite functions, and, for illustration, be able to apply to
them some such terms as "hepatic cells," "renal cells," "splenic cells," etc.
Tail. The tail in Marionella takes on one of two distinct forms, accord-
ing as there is or is not a spinneret present. If there is no spinneret the tail
is conoid from the anus to the acute terminus, sometimes however tapering
a little more rapidly in the anterior portion than elsewhere. In species
possessing this form of tail, usually the tail of the male is the shorter, and
the narrow conoid posterior part may appear rather as an appendage to the
short but bulky anterior part. Most of the species, however, possess three
well-developed unicellular caudal glands and a blunt, conoid, unarmed, and
symmetrical terminal spinneret about one-fourth as wide as the base of the
tail. If any setae occur on the tail, they are exceedingly small and very
inconspicuous. The three quite separate ducts of the caudal glands are
plainly visible in the tail and end posteriorly in three separate ampullae.
The unicellular glands themselves are arranged in a loose tandem in front
of the anus, the foremost being removed a distance from the anus several
times as great as the corresponding body diameter.
Lateral fields: glandular cells. The lateral fields are usually about half
as wide as the body, and contain large, granular, ellipsoidal, glandular cells
about one-third as wide as the body and emptying on the surface of the
cuticle by means of exceedingly minute pores. These large glandular cells
are situated from point to point throughout the length of the body, the
distance between them being from one to four times as great as the width
of the body
Renette. The renette cell is invariably situated behind the neck and
empties by means of a long, narrow, faintly visible duct. The narrow in-
MARIONEIyl/A 357
-conspicuous ampulla is situated nearly opposite the base of the pharynx.
The obscure excretory pore is invariably located in the lip-region opposite the
row of cephalic setae. The presence of the duct and ampulla usually causes
the pharynx as well as the portion of the oesophagus near the head to be a
little nearer to the dorsal side of the body than to the ventral.
Nerve-ring. The nerve-ring is always a rather conspicuous feature. As
a distinct collar it surrounds the oesophagus a trifle obliquely and is of me-
dium size, and has arranged both in front of it and behind it numerous large
nuclei, whose grouping, however, does not appear to be very orderly.
Female organs. The female sexual organs are invariably double and re-
flexed (T). The vulva, though large, is more or less continuous and not
very conspicuous. The well-developed vagina leads inward at right angles
to the ventral surface about two-fifths of the way across the body, and,
though fairly muscular, is not very amply cutinized.
The two straight uteri are of such a size as to contain two or more eggs
at a time, arranged tandem; these latter are thin-shelled, smooth, usually
ellipsoidal or somewhat elongated, and are deposited before segmentation
begins. The reflexed ovaries are broad, or of medium width, taper more
or less, and extend one-half to two-thirds the distance back to the vulva.
The ova in them are arranged single file except near the blind end, where
they are arranged irregularly.
Male organs. -The tail of the male is like that of the female except that
it is usually shorter and more pronounced in its features, especially in species
lacking a spinneret. Tn all the species that have been carefully examined
in this respect, namely in the majority of the species, there are two outstretched
testes extending in opposite directions, the anterior one ending a neck -length
or more behind the cardia, the other near the beginning of the posterior
fourth of the body. The two equal spicula are invariably arcuate, and
occasionally strongly so. At their widest part they are one-sixth to one-
eighth as wide as the corresponding portion of the body. They are from
one and one-fourth to two times as long as the anal body diameter, and
when viewed in profile their proximal ends appear to lie opposite to or slightly
dorsad from the body axis, very rarely ventrad. The proximal ends are
almost always very slightly cephalated by expansion, but they are some-
times faintly cephalated by constriction or by contraction. They are some-
what slender, of rather uniform width, and rather blunt at the free end,
where they sometimes terminate in a simple or denticulate crochet. The
gubernaculum, placed at right angles to the distal parts in the spicula, though
sometimes of uniform width, usually tapers internally to a blunt or acute
point, which lies opposite to or dorsad from the body diameter. From
this apophysis muscles lead fore and aft to the dorsal body wall. The por-
tion of the gubernaculum applied to the spicula is one-sixth to one-eighth
as long as these latter.
Supplementary organs. Invariably two large, ventral, pre-anal supple-
mentary organs are present, though in a few species they are more or less
vestigial. They are placed in front of the anus in such fashion that the
posterior one is about as far in front of the anus as the spinneret is behind
it, and the anterior one about as far in front of the posterior as this latter
is in front of the anus. There is, however, some variation in the situation
of this pair of supplementary organs in the different species. Nearly al-
ways the posterior supplement is a little smaller than the anterior, some-
358 MARIONEIXA
times markedly so. When well-developed, these organs consist of highly
refractive elements, both external and internal, which are very striking in
their appearance. To a considerable extent these supplements can be pro-
truded and withdrawn. When protruded they are very prominent. When
withdrawn they may leave the ventral contour comparatively even; and
yet, even when withdrawn, they are hardly less conspicuous than when
protruded, owing to their highly refractive character. The most striking
internal elements are two in number to each supplement, extending, one
forward and the other backward, and may appropriately be termed "levers'*
These levers are somewhat finger-shaped pieces of cutinized material that
serve for the attachment of muscles. They usually taper but little, and
their internal extremities are invariably blunt. The two levers of a given
supplement are usually practically equal in size. When the supplement
is at rest, the levers lie near the ventral side of the body and parallel to it.
In such circumstances the exterior portion of the organ protrudes only slightly;
but when the free inner ends of the levers are drawn inward so that they lie
at an angle with the ventral surface, sometimes as great an angle as forty-
five degrees, the external portions of the supplements are protruded. The
external portion of each organ has the form of a laterally compressed cup,
or trough, whose profile is exteriorly flat, or more often slightly concave,
and interiorly more or less semi-circular. While the depth of the organ may
sometimes equal its width, often it is less, and sometimes only one-half or
one-third as great. Those species showing the maximum development of
the supplementary organs present cases where the depth of the organ is
one-fourth as great as the corresponding diameter of the body. In one species
the supplementary organs are asymmetrical, the anterior lever or anchor
having become vestigial, and the anterior portion of the cup or trough having
diminished relatively in size, so that the contour of the longitudinal section
of the organ is triangular rather than semicircular. By means of a duct
each supplementary organ is connected internally and forward with a large
glandular cell, as in Bolbella.
Setae on the male. Just in front of the anus on the male there are usually
to be found a few minute setae, either ventral or subventral in position.
They are very short and very inconspicuous. There may be a single one
at the anus; more often there are one or two subventral ones on each side
Occasionally there are two rows extending to near the posterior supplement.
These setae are arcuate, acute, and when two are present on each side of
the anus, one of the pair is usually located immediately behind the other
and is of smaller size. No other papillae or setae have been observed on
the tail end of the male. There is no bursa.
Habitat. The genus Marionella has hitherto been supposed to be of rather
small size. It is in reality large, and is widespread in the various oceans.
While the individuals of a given species may not be numerous, or very wide-
spread, the number of specific forms observed is yearly augmenting. The
two sexes are about equally common.
The genus is most nearly related structurally to Bolbella, Symplocostoma,
Thoonchus and Catalaimus.
Marionella spectabilis (Marion) is still retained as the type species.
GREEFFIELLA'
(Trichoderma Greeff, 1869; not Trichoderma Steph. 1835)
CONTRIBUTIONS TO A SCIENCE OF NEMATOLOGV, XII
BY N. A. COBB
United States Department of Agriculture
In 1869, Greeff described an externally peculiar and very interesting
small animal form under the name Trichoderma. Though it proves
in the end to be internally a typical nema, it is only after many years
that the fact becomes fully established. The minute size of the species
and the fact that the setose cuticle obscures the internal organs, taken
together, have delayed a fuller understanding of the internal anatomy.
Opportunity has occurred to reexamine a species of this genus in a
living condition, and the results are presented herewith. They serve
to establish the view that the genus comprises typical nemas pre-
senting striking relationships to Desmoscolex. Greeff 's original
discovery is commemorated by renaming the genus Greeffiella.
G. oxycaudata (Greeff) is retained as the type species.
Greeffiella, nom. nov.
Trichoderma Greeff, Arch. f. Naturg., Berlin, v. 35, bd. 1, 1869. Not
Trichoderma Steph., 1835, or Swains., 1839.
1-5 10.4 13. 56. 70. .
Greeffiella dasyura n. sp. 3. 4 $.(>, 13. 15. " 9.s " The thin layers
of the transparent, colorless, hairy cuticle are traversed by about fifty-six
plain transverse annules, easy of resolution, which are not materially altered
on the lateral fields. The number of annules corresponds with the number
of encircling rows of somatic setae. While there are no wings opposite the
lateral fields, wing spaces are faintly indicated by a slight spareness, or absence,
of setae near the lateral lines ; this however is a faint feature extending only
from the neck to the anus, and is perhaps more pronounced on the female than
on the male. The contour of the body is crenate, especially toward the
head. There appear to be toward thirty small unequal cephalic setae on the
front of the head, disposed, apparently, in two closely approximated cir-
clets. These setae average to be about as long as the head is wide and are
apparently too numerous and crowded to permit of any exact order ; however,
about twelve of the anterior ones are spread outward and forward while
all the others spread out more or less backward. These somewhat curved,
rather slender, tapering acute, somewhat stiff cephalic setae are of the same
1 This paper was published in the Journal of the Washington Academy of Sciences,
vol. 12, no. 13, pp. 229-303 (issued July 19, 1922). It is printed with changed pagina-
tion but without other material alteration.
360
GREEFFIELLA
set mi
X1000
character as the great bulk of the somatic setae. Among the somatic setae how-
ever are a few relatively large, hollow, open bristles of another character, resem-
bling the locomotor bristles found on Draconema, Desmoscolex, etc. For in-
stance, on the third and eighth
annule of the female, and on the
second and seventh annule of the
male, that is to say in the rows of
setae on these annules, there occur
subdorsal (on the second and third
annules) and dorsally submedian
(on the seventh and eighth annules)
pairs of spreading tubular open-
mouthed setae, or bristles, a little
longer than the regular somatic
setae. These special setae have
extra large bases and are probably
connected with glands. The rows
of ordinary cervical setae have a
fringe of shorter setae in their
midst. As before remarked, the
somatic setae are in fifty-six or
fifty-seven transverse rows, ex-
cluding those on the head, but
counting the finely pilose region
in front of the spinneret as two
annules. See Fig. 3. Passing back-
ward, the setae grow steadily longer
from the head to the tail ; the poste-
rior ones are about one and one-half
times as long as the spinneret,
while the anterior ones are some-
what shorter than the spinneret.
Back as far as the beginning of the
intestine, the rows of setae present
minute toothed fringes, accentu-
ating the annules. The conoid neck
ends in a rounded, somewhat
flattish hemispheroidal head, set off by a narrow, deep and distinct constric-
tion. The lips are amalgamated and fixed. Nothing is known concerning
the labial papillae. The pharynx is exceedingly minute and easily overlooked,
but is, in fact, a minute, simple, obscure, straight, regular, tubular, closed,
unarmed region about one-sixth as wide as the head and twice as long as wide ;
these measurements include its enclosing pharyngeal tissue. Under ordinary
circumstances there is to be seen here only a closed lumen. Passing back-
ward from the pharynx, the oesophagus for a distance two and one-half times
as great as the width of the head, is cylindroid; however, it widens slightly,
so that it becomes as wide as the head, or one-half as wide as the corresponding
portion of the neck, that is to say that portion of the neck marked by the fifth
circlet of cervical setae. At this point there is a rather faint diminution of
the oesophagus, which continues thence a little narrower, afterward widening
out, and then soon coming to contain granules like those found in the cells of
the intestine. This latter appears to begin about opposite the tenth row of
setae. There are two narrow ducts, one emptying into the posterior part of
Fig. 1. Head end of Greeffiella dasyura. The
setae on several annules immediately behind the
head have been omitted so as to show internal
details more clearly, amph, amphid ; an, annule ;
int, location of the beginning of the intestine
(see also Fig. 2.) ; lum oe, lumen of the oesopha-
gus; oe, oesophagus; or, mouth opening; ph,
pharynx; set cph, cephalic setae, a number of
which are omitted ; set som maj, one of the larger
somatic setae; set som min, one of the smaller
somatic setae; set tb, tubular setae.
361
srt cp/i
each amphid; these ducts can be followed backward to near the pigmented
bodies soon to be mentioned, and possibly may be connected with them. The
external expressions of the amphids, each of which is symmetrical to two
lines, are of unequal diameter, without central markings, and are located
toward the front of the head; they are about as wide as the corresponding
portion of the head, each being about twice as wide as long. The two
greenish pigmented bodies mentioned above (org?, Fig. 2), are olive green in
color and present a nucleus in the midst
of a colorless spherical cell ( ?) as wide
as one of the cuticular annules in the
immediate vicinity. These bodies are
naturally rather difficult to observe
on account of the hairy nature of the
cuticle through which they are viewed ;
they are located well outside the in-
testine, one on each side of the body,
somewhat behind the base of the neck.
The broad cardiac constriction lies
opposite the eighth to tenth rows of
setae, and is about as wide as the
distance between these rows. The
thick-walled intestine presents a faint
lumen and is composed of cells of
such a size that about twelve occur
in each cross section. In the male, at
least, the intestine gradually becomes
one-half as wide as the body. There
is no pre-rectum. From the minute
anus, whose anterior lip is somewhat
elevated, the inconspicuous rectum
extends inward at right angles to the
ventral surface half way across the
body; the intestine itself extends past
the anus. No anal muscles are to be
seen. There are two kinds of colorless
granules of variable size to be seen in
the cells of the intestine; the largest
of these have a diameter equal to the
distance between the rows of somatic
setae; the finest of the granules are
exceedingly fine. The granules are not
so arranged as to give rise to a tessel-
lated effect. The more or less convex-conoid tail tapers from in front of the
anus to the tubular spinneret, which comprises two-sevenths of the whole
tail. This tubular spinneret is about as wide as one of the spicules of the
male; it is a simple truncate affair which tapers but very little. A marked
peculiarity of the posterior extremity of the nema is the existence of numerous
minute setae ; for a distance equal to the length of the spinneret the setae on
the portion of the tail immediately in front of the spinneret are very much
reduced and more numerous. The spherical caudal glands are located behind
the anus in the anterior fourth of the tail and empty through separate ducts;
each is about one-fifth as wide as the corresponding portion of the tail, or as
wide as one of the somatic annules opposite. Only two nuclei were seen in
dint
X100
grnmajint
Fig. 2. Internal anatomy of the head
end of Greeffiella dasyura. Lettering as in
Fig. 1. d int, one of the cells of the
intestine; crd col, cardiac collum; del amph,
duct connecting with the amphidial pore;
grn maj int, one of the larger intestinal
granules; grn min int, smaller intestinal
granules; int, intestine; lum int, lumen
of the intestine; nr, nerve ring; org ?,
organ of doubtful significance; set tb,
tubular seta.
362
GREEFFIELLA
connection with these glands, and these were located in the vicinity of the anus,
their number indicating that the number of caudal glands may be less than
the usual three. The excretory pore lies near the nerve-ring opposite the sixth
annule in the male and opposite the seventh in the female ; its spherical ampulla
is one-fourth as wide as the corresponding portion of the neck. The nerve-
ring surrounds the oesophagus somewhat obliquely where it first diminishes
in diameter somewhat behind the middle. In the dorsal side of the neck,
opposite the 9-14 rows of setae there are some relatively large organs,
probably two or more finely granular cells. From the somewhat inconspicu-
ous, small, elevated vulva, which is surrounded by minute setae, the small,
weak, non-cutinized, tubular vagina leads inward at right angles to the
ventral surface about one-third the distance across the body. Little is known
concerning the double symmetrically reflexed female sexual organs.
1.5 6.6 10.6 'M
set m.
set min
. set m
X1000
>0.34.
set tit
3.2 7.7/ 11. 18. -Ml.
The slightly arcuate, irregularly
conoid, faintly sigmoid tail of the
male, on the whole, rather re-
sembles that of his mate. The
two equal, straight, very slender,
uniform, acute, colorless spicula,
which are slightly cephalated by
expansion, are about one and one-
fourth times as long as the anal
body diameter. If swung around
behind the anus, they would just
about reach to the base of the
Fig. 3. Tail end of Greeffiella dasyma. Let- spinneret; they are about twice as
tering as in Figs. 1 and 2. ann pnlt, penultimate wide as the bases of the somatic
annule; ann ult, ultimate annule; spn, spinneret, setae, are a little larger distally
than elsewhere, and are perhaps
winged. No gubernaculum has been seen. On the fifth and eleventh
annules in front of the anus occur ventrally submedian papilla-like organs,
indicated by the presence of minute setae arranged in a cluster about a
nerve ending (?), about ten setae on the fifth annule and a much smaller
number on the eleventh. There are also similar ventrally sublateral bunches
of setae on the annules preceding the large (duplex?) conical one bearing the
spinneret. On the lateral field near the middle of the male, a bunch of minute
setae was observed like those on the fifth annule in front of the anus. The
nature of these special organs, for such they must be, remains in doubt.
It seems quite possible that some of them are male supplementary organs.
The wide cylindrical testis is one-half as wide as the body and is reflexed to
near the proximal ends of the spicula.
Habitat: Found in sponges, Biscayne Bay, Florida, U. S. A., March, 1916.
Male examined and measured in a living condition ; female fixed in Flemming's
solution and soon after examined and measured in water. The form of the
pharynx and oesophagus; the presence of special tubular setae; the structure
of the spinneret, and the relatively small number of annules, seem to indicate
a closer relationship of Greeffiella with Desmoscolex than has been hitherto
imagined. Perhaps Greeffiella should be placed in the same family with
Desmoscolex, Tricoma, etc.
An Amendation
of
HOPLOLAIMUS DADAY 1905 nee auctores
CONTRIBUTIONS TO A SCIENCE OP NEMATOLOGT, XIII
BY N. A. COBB
In 1905 Daday proposed the new genus Hoplolaimus on the basis
of a single female nema from soil in Paraguay.
Hoplolaimus was so imperfectly characterized that numerous
subsequent authors have referred to it a variety of species that seem
certain not to belong to it, in the light of recent discoveries now to be
described.
Hoplolaimus Daday 1905 amend.
Coarsely annuled typical tylenchidae with a prominently set off, lobed
lip-region composed of several annules, and an onchium with more
or less lobed basal bulbs, -f- and -m. Males with
lobed bursa encompassing the tail.
iL _ ^ 8 -I 2 -- _ ~ 56- ~_ ! 8 -_i
H. coronalus n. sp. ?-.* 2 -^~A' ' 3.3 2.4 L
The transparent colorless layers of the naked cuticle
are traversed by plain, transverse striae, all alike,
about three microns apart and easy of resolution, which
are not further resolvable, and which are altered
materially on the lateral fields by the presence of
three longitudinal wings, occupying a space, measured
midway on "the nema, one-third as great as the width
of the body. The optical expression of these wings the right laterai^horci of the
consists of four parallel lines, of which the two outer interesting u^pai'red^pheroi-
are rather distinctly crenate, while the two inner, f d a u r tTa P s hi S\s th a e n bod^
occupying a little less than a third of the wing space, having connections fore and
connect with refractive cuticular alterations of the Se^gSfnffiSLrf
striae, which thus give rise to a rather distinct more ni icronr s acr d os8 nea see ir above 8
or less quadrangular network on the lateral fields.
On the neck the wings become reduced to two. The cuticle, about two and
one-half microns thick, is striated internally as well as externally. As usual,
the annules close to the lip region are somewhat narrower than those farther,
back. From somewhat behind the anus the final striae on the tail of ithyei
female make a gradually smaller angle with the lateral line and finally encircla
the terminus in the lateral plane. Very slightly oblique longitudinal striae,!
due to the attachment of the musculature, are visiblenin: mast regions of- the
body. There are no dermal appendages and: no '.series /of pores-has beea!
seen in the cuticle, but there is an unpaired lateral organ a bexfch the female
and male. (See Fig. 1.) The cylindroid neck becoihes coaVex-conoid at the
rounded head, which is continuous ; ancj presents a central mouth, opening oiily>
very slightly depressed. The lip region however is a flat/ blimtisk; cone, about
twenty microns broad by eight mieroos Jiighjlit !&>aefc apart ;by a v&ry\distincb
363
364
HOPLOLAIMUS
M3S-
reglb.
kblblG)
,
WMoii Wsubnmh x500
Fid. 2. An oblique
dcrso-ventral view of
head of H. coronatus n.
sp. The quadrangular
nature of the cap is
shown in the front view,
above.
constriction so that it constitutes a sort of cap on the
front of the head. This somewhat quadrate cap is longitudi-
nally faintly six-lobed and each lobe is again longitudinally
as well as transversely subdivided. See Fig. 2. The lip
region of the male is like that of the female except that
it is more nearly hemispheroid, that is, relatively higher
and slightly larger. There is a rather robust six-ribbed,
yellowish, dome-like structure as the framework of the lip-
region, through it is obscured by the nature of the cuticular
covering. This framework extends a little back of the
labial constriction and its yellow color becomes more evi-
dent here. See Fig. 3. Needless to say, therefore, the
amalgamated lips are fixed, and shut closely around the
anterior extremity of the onchium. Whether the lip region
is innervated remains unknown, but no innervations have
been seen. The tylenchoid pharynx is of a very robust na-
ture and reminiscent of that of Nemonchus. The base of
the onchium, or spear, thirteen microns wide by ten high, is
very distinctly three bulbed and is about one-fifth as wide as
the corresponding portion of the head. Each of the three
bulbs is anteriorly somewhat li lobed," presenting sometimes
two and sometimes three rather distinct forward pointing
knobs. Owing to its index of refraction this lobed base of
the onchium, as well as the "hilt," are almost totally invisible in balsam mounts;
while the acute tapering anterior part remains distinctly visible, another
evidence of the two-fold character (and origin) of the tylenchoid onchium.
The posterior attachment of the musculature comprising the ellipsoidal
pharyngeal bulb, which is one-half as wide as the head, is not only to the front
portion of the bulbs of the onchium but also to their posterior surfaces. The
hilt is about half as wide as the bulbous base; the anterior end of the spear is
blunt, and the lumen relatively unusually narrow; all which makes the spear
an unusually substantial structure, capable of puncturing tissues offering con-
siderable resistance. In harmony with this, the ellipsoidal to'obpyriform
spear guide is of strong construction, consisting in part of six outwardly bowed
elastic elements surrounding the anterior third of the spear and springing back-
ward from the base of the cutinized lip region. (Figs. 2 and 3.) This six-fold
spear guide has a variable length and width, its form changing with the atti-
tude of the spear; when at rest, with a length of fourteen microns, its width
is about eight microns, that is, it is about one-third as wide as the correspond-
ing portion of the head. In addition to this spear guide the cutinized lip-
region fits closely around the anterior portion of the spear for a considerable
distance. Both the spear and the spear guide appear to present traces
of transverse striation corresponding in fineness with the minute subdivisions
of the annules sometimes visible in the subcuticle. The two parts of the
spear are rather distinctly set off from each other by a very fine transverse
junction mark, as in many Tylenchi. No amphids, deirids or phasmids have
been seen. There are no eyespots. The oesophagus is tylenchoid, presenting
however, as already indicated, a rather distinct pharyngeal bulb, something
rather uncommon in the Tylenchidae. The spherical or oblate median oeso-
phageal bulb is half as wide as the corresponding portion of the neck, and is set
off both fore and aft from the remaining narrow portions of the oesophagus,
very abruptly behind and rather abruptly in front. Behind the median bulb
the narrow oesophagus gradually enlarges to form a rather obscure posterior
HOPLOLAIMUS 365
long-clavate swelling which at its widest part is one-fourth as wide as the base of
the neck. It is however natural to imagine the swollen salivary glands to be
joined with this inconspicuous posterior portion of the oesophagus and thus at
first to get an idea that the posterior part of the oesophagus comprises a wide
clavate swelling, three-fourths as wide as the base of the neck. We may say
therefore that the oesophagus behind the pharynx is about one-seventh, at the
nerve-ring also about one-seventh, and finally about one-fourth as wide as the
corresponding portion of the neck. The lining of the oesophagus is a distinct
feature arteriorly and consists of a narrow highly refractive tube; posteriorly
the lining is inconspicuous. The musculature is fine and colorless. There are
three salivary glands clustered opposite the posterior two-fifths of the oesopha-
gus. One of these cells comprises the anterior portion of the cluster, while the
other two may lie more or less opposite each other as the posterior part.
The salivary glands are very well developed, and two of them,
submedian, empty through ducts into the base of the valve of
the median bulb, while the third, the dorsal, passes forward and
empties into the dorsal side of the oesophageal lumen not far
behind the base of the onchium. At the mouth of each duct
a faint ampulla is usually visible. The median oesophageal
bulb presents a spheroidal, simple, strongly refractive
valve one-sixth as wide as the bulb itself. There is no
distinct cardia. The thick-walled intestine, which presents
a distinct refractive lumen, is not set off from the oesoph-
agus by a cardiac collum, the change from oesophagus to
intestine being gradual. The intestine has its cells closely
packed with granules of variable size, the largest being
one-twelfth to one-sixteenth as wide as the body. These
colorless, non-birefringent, spherical granules gradually de-
crease in number in the cardiac region and cease altogether
opposite the posterior portion of the salivary glands; they are
sometimes so arranged as to give rise to a tessellated effect. er f, IG vi g W H c
The intestine somewhat gradually becomes four-fifths as wide natus n sp Bei ow>
as the body, and is composed of cells of such a size that two to a semi-contour of the
three are presented in each cross section. The cells of the body in the same
intestine are so closely packed with granules as to make it JJJ ^f n g win *
difficult to examine successfully in living specimens details
of the anatomy of adjacent organs. The exceedingly small
anus and the rectum are very inconspicuous. There is no pre-rectum. The tail
is of an elongate hemi spheroid form, very broad and rounded at the extremity,
and symmetrical. There is no spinneret and there are no caudal glands.
Measured at the latitude of the nerve-ring, the lateral chords are as wide as the
cuticle is thick, or wider; somewhat farther back, they are about one-third as
wide as the body. They contain scattered colorless refractive spherical gran-
ules of variable size, considerably smaller than those of the intestine. Behind
the base of the neck, at a distance about equal to the diameter of the body,
there is a cell which presses the intestine well to one side. This cell is about
as long as wide but not spheroidal. It is finely granular, one-half as wide as
the body, and seems very probably to be connected with the renette. The
excretory pore, which is opposite the base of the neck, is rather distinctly to be
seen, though of. small size. It lies between two annules, and the nearer stria-
tion may bend a little to one side for it. The renette duct leads inward and to
the right alorg the right lateral chord. From the somewhat depressed, rather
large and rather conspicuous vulva, which is a transverse slit two-fifths as long
366
HOPLOLAIMUS
as the body is wide, the strongly cutinized medium sized vagina extends inward
at right angles to the ventral surface half the way across the body. From to-
ward the ends of the valvular open-
ing four muscles pass obliquely to
the ventrally submedian regions
of the body, two forward and
two backward, two to the right
and two to the left. Furthermore
there are two transverse valvular
muscles attached near the ends
of the opening and fanning out
to the lateral parts of the body
wall, one right and the other
left, each partially encircling the
intestine. Each of the two out-
stretched uteri, about two body-
widths long and about one-fourth
as wide as the body, at its distal
extremity presents a spermatheca
three-fourths as wide as the body,
sometimes containing what appear
to be toward one hundred sausage
shaped sperm cells each some-
times having a bunch of chromo-
somes at ode end . These sperma -
theca are located at a distance
from the vulva two or three times
as great as the diameter of the body. In the late autumn they are a very uni-
form feature of the adult females which have deposited no, or very few, eggs.
As thus far seen, the slender outstretched ovaries are about one-fourth as wide
as the body; both lie on the left side. They are narrow and somewhat cylin-
droid and contain one hundred or more ova arranged somewhat irregularly.
The male is like the female in form. The
Fio. 4. Lateral and ventral views of the tail end of the
male of Hoplolaimus coronalvs n. sp. Treated with potas-
sium hydrate to obliterate non-cutinized structures.
3.4 8.9 _ 13. M 97.3
spicula are colorless. A portion of the - 2~ s ^~3~2. T5~ ~~~^2~2 "
gubernaculum lies ventrad. (telamon of "
Hall). See Fig. 4. There are no preanal ventral supplementary male
organs, and no ribs occur in the bursa. The striae of the bursa on the
ventral side are less distinct near the ventral line. The terminal lobe of
the bursa appears destitute of striation; if any striae are present they
must be exceedingly fine. The vas deferens appears to be about one-half as
wide as the body. The narrow cylindroid testis tapers a little, and at the blind
end is only one-fourth as wide as the body. The granular sperm cells seen in
the vas deferens are about one-tenth as wide as the body; the spermatocytes,
farther forward, one-eighth.
Habitat: Found in soil immediately about a Mermis "nest," (Agamermis
decaudatd), Four Mile Run, Falls Church, Va., U.S.A. Nov., 1922.
The movements of this nema are very slow. The limber body readily takes
on sharp sigmoid curves and is sometimes seen coiled; in fact the males can
coil rather closely. From this amended characterization it seems evident
the Hoplolaimus Daday (not of other authors) is a rather clearly marked
genus. A close relative of Hoplolaimus is Dolichodorus Cobb 1914.
NOTES ON PARATYLENCHUS, A GENUS OF NEMAS
BY N. A. COBB
Contributions to a Si ience of Nematology, XIV.
The following paragraphs contain new information with regard to
the lip region, vestibule, spear guide, structure of the spear, median
oesophageal bulb, salivary glands, deirids (cervical papillae), renette,
eggs and their deposition, and gonism of Paratylenchus Micoletsky.
. - . fl
Paratylenchus nanus n. sp. 3.7 4.3 / 4,j 4.2 2. The trans-
parent, colorless, naked cuticle, about 1.5 microns thick, is traversed by plain,
transverse striae, 2.0 microns apart except near the extremities, all alike and
fairly easy of resolution, which are materially altered on the lateral fields by
the presence of wing regions, about one-seventh as wide as the body, beginning
on the neck and ending on the tail. The optical expression of the wings on
living specimens usually consists in four parallel longitudinal lines on each
lateral field, the two outer of which are fainter than the two inner. Very
slightly oblique longitudinal striae of the subcuticle, all alike, due to the
attachment of the musculature, are rather easily to be seen in nearly all regions
of the body. The contour of the body is crenate or very faintly serrate-
crenate. There are no dermal appendages and there are no series of pores to
be seen in the cuticle. On the neck opposite the excretory pore, lat. 22.2,*
there is a papilla on each lateral line, and, leading inward, ventrad and slightly
backward from the middle of each papilla is an obscurely sinuous element
connecting with the nervous system. These organs are believed to be deirids.
The neck, which is cylindroid posteriorly, and to a considerable extent also
anteriorly, becomes decidedly convex-conoid farther forward, and ends in a
rounded or subtruncate, continuous head compassing about thirty annules
of the cuticle, which presents a somewhat depressed, very minute, central
mouth opening, closely surrounded by six equal, exceedingly minute lips. The
truncation of the head occurs at the lip region, which has at this point, that is
at the anterior extremity of the nema, a width of about two microns. The lip
* The Word "Latitude" in Descriptive Nematology. I have lately come to use the
word "latitude" in a conventional sense in dealing with nema anatomy, and find it so
useful as to lead to this attempt more accurately to define the word as thus used.
The meaning of latitude in this connection arises from geographical usage, but in
nematology the term applies to a transverse plane or section of the organism, and not to
a circle on the surface only, as in geography, and it has not seemed desirable to have two
sorts of latitude, such as north and south.
One hundred degrees of latitude is assumed, with zero at the anterior extremity of
the organism. Thus an element of the organism in latitude 50 would be at the middle;
and in latitude 100 at the end of the tail. The terms can be abbreviated. Thus: lat. 60.
In the case of nemas, which are so nearly round in cross section, a similar use of the
word "longitude" sometimes becomes useful, the ventral line being taken as zero.
The conventional use of the words latitude and longitude in this way is more or less
"logical", and very easily acquired, and, according to my experience, is a decided saving
in time and space, and has the merit of definiteness, as well as brevity.
368 PARATYLENCHUS
region is supported by a faintly visible six-ribbed, refractive, somewhat dome-
shaped, cuticular framework, six to seven microns across at the base, and
about two-thirds as "high" as it is wide. The more or less immobile lips are
usually closed.
There is a small combined vestibule and spear guide, about as wide as the lip
region and some ten microns long, more or less visible on account of the refrac-
tive nature of its elements. This portion of the labial structure has for one of
its main functions the guidance of the spear when in action. The vestibular
part is about four microns deep and varies somewhat in diameter according to
the attitude of the lips and spear. Leading backward from the base of the
vestibule there is a symmetrical set of outwardly bowed, somewhat flexible,
rather slender, longitudinal elements constituting the main portion of the spear
guide. The relatively very robust spear is about twice as long as the base of
the head is wide. It ends posteriorly in a distinctly three-lobed expansion
toward one-third as wide as the base of the head, the dorsal lobe being slightly
farthest back, and, sometimes at least, presenting a dorso-posterior condyle.
It is somewhat behind, and in a line with, the axil of the dorsal lobe that the
dorsal salivary gland empties into the oesophageal lumen. The spear often tapers
more or less regularly throughout its length; nevertheless there is a distinct
basal part, comprising about two-fifths of the whole, set off by a minute but
distinct junction mark, and averaging about one-sixth as wide as the corre-
sponding portion of the head. At its distal end the spear is exceedingly finely
pointed. Well developed muscles for the protrusion of the spear are readily
seen and often lie rather close to the spear, not forming any very marked
swelling when at rest. Anteriorly there are six of these muscles, one passing
to each sector of the labial framework.
No amphids have been seen. There are no eyespots.
The oesophagus is tylenchoid and presents a very definite, somewhat pine-
apple-shaped, non-muscular, valueless cardiac swelling, half as wide as the base
of the neck. The very long, large, rather ob-clavate, median swelling, which is
two-thirds as wide as the middle of the neck, is set off abruptly behind, but is
decurrent in front and reaches to, and somewhat includes, the base of the
onchium; in its posterior part it presents a well-developed, elongated-fusiform,
triplex valve, occupying one-third of the diameter, to which are attached the
usual radial muscles for the opening of the valve in the act of swallowing. An
interesting peculiarity of the median swelling is that the contained robust
tubular oesophageal lining, which is disposed in a single loop or coil when at rest,
takes on this attitude without much disturbance to the evenness of the contour of the
swelling itself, thus showing the "clavate swelling" to be a distinctly two-fold
affair, partly (posteriorly) muscular, and partly (dorsally throughout) gland-
ular, and with the two tissues so little connected that the glandular part is
comparatively separate and responds but little to the movements of the tubu-
lar lining. Ordinarily one would expect the anterior narrower part of such a
long median swelling to curve or coil along with the lining. Though the
limits of the true median bulb (not the clavate swelling but the included
median bulb more properly speaking), are of ten somewhat indefinite anteriorly,
it may properly be described as ellipsoidal, two-thirds as wide as the neck and
two and one-half times as long as wide; in other words the entity of the median
muscular bulb is not entirely lost. Behind the pharynx the oesophagus is one-
sixth, at the nerve ring only about one-tenth, in front of the cardiac swelling
about one-eighth, and finally one-half, as wide as the corresponding portion of
the neck. The lining of the oesophagus is tubular and narrow, and distinct
except in the posterior glandular bulb, most distinct in the clavate swelling.
There are well developed salivary glands. The nucleus of one of these organs
may be seen in the dorsal sector of the cardiac swelling, as already described,
PAFATYLENCHUS
369
dorsad and occupying the major part of it, and emptying into the oesoph-
rl lumen near the onchium. It is doubtful if salivary secretion passes
into the base of the fusiform median valve, though there seem to be two
subordinate nuclei in the cardiac swelling.
There is no cardia. The thick walled intestine, set off by a rather
faint cardiac collum one-half as wide as the base of the neck, presents a
faint, though fairly capacious lumen. It is composed of cells of such a size
that probably only about two are presented in each cross section. It becomes
at once two-thirds as wide as the body. From the very inconspicuous, con-
tinuous anus, the rectum, which is also very inconspicuous, extends inward
and forward. There is no distinct pre-rectum. The numerous, colorless
granules found in the cells of the intestine, the largest of which are about one-
tenth as wide as the body, namely about two microns in diameter, are not so
arranged as to give rise to a tessellated effect. Sometimes the cells throughout
the intestine are uniformly filled with granules ; more often the granules are
absent here and there, so as to create a "segmented" effect.
The tail, which compasses about twenty annules of the cuticle, is conoid,
subarcuate, and tapers from in front of the anus to the rather blunt, or some-
times subacute, unarmed, symmetrical terminus. There is no spinneret.
There are no caudal glands and there are no caudal setae.
Apparently the lateral chords are about one-
third as wide as the body. The rather prominent
excretory pore is located just behind the nerve ring
and the excretory duct can be followed inward and
backward along the right lateral chord at least as
far as the middle of the body.
The nerve ring is oblique, of medium size and
accompanied, fore and aft, by numerous nerve cells,
some of which lie as far forward as opposite the
middle of the median oesophageal swelling.
The single female sexual organ is outstretched
forward. From the unusually large, depressed and
very conspicuous vulva, the vagina, which is large,
extends inward obliquely forward, three-fourths the
distance across the body. Its walls are rather
strongly cutinized. The larger anterior lip of the
vulva may be slightly elevated. The body of the
nema decreases a little in diameter rather suddenly
at the vulva and tapers more rapidly thence back-
ward. The thin-shelled, smooth, elongated egg is
nearly thrice as long as the body is wide and meas-
ures about 60 x 20 microns. Only one egg occurs in
the uterus at a time. A prolate compact mass of
sperm cells, often comprising some two to five hun-
dred minute, spherical, refractive elements, occurs
regularly in the uterus of newly adult females; this
sperm mass is often two-thirds to three-fourths as
wide as the body. From the formation and size of
the sperm cells it is concluded that the species is
syngonic. No males have been seen among about
fifty females, many gravid, from two North Ameri-
can regions. The medium sized ovary is usually
cylindroid posteriorly, and tapers anteriorly; it aver-
ages to be about one-third as wide as the body.
Toward fifty ova, arranged for the most part sin-
gle file, are to be seen in the ovary. There is prac-
tically no post-vulvar rudiment of a sexual organ.
grnmt;
1. Anterior part of a
Paratylenchus nanus.
370 PABATYLENCHUS
There are two or three somewhat ellipsoidal organs, half as wide as the body,
about two-thirds as wide as long, located just behind the base of the neck, and
closely associated with the beginning of the intestine. These regularly darken
in Flemming's solution and are as yet of unknown significance.
Habitat: Found in soil about the roots of grasses, Devil's Lake, North
Dakota, April, 1915;' and Four Mile Run, Falls Church, Va., August, 1922.
Flemming's solution to glycerine jelly. In many respects this species closely
resembles Tylenchus macrophallus de Man, but differs in the following particu-
lars; the spear is somewhat longer and possibly somewhat more robust; the
striation is coarser; the body is wider; the tail of nanus compasses twenty
annules while that of macrophallus appears to compass about fifty; opposite the
spear in nanus there are about twenty-five to thirty annules, while in macro-
phallus there appear to be about forty. Should opportunity occur it would
perhaps be advisable to re-examine the median oesophageal region of macro-
phallus. For the present at least it seems best, unless the undiscovered male
of nanus should prove to be extraordinarily like the male of macrophallus, to
regard the two species as distinct. Paratylenchus is related to the very well-
defined genus Iota, a genus whose numerous representatives typically are
minute, very short, very broad, coarsely annuled, rather inflexible nemas
found in acid soils, and having the single outstretched female sexual organ
emptying through a vulva located very close to the minute, inconspicuous anus
and often possessing external coarse retrorse cuticular elements, ridges, scales,
spines, fringes, etc., according to the species. There is a number of as yet
unpublished species of which it is not easy to make a satisfactory assign-
ment as between Iota and Paratylenchus. The unknown males of nanus, if
such exist, may be expected to throw more light on the generic relationships.
P. nanus may be synonymous with P. bukowinensis Micoletzky, 1922.
.". .*: , A 1 - . ~ 8 >. . 9 ?- . 0>36 ..
4- 8 5^i '", 5.6 5.1 3.1 are the measurements of a living specimen
of P. nanus under slight pressure and therefore a little flattened, and further-
more showing a neck-length unaltered by fixation and preservation.
24. 28. __ 34. Y 92.6<?>
Paratylenchus ancepsn. sp. 5-3 5.3 /5.J 4.6 3.6 ' " P. anceps so
closely resembles P. nanus that only the differences need be here noted. The
striae are one micron apart. The optical expression of the wings is a pair of
refractive parallel lines whose distance apart is about equal to the width of
two annules of the cuticle. The conoid neck becomes convex-conoid at the
head, at the front of which the lip region is about four microns wide. The spear
guide is six microns long, and the spear about half as long as the neck, the
long slender anterior part comprising three-fourths or four-fifths of the whole.
The three-lobed, flattish basal bulb of the spear is about one-fourth as wide as
the corresponding portion of the neck, that is about four microns wide. The
somewhat elongated-pyriform or pineapple-shaped posterior bulb is three-
fifths as wide as the base of the neck. The deirids are near the base of the
neck. The tail is slightly conoid to the broad, rounded terminus, which is
half as wide as the base of the tail. The vulva was about to appear at the
same relative position as in P. nanus. In all other respects almost precisely
as in P. nanus.
Habitat: Roots of Umbellularia californica, Riverside, California, 1912.
BIOLOGICAL RELATIONSHIPS OF THE MATHEMATI-
CAL SERIES 1,2, 4, ETC.
WITH A DESCRIPTION OP A NEW NEMA, TYLENCHUS CANCELLATUS
Contributions to a Science of Nematology. XV
BY N. A. COBB
The behavior of the components of matter, e.g., in chemical reactions,
appears to compel discontinuous variation in the evolution of organisms.
Organic evolution has been thought continuous, but mutation now suggests
that it is discontinuous. Must it not necessarily be discontinuous 1 from the
very ' nature of the composition of matter? Morphological changes in
organisms originate in chemical changes in the matter of which they are
composed. Now, a chemical change is one that either takes place or does
not take place; nothing intermediate is known. Hence it seems that the
fundamental changes in the evolution of organisms, so far as we can conceive
at present, i.e., chemical changes, must be saltatory. But we cannot con-
ceive of the greater and obvious (visible) changes, except as summations of
these minute changes. The visible changes then must per force be con-
sidered of the same character as that of their components, i.e., all visible
evolutionary changes in organisms must be of a saltatory nature.
The mathematics of the morphology of organic evolution may therefore
be considered as, at least mainly, discontinuous, -arithmetical.
The material basis of life is discontinuous, but is the only known form of
matter so organized as to grow and multiply by assimilation; in this lies the
fundamental difference between living objects and all others; not a mathe-
matical difference.
Matter is dual r or, less abstractly, there exists in matter an exceedingly
widespread, probably universal, "bipolarity", exemplified, therefore, in organ-
isms. The universality of "bipolarity" is more or less understood and
generally admitted. Its universality might be assumed to prove, and at
least very strongly suggests, its necessity. Assuming its necessity, this
bipolarity determines that cells, as well as many of their components, multi-
plying, do so by binary division in a bipolar manner. 2
1 Mathematics. Arithmetic and its derivatives arose through everyday problems
connected with matter, which is discontinuous. The Calculus, mathematics of con-
tinuity, arose through problems like those of astronomy, where the continuity of space
and time impress us most vividly.
Quantity. It may be said we cannot conceive of anything so small that it cannot be
divided, or so large that nothing can be added to it ; but as the two opposite statements
seem just as true, we find ourselves within two limits at each of which we confront some-
thing that must be so, but can't be so. Between these two irrationalities lie quantities
we can handle rationally by mathematics.
2 Thence "fore-and-aftness" and bilateral symmetry in organisms arose (doubtless
modified by gravity). Bilateral symmetry seems the invariable result of the growth of
what we may call, for lack of a better term, "untrammeled protoplasm." When proto-
plasm is "hampered," say by inorganic materials tending to produce other forms of
symmetry as, for instance, through the laws of crystallization then bilaterality may
be more or less masked; otherwise it is manifest. We readily recognize it in nearly all
animals and plants.
.371
372
TYLENCHUS CAXCELLATUS
nirm
tm OP
A fundamental result of this phenomenon is
that organisms thus become exact or modified
expressions of the mathematical series 1, 2, 4, 8,
16, etc., a comparatively unheeded basic fact
worthy of careful attention.
Is it not possible, simply by way of instance,
/ /// / ^ R t ky studying carefully this more or less
MPlMDIttu apparent widespread mathematico-biological ex-
pression, we may reach a clearer understanding
of organic form and of phylogenetic relation-
ships? This question suggests others of deeper
tib Cfd import, since form is largely an expression of the
interplay of internal forces.
Such a query leads to counting and comparing
more carefully the various features of organ-
isms, repetitive and otherwise. Among a multi-
Fig. i.-Femaie T v i- tude of others, such questions
enchus cancettatus n. sp. ., ,, . TITI -j.
The characters are set as this then ariSC! Why IS it
forth in the drawings and , , ,1,1,1 i e
formula. Above, front that both the number ot
view of head, followed by , . i , ,
frm 7 cross-sections arranged transverse annules and the
"'" about opposite the por- , . -. ., , , i
tions of the body sec- number of longitudinal ele-
ments in the cuticle of
many nemas is likely to
suggest some definite
relationship to the geo-
metrical series 1, 2, 4, 8,
16, etc.? The observed
numbers are certainly
cellular expressions of
the 1, 2, 4 series, or vari-
ants, but why and
according to what law
is it that very often
the numbers of ele-
ments met with are not
members of the series
but integers lying
between? Why is
it that chromosome-
counts are suggestive
of this same mathe-
matical concept? And
so on throughout the
range of organic struc-
2 4 -0.5 TOTO tures. Are not these
BIOLOGICAL RELATIONSHIPS OF THE 1, 2, 4, SERIES
373
numbers not only necessarily and definitely, but perhaps somewhat simply,
modified mathematical expressions of the fundamental mathemati co-biologi-
cal phenomena inevitably arising from the fact that cells (as well as some of
their components) divide in accordance with the 1, 2, 4 series?
Variations of the 1, 2, 4 series, as expressed in cell multiplication, say in a
segmenting egg, can be readily diagrammed. (See Fig. 3.) If in such a cell-
division diagram any particular multiplying cell or cells be pictured as halted,
while the others continue to divide, the next step will bring about a variation
from the geometrical series. If the reader will draw a few simple diagrams,
he will find it easy, by such variations, graphically to represent, as existing
at successive early stages in the imagined ontogeny, numbers of cells, say,
from 1 to 10 inclusive, and will see that conceivably this could go on indefi-
nitely, and that therefore any number whatever is a possible biological variation
of the 1, 2, 4 series. But this broadening of the possibilities must not be
allowed to obscure the basic fact that the numbers are neverthe-
less definite mathematical variations of the 1,2,4 series due to the
binary division of cells and their components; -which in turn seems
compulsory owing to the nature of matter itself. Our problem seems
to be: Which of these numerous variations are the more sig-
nificant, and what are their mathematical and biological relationships? 1<
A new triplonch, Tylenchus cancellatus n. sp. (Figs. 1 and 2),
infesting the roots of peonies, will serve, in a very limited way, to
illustrate the foregoing remarks. The figures (Fig. 1) show the
existence, near the head, of sixteen external longitudinal grooves.
Near the middle of the neck this number changes to eighteen by
the splitting, on each side of the nema, of one of the lateral, or
sublateral, elements of the series, so that most of the body presents
18 grooves. Posteriorly this number reduces to 14, 10, then 8.
(Fig. 1.)
This emphasizes the value of pondering the variants of the
1, 2, 4 series. If the numbers of the various elements were con-
fined to the 1, 2, 4 series, they would be less significant, hence less
useful; -e.g., in the interpretation of relationships. But variations
abound, and are, as yet, for the most part unexplained; probably
often highly complex. It is certain, however, that if these variations Peo ^' 2 r ' oot
can be envisaged and understood, they will serve as basic data. ( ^naiis) a nat~
There seems at present no way of stating exactly the upper f^^d 11 !*
limit of the numbers representing these variations of the 1, 2, 4 S^fcaSfc
series as exemplified in an organism. It may in some organisms latus -
reach twenty figures, and therefore the discovery and interpretation of some
of the highest members of this modified geometrical series, as exemplified in
organisms, may be beyond our present compass. Nevertheless, does it not
seem likely that relationships traced in this manner may at .least be set upon
a firmer basis than is the case when data of other sorts are used, or even
upon an entirely new basis?
374
BIOLOGICAL RELATIONSHIPS OF THE 1, 2, 4, SERIES
In a 1, 2, 4 series, let PN be the final product and N its series number,
then P N = 2 N -'; thus, 16 = 2 5 " 1 .
Similarly in a simple organism, at any particular instant in its growth,
let PN have a corresponding value, that is to say, be the number of cells
that either actually exist or would have arisen by the uniform and continuous
dichotomous division of the single primal cell. Such simple and easily
understood organisms occur among the lower forms, and in the early embry-
onic stages of the higher forms, but are rare among the adult stages of the
higher forms, because in these latter some cells lag or cease in their dichotomy,
and because of losses of cells from various causes. Hence, the number of
cells actually present in an organism at any particular instant is likely to be
PN minus a certain number of cells, (X), due to delay or failure in some part
or parts of the dichotomy, or to loss. In this discussion account is taken of
all the cells that have been produced during the growth, whether present
in the organism at the proposed instant or not. This is in order to allow for
worn out or wasted cells; these, possibly vanished, cells are included in PAT
The general 1, 2, 4 equation of an organism thus becomes P N = 2 N-1 X,
1st. Jtaoe
Ectoderm +,
Fig. 3. Diagram of 8 generations of cells produced by dichotomous divisions; as, for
instance, in a segmenting egg. Three general characters of tissue are shown: (1) Sexual,
(2) intestinal and related tissues, (3) ectoderm and related tissues. The sexual and in-
testinal tissues are shown to have lagged behind those of the ectoderm, so that P N in this
instance equals 71.
in which X is a whole number and a function of one or more "p's" of a lower
order, i.e., of the 1, 2, 4 character, or p = 2 n-1 character, in which, of course
p is smaller than P and n is smaller than N. These smaller (ascertainable)
groups are 1 , 2, 4 groups of cells due to the lag or failure of "earlier" generations
than N. (See the loop (X) in Fig. 3.)
PN = 2 N-1 X is a general equation, which, when X = 0, represents a
strictly uniform and continuous mathematical dichotomy, found only in the
lower organisms or in the early embryonic stages of the higher ones.
The various "p's" from PN down to P = 1, (the primal number) become,
therefore, historical insignia, indicating particular generations of cells, and
may be made the basis of a definite and fundamental mathematico-biological
nomenclature applicable to the generations of cells in an organism, and hence
to the organism itself. Applications of the equation are endless.
NEMIC SPERMATOGENESIS
With a suggested discussion of simple organisms, Litobionts
CONTRIBUTIONS TO A SCIENCE OF NEMATOLOGY XVI
BY N. A. COBB
Definitions. Spermatidium: one of a plurality of cells derived
from a spermatid by subdivision; a secondary, tertiary, or quaternary,
etc., spermatid. Spermule: an individual
spermatidium which, after growth and
transformation, is capable of activating
or fertilizing an egg, being not a meta-
morphosed spermatid, but a descendant
of a spermatid, one or more cell-genera-
tions removed.
The definitions will be better under-
stood by at once consulting the illustra-
tions, especially spmtd and spml Figs. 2
and 12.
Spermatogenesis. At the blind end of
the single testis of the nema, Spirina para-
sitifera (Bastian '65) Filipjev (Figs. 1
and 2) , a free living marine species, com-
mon an inch or two deep in sand and
among small stones between the tide
marks of protected coasts on both sides
of the North Atlantic through a wide
range of latitude, the primordial gonic
elements give rise by 14-chromosome
mitotic division to numerous twin cells
(Figs. 2, 14), which arrange themselves
tandem in the testis (Fig. 3) where each
dgng.
Fig. 1. Lateral view of the
head of Spirina parasitifera.
The amphidial nerve, nrv amph,
expands into a sensilla, then
again into a 10-12 celled ganglion
(seen through the lateral chord,
chrd. lat.) joining the nerve-ring,
cor nrv.
Waverly Press, Baltimore, Md., June 9, 1928.
material alterations.
From Jour. Wash. Acad. Sc., Jan.
Repaged without
376
ANATOMY OF SPIRINA
Method. Mount live nema in
sea water on large cover-glass;
cover with round one. Draw
off excess water till nema can
barely move. Seal with hot
wax. Use high immersion ob-
jective as condenser, its mate
as objective. Slight move-
ment of nema aids deciphering.
Stain ruptured nemas for fuller
examination.
94.8
2JO
dU''M
. .isc&zd cs
X250
Fig. 2. The male of S. parasitifera drawn from life. The tinting of drawing modi-
fied in accordance with study of stained specimens. Nearly all details shown were seen
in the living specimen. The front view of head, however, is from a decapitated speci-
men. In life the chromosomes have not been seen definitely enough to admit of accurate
counting. Most of the subsequent camera lucida drawings were obtained from fixed
and stained material. In nearly all cases the fixing and staining were done simulta-
neously by means of acetic acid methyl green. Just to the right are placed, in the
form of the decimal formula, the average measurements of specimens used. Material
collected at Woods Hole, Mass., U. S. A.
The self-explanatory abbreviations are the same throughout the various figures,
and are of necessary Latin anatomical terms; thus, chrd lat, chorda lateralis, lateral
chord; qrt, quartet of spermatids; chrtd, chromatoids; spmtd, spermatid; alv ncl, alveoli
of nuclear space; micrsm, microsomes, of spermatid; 14, a 14-chromosome spermato-
gonial mitosis; mil, mitotic figure; grn, a cell of primary spermatidian tissue containing
four granules; grn 16, cell o? spermatidian tissue containing sixteen granules; locus
ncl alv, locus of the diminishing alveolated nuclear space; spmtd polyncl, polynucleate
spermatid in process of becoming a 64-celled tissue; textus spmtdi, spermatidian tissue.
REDUCTION DIVISION 377
cell, growing, forms a primary spermatocyte. At the end of the
growth period the primary spermatocytes, one after another, divide
transversely, i.e., at right angles to the nema's body axis, and then,
sometimes almost simultaneously, longitudinally, to produce four simi-
lar, juxtaposed spermatids (Fig. 2, qrt), each soon packed with several
thousand very slightly elongate microsomes, nearly all of which are
located outside the large central, faintly alveolated, diminishing nuclear
space. (Fig. 2, micrsm and alv ncl; and Fig. 14.)
The microsomes seem to arise toward the center of the spermatid
and migrate outward till the entire cell is colonized by them. Seen
toward the center of the spermatid they usually have their long
axes arranged radially, as if moving outward, end on. Some 8-
10,000 uniform microsomes come thus into existence in each sperma-
tid. The arrangement of these around 64 centers is the first indica-
tion of the formation of the first generation of 64 spermatidia. In
the living spermatids the microsomes are the only objects seen
visibly connected with such a division of the cell contents as is
necessarily postulated to account for the phenomena of heredity.
l
Fig. 3 Fig. 4
Fig. 3. View near blind end of testis of S. parasitifera, showing pairs of cells result-
ing from division of primordial nuclei. This testis had broken open and become par-
tially evacuated so that these pairs of cells in tandem could readily be distinguished as
such. Normally these nuclei are so packed that the mass effect obscures the fact
that they are twins.
Fig. 4. Second stage of reduction division of a spermatocyte of S. parasitifera,
which will result in 4 similar juxtaposed spermatids, as at qrt, Fig. 2, each having 7
chromosomes. The compound chromosomes present considerable individuality.
Between the 2 double groups of chromosomes is seen portion of the new cell wall.
X 1200.
In the first of these two divisions the chromosome number is re-
duced to seven. Probably the smallest one of the seven chromosomes
of the secondary spermatocytes differs slightly in relative size in the
two cells. Thus far the spermatogenesis presents nothing very new
or striking, but the amount of growth, from 3 to 60 microns (tst,
Fig. 2),- is worthy of note, and, connected with reduction, there is
378 SYNAPSIS; SPERMATIDIAN GRANULES
a more or less orderly (e.g., more or less definitely oriented) extrusion
from the spermatids of structureless looking chromatoid substance,
(chrtd Fig. 2 and Fig. 14), barely possibly by a very "degenerate"
mitosis; these chromatoid masses are soon absorbed.
"Normally," the four cells just described would develop into four
sperms, but here the spermatogenesis proceeds as follows: Moving
along the testis with soldier-like precision, the two caudad members
.nd
H200
Fig. 5
Fig. 5. Nucleus of full grown spermatocyte seen in synapsis. The nuclear mem-
brane is still intact and the spherical nucleolus is still visible. The chromosomes are
in seven pairs. It was possible to resolve the chromosomes into numerous components,
suggesting a possible explanation of the difference in chromosome counts in certain
nemas, e.g., in Ascaris; i.e., differences between counts at this stage and counts in later
somatic divisions; for, should such loosely organized chromosomes later break apart,
the count would be much increased.
Fig. 6. A single spermatidium of first generation with its nucleus and sixteen
granules. From life. In this case the cell wall is shown.
Fig. 7. Above, camera lucida drawing of nuclei and granules in spermatidia of
S. parasitifera at the point grn (4), Fig. 2. Below a diagram of four spermatidia. The
diagram is derived from drawing above, and shows more clearly the numerical rela-
tionships of nuclei and granules. The boundaries of the spermatidia are almost in-
visible and are not shown. The granules are shown black, white or, when seen through
the nucleus, gray. The larger ellipsoidal objects are nuclei. In the drawing, at top
and on the hither side, a nucleus with its accompanying four granules, the nucleus
being this side of granules. In the drawing, on the farther side, again at top, a sperma-
tidium three of whose granules have already given rise to four smaller granules each.
In the drawing and below, a spermatidium none of whose four granules have divided,
one of them shown behind the nucleus, grn (16) shows a spermatidium with a nucleus
and 16 granules. The lower figure is only somewhat schematised. Very rarely are
spermatidian cells so systematically arranged as to disclose so clearly the relationships
of granules and nuclei. In this diagrammatic lower figure the far spermatidium is
shown in an intermediate state. Illustration derived from material stained with
methyl green.
of the quartet form a tandem, followed by the other two, also in
tandem; i.e., the quartet falls into single file. These spermatids in
file grow, and one after another divide internally without evidence
of mitosis into 64 uninucleate elements which proceed to surround
themselves with walls and form a tissue of 64 cells. (See lowest part
of Fig. 2.) As this tissue leaves the testis and enters the duct it
ENDOGENOUS DIVISION OF GRANULES
379
elongates (2-4 nuclei abreast), and each of its 64 cells in turn, following
on the disappearance of the microsomes, acquires four equal, refrac-
tive, spherical granules (4 microns in diameter), and the tissues thus
take on a granulated appearance, the nuclei and cell-walls being
almost completely hidden by the closely packed granules. By the
time the cephalad part of each tissue enters the duct the caudad part
has undergone a further change, in that the four granules, each dividing
endogenously into four similar but smaller spherical granules, popu-
late each cell with 16 granules (grn 4 and grn 16, Fig. 2).
This very interesting behavior of the granules (Figs. 7 and 9)
more than suggests a different order of mechanism from that typical
Fig. 11
:1200'
Fig. 8. Reduction division. Sublimate-acid carmine toto preparation. The
smallest chromosome differed somewhat in size in the two sets. Fixation less delicate
than with acid methyl green.
Fig. 9. Two granules from the spermatidia of S. parasitifera;one showing 4
smaller granules formed endogenously, the other 8. The right hand granule is from
near grn 4, Fig. 2. The left hand granule, taken from farther back in the testis, where
microscopic details are so fine that exact relationship of granules and their descendants
has not as yet been fully deciphered.
Fig. 10. Spermatidia each containing sixteen refractive spherical granules. From
life. The cell walls and nuclei of this tissue are nearly invisible in life.
Fig. 11. Nuclear spindles in later mitoses of spermatidia taking place in vas
deferens. Polar views of spindles show 7 chromosomes; see small figures to right,
from another part of the same specimen.
of cell division, but since irritability, ingestion, transportation, trans-
formation and so forth, all seem involved, it appears necessary to
base the concept on what is known of cell physiology and mechanics;
the changes, however, are carried out on a smaller scale and doubt-
less with a more limited variety of molecules forming a different
kind of plasm litoplasm. In short, the facts indicate a distinctly
lower order of "organism." Many of what now are often called
lower organisms might better be regarded simply as less multiplicate.
Thus certain ciliates are smaller and less multiplicate, rather than
"lower," as compared with nemas for instance. This matter is
380
FERTILIZATION
ndooajt
.inn of
.rag
^ H fl\ -or briefly discussed on a later page, under the
Y heading, Size and Number as related to Or-
ganisms.
As the tissue proceeds along the duct, the
cells containing 16 granules undergo a further
diminution in the size of their granules, and a
change in the number and nature of the gran-
ules, so that the cells become more transparent;
at the same time the nuclei divide mitotically,
Mspmtd (7 chromosomes), giving rise to a tissue of 128
cells. The evidence that this increase is by
rf mitosis is as follows: 1. At the part of the duct
where this change is taking place (Fig. 11) the
sizes, form and position (in pairs) of the new
* nuclei are what would be expected from mitotic
division. 2. The new smaller nuclei, pos-
terior to the larger, as yet undivided, nuclei,
stain more strongly. 3. Occasionally 7-element
spindles can be seen. 4. No trace has been
seen of any other sort of division.
Two or more such tissues as that described fill
the duct of the male nema, the number of tis-
sues varying with the age of the nema and with
the copulatory history. The tissues seem to be
of two styles, and, if so, perhaps correspond to
the two styles of chromosomes in the second-
ary spermatocytes (textus spmtdi, Fig. 2).
Fertilisation and Syngamy. The two sexes
of S. parasitifera seem about equally common.
During copulation the male passes the sper-
matidian tissues on intact to the female, and
afterward they may be seen in the uteri,
nd OOcyt Fig. 12. Carefully proportioned free-hand sketch of
gonads of female S. parasitifera after impregnation. The
two uteri, outstretched in opposite directions, are filled
with spermatidian tissue. The young ovaries are just be-
.Ja Of ginning to function and the ova next the flexures, flex ov,
are about to enter the uterus. The spermatidia adjacent to
the ova about to enter the uteri have metamorphosed into
x g~ spermules, spml, and have taken on the form characteris-
tic of nemic sperms as hitherto described. In this case
two other cells of the spermatidian tissue nearer the vulva have also begun to meta-
morphose, trm, blind end of ovary; flex ov, flexure of ovary; txt spmtd, spermatidian
tissue; gl vag, vaginal gland, for which see also Fig. 16.
.glrag
Mspatd
trm or
spoil
SYN APSIS 381
often jumbled, sometimes extended along the length of the two
uteri.
Fertilization is preceded by increase in size of that cell of the
speraiatidian tissue adjacent to the ovum next to be fertilized and
its transformation into a cell, spermule, having the form, and dis-
charging the functions, of a nemic sperm as hitherto understood;
a transformation involving a growth of about 50 per cent in diameter
together with a greater growth longitudinally, and & marked change
in the granulation of the cytoplasm (spml, Fig. 12). These trans-
formed cells, detached one by one, fertilize the eggs in what seems a
normal manner. The polocytes seem normal. The female gamete
has seven chromosomes (Fig. 13).
The spermatidian tissues -tissues J 1
,
whose history seems to justify US in parasitifera, in synap-
j . , i i sis. Above, cf zygote.
regarding them as spermatophores, Below, 9 nucleus in
may be removed from either the male synapsis; one set of
chromosomes shown
or the female nema and then separately behind the other and
stained and examined, and this has
been repeatedly done; hi which case scured by their posi-;
the details of their structure can of
course be seen with greater ease and ||
distinctness than is the case with such |;
living preparations as are shown in |;|
figures 1 and 12. The enumeration %|
of the elements of the 128-cell stage ; < V
of the spermatidian tissue was found ^~~^<^_^~~~^^
possible in this way, as well as in balsam specimens fixed in corro-
sive sublimate and stained in Mayer's acid carmine.
This method of spermatogenesis is normal to nemas. A large
number of species belonging to numerous and varied genera are
known to the writer in which the general appearances in the gonad of
the male so closely resemble those of Spirina parasitifera as to leave
him no doubt that the details of their spermatogenesis will show the
features here described, or something similar. The formation of the
spermatidian tissue is not an essential feature; in others of the above
species the spermatidia may remain separate.
Current postulates must be modified in order to account for heredi-
tary transmission in this and similar animal species. The factors
usually believed to reside wholly, or in part, in the chromosomes
must here, in order to accord with the usual theories of heredity,
382 DIAGRAM OF SPERMATOGENESIS
Twin 5pmotogonia
:Xl25
Fig. 16
Fig. 17
ad..
Fig. 14
Fig. 15
Fig. 14. Boverian diagram of spermatogenesis of Spirina. Spermatids are formed
in the "conventional" way. four from a spermatocyte. Instead of metamorphosing
into ciliated spermatozoa, the spermatids undergo further changes and divisions, which
give rise to a spermatidian tissue of 64 cells from each spermatid. These by mitotic
division produce 128-celled tissues. One by one the spermatidia, when transferred to
the uteri of a female, grow into spermules, capable of activating an egg and initiating
normal development. Whether every one of the 128 metamorphose in this way is as
yet undetermined.
Fig. 15. Two views of one of the lateral glands of 5. parasitifera. At the left only
the pore and distal portions of gland are shown. The gland is uninucleate and consists
mainly of spherical granules. Spent glands contain fewer granules than that shown.
Fig. 16. Ventral view of vulva and vaginal glands of 5. parasitifera. See also
Fig. 12.
Fig. 17. Lateral view of one of the lateral glands of S. parasitifera. The gland
in a different state, or stage of development, from that shown in Fig. 4.
LATERAL PORES AND GLANDS 383
be "divisible" in the spermatid into numerous parts such that when
they appear in the spermule they are capable of bringing about
"normal" syngamy.
It will be interesting to discover how factors or genes, concepts
essential to clear thinking on the subject of heredity, can be imagined
to "carry on" through the mazes of the division that, extending
throughout the spermatid, gives rise without mitosis to 64 apparently
equivalent elements in the spermatidian tissue (see spmtd polyncl,
Fig. 2). The spermatidian tissues (aggregates of haploid cells,
gametophores Fig. 12) seem more clearly reminiscent of the alter-
nation of generations in plants than any animal structure hitherto-
made known.
Subjoined is an alteration of the Boverian diagram illustrating
the spermatogenesis here described. It will be seen that in this
Boverian diagram (Fig. 14) the proportions of the camera lucida
drawing (Fig. 2) are to a large extent adhered to. The microsomes
and the alveolated nuclear spaces are shown with no very great
departure from nature. The number and size of the microsomes is
approximately correct and the new arrangement of the microsomes
around 64 centers as shown in the diagram is not violently schematized.
The same is true of the size, color and disposition of the chromatoid
bodies. For simplicity the spermatidian tissues are reduced in the
diagram to masses of 64 and 128 nuclei respectively.
The features accompanying and following the oocytic synapsis seem
at least a gesture toward the path followed in the spermatogenesis,
but they have not yet been carefully studied.
Occasion for staining the gonads of Spirina parasitifera offered an
opportunity for a more careful study of the unicellular glands of
this species that "empty" through minute pores in the cuticle of most
regions of the body, but particularly along the lateral fields. Uni-
cellular structures of this character are known to be widespread
among nemas, having been recorded for a great variety of free-living
genera and a few parasitic genera. It is not known whether the
various unicellular organs of this character hitherto recorded are
homologous or whether they are connected with a variety of func-
tions. The fact that they are well developed on aquatic forms that
experiment proved to be in urgent need of oxygen has led the writer
to suggest the possibility that these "glands" or some of them, may
be connected in some way with respiration. This would seem in
accord with the failure hitherto to observe any such organs in the
384 SIZE AND NUMBER AS RELATED TO ORGANISMS
vast majority of the parasitic species, whose "respiration" it would
seem natural to explain in other ways.
In Spirina parasitifera these organs are very small, and it therefore
seems not unlikely that the present methods, when applied to more
suitable material, may give results much more detailed and intelligible.
The structure of one of these glands of S. parasitifera, so far as deter-
mined, is shown in Figs. 15 and 16. The great difference in the size
of the organs in the two cases, as well as the difference in structure
and space relationships, suggests the probability that the shape of
the organ changes materially, perhaps rapidly, under various condi-
tions. To this surmise it may be added that the method of collect-
ing the spirinas, and the varying length of time between their exis-
tence under natural conditions and the time of examination, would
result in a very material alteration in the environment; and it is
believed that the longer this time became the less free oxygen would
exist in the sea water in which the specimens were kept. This length
of time varied widely.
SIZE AND NUMBER AS RELATED TO ORGANISMS
The interesting behavior of the spermatidian granules as described
on pages 38 to 41 has suggested the following sketchy discussion of
the relationship of organisms to size and number.
Why not vertebrates a mile long and a thousand feet high? Why
not vertebrates only a quarter of an inch long? The known facts
clearly indicate limits in both directions.
Among the reasons for the existence of the upper limit are, circula-
tion difficulties due to friction in the blood vessels; accumulation of
an excess of excreta in the blood during the long journey to the dis-
tant extremities and back; the difficulty of maintaining the requisite
temperature at the extremities; limits set by the strength of ma-
terials, bone could not be strong enough or muscles efficient enough
properly to support and move so large an organism; food supply
difficulties; space limitations connected with protecting such an
organism from the elements, etc., etc.
Reasons for the non-existence of exceedingly small vertebrates
also come readily to mind. The complicated vertebrate mechanism
would be in the way in an organism of such small size. Why an
elaborate pumping system to pump blood for a distance through which
it might diffuse without such a system? So with "centralized"
respiration. An internal skeleton plus the necessary protective
SIZE AND NUMBER AS RELATED TO ORGANISMS 385
cuticle become incompatible in this range of sizes. The competition
of such imaginary small vertebrates with other organisms, say insects,
of simpler structure better adapted to such small sizes would be a
hopeless struggle.
Why not insects as large as moles or as small as microbes? Here
again the mechanical relations of the organism to the menstrua
furnish numerous reasons for the known size limits.
Generalizing, why not multicellular organisms beyond certain
maximum and minimum limits? A little thought shows that limits
are set by the relationships of particular mechanisms to the sizes and
distances involved; and as size, in such cases, is a function of the
number of cooperating cells, the limits are set in numerical terms.
This becomes clearer when we consider our ability to represent a
cellular organism by a strictly numerical expression, the bioequation, 2
and all the more certainly true when, continuing the same line of
thought, we consider the size limits of cells.
Why do we not have cells a meter long; and why not typical cells
below the limits of a micron or two? Again, among other reasons,
in this range of still smaller sizes the mechanism of the typical cell
becomes so complex as to "be in its own way" when the distances
involved become sufficiently small and the number of properties to be
transmitted sufficiently few, as will be indicated in a moment.
Size limits in these various cases are set by a fundamental neces-
sity, having its "final" source in the size of the electronic combinations.
Particular attention is called to the fact that, usually, the size
limits of "adjacent" higher and lower groups of organisms reciprocally
overlap (e.g. Vertebrates and Insects); as well as to the fact that
individuals of certain species of unicellular organisms are larger
than some of the multicellulars; or, to emphasize by reversing, many
multicellulars are smaller than some of the larger unicellulars. There
is a distinct lapping of the size limits of one on to the size limits of
the other.
Organisms of greater size; "social organisms." Developing a more
complex nervous system, the higher organisms have evolved "mental
pictures" of distant and invisible things and events, and have in-
vented means for transmitting through various media signs that
represent these mental pictures. Along this path the social organisms
evolved. When we speak of a social organism it is usually assumed
"Biological Relationships of the Mathematical Series 1, 2, 4, etc." Contributions
to a Science of Nematology XV.
386 INDIVIDUALITY OF CELLS
that we are using analogy, but an interesting formulation might be
made out for homology. Are not the interactions between rela-
tively widely separated intellectual individuals, existing in the sea
of air surrounding the earth, in many ways actually homologous with
the passage of stimuli, etc., through more viscous fluid media between
cells? As, for instance, when two small organisms live in symbiosis;
or, where cells exist together as they do in blood; or, between cells
even more intimately organized.
The concept of organisms of this higher or social grade suggests
the possibility of there being also low r er orders of organisms at the
other end of the accepted series. This idea is not new, for their
existence was specifically asserted by acute observers and adventurous
thinkers in the plainest of language at least half a century ago; but
at that time the supporting evidence was so meagre that the idea
did not rise to the dignity of an acceptable working hypothesis.
Now it is quite different. Today what we know about certain small
living elements, both inside and outside of cells, compels such a
working hypothesis/ if mayhap we are not already beyond the
hypothetical stage.
Here again, size seems a prime determining element. When a
cell (really a relatively complex and large organism) transmits its
exceedingly numerous properties to its "descendants," nothing short
of an elaborate mobilization and census is adequate to the coming
transmigration. Hence follow mitosis and its complications.
We are perhaps prone to forget that every cell has, in a great degree,
to care for itself; and so must have many of the multitudinous proper-
ties characteristic of the groups of cells constituting higher organisms.
It must nourish itself. "You can take the horse to food (or vice
versa), but you cannot make him eat; he must do that himself,"
seems to summarize the situation. If the cell assimilates ("eats"),
and is to continue, then it must have mechanism adequate to select,
transport, digest, excrete, etc., and at least to take some part in
reproducing itself. All this complexity is because of the number of
its characteristics, and because of the size, i.e., the distances involved.
But what if all these be a hundredfold or more reduced, and the
system be at the same time "isolated" or individualized? Plainly,
the requirements would call for a simpler mechanism; cell-mechanism
would be so complicated as to be in the way. Under such conditions
simpler organisms, organisms simpler than cells, seem a logical
necessity.
LITOBIONTS 387
Litobionts.l have ventured to suggest a general or inclusive
name, Litobionts, for the organisms which my observations lead me
to believe to exist, these very organisms of lower grade; (Xtros,
simple), simple-organisms. The Litobionts have distinctive char-
acters, such as small size, and simplicity of composition, but neverthe-
less, live, assimilate, grow, multiply; not only segmenting somewhat
after the manner of some higher, more or less filamentous organisms,
but multiplying by endogenous division, this latter being one of the
present observations, the endogenous process being exemplified in
the "granules" of the spermatidia of Spirina. (See p. 41.)
Yet it is possible to over-emphasize the smallness of Litobionts.
It seems likely that we have been looking at Litobionts a long time,
Litobionts of the larger size, without recognizing their nature, just
as observers previous to the tune of Schleiden and Schwann had
been looking at cells without recognizing their nature.
Just as the multicellular and unicellular organisms overlap each
other in the matter of size, so the unicellular organisms (having the
characteristic properties of cells as now defined) overlap the Lito-
bionts. There are unicellular organisms smaller than some Lito-
bionts. Or, in reverse, some Litobionts larger than some unicellular
organisms.
That the Litobionts are much simpler than cells, is indicated by a
number of considerations. Their effects on light indicate that in
the main, they are composed of a smaller number of kinds of molecules
of a more orderly arrangement, what may perhaps be thought of
as forming a simpler plasm, Litoplasm. The fact that some of them
are soluble in certain chemical reagents (e.g., acetic acid), is another
indication of relative simplicity. In a word, we must conceive of
the Litobionts as made up of a smaller number of kinds of simpler
molecules manipulated through very much smaller distances, and
therefore necessarily (a matter of "economy," 'least resistance") by
simpler mechanism. It is quite conceivable that some Litobionts
may be smaller than some of the largest molecules. Not needing
these large and complex molecules, the mass of the Litobiont may
even be smaller than that of some such molecules.
The duality characteristic of all matter must lead, however, to an
arrangement of the parts in Litobionts such that we can only think
of them at present largely in terms of what we know of cell physiology
and mechanics; simply because knowledge progresses exclusively
through the known to the unknown. Our knowledge of cells must be
one of the main sources of our Litobiont concepts.
THE SCREW NEMAS
(Ascarophis van Beneden, 1871)
PARASITES OF CODFISH, HADDOCK AND OTHER FISHES
CONTRIBUTIONS TO A SCIENCE OF NEMATOLOGY XVII
BY N. A. COBB
The screw-nemas, as it is here proposed to call them, have yet to be
adequately studied. Not very much has been added to van Beneden's
original description. Almost nothing
is known about their life history and
habits. However, the present commun-
ication adds considerably to our knowl-
edge of their morphology. The sug-
gested explanation of the remarkable
screw form, and its probable mode of
evolution, present the nemic cuticle in
a new role. (See Figs. 5, 6, and 7.)
Considering the number of screw-
nemas thus far seen, it is remarkable
that no males have been discovered.
Nicoll records screw-nemas as "ex-
tremely numerous" in haddock. Van
Beneden found them originally in the
codfish; Nicoll, in the codfish and had-
dock, and in the fishes Hippoglossus
vulgaris and Coins bubalis; MacCallum
now finds a species in the stingray.
Nemas so widespread and numerous
probably have economic significance.
This probability can not be dismissed
by citing the absence of definite evi-
dence to the contrary, for, at rather
frequent intervals nowadays, nematolo-
gists are showing that nemas long
known and lightly regarded, are not
only of some importance in their rela-
tionship to mankind but sometimes of
great importance; and the multitudi-
X400
Fig. 1. Head and tail end of
Ascarophis helix n. sp. Above, to
the right, front view of the lip
region. The head end is nearly a
ventral view, but slightly oblique.
The tail end is a dorsal view, and
the anus, being on the far side, is
but indistinctly shown.
nous ways in which this comes about may well give pause to any who,
Waverly Press, Baltimore, Md., June 9,
out material alterations.
From Jour. Wash. Acad. Sc., Feb. 19, 1928. Repaged with-
POSSIBLE ECONOMIC SIGNIFICANCE 389
basing their views on past records and much current opinion, see in the
presence of such parasites merely an interesting phenomenon.
For example, it is now found that the presence of nemic parasites
not infrequently has a profound effect upon the reproductive organs
of the host, a limited number of the parasites even producing complete
sterility in a host otherwise apparently normal. That such cases in their
most definite form have thus far been found mainly in the invertebrate
phyla does not invalidate the application of the idea to vertebrates,
even were such cases wholly unknown in the vertebrata, which
they are not. Considering the well known universal specificity of
certain chemical reagents, chloroform for instance, a "universal"
anaesthetic, we should be prepared to accept without very much
surprise some such universal specificity in the action of some hormones,
particularly sexual hormones, whose origin traces back to comparatively
simple, but fundamental, ancestral cell phenomena.
Again, there is abundant evidence of high infant mortality in a great
variety of animals and plants, due to nematism. This, coupled with
our ignorance of the early life histories and food habits of fishes, even
common ones, makes it unwise to ignore the possible economic impor-
tance of the nemic parasites of fishes.
Many other examples could be cited of the multitudinous and
unexpected ways in which nemas are being shown beneficial or in-
jurious to mankind.
Ascarophis helix n. sp.
fed ?/ "bio ""*&" Sgl-ia* i. The thick layers of the
transparent, colorless, naked cuticle are traversed by obvious plain transverse
striae, which vary markedly in different portions of the body. On the head,
however, the transverse striae are hard to resolve; yet critical examination
of the striae immediately on and behind the lip region even resolves them
into rows of dot-like elements. In this region the crenations of the contour
seem duplex, four double crenations a short distance behind the head occupy-
ing 10 microns, so that each crenation encompasses about 1.25 microns.
In the latitude of the nerve-ring the striae are 1.7 microns apart; thence
backward they are gradually coarser and more distinct, each striation
becoming a double line. Furthermore, it is soon apparent that the stria-
tions pass around the body in the form of right-handed helices coarser and
coarser, and more oblique, with increasing latitude, so that at the base of
the long neck the coils are about 8 microns apart and lie at an angle of
about 23 with a transverse plane. This obliquity increases until, near the
middle [of the body, it reaches a maximum of about 30 (Fig. 2). Thence
onward, however, the obliquity diminishes. Somewhat behind the middle
of the body, certain coils of the helix fade, so that the other, now more promi-
nent, striae are as much as 20 microns apart, while their width is nearly
two microns, namely the distance apart of the double "lines" representing
the striae. This "dropping out," or fading, of course, is evidence of the exis-
tence of a plurality of helicoid "striae." In this way the body of the nema takes
390
ASCAROPHIS HELIX
on the external form of an ordinary multiple-threaded screw. Here, in the mid-
dle, the contour of the body has become very coarsely and very pronouncedly
compound-crenate. The more pronounced striae come to subtend twelve
minor ones (Fig. 3). Finally near the tail end, the more pronounced striae
subtend six minor ones (Fig. 3) ; this is near where the body is bluntly rounded
off, in a hemispherical-conoid manner, in the course of a distance equal to
about one and one-half body widths (Fig. 1). At first sight the deceptive
appearance of the cuticle toward the posterior end of the nema suggests
moulting, and consequent wrinkling of the cuticle. Longitudinal "striations,"
about 2 microns apart, due to the attachment of the mus-
culature, are visible in most regions of the body. Posteriorly
these longitudinal "striae" are still slightly oblique, and
this slight obliquity extends practically to the terminus.
There are no cuticular wings. With the nema in profile
the lateral chords appear about one-seventh as wide as the
body.
The groove-like unarmed " vestibule" is very simple and
shallow, about as deep as the height of the two prominent,
lateral, forward-pointing, conical labial projections (Fig. 1,
proj #>). The vestibule leads through the slit-like mouth
opening into a long, uniform, tubular pharynx, extending
more than halfway to the nerve-ring. The pharynx is a
marked feature of the front end, though it is so transparent
and dimly refractive that it might, perhaps, under some
circumstances, rather easily be overlooked (Fig. 1). Van
Beneden seems to have figured the pharynx; Nicoll not, or
at least not definitely. The mouth seems to lead into a
minute pharyngeal or vestibular cavity, not very much wider
than the amphids, perhaps six to eight microns wide, a
little longer dorso-ventrally than transversely. The
median axil between the two lips is not sharp and distinct.
The inner surfaces of the conical labial projections are
not uniformly rounded and striated, like the outer sur-
faces, for, near the middle, in their inner lateral lines
or fields there are refractive longitudinal elements ex-
tending from the tips back to the mouth opening. It
seems quite certain that there is an axial element ex-
tending to the apex of each of these conical projections,
and when this is viewed in optical section, as one focuses
from front to back, the appearances give rise to the opinion
that there is a single innervation to each conical pro-
jection. One sees no evidence of radial musculature
round the vestibule. There are no eyespots; and there is no pigment near
the head, or elsewhere in the nema.
Returning now to the profile and dorsal views of the head; four to five
microns behind the tips of the two cephalic projections, exceedingly minute
openings in the lateral region indicate the external amphids. As viewed
dorso-ventrally, the anterior part of the walls of the pharynx, without diminish-
ing much in thickness, bend together and nearly meet near the base of the
vestibule, thus giving rise to the narrow mouth opening; in this anterior
portion of the pharynx, the transverse striation is less apparent.
Behind the pharynx the oesophagus is a little less than one-third, at the
nerve-ring about one-fourth, twice as far back as the nerve-ring a little less
Fig. 2. Camera
lucida drawing of
an oblique view of
the eight-fold heli-
coid striae of As-
carophis helix, at
lat. 23, near the
beginning of the
intestine. The an-
astomosing occurs
opposite the lateral
chords.
ORIGIN OF HELICOID STRIAE
391
than one-third, and then again soon rather suddenly increasing a little
more than one-third, and finally is one-half, as wide as the corresponding
portion of the neck. The lining of the oesophagus is a rather distinct
feature throughout its length, and finds its main optical expression as a
somewhat sinuous axial element. The musculature of the oesophagus is
rather fine. Behind where the above-mentioned enlargement takes place
there is a considerable amount of granular matter in the oesophageal tissues.
Fig. 3 Fig. 4
Fig. 3. Helicoid striae of^Ascarophis helix considerably behind the middle of the
body.
Fig. 4. Camera lucida drawing'of the contour of Ascarophis helix near the tail
end of a female.
In front of this region the radial fibers are of a finer nature, closer together,
and the granulation much less apparent, if present at all; in other words,
there is a distinct change in the structure of the eosophagus at a point twice
as far back as the nerve-ring. The intestine becomes almost at once two-
thirds as wide as the body; it is separated from the oesophagus by a distinct
cardiac collum somewhat less than half as wide as the body.
Fig. 5. Diagrams illustrating a theory of the mode of origin of helicoid striae through
anastomosing of the ordinary transverse striae of the nemic cuticle. Let 1 represent
seven ordinary annules of a nemic cuticle, and suppose the anastomosing to take place
on opposite sides of the nema at the places indicated by the arrows; 2 represents the
anastomosing as having taken place, precisely as indicated by the arrows in 1 ; while
3 and 4 show the further theoretical transition to perfect helices. It will be observed
that two helices are formed. Bilaterally symmetrical growth would necessarily lead
to helices of even number, as exemplified in Ascarophis. See also Figs. 6 and 7.
392
ORIGIX OF HELICOID STRIAE
The wall of the intestine, while not very thick, is somewhat irregular in
thickness, the lumen appearing zigzag. At places the wall of the intestine
is one-fourth as thick as the intestine is wide; at other places nearby its
thickness may diminish by two- thirds. There is a distinct lining to the
intestine, apparently made up of "columnar" elements vertical to the inner
surface, though these have not been very clearly seen (Fig. 8). The granules
contained in the intestinal cells are rather uniform in size, but their histo-
logical characters can not be made out on account of the state of preservation
of the specimen. Well forward, near the blind end of the ovary, the intestine
is not over one-third as wide as the body; and in this region the body wall,
including the cuticle, occupies about one-fourth the radius, of which amount
the vaguely retrorse cuticle occupies eight microns and the muscular tissue
fifteen microns. There seems to be a very short rectum. The portion of
the intestine just in front of the rectum is saccate, and, for a very short dis-
tance about half as wide as the corresponding part of the body; whereas
in front of this enlargement the intestine is only about one-third as wide as
the body.
Fig. 6
Fig. 7
Fig. 6. Should two ordinary adjacent annules on each side of the nema behave as
shown in 1, the result would be four helices; four such would originate eight helices.
See also Fig. 7 and Fig. 5.
Fig. 7. Should anastomosing take place simultaneously in successive annules oppo-
site any four of the longitudinal chords a, b, c and d, say the four submedian, or the
two lateral and the two median, the result would be four helicoid striae. See also
Fig. 6.
The blind end of the anterior ovary, about as wide as the distance between
two of the adjacent oblique winds of the cuticular helix, is about two-thirds
as far behind the cardia as this latter is behind the anterior extremity. In
this region, in the body cavity, which is relatively of considerable capacity,
there are "floating" organs made up of ellipsoidal or subspherical, fine granules,
the largest of which are about eight microns in diameter (Fig. 8, org fluit).
These "loose" organs are reminiscent of those known and figured in some of
the ascarids, e.g., Ascaris kukenthalii. The ovaries lie in elongate coils,
and at first contain oocytes about four microns across, which soon increase
and become packed in the ovaries in the form of polyhedrons whose optical con-
tour is often hexagonal, and which are 10 to 12 microns across where the ovary
is one-third as wide as the body. The stretched-out ovary would be about
DIAGNOSIS OF ASCAROPHIS HELIX
393
twenty times as long as the body of the nema is wide, and at its greatest
width about one-third as wide as the nema. Sperms have not been seen,
nor has the extent and nature of the oviduct been observed. The two
uteri are filled with six to eight hundred ellipsoidal eggs about one-third as
long as the body is wide and averaging 40 X 24 microns. For a short dis-
tance near their equator the eggs are practically cylindrical. The shells
are thick a little over 2 microns and structureless looking; are of uniform
thickness throughout; and, as seen in the uteri, are without any surface
markings or appendages. No indications were seen of "two flagellae at one
pole," as noted by van Beneden and Nicoll. It is possible that appendages
might arise later, e.g., from some vaginal secretion coagulated during deposi-
tion. The eggs, before deposition, contain fairly well developed larvae.
There is a single ovijector of considerable length passing inward from the
vulva; apparently the ovijector is several times as long as the body is wide,
say at least three times. Its walls are thick and muscular; viewed in
optical section it is nearly one-third as wide as the body, being somewhat
flattened when collapsed, and so, in cross-section, a little more than half
as wide as long. Its lining is thin
and strongly refractive; the wall,
when seen in optical section, is
glassy internally and fibrous ex-
ternally. The vulva is a transverse
ellipsoidal affair near the middle
of the body, about one-fifth as wide
as the corresponding portion of the
body and interrupting two to three
of the spirals. It is about twice as
wide as long, is distinctly marked,
and presents a double refractive
contour, especially posteriorly.
The excretory pore is an opening
of considerable size, taking up the
space of about three annules of
the cuticle. For a short distance
the tube is strongly refractive,
then suddenly becomes almost in-
visible. In the specimen under
examination it is impossible to follow it far enough to say whether in its
course it becomes double and symmetrical or remains single and asymmetrical
(Fig. 1, p ex.)
Diagnosis: Ascarophis having a length of 13 mm.; striae helicoid, the
sub-cephalic ones very fine and not retrorse, the posterior ones very coarse
and compound, their maximum obliquity, behind the nerve-ring, 30;
the two labial projections broadly conoid; pharynx tubular, 1.1%; tail
convex, and rather symmetrically short-conoid, 0.2%; eggs without polar
filaments.
Habitat: Gills of the fish, Dasyatis centrum, Sting-ray. G. A. MacCal-
lum, Woods Hole, Mass., August, 1927. Hitherto Ascarophis has been
found only in the intestinal canal of fishes. The plurality of helices has
probably evolved through anastomosis; this anastomosis, if increased in
extent and systematized as shown in the diagrams (Figs. 5, 6 and 7) could
give rise to helical striae. \ The anastomoses in A. helix, as far as seen, are
lateral.
Mix ^^====^^
Fig. 8. Somewhat schematized drawing of a
cross-section of Ascarophis helix, taken not far
UNGELLA SECTA
n.gen. n. sp.
A nemic parasite of the Burmese Oligochaete (earthworm),
Eutyphoeus rarus.
CONTRIBUTIONS TO A SCIENCE OF NEMATOLOGY XVIII
BY N. A. COBB
Ungella secta n. gen. n. sp.
The transparent colorless cuticle is traversed by transverse striae, about
one micron apart, hard to resolve even with high powers, at least in alcoholic
specimens. In certain stages of the nema the striae are
much more (obvious and double [in jsize. Though inter-
rupted, the striae are not altered, on the lateral fields,
where there are only faint single wings non-existent or
faint on the neck and anterior portion of the body, but
somewhat readily seen along the middle of the body. The
very slightly oblique longitudinal striae, due to the at-
tachment of the musculature, are more readily visible than
the transverse striae. (Fig. 3, str longt) Between the
longitudinal striae are faint rows of dots, reminiscent of
the cuticular markings of Diplogaster,
And here it may be said that, though valveless, the
oesophagus also is reminiscent of Diplogaster; and that
of all the free-living genera, Diplogaster is that to which
Ungella seems most closely related. It is readily conceiv-
able that the submedian duplex onchium (Fig. 1), could
have been evolved from an armature such as characterizes
one of the types of diplogastric pharynx.
Onchium. The duplex onchium of Ungella has its amalga-
mated roots mo vably imbedded in the head end of the nema
backward for a distance equal to two-thirds the width of
the head or mo re, 'it is assumed therefore that this represents
the depth of the otherwise unarmed pharynx. The onchium,
which can be exserted for the greater part of its length, is a strong refractive
organ, colorless except distally, where it is yellowish; it is a conspicuous feature
of the head, especially when protruded. The two equal claws of the onchium
are joined rigidly in such a way as to make it impossible for them to be juxta-
posed, and their internal structure makes plain that they represent the two
ventrally submedian sectors of the oesophagus. Thus the onchium and its
Fig. 1. Ungella
secta. Side, dorsal
and end views of
the same head.
M'br, the intussus-
ception membrane.
Waverly Press, Baltimore, Md., June 19, 1928. From Jour. Wash. Acad. Sc., Apr. 4, 1928. Repaged without
material alterations.
MALE AND FEMALE UNGELLA
395
"hilt" have the general form of the ulti-
mate two-clawed segment of a beetle's
tarsus. (See Fig. 1.) Rather weakly
developed retractor muscles are at-
tached to the 'amalgamated onchial
apophyses. It seems not unlikely that
the caudal "suckers" may also aid as
a base of resistance in the use of the
onchium, the object of which must be
to claw; it must wound by clawing,
hence the specific name secta. When
the onchium is withdrawn and at rest,
as in the female of Figure 2, the outer
or distal parts of the two claws rest in
special lateral depressions on the out-
side of the front of the head (see concav
Fig. 1) and to that extent are not
withdrawn into the head.
Oesophageal glands. The median
dorsad pore in the front of the head,
por dsl, is the exit of a large well de-
veloped special cervical gland, gl crv.
The excretory pore of the renette, p
ex, is farther back and ventral. There
is an almost imperceptible short alter-
ation in the oesophageal lining be-
tween the fore and after parts of the
oesophagus, probably the vestige of
a median bulb. The indistinctly cla-
vate, posterior,'non-valvate, oesopha-
geal swelling contains a single, bright,
refractive, three-micron nucleus near
the base in the dorsal sector, proving
the presence of an oesophageal gland.
Radial oesophageal muscles are only
faintly to be seen.
Intestine. A cross-section of the
intestine cuts through only about two
relatively large cells. The refractive
lining of the intestine often is distinctly
to be seen. In the front portion of the
body the wall of the intestine is hardly
as thick as that of the body; here the
lumen of the intestine often is more
than twice as wide as the thickness of the intestinal wall.
org wt?.
'sub cut 'mac
Fig. 2. Male
tna and female U.
secta. From al -
coholic earth-
worm speci-
mens. All nemas
adult, females
outnumbering males.
X400
396
"SUCKERS"
Renette. The renette duct, dct ex, is distinctly refractive and nearly two
microns across; it passes inward at right angles to the ventral surface and
then turns backward on the left side and becomes narrower and apparently
bifurcate.
Caudal "Suckers." The tissue composing the mouths of the two lateral
caudal "suckers" is comparatively structureless looking, and externally par-
takes of the general character of the cuticle. These two large lateral open-
ings, found on the tail of adults of both sexes, when viewed dorso-ventrally
are seen to lead inward and forward into two
well developed pockets or "suckers," so massive
that this portion of the tail, in the median aspect
appears about 50 per cent wider than the portion of
the tail immediately behind (Fig. 3, org suci).
The cavity of each organ is lined with thick striated
tissue whose most obvious elements are arranged
at right angles to its inner surface, which presents
a very definite internal sectional contour, due to
the refractiveness of this tissue; so that the whole
organ is a relatively conspicuous affair. A strand
(contractile?) leading forward from each "sucker"
into the corresponding lateral chord is at first
rather wide, then narrows (text org suet, Fig. 3).
The "suckers" seem to make their appearance on
both sexes at the last moult (Fig. 4).
Gonads. The elevated transverse vulva ap-
parently is not very wide. Near the flexure the
gonad presents a spermatheca, spmth, containing
numerous spherical sperms of such a size that
about a dozen would be required to span the
body diameter. These possess refractive, faintly
lobed nuclei, indicating the presence of a small
number of chromosomes probably about five.
Contained in the uterus of adult females, as a gella secta > showin g * n * h e
rule, is a single thin-shelled, smooth egg, ov, lower part
about one and one-half times as long as the body
is wide and about one-third as wide as long. No
segmented egg has been seen in the uterus. The blind end of the ovary
lies between the caudal "suckers" or somewhat farther forward. From
the blind end of the ovary forward the oocytes very soon become smaller,
as if by division, and not far from the anus are arranged several abreast,
and so continue, increasing meanwhile in size, for a good fraction of the dis-
tance to the vulva; thence, owing to increased size, they are arranged single
file, each ovum cylindroid and somewhat longer than wide.
X800
sir long it
tf^t org suet
owyt.
strJfflff/t
car org suet
as org suet ?
tnaw . .
Fig. 3. Ventral view of
the post-anal region of Un-
two lateral pockets or suck-
ers, cav org suet.
DIAGNOSES 397
The male. The relatively large gubernaculum, gub, is single, rather shallow,
nearly straight, and extends inward nearly at right angles to the ventral sur-
face, so that its proximal end is considerably dorsad of the body axis. It
appears quite as massive as the two equal spicula, and has the form of a rela-
tively very broad, shallow, somewhat boat-like trough, deepest amidships,
its depth being about one-third 'its length. The long
narrow bursa, brs, presents seven whiplash-like ribs (1-7,
Fig. 2) extending into each of the colorless, thin, glassy-
looking, ventrally submedian, bursal expansions of the
cuticle.
Since the suckers are common to both sexes, they can
hardly be considered secondary sexual organs. Figure 4,
X 800 1 -:"'' derived from one of the few immature specimens thus far
Fig. 4. Ventral seen, seems to indicate that these interesting organs come
view of the suckers into existence at the last moult, for, just previous to the last
ust beTre^theTast m Ult> they ^^ immature or "embryonic." It seems
moult 6 hardly possible that these organs can be homologous with
the phasmids; nor does it seem possible to link them with
such ventral suckers as occur for instance on male Heterachids. In short,
further observation is needed fully to determine their function.
Habitat: Body cavity and muscles of the earthworm, Eutyphoeus rarus;
fide Mr. G. E. Gates, to whom the discovery of the nema is due. Locality,
Prome, Burma, India.
Ungella, n. gen.
Genus Diagnosis: Amphigonic onchia hooked protrusile, dorsally arcuate;
and special cervical gland; oesophagus degenerate-diplogastroid; adults
with posterior lateral pockets or "suckers;" 'm and 'f ; males with two equal
spicula and a gubernaculum, and an elongate pre- and post-anally ribbed
bursa. Parasitic in earthworms. Proposed as type species is:
Species Diagnosis: Flexible-tailed ungellas, dimensioned as in the formulae
and illustrations, with two practically submedian, amalgamated onchia
(ungellae), having the form of the final joint of a beetle's tarsus; cervical
gland just behind the cardia, its outlet dorsad on the lip region; pockets or
suckers not far in front of the middle of the tail; external amphids more or less
circular and opposite the base of the pharynx; oviparous; males with three
pre- and four post-anal slender ribs to the bursa, as shown in Figure 2 ; pos-
terior part of the tail cylindroid, fine yet blunt, in the male distinctly set
off.
Only a more careful study of the nemas thus far described as para-
sitic in earthworms can determine the nature and limits of most of the
genera and species that have been proposed for their reception.
For literature consulted see the list of Pierantoni (Boll. Soc. Nat.
Napoli, 1915, p. 150-3) and Baylis & Daubney (Synopsis, 1926).
A NEW SPECIES OF
THE NEMIC GENUS SYRINGOLAIMUS
With a note on the fossorium of nemas
CONTRIBUTIONS TO A SCIENCE OF NEMATOLOGY XIX
BY N. A. COBB
The writer's collection of Syringolaims shows them to live on tem-
perate and tropical sea coasts in many parts of the world. Among
other places, his Syringolaims (1888-1927) represent the East Indies
(Larat), Polynesia (Noumea, Hawaii), the Atlantic and Pacific Coasts
of Panama, the Atlantic Coast of the United States, and the English
Channel. The manuscript record of these collections contains full
descriptions of a number of new but unpublished closely related species.
Our knowledge of this genus has increased but little since de Man
described the type species, his S. striatocaudatus. The present publi-
cation adds information concerning (1) the labial papillae, (2) the
amphids, (3) the phasmids (?), (4) the fossorium, (5) the intestine,
(6) the male gone, (7) the food habits, and (8) the geographic distribu-
tion.
Syringolaimus smarigdus, n.sp. |;J *%$ *%%
The transparent, colorless cuticle is traversed by plain transverse striae
very difficult, or almost impossible, to resolve, which are not altered on the
lateral fields. Faint traces of wings occur, beginning near the head and end-
ing on the tail. Longitudinal "striae," due to the attachment of the muscula-
ture, are visible in nearly all regions of the body. No series of pores have
been seen in the cuticle. Of the highly mobile lips there probably are three,
but they are no more than sub-distinct, and are small and somewhat rounded.
The pharynx is armed in front with three duplex (somewhat lobster-claw-
like), in profile somewhat inverted-comma-shaped, subacute odontia (Fig.
1, mnd) having an outward throw of about 180, a movement seen on more
Waverly Press, Baltimore, Md., June 9, 1928. From Jour. Wash. Acad. Sc., May 4, 1928. Repaged without
material alterations.
MALE SYRINGOLAIMUS SMAR1GDUS
gld &
Fig.l
400 ANATOMY OF SYEINGOLAIMUS
than one occasion to occur every second or so when the live nema was placed
under the microscope under slight pressure (Fig. 1). The cross-section of the
pharynx is round-triquetrous, almost circular, with faint subordinate mark-
ings in the middle of each side, indicating on the whole a hexagonal structure.
There are no eyespots. The base of the pharynx may be surrounded by a
very faint ellipsoidal swelling. There is only a faint pharyngeal muscular
swelling, though there are fairly well developed mandibular muscles, lying
along the outside of the pharynx (Fig. 1, msc mnd). There is a rather distinct
but small conoid cardia, one-third as wide as the base of the neck, or less.
The ventriculus stains differently from the remainder of the intestine, showing
a distinct function to be discharged here ; in the li ving condition however the
ventriculus appears somewhat "structureless" (vntrc). The granules in the
cells of the intestine are of several distinct kinds: some of them are colorless
(grn trnsp int), others are emerald-green (grn vrd int) hence the specific
name smarigdus; none are birefringent. The content of the intestine is
usually reddish or greenish, and often is derived specifically from an alga be-
longing to the family Half siae (Fig. 3) , among which specimens of Syringolaimus
smarigdus are often found. There is no prerectum. From the somewhat
elevated lips of the anus, of which the anterior lip is the more elevated,
the cutinized rectum extends inward and forward a distance about equal to
Fig. 2. Snails, natural size, covered with a very dark green "pile" or "felt" consist-
ing of microscopic algae. The nature of this growth is illustrated in Fig. 3.
two-thirds of the corresponding body diameter. The lateral chords enlarge
from one-fifth (terminad) to one-half (mediad) as wide as the body. From
the medium-sized continuous vulva, the cutinized vagina leads inward at
right angles to the ventral surface three-fifths the way across the body. The
uteri contain only one egg at a time, are straight, three to four times as
long as the body is wide, and from one-fourth to one-sixth as wide as long.
The two opposite, equal, symmetrically arranged ovaries, about half as wide
as the body, are reflexed about two-thirds the distance back to the vulva and
contain ten to fifteen ova, mostly in single file. The elongate egg may be
3 to 4 body-widths long, appears relatively narrow, and seems to be deposited
before segmentation.
;| }f ^ 4 - 7r ^.3' ' ' JjJ^-XJ.eswm The single gubernaculum (gub}
may consist of two arcuate, subslender, parallel, amalgamated pieces, and is
rather closely applied to the spicula. Phasmids(?) (Fig. 1) occur on the
Fig. 1 .Male of Syringolaimus smarigdus, together with four different views of the
head end. Below, a diagrammatic drawing of the front view of the head. Above, three
sketches showing different attitudes of the "mandibles" or fossores. The fossores are
also shown in both the other illustrations. The lettering of the illustrations consists
of self-explanatory abbreviations arranged in the Latin order; grn vrd int granulum
viride intestinalis, green granule of the intestine; etc.
FOSSOR1UM OF NEMAS
401
lateral lines near the middle of the tail on
both sexes. While there is no distinct bursa,
the cuticle is faintly thickened in the sub-
median region near the anus, possibly a very
rudimentary bursa.
Habitat: Common among minute filamen-
tous algae on the surface of marine mollusks,
especially the snail Alectrion obsokta (Fig. 2).
Also found in sand on beaches, and in sand
in several feet of water off shore. Woods
Hole region, 1916 to 1927. There is good
reason to suppose it ranges both north and
south from Woods Hole along the Atlantic
Coast. It occurs in beach sand from near
Falmouth; and in clear white sand in five
feet of water in a cove at the entrance to
Buzzard's Bay; also at Waquoit, Mass.,
among algae on the shell of the living snail,
Alectrion obsoleta (Nassa) ; and on the shells
of live snails from the Eel Pond at Woods
Hole. Its food seems always to be vegetable
matter, and in many cases consists entirely
of the contents of the cells of a microscopic
alga belonging to the genus Ralfsia (?).
OUTWARD ACTING NEMIC "MANDIBLES"
Fig. 3. Slight portion of the
algal growth from the snails shown
in Fig. 2, broken or dissected away.
Below is the shell of the mo Husk.
On it an "incrustation," orange in
color, consisting of an alga belong-
ing to the family Ralfsiae, prob-
ably to the genus Ralfsia. On this
incrustation there is a thick felt-
like growth, consisting of blue-
green and yellow-green algae.
Syringolaimus smarigdus feeds
upon the orange-colored alga,
which it can reach only by digging
through the green algal growth
above.
The writer's study of the attitudes in
which the mouth parts became fixed led
to the conclusion that in Axonolaimus
and its relatives, as well as in a large
number of other nemas, the onchia (and
odontia) had an outward throw. If so, it
was an obvious deduction that these
organs were digging organs, for which
the word f ossor 2 seems indicated. This deduction led the writer long
ago to introduce into generic names of such nemas root words indi-
cating a digging function on the part of the mouth organs, as for
instance in the genus names Scaptrella, Diploscapter.
It is, however, difficult to observe these organs in operation, and
hence of interest to record that such organs have been seen in action
in a Syringolaim (Fig. 1), and furthermore that S. smarigdus has been
observed under conditions constituting strong additional circum-
stantial evidence that these organs are verily digging organs. S.
* F ossor (plural, fossores; collective, fossorium); a tool or organ used for digging,
usually existing in a plurality and acting symmetrically outward from a plane or axis.
Related to "fossorial" said of animals that dig.
402 SYRIXGOLAIMUS DIGS
smarigdus is found in algal "incrustations" of the family Ralfsiae,
and probably genus Ralfsia. 3 It is very apparent that the nema feeds
upon the Ralfsia, for the color and structure of the contents of the cells
of this alga are strikingly characteristic, and the intestinal content of
the associated Syringolaims not only has exactly the same color, but
frequently is otherwise of such a character that it could be derived
only from the interior of the Ralfsia cells. Often, however, there are
scattered foreign birefringent particles (carbonate of lime) mixed with
the ingested food; but these birefringent particles are similar to those
found among the filaments of the Ralfsia, and, taking into account
the relative size of the mouth parts of the Syringolaim, it is very
natural to suppose that some of this foreign matter would be taken in
with the food.
No one had previously explained the precise nature of the mouth
organs of Syringolaimus. They consist of three small, arcuate, more
or less acute odontia with a spirally outward throw, well adapted to
boring and digging (Fig. 1). Now, it so happens that the location and
structure of the incrustation formed by the Ralfsia w T ould require
digging on the part of the nema in order to obtain food from it, for the
Ralfsia incrustation on the snail shells (Alectrion} is usually overgrown
with a thick comparatively impenetrable felt of filamentous green
algae (Fig. 3) ; hence the Ralfsia can be reached by the Syringolaimus
only by digging.
The snail, Alectrion obsoleta (Nassa), lives between tide-marks and
hence twice daily is exposed to the air, and on each such occasion any
algal growth on it naturally dries up more or less. Here then is an
additional complication hi the environment of the Syringolaim a
highly and rapidly variable temperature and salinity. It is reason-
able to suppose these unusual circumstances might give rise to a pecu-
liar nemic form adapted to the environment. Thus a clue is found to
the marked peculiarities of form and structure noted in Syringolaimus.
3 Ralfsia; fide Dr. I. F. Lewis.
THE CHROMATROPISM OF MERMIS
SUBNIGRESCENS
A Nemic Parasite of Grasshoppers
CONTRIBUTIONS TO A SCIENCE OF NEMATOLOQY XX l
BY N. A. COBB
The adult female Mermis subnigrescens, when ripe for ovijection,
has away of moving her head in more or less horizontal curves; her
head, directed skyward, is waved in "circles," now clockwise, now the
reverse. This seemingly purposeful behavior occurs when she emerges
from the soil and while she is ascending the herbage to deposit her eggs.
Inasmuch as the head of the egg-laying female, unlike that of the
young female as well as that of the male (neither of which ever quits
the subterranean darkness), contains reddish transparent pigment
rather definitely distributed with reference to certain cephalic nerves,
the question arose whether we do not have here a phototrope 2 and an
1 Reprinted from the JOURNAL OF THE WASHINGTON ACADEMY OF SCIENCES, Vol. 19.
No. 8, April 19, 1929.
2 It is suggested that the mechanisms through whose activation the responses of
organisms termed tropisms find expression be called "tropes;" "tropism" to be taken
in almost any of its more or less well accepted meanings.
These meanings (interpretations of various investigators, see Mast, 1915) vary all
the way from (1) "an inherent tendency to respond" (Standard Dictionary), to (2) an
"irresistible" or "predictable" orientation as definite and mechanical as that of a magnetic
needle; but whatever the accepted interpretation, the reaction-mechanism must always be
present, and be a system of intimately connected elements or organs, as is the digestive
system, for instance, or the excretory system. Since we have for this system of inti-
mately connected elements no inclusive single descriptive term, and since it is found
highly convenient, or even necessary, for purposes of thought and discussion mentally
to "isolate," and separately to denominate, the digestive system or enteron, and other
systems, it is suggested that in behavior studies a like situation be met by a similar,
Waverly Press, Inc., Baltimore, Maryland, June, 19SO
404 PHOTOTROPE
affirmative answer was forecast, for the obvious reason, among others,
that, as the pigment must absorb certain light frequencies and transmit
others, the absorption might well result in some such changes of energy
as characterize vision. Very suggestive also is the fact that the trans-
parent, colorless parts of the head immediately in front of, and along-
side, the suspected phototrope condense light rays upon it. (See
Fig. 1.)
Previous experiment showed the spectrum frequencies concerned in
bringing about ovijection in this nema probably to be some of those
in the light-blue and low violet region of the spectrum, together with
red (also infra-?). 3 It would therefore be natural to suspect, under
all the circumstances, that the cephalic pigment characteristic of the
adult female absorbs, and "makes use of," the frequencies present
just previous to and during ovijection. Hence a wish, (1), to deter-
mine what frequencies are present during and just previous to natural
ovijection; and, (2) to determine what frequencies are absorbed by the
cephalic pigment.
In this field comparatively little seems to have been published,
though somewhat pertinent papers by Crozier, Mast, and others exist.
Investigators have been mainly occupied with the optics of the various
colorless, transparent, organic elements; the relative location and
probable function of certain pigments, usually dark or black (opaque) ;
and the "migration" and other changes of pigment, such as visual
purple, due to the action of light; and, of course, with the associated
nervous and contractile elements. Little has been published with
regard to tropism definitely due to the absorption of rays of a particular
frequency solely by transparent, colored pigment (other than visual
but if possible better (to wit monosyllabic), terminology. The advantages of a mono-
syllable from which short, convenient adjectives, verbs, adverbs and other nouns can
readily be derived, are almost too obvious to need mention, tropic, tropically, to trope,
troping, etc., etc. Most helpful, perhaps, will be its use as a component, e. g., in
"chromatrope."
Primarily "trope" denotes action, action that is in progress rather than completed.
By metonymy the word denoting an action (here, what is called a reaction) may be
applied to the (re)action-mechanism, i.e., in the present case, to the responding system
of intimately connected organs.
Following this suggestion, we may speak of a reaction mechanism that aids or causes
an organism to face toward or away from light, as a phototrope; a reaction mechanism
used in orientation with reference to gravity, a geotrope, etc., etc., etc., etc.; thus the
statocystic mechanism of crustaceans is a species of geotrope.
Accordingly, certain cephalic apparatus of Mermis subnigrescens is here spoken of as a
phototrope; or, better, because more specific, as a chromatrope, inasmuch as its reac-
tions apparently are to definite frequencies (colors) of the solar spectrum. Glaucotrope
y\avKO(7 = blue) may prove to be even more precise.
3 Species of Mermis. Journ. Parasitology, 8 : 66. 1926.
STRUCTURE OF THE CHROMATROPE
405
purple) located definitely with reference to nerves, these nerves them-
selves so located as possibly to be sensory.
SPECTROSCOPIC TEST OF THE PRESUMPTIVE CEPHALIC CHROMATROPE OF
Mermis subnigrescens
One-third of a millimeter of the front end of an adult female Mermis
subnigrescens, including the head, was ligated and cut off, and then
mounted on a microscope
slide in water. The head
was examined under a 1.5
mm. apochromatic micro-
scope objective, having a
similar objective as a con-
denser, in such a way that
the image would fill as much
as possible of the micro- ^f fit
scope field with the color of
the pigment. (See Fig. 1.)
The microscope was fitted
with a spectroscopic eye-
piece.
Sunlight was taken from
a flat planished aluminum
reflector placed so that a
maximum of sunlight was
reflected through both in-
struments,^., the above
apochromatic-micro -spec-
troscope and a comparison
spectroscope. The pig-
mented tissue was brought
into focus, and then the iris
diaphragm of the micro-
scope thrown open, so as
to admit a "flood" of light.
This produced a spectrum
fairly readily seen in a
darkened room, notwith-
standing the very high
magnification.
Much of the violet end
of the spectrum (well into
X200
Figure 1. Head end of Mermis subnigrescens,
showing the chromatrope. os, mouth; ppl (2), the
two lateral so-called "papillae;" amph, amphid;
nrv chrtrp, nerves of the chromatrope; lum oesoph,
lumen of the oesophagus; pgmt rub, reddish pig-
ment of the chromatrope; chrd md, median chord;
annnrv, nerve-ring; msc, body-wall muscles; cut,
cuticle; oe, oesophagus; ppl subm (4), the four
submedian papillae; nrv amph, nerve of the
amphid; ar mcrscp, shows the circular area of the
microscopic field that was tested spectroscopically ;
pgmt lut, orange-colored pigment of the chroma-
trope; chrmtrp, chromatrope; chrd lat, lateral
chord; sub cut, the thick subcuticle; crbrm, the
cerebrum; trphsm, anterior end of the trophosome.
406 ABSORPTION BY THE CHROMATROPE
the blue) was absorbed to a very considerable degree by the living
cephalic pigment of the Mermis subnigrescens. The microscope field
was never completely and uniformly filled with the color of the
pigment. There were streaks at each margin of the field, and another
through the middle, that showed little color (see Fig. 1), so that
doubtless the absorption was not so pronounced as would be obtained
by dissolved pigment of equal density filling the entire field of the
microscope.
A satisfactory demonstration was made by placing the object under
the microscope so as to produce absorption, and after the spectra had
been arranged for comparison, suddenly removing the pigmented
tissue. The effect produced by this instantaneous change was very
pronounced. The blue and violet region of the spectrum, hitherto
obscured by absorption, of course instantly assumed the same colors
as in the comparison spectrum.
There seemed also to be some absorption in the outermost part of
the red of the visible spectrum, but, if so, it was very slight. No
absorption was noticed in the orange, yellow and green, and little if
any in the bluish green.
The experiment was particularly satisfactory in that the pigment
was in a living condition. True, the head had been ligated and cut off
immediately before the spectroscopic examination, but from much
experience it is known that such a head continues to "live" and move
anywhere from a few hours to a day, or even more.
Phototropes of somewhat the character here described probably
occur in the cervical region of many other nemas, particularly free-
living ones, the outer tissues of the neck serving as a cylindrical lens
for condensing light upon the pigmented tissues. Aquatic nemas so
situated as to utilize light rays penetrating water, not infrequently
present structures that may be suspected to be phototropes, now
that we have a clue to the nature of such structures in this phylum.
These primitive phototropes may well have been the forerunners of
the more highly developed phototropes, ocellate systems, of certain
nemas (e.g. Enchelidium).
A general review of the nature and relationships of localized trans-
parent pigments in organisms in the light of the foregoing experiment,
may, perhaps, suggest new ideas and experiments with regard to their
functions both in animals and plants.
EFFECT OF INFRA RED 407
NATURAL CONDITIONS UNDER WHICH Mermis subnigrescens
DEPOSITS ITS EGGS
At Woods Hole, Mass., U. S. A., on July 28, 1928, from long before
daylight up to 10 o'clock A.M. the weather was warm and showery.
The showers were gentle but subcontinuous, with light-intervals
between; i.e., during two or three brief intervals the sunlight actually
came through the fog and clouds rather clearly.
Two full-grown female specimens of M . subnigrescens, very much
alike, were found depositing eggs naturally on grass etc. in an experi-
ment field. As each nema still contained a good many eggs, both
were taken to the laboratory in cold tap-water, and both subjected to
radiant heat of low frequency, emanating from hot steel. The results
of three trials on one of the nemas and four on the other were quite
consistent.
An ordinary steel file about nine inches long and three-fourths of an
inch wide was heated until hot, though not red. As near as could be
judged the temperature of the file during the trials was from 400-500
C. The hot steel was held within an inch and a half to two inches of
the nemas. Held at this distance from one's cheek, it caused an
agreeable warm sensation; no disagreeable sensation of heat, how-
ever/ no suggestion of scorching.
When the nemas were brought into the laboratory, both were still
slowly depositing eggs; one, however, very slowly, putting out only
one or two eggs semi-occasionally. When one of these ten-centimeter
nemas in this laboring condition was removed from water and stretched
out on a broad-leaf plantain, Plantago major, and the hot file brought
near, she immediately responded by increased rapidity of movement,
and in from ten to twenty seconds became coiled, sometimes rather
closely, so that the entire space occupied by her would not be over
fifteen to twenty millimeters across. Barely enough water was used
on the plantain leaf so that only at her points of contact with the leaf
was she in contact also with water. Doubtless the warmth may have
caused the water to evaporate a trifle more rapidly, notwithstanding
the saturated condition of the atmosphere, and one cannot say that
this change in rate of evaporation may not have had some effect on- the
behavior, but the inevitable inference is that the "radiant heat" caused
the change in behavior, corroborating, in a reverse way, experiments of
previous years with direct sunlight and sunlight passed through
heat-diminishing screens (both green glass and living foliage).
408 EFFECT OF INFRA RED
After the nemas had been rayed and returned to water in a watch-
glass, and after they had resumed their former less active somewhat
outstretched state, they were tested again and again with the infra-
red rays. Two observers, noting the nemas before they were removed
from the watchglass of water and after they had been rayed, declared the
ovijection to be stimulated, and in one case the stimulation to be very
marked indeed. In this case, at the time when the nema was removed
from the glass, oviposition was diminishing to almost nil, only now and
then an egg being deposited, at intervals of half a minute or there-
abouts; however, after she had been rayed and returned to the water
where her behavior could be observed more accurately, deposition
was going on vigorously, batches of something like twenty eggs were
being ejected at intervals of five to ten seconds. It should be re-
membered that these two females already had their egg-laying capacity
partially exhausted and were therefore probably less favorable speci-
mens for experiment than if they had just issued from the ground.
The conclusions drawn from the experiments were that, without
doubt, the radiant heat from the hot steel met with instant response by the
nema and that the response was very definite and that the egg deposition
was very markedly stimulated by the rays.*
Apart from ultra-violet, apparently very little is known about the
relative amounts of various light frequencies that are passed through
different quantities of fog and watery vapor in the atmosphere. It is
known that fog and vapor are more or less impervious to ultra-violet,
but pervious to many other frequencies, among them blue and a cer-
tain amount of red and infra-red. However, nobody appears to have
devised a method or instrument by which the amount of any particular
one of these various other frequencies penetrating under various atmos-
pheric conditions can be satisfactorily measured, although there is
reason to hope that such data can be established.
It is very evident, however, that during the morning under con-
sideration, which was showery with light rain much of the time, the
weather varying all the way from thick fog to almost sunny, fog so
thick that the fog-horns were blowing, and yet at times the sky toward
the east such that the sunlight came through rather clearly , it is
very evident that the amount of any given spectrum frequency reach-
ing the experiment field probably would vary during the morning
nearly through the entire daylight scale, or at least much of it.
* But whatever stimulus, if any, the nema received from the sky was not sufficient
by itself to cause any marked oviposition.
EGG LAYING OF M. SUBNIGRESCENS 409
APPLICATION TO THE oviJECTiON OF Mermis subnigrescens.
The observations to date seem to shut out the possibility that ultra-
violet has much of anything to do with ovijection taking place natu-
rally in the open. The present observations seem again to make it
exceedingly probable that radiant heat must have much to do with it.
Recalling that the early morning light is relatively rich in red and
infra-red, and that as moisture (dew, rain) is essential, or at any rate
highly favorable, to the oviposition of M. subnigrescens, then obviously
early morning and forenoon would be a favorable time of day for the
oviposition. It is certain, from spectroscopic tests made during the
morning in question, that all the time after sunrise a good deal of blue
light was being passed through the atmosphere; and it therefore might
have been a behavior stimulus, and no doubt was so.
All this harmonizes with previous experiments on the ovijection of
this species, an account of which is already published, and explains
the motive for the tests described above.
Thus we have a fairly complete theory of the above-ground egg-
laying activities of Mermis subnigrescens. When the nema is ripe for
labor, she moves from her pitch dark, subterranean "domicile" to the
surface of the ground. Her movements during this trip no doubt
exemplify apogeo-, hydro-, thermo-, rheo-, thigmo-, and finally, just
before she reaches the surface, photo-tropism.
Once her head is free of the surface of the ground, her chromatrope
comes into full play, "detecting" the direction and amount of light
from the sky, particularly, perhaps only, blue light. The structure of
the chromatrope is particularly adapted to the reception of light
from above or from any side, for the light will be concentrated in the
chromatrope by the transparent front tissues of the head acting as a
hemispherical lens, and the side tissues acting as a cylindrical lens.
As she clambers higher and higher on the herbage, she responds to
such blue sky light as is not intercepted by the green blades of grass
and other foliage above and around her. Led by the blue light and
the urge to deposit, she will at last reach an elevation on the herbage
subject to a more direct action of the sun's rays, when the ovijector
and uterine muscles will be affected by "red" rays and ovijection will
begin; and this place in many instances would be at the altitude of
grazing grasshoppers, the definitive hosts.
This would be a new and special parallel to the ordinary sequence of
events in ovijection and parturition. In other words the "voluntary"
nervous system comes first into play, bringing the organism into con-
410 EVIDENCE FOR CHROMATROPISM
ditions favorable to the events about to follow. Thereafter the be-
havior is more or less "involuntary," as has been shown in the present
instance by the fact that ovijection continues under the stimulus of
sunlight, even if the head, including the chromatrope and central
nervous system, be removed, seared off.
CIRCUMSTANTIAL EVIDENCE FOR THE CHROMATROPISM OF
Mermis subnigrescens
1. The commonly infested grasshoppers graze mostly within certain
limits above the ground; harmoniously, the eggs of the mermithid
parasite are found to occur preponderantly within these limits, sug-
gesting highly developed egg-laying instincts on the part of the nema
that might well presuppose tropism.
2. A definite mechanism, believably a phototrope [includes chroma-
trope, (includes glaucotrope)] embodying what are believably recep-
tors, transmitters, and effectors, is present; a mechanism not other-
wise readily explicable. The only mermithid individuals known to
possess such a mechanism fully developed are those whose blackish
eggs are deposited in the way characteristic of Mermis subnigrescens.
3. The putatively-chromatropic pigment absorbs, i.e., can be
sensitive to, blue rays.
4. Only adult, chromatroped, egg-laying females clamber as de-
scribed. Males and young females having no power, or occasion,
to deposit eggs are not chromatroped.
5. The clambering of the nemas ripe for oviposition is skyward;
i.e., toward blue sky, rather than vertical (distinction from negative
geotropism). Beams of blue light from the sky, often oblique, and
coming from many widely different directions, are those most certain
promiscuously to penetrate the depths of the herbage, and thus reach
to near the ground. The nema's lens-like tissues concentrating light
upon the chromatrope, accept it from above and from all sides; this
harmonizes with the distribution of blue sky light.
6. Oviposition is stopped, or very much slowed, by green screens
(including living foliage) that absorb red and infra-red; indicating a
necessity for the nema to escape from exclusively green light before
oviposition can take place. In the grasshopper habitats, blue light
(sky-light) is the most diffused and most likely to be useful in leading
to the known consummation, should chromatropism come into play
at all. In nature, clambering skyward ('"blue-ward") from out the
green, brings the nema soonest under the incidence of the longer wave
lengths so stimulative to the ovijectors.
INITIAL STRATIGRAPHIC SURVEY OF NEMAS
In the upper 20 mm. of
MARINE BEACH SAND, NEAR LOW TIDE MARK
CONTRIBUTIONS TO A SCIENCE OP NEMATOLOQY XXI
BY N. A. COBB
In 1916 studies at the laboratory of the Bureau of Fisheries, Woods
Hole, Massachusetts, showed that sandy beaches, far from being
utterly barren, carry a comparatively rich fauna of microscopic organ-
isms. What biological and economic role these organisms may play is
little known. Conceivably they may be more important than would
at first be suspected. Recall that many larger aquatic organisms,
at one period or another, may pass a certain amount of time on the
bottom. During this sojourn their relationship to the microscopic
inhabitants of the sand, mud, etc. constituting the bottom, is a matter
about which we know very little, but it is easy to imagine that some-
times the relationship may be important. Again, the sand- and mud-
inhabiting organisms themselves may be temporary stages (eggs,
larvae) in a varied life history.
Such thoughts led to a stratigraphic examination of marine beach
sand at Woods Hole, August, 1928. A small sheet-metal box, 10
centimeters square, carrying a series of thin metal slides was devised,
such that by its aid layers of sand 5 mm. thick, lying one above another
in series, could be collected (Figs. 1 and 2). In each of two collec-
tions four such successive horizontal layers were examined for their
nemas. The results are indicated in the following tables :
Collection I: Layer No. I topmost 1st 5mm. 100 sq. cm. 905 nemas
" II 2nd " " " 1,355 "
" HI 3rd " " " 1,009 "
" IV 4th " 175 "
Collection II: Layer No. I topmost 1st 5 mm. 100 sq. cm. 1,512 nemas
" II 2nd " 1,403 "
HI 3rd " " " 981 "
IV 4th " 226 "
Only two collections were made, as the census is a very tedious one.
It will be seen that the two collections, taken a few yards apart, give
Reprinted from the JOURNAL OF THE WASHINGTON ACADEMY OF SCIENCES, Vol. 19,
No. 10, May 19, 1929.
412
STRATIGRAPHIC APPARATUS
rather consistent stratigraphic numbers; so that we may say, as a result
of these two examinations, that probably the number of nemas in each
successive layer decreases, rather gradually at first, but rapidly below
the third 5 mm. layer; i.e., to a depth of about 15 mm. the sand is
thickly populated with nemas; below that level the number falls off
rapidly. The deeper layers contain fewer nemas, and fewer species.
Fig. 1. See also Fig. 2. Apparatus for collecting layers of sand and mud on beaches,
mud flats, and at the bottom of ponds, lakes and seas. The unassembled apparatus is
shown at the left; its use in collecting is explained in the successive illustrations in Figs.
1 and 2, reading from left to right. All the operations except the last must be performed
at the time of collecting. The last operation may take place in the laboratory. The
rectangular collecting box, with two sides missing, is forced into the sand or mud. The
two missing sides (gate and loose bottom) are then inserted, as shown above. To insert
the loose bottom the adjacent sand is pawed away.
Fig. 2. See also Fig. 1. After the sample of sand is removed from the bottom, it is
placed in a holder having three thin metal slides (1, 2, 3), that can be forced through the
sand parallel to each other, thus cutting it into four layers; in this case each layer is
5 mm. thick. After the slides are forced home, as shown at the right, the loose bottom of
the box is removed, disclosing the lowest layer of sand, 5 mm. thick. This is washed
into a beaker and treated as desired. The top of the box has fine perforations in order to
allow the supernatant water to escape without disturbing the top layer of sand or mud.
To prevent the possible escape of small organisms, this perforated top may be further
covered with the finest bolting silk, stretched on.
Averaging the figures from the two collections mentioned above,
it will be seen that, if they are typical collections, the beach sand
examined carried about 3,742,000,000 nemas per hectare in the top
20 mm., or about 1,500,000,000 per acre. In 1916, but earlier in the
summer, an examination of the same beach showed at least 1,040,000,-
000 per acre in the topmost inch of sand.
THE AMBULATORY TUBES AND OTHER FEATURES
of the ncma
DRACONEMA CEPHALATUM
CONTRIBUTIONS TO A SCIENCE OF NEMATOLOGY XXII 1
BY N. A. COBB
There is no adequate published description of the locomotion of
Draconema and its numerous marine relatives ; very few persons have
ever witnessed one of these nemas perambulating its natural sub-
stratum.
Draconema moves much after the manner of the ordinary inchworm,
or measuring worm. The caterpillar called the "inchworm" has two
bunches of feet, a bunch near each extremity. Standing on the bunch
of hind feet, it stretches forward and takes hold with the front bunch.
Then, releasing the hind bunch, it draws the body forward into a loop
so that the posterior bunch may attach itself near the front one.
Loosening the front bunch, the caterpillar again stretches forward,
etc.
It is convenient to speak of the two attachment organs of the adult
Draconema as "soles." The method of attachment of these soles to
the substratum in Draconema is very different from that of the inch-
worm. The sole of Draconema is armed with projecting hollow setae
connected with internal glands supplying a sticky and, presumably,
non-water-soluble secretion, and it is by the aid of this secretion
emerging from ends of the hollow setae that the sole is attached.
Reprinted from the JOURNAL OF THE WASHINGTON ACADEMY OF SCIENCES, Vol. 19,
No. 12, June 19, 1929.
414
THE MAIN SOLE OF DRACONEMA
X200
Junint
sfflrac....
set irar
fh tst asrsoa
Fig. 1. Male Dra-
conema cephalatum,
showing the two soles
armed with ambula-
tory setae. One of
the setae is shown
below more highly
quirt magnified, set amb.
The labial sole is very
much the smaller.
rnt
dm
sir rm
sd<jilil6! s>1 naib
him in A glance at Fig. 1 will enable the reader
at once to understand the posterior "sole"
of Draconema cephalatum. It is of con-
siderable extent, occupying most of the
posterior fifth of the ventral surface of the
body, and is characterized by very obvious,
longitudinal groups of curved ventrad
setae.
The much smaller anterior sole is very
near the front of the head on the dorsal
mill f side, and is characterized by setae, smaller
than, but similar to, those of the other
sole.
The main sole. Favorably stained speci-
mens exhibit the structure of the am-
S1 //, bulatory adhesion tubes, as well as of the
associated multicellular ventral glands ar-
ranged in a long ventral group opposite to
and a little in front of the major sole.
Each adhesion tube connects, at its base,
with a duct that leads to a separate gland.
The anterior pair may be taken as typical
of any group-member of this compact
f composite series of glands (see Figs. 1 and
; 2) . This anterior pair is sometimes more
distinctly separated from the general mass
of the glands than are any of the subsequent
THE MINOR OR CEPHALIC SOLE
415
pairs or groups ; and each of these two glands proves to have three nuclei.
(See Fig. 2.) The cells of each gland, as well as their spheroidal
nuclei, increase in size from front to back, the anterior, i.e., distal,
cell having less than one-eighth the volume of the posterior; the
nucleus in the small anterior cell is also less conspicuous. This group
(pair) of glands is more or less clavate in form and is nearly as long as
the corresponding body diameter. Posteriorly, each gland diminishes
suddenly in diameter to form a duct about half as wide as one of the
adjacent annules of the cuticle. Near the gland the wall of the duct
contains somewhat elongated nuclei of considerably smaller size than
the nuclei of the glands. The duct also lacks the
granular character of the glandular cells themselves.
The two ducts, at first ventral, diverge backward
to the two foremost adhesion tubes, and are one to
two times as long as the glands. Near where a duct
enters the somewhat swollen base of an adhesion
tube, there is a small duplex enlargement or ampulla.
In the specimens under examination, only in the very
basal portion of the adhesion tube is there any
indication of the staining action of the acid carmine.
The numerous glands composing this ventral
series are so closely packed together that, as a rule,
it is difficult to distinguish the exact number of
groups, but it is evident that throughout the series
the glands are arranged in groups side by side,
apparently mostly in pairs or quartets, the number
of glands being commensurate with the number of
adhesion tubes. On occasions when the entire
group of glands is slightly separated from the body
wall, and therefore from the bases of the adhesion
tubes, the ducts leading to the tubes are distinctly
visible, and have the appearance, when viewed
laterally, of a rather complicated plexus.
The minor, or cephalic, sole. The dozen or so
adhesion tubes and glands of the cephalic sole have
the same general plan as the sublateral and sub-
ventral ones of the posterior sole just described.
The glands connected with the cephalic tubes
(gl. pint) are located mainly dorsad in the anterior two-fifths of the
neck between the oesophagus and the body-wall; there are two dorsally
mi!,
Fig. 2. Anterior
ambulatory seta of
D. cephalatumvrith
its 3-celled gland,
its 3-celled mate
concealed, though
part of its duct
shows, del snst.;
som, body wall; cl
msc, somatic mus-
cle; an cut, cuticu-
lar annules; mur
ext and rwwr int,
outer and inner
walls of ambula-
tory tube; os tb,
secretory pore.
416 THE AMBULATORY TUBES
sublateral groups of glandular cells and four subdorsal groups, cor-
responding to a similar grouping of the six pairs of adhesion tubes.
The glands of the cephalic sole are sometimes rather more strongly
stained than those of the posterior sole in the same specimen, but
present the same general anatomical and histological structure.
Referring to the dorsally sublateral cervical glands as examples (see
Fig. 1), these are distinctly granular in structure and apparently
duplex, that is, have a well marked constriction near the middle, on
opposite sides of which, fore and aft, is a considerable volume of
nuclear (?) matter; the remaining portion of the cells is rather coarsely
granular, the granules measuring nearly l/j. in diameter. This duplex
glandular mass is hah" as long as the neck and anteriorly tapers to a
tubular portion not much wider than one of the cervical annules.
This narrow portion of the gland in turn tapers to a very narrow duct
about 2ju in diameter, which swells to form a fusiform duplex ampulla
as wide as one of the coarser cervical annules. The ampulla empties
forward through a short narrow duct, 1 to 2 /j. wide, directly into the
base of the corresponding adhesion tube, where a little stained matter
may usually be seen. The adhesion tubes reach exactly to the lips,
so that their outpour is practically terminal. All these details are
shown on a small scale in Fig. 1, ampullae reduced to two dots.
The distal extremity of the ambulatory tube is somewhat bell-
shaped, and the lumen of the tube is prolonged into the cavity of the
bell through a short conoid extension. The significance of this bell-
shaped structure remains more or less problematical. No elements
have been seen in the tube, or hi the bell, that could be regarded as
contractile, and one therefore seems obliged to assume that whatever
changes of form are exhibited by this bell-shaped structure are due to
such factors as its own elasticity, the pressure of the internal secretion
and counter pressure of the external water. It would seem advan-
tageous to the nema if the secretion which flows out through the bell-
shaped organ could be "cut off" at will, and it is conceivable that this
bell-shaped affair in some way accomplishes that end. Again, it is
conceivable that the bell may mechanically give to the end of the tube
a greater adhesiveness, conceivably through suction, a suction that
might be made to vary with the relationship of the distal end of the
tube to the substratum, as in the familiar elastic concave rubber
suction disc.
The facts that the setae of the inner rows are always the shorter,
and that all the setae are incurved, suggest that a suitable substratum
may be a microscopic filament, or a thin edge of something. This
INTERNAL ANATOMY 417
thought arises from the fact that the main sole appears "bow-legged,"
as it were. Such apparently suitable thin and narrow forms of sub-
stratum occur on certain marine algae and, as a matter of fact, at
least two observers Cobb and Chambers have seen Draconema per-
ambulating the surface of algae.
In balsam specimens from Hudson Bay the body-wall tissues sur-
rounding the mouth-opening have a golden yellow color and take on the
form of a six-parted, but twelve-pointed, star.
Probably the excretory pore is at the lips. I formerly referred to a
cell just behind the cardia as possibly representing the renette; this
suggestion may not be well founded. In this region I observe two of
these cells lying side by side in sub ventral position (see Fig. 1), sepa-
rated by a small space. In the same latitude, just behind the minute
cardiac cavity, on each side of the intestine, there is a rather compact
group of granular cells containing about a dozen nuclei. These groups
are as long as the corresponding body diameter, and about half as wide
as long. Between the two groups, on the dorsal side, there is a pair of
subdorsal granular cells rather closely resembling the subventral ones
just described. As to the function of these lateral groups of cells, it
seems not impossible, as they are free at their posterior ends and seem
connected with the intestine anteriorly, that they may be special
glands associated with digestion. There is a similar pair of lateral
groups of cells in front of the cardia, emptying (?) backward. I do
not think the possibility is excluded that some of these cells are nerve
cells.
The intestine is composed of cells of such a size that about six are re-
quired to complete a circumference. The thin refractive lining is hardly
1 n thick. The cardia, as usual, presents a distinct group of closely
packed nuclei, indicating that it is composed of cells of rather small
size, of which the number is probably about fifteen to twenty. Notable
is the presence of scattered cells in the wall of the intestine which stain
differently from their neighbors. These, no doubt, discharge some
special function. Thus far they have been observed only in the an-
terior portion of the intestine.
The portion of the neck opposite, and adjacent to, the oesophageal
constriction, except such portion as is occupied by the glands of the
minor sole, is rather closely packed with nerve cells.
The lateral fields are one-third as wide as the body and contain
a considerable number of nuclei rather irregularly arranged.
The cuticle in the posterior region of the tail is traversed by ra-
dial elements that give rise to a finely punctate appearance on
the surface (see Fig. 1).
418 GONADS. NOMENCLATURE
An interesting observation is the apparent connection of the tandem
group of three caudal glands with the dorsal field by means of a narrow
strand running forward, possibly of a nervous character, as is sug-
gested: 1, by its form and position; 2, by its size and structure.
The internal extremity of the gubernaculum lies near the body axis
and is connected fore and aft with the ventral body-wall by slender
strands of muscular tissue. The testis is now believed to be reflexed,
not outstretched as formerly figured.
The broad, rapidly tapering ovaries, the anterior lying to the right,
the posterior to the left, are reflexed to nearly opposite the vulva and
contain comparatively few ova, arranged in single file in the wider
part, elsewhere irregularly. Hundreds of subspherical sperm cells
may occur in the uterus. Usually there is one egg at a time in the
uterus, thin shelled and smooth, and deposited before segmentation
begins. The eggs are three-fourths as wide as long and about two-
thirds as long as the corresponding body diameter.
Some of the results of the present investigation have been more or
less definitely forecast by various observers on several occasions,
notably by Steiner and Irwin-Smith, both of whom from inadequate
material, have, with admirable insight, suggested the probable con-
nection of the adhesion tubes with internal structures and also the
possibility of the glandular nature of these latter.
While no doubt now remains that both the major and minor soles
are glandular and are organs of locomotion, it still seems to me quite
doubtful whether we fully understand the bodily structure of Dra-
conema. The form of the head and neck and other parts do not seem
to be explained merely on the basis of the use of these two "sticky"
soles in locomotion. There probably are other unknown factors play-
ing a part in the activities of Draconema that will further explain its
highly peculiar and interesting structure. 2
J Nomenclature. The proposal of the genus Draconema in 1913 appears reasonable
in view of the fact that at that time the published descriptions of the species belonging
to its family, though in no case as complete as desirable, indicated the existence of two
(or more) genera, the type species of one of which should be that originally named by
Claparede Chaetosoma ophiocephalum 1863 (not Chaetosoma Westwood, 1851, Cole-
optera). Draconema cephalatum, was then, and continues to be, thought generically
different from Claparede's ophiocephalum. The name Chaetosoma, being preempted,
should be replaced by its synonym Notochaetosoma Irwin-Smith 1917. Should the opin-
ion prevail that all the described forms of the family belong to one genus, then the
oldest synonym for Chaetosoma would be Draconema, and should be substituted. In
that event, the family name would naturally become Draconematidae; in any case, it
seems likely that Draconema is a better representative of the group than the only other
genus so far proposed, Notochaetosoma.
Draconema cephalatum is cosmopolitan, and seems to have been described by several
different authors under as many different specific names, e.g., annulatum Ditlev.,
haswelli Irwin-Smith. hibemicum Southern.
OBSERVATIONS ON THE MORPHOLOGY
AND PHYSIOLOGY OF NEMAS
Including notes on new species
CONTRIBUTIONS TO A SCIENCE OF NEMATOLOGY XXIII
BY N. A. COBB
1. A NEW SUBGENTJS OF RHABDITIS
There is a group of slender-tailed amphigonic rhabdites having
lips and pharynx as shown in Fig. 1, the males of which have weakly
developed bursas. Such rhabdites have been described from time
to time but no author seems to have had adequate material for a
completely satisfactory description. Having examined living speci-
mens of both sexes of a new species of this group I took the occa-
sion to prepare a fuller description of it, and propose it as the type
of Rhabditella, a new subgenus of the genus RhabditJs Dujardin.
Rhabditis (Rhabditella) leptura n. sp .
Thin layers of the transparent, colorless, naked cuticle are traversed by
excessively fine, plain, transverse striae, resolvable only with the highest
powers. Longitudinal striations, due to the attachment of the musculature,
are visible in most regions of the body. No deirids have been observed.
The neck is very slightly conoid. The cross section of the pharynx is
roundish-triangular; yet the almost imperceptibly sigmoid pharynx is nearly
equidiametral throughout, though anteriorly the walls are a trifle more
strongly refractive. The glottis is a trifle oblique, but otherwise fairly typical.
The oesophagus presents a median, fairly prominent, ellip-
soidal swelling, or bulb, two-thirds as wide as the middle of the
neck, and a somewhat ellipsoidal, or obscurely pyriform pos-
terior bulb two-thirds as wide as the base of the neck, both
swellings of approximately the same diameter. The median
swelling presents an elongated, obscure but rather large,
valvular apparatus, while the cardiac bulb presents a rather
strongly refractive, somewhat three-fold, striated valvular ap-
paratus, located a little in front of the middle of the bulb. At
the nerve-ring the oesophagus is one-third, and in front of the
cardiac bulb about one-fourth, as wide as the corresponding
portion of the neck. There is a distinct cardiac collum con-
stituting a rather broad constriction, so that the anterior
portion of the intestine through a distance nearly equal to one ..... _____
body-width enlarges from about one-third to five-sixths as Fig L Front and
wide as the body. This appearance, however, is somewhat ^f^^fj^l
variable. The nerve-ring surrounds the oesophagus obliquely, hptwa. Thebegin-
The intestine, the lining of which is somewhat refractive, is ^Vlhown 15 P the
made up of cells of such size that probably only about two lower illustration.
are presented in each cross section; these cells contain granules
of variable size, which are not strongly birefringent. With crossed nicols
there is no suggestion of a St. Andrew's cross; not at all like the strong
birefringence of R. monohystera. The posterior Up of the anus is very slightly
raised. The rectum, whose lining is only slightly refractive, is one and one-
Reprinted from the JOURNAL OF THE WASHINGTON ACADEMY OF SCIENCES, Vol. 19,
No. 13, July 19, 1929.
420
MALE RHABDITIS (RHABDITELLA) LEPTURA
third times as long as the anal body diameter. The vulva is slightly de-
pressed, though its lips are slightly elevated. The ovaries extend two-thirds
the distance back to the vulva, and are only about one-
sixth as wide as the body of the female. The smooth, thin-
shelled, ellipsoidal eggs, about as long as the body is wide and
two-thirds as wide as long, have been seen in the uteri one at a //
time. Their yolk is made up of closely packed, faintly refrac-
tive, spherical granules, scattered among which are a few
exceedingly small granules less than one micron in diameter.
*"?" ""La/ "^4! ".2"VS,3.iL >61mm There are two, equal,
separate spicula. The nema must be tipped a little in order
to bring the slightly developed obscure bursa into profile view.
The foremost papilla, or bursal rib, is somewhat variable in
position and is sometimes found nearly as far forward as the
proximal ends of the spicula. Fig. 2.
The testis is reflexed at its free end for a distance equal to
about two body diameters. This portion of the testis is only
about one-fourth as wide as the body, though it is very slightly
swollen at its extremity. Behind the flexure for some little
distance the testis still remains narrow, only a little wider
than the reflexed portion lying alongside. Then, however,
it rather suddenly enlarges and soon becomes half as wide as
the body and so continues, enlarging slightly, however, for
three or four body widths. In this portion of the testis the
spermatocytes pass through their growth period; they appear
as if in two rows and in pairs side by side, and one gets the
impression that these pairs are twin cells. Their nuclei are
large, becoming at last half as wide as the elongated sperma-
tocytes themselves, i.e. one-fifth as wide as the nema About
halfway from the blind end of the testis to the anus the full
grown spermatocytes, here half as wide as the body and
about as long as wide, apparently break successively into
quartets, the resulting subspherical cells being a little more
than one-fourth as wide as the body. For a distance equal
to about two body diameters forward from the spicula the
sexual organ is narrower, about one-third as wide as the
body. Whether the cells of the quartet divide further remains
unknown.
Examination of one of the members of a quartet indicated
the probable presence of about seven chromosomes.
Habitat: Decaying fruit of luffa acutangula from Tela,
Honduras, October, 1926. Sent by Horace S. Dean.
Diagnosis: Rhabditella subg. nov. Rhabdites having lips
and pharynx as shown in Fig. 1, the males of which have*
weakly developed costate bursa and long slender tails.
Diagnosis: Rhabditis (Rhabditella) leptura n. sp. Rhab-
ditellas dimensioned as shown in the formulae; male with
two separate spicula, a simple inconspicuous gubernacu-
lum, and with nine bursal ribs arranged as shown in Fig.
2; phasmids present.
'In
p/i.w
Urn
X750
OXYURIDS OF MILLIPEDS
421
int.
2. MYOLABIA ON A NEMIC PARASITE OF MILLIPEDS
The front view of the lip region of Thelastoma attenuatum Leidy, a nema
from the intestine of the milliped Sporobolus marginatus, gives the impression
at first that there is a circlet of 10 "lobes" surrounding the usual three
lips. Careful scrutiny shows that two of these ten
lobes, the lateral ones, are the external amphids.
This leaves 8 other lobes arranged in 4 submedian
pairs.
A similar condition exists on another, and new,
species of Thelastoma occurring in the same host, ex-
cept that in this new nema the amphidial lobes do not
so closely resemble the other 8. Fig. 3. In the new
species the first slice behind the lip
region discloses the anterior parts of 8
muscular fields that extend throughout
the body, as may be shown by cross
sectioning. Fig. 3. Furthermore, it is
quite evident that the 8 labial "lobes"
are the external cephalic expression of
these 8 longitudinal muscular fields.
It is therefore very interesting to find
that in a second new species of Thelas-
toma, belonging to a new subgenus and
infesting a different host (namely the
milliped Fontaria marginata Say, as
found in Virginia, U. S. A., near the " X 175
District of Columbia) the 8 organs which g^ 4 and Fl ^S f f
in Thelastoma attenuatum are rather in- Tkeiasiom
conspicuous lobes surrounding the true
lips, have entirely displaced the f .i. f /
ordinary lips, forming a lip region '
prominently set off by constric-
tion, and consisting of 8 prominent
subequal contiguous parts folded
completely together over the phar-
t ynx and constituting lips of a new
Fig. 3. Measurements, front r -
view of the lip region and near- SOrt.
by cross-sections of Thelastoma
(Thelastoma} spicatum n. sp.
Figs. 4 & 5. This
F resents, in cross-section,
muscular fields. Fig. 5.
These lips may be called pseudolabia; or, because of
their connection with the longitudinal muscular fields of
the nema, myolabia. No cephalic papillae have as yet
been seen on these myolabia.
Diagnosis. Thelastoma (Thelastoma) spicatum n. sp.
Much like T. attenuatum Leidy, but smaller and with
shorter spicate tail and more completely differentiated,
though still rather vague, myolabia. Dimensioned as
shown in the formula. Fig. 3. Attenuatum and
spicatum may occur together in the intestine of the mil-
liped, Sporobolus marginatus.
Diagnosis. Thelastomellum subg. nov. Thelastomas
with 8 well-developed myolabia as in Fig. 5. Type
species T. myolabiatum n. sp.
myoiabiatum spec.
422
SYNGONY IN OXYURIDS
Diagnosis. Thelastoma (Thelastomellum) myolabiatum n. sp. Dimen-
sioned as shown in the formula, and with lips and amphids as in Fig. 5.
3. SYNGONY IN A NEW NEMA FOUND IN MILLIPEDS
Hitherto undescribed nemic parasites found in the intestine of the milliped
Fontaria marginata Say and belonging to the genus Thelastoma Leidy,
prove syngonic. Thelastoma would be assigned by
most authors to the group Oxyuridae.
The discovery of syngony in this group opens up an
interesting field for speculation and research. It has
long been felt that the "Oxyuridae" present many
resemblances to the rhabdites. The gonism of the
rhabdites has been found very varied, particularly
through the researches of Maupas. Query: To what
extent, now, will the variations exhibited by the
rhabdites be found to occur in the "Oxyuridae?''
Male "oxyurids" usually are less common than the
corresponding females, quite frequently are rare, and
in some cases are unknown. The striking nature of
the recorded sex ratios has been explained by saying
that the males, being very much smaller, are easily
overlooked, and that possibly they die soon after
copulation; and that these two factors, their small-
ness and (assumed) relatively early death, account
for their supposed rarity.
In the rhabdites the evidence fully warrants the
matic'drawf^of'tiTfe^ vi ew that syngony has evolved from amphigony with
male gonads of ^Thelastoma a gradual diminution or disappearance of males;
" for many stages between the two extremes still exist
as evidence of the possibility of such a change. There-
fore the discovery of syngony in the "oxyurids" at
once suggests a new explanation of the scarcity of
"oxyurid" males, namely, the one now usually accepted
in many cases for the rarity of male rhabdites. If
this be true of the "oxyurids," it may have a con-
gonicspermsof sHWoSomd- siderable bearing on veterinary and medical questions
lwm ' connected with "oxyurid" parasites in man and
domesticated animals, and in other hosts.
Species that have been assigned to the "Oxyuridae" are common parasites
of insects and some other annulata.
inl
ordct
iX40 an.
(right), sp. the. sperma-
theca.
THE DEMANIAN VESSELS IN NEMAS OF THE
GENUS ONCHOLAIMUS
With Notes on four new Oncholaims*
CONTRIBUTIONS To A SCIENCE OF NEMATOLOOY XXIV 1
BY N. A. COBB
Continuing the work of deMan, 1884, and zur Strassen, 1896, observations
have been made on Ad&ncholaimus fuscus (Bastian), Metoncholaimus pris-
tiurus (zur Strassen) and other Oncholaims (listed on p. 425) with particular
reference to the system of tubular organs discovered by deMan. Building
on the foundation laid by these eminent observers, it has been possible to
define the demanian system, and, within limits, assign it a function. The
following definition and table of homologous terms, together with the accom-
panying text appreciably advance our knowledge of this remarkable system
of organs.
DEFINITION
Demanian Vessels: In adult female nemas (Oncholaims) a complicated
double system of efferent tubes; connecting, (1), with the middle or posterior
part of the intestine through an osmosium (see p. 428), and (2), with the
uterus (or uteri); these two efferents being confluent at a special glandular
"gateway," the uvette (see p. 427), and emptying thence backward and
outward, through one or two ducts having more or less moniliform affluent
glands (see p. 426, Fig. 1). Normally, the ducts lead to exit pores in the
body wall, usually laterad, one or more on each side, near the base of the tail.
In certain cases at least, apparently homologous tubular organs connect
with the gonad of the male near the beginning of the vas deferens. For
example, in Metoncholaimus pristiurus, Adoncholaimus fuscus and Oncho-
* Investigations carried on in part at the U. S. Fisheries Biological Station, Woods
Hole, Mass. The abbreviations used are mostly self-explanatory; e.g. onch dsl, (on-
chium dorsale), dorsal tooth. Full list of abbreviations on p. 341.
1 Reprinted from the JOURNAL OF THE WASHINGTON ACADEMY OF SCIENCES, Vol. 20,
No. 12, June 19, 1930.
423
424
ORIGIN AND TERMINOLOGY OF THE DEMANIAN SYSTEM
laimium appendiculatum I observe a tubular glandular vessel, outstretched
forward and emptying backward into the vas deferens, that appears homol-
ogous with parts of the better known demanian system of the females. See
Fig. 2.
In female nemas the functioning demanian vessels (e.g. pristiurus) elabo-
rate a copious, elastic, sticky, non-water-soluble, nearly colorless secretion,
possibly utilized ("spun"?) during agglomeration and copulation, and also
presumably to protect and preserve the batches of eggs after deposition and
during segmentation.
The demanian organs seem to prevail in mud-inhabiting, and sand-inhabit-
ing oncholaims, i.e. those of stagnant habitat; and to be absent or less
prevalent in oncholaims living in more thoroughly oxygenated water, on the
surface of eelgrass, and among algae, e.g. in Prooncholaimus Micoletzky,
1924.
Origin. As to the primitive nemic tissue from which the demanian vessels
may have originated, we seem driven to accept the primitive gonadic tissue as
the probable source. The histology of the demanian system reminds one
most strongly of the structure of nemic gonads; most of the histological
elements known in the demanian system have homologues in the gonadic
system of nemas; while on the contrary there is no such tunic, and there
are no such forms of nuclei, known in connection with the enteron.
Equivalent terms of various authors
Author, de Man
Author, zur Strassen
Author, present
Rohrenformiges Organ
Organe tubiform
Rohrenformiges Organ
Demanian System
Hauptrohr (fuscus)
Canal principal (albidus)
Stammrohr
Enteric efferent
Verbindung zur Stiitze
Blindes Vorderende
Offene Verbindung
Mundungsorgan
Osmosium, or Selective demanian
intake (enteric)
Verbindungsrohrchen zwischen
Warze und Uterus
Tube de communication
No mention
Uterine efferent
Ausf iihrungsgang in den Uterus
Blindgeschlossener Sack
Demanian intake (uterine)
Warze
Papille ovulaire
Rosette
Uvette
Rothbraune drusen (fuscus)
Tubes latereaux (albidus)
Endschlauch des Rohrorgans
Moniliform Glands
DIAGNOSES OF THE GENERA AND SPECIES MENTIONED HEREIN
ONCHOLAIMINAE Filipjev, 1918 and 1925
(but without Anoncholaimus, Pelagonema, Anoplostoma, Trilepta, Krampia.
Filipjevia.)
DIAGNOSES OF VARIOUS ONCHOLAIMS 425
ONCHOLAIMIUM, n. gen.
Monodelphic Oncholaiminae with demanian system, whose males have a
versatile, preanal, ventral appendicule. See Figs. 2 and 3.
Oncholaimium appendiculatum, .*.-?. -.9 *?. ff'.T*-;
n. sp. Oncholaimium with appar- *.... . j. W. i2M_ oo!r
ently deteriorated moniliform *** ' ** '- 1 '" " THr"""",^ "iS**^**
glands without exit pores, and with very simple ampulliform uvette. Appen-
dicule "hinged" and mobile. Figs. 2, 3, 8, 9. Moniliform glands 24-fold,
(8 + 16). Exceptionally 32-fold.
Oncholaimus nigrocephalatus ft. .J.4 to*. ***as. or.
, . . , ao / 1.6 "1.9 22 an """
n. sp. Oncholaimus with very 1? ^ ia iaM_ 00.2
slightly compound, non-refrac- '** ' *** ** *- 5 i-'i. >3 - 4im "
tive uvette, pigmented head, and hemispheroid, immobile, preanal, ventral
male supplement; demanian system with two rather inconspicuous exit pores,
eachlaterad; cells of the rouleaux (moniliform glands) oblique, little flattened.
Oncholaimus serpens, n.sp. On- f*-T. ?*. .: ."!?*-. ^^>43 mm
cholaimus whose moniliform o!z T! 12. .***_ pro
glands are vaguely seriated but not a6 ' *' *' "^ *
in rouleaux. Compound uvette not condensed and refractive.
Metoncholaimus pristiurus (z. ?. *?* !*:
Str.). Specimens from Woods o'.a w 11.
Hole gave the opposite measure- 0-a ' ** w
ments. Moniliform glands 64-fold.
t i j 7 . . 1.1 T.T IT. *33.* OS 3
Adoncholaimus pamcus, n. sp. jia/""."a a.j a.i" i'.g^ 4 - 1 """
Adoncholaimus having a transverse row of seven demanian exit pores on each
side. See Fig. 7.
Adoncholaimus fuscus (Bast.). Moniliform glands 8- or 16-fold, see Fig. 1 .
One soon appreciates the weight of zur Strassen's words where he says,
in speaking of the demanian system of various oncholaims, "In fact, the
differences are such that, were they equally pronounced in any other system
of organs, they would lead to the proposal of separate genera, or even families."
In this connection the present studies lead to the belief that the demanian
system not only varies markedly in the different groups of oncholaims, but
that in all probability the system is present but has been wholly overlooked in
many of the forms described. Hence it seems premature to attempt a com-
plete subdivision of the oncholaims into genera and subgenera. It may be
doubtful whether the genera and subgenera so far proposed are natural ones.
In particular, Oncholaimus, the group connected with the type species
atte?iuatus, seems chaotic; yet no better course appears, at present, than to
leave serpens and nigrocephalatus in this ill defined group:
426
UTERINE EFFERENT
w dct:
uwtte
int
Fig. ! Amended diagrams of the demanian system of
M etoncholaimus pristiurus (dorsal view) and Adoncho-
laimus fuscus (side view), modified from the diagrams
of zur Strassen and deMan respectively, eff int,
enteric or intestinal efferent; eff ut, uterine efferent;
vlv, vulva; ov dct, oviduct; gl cdl (3), the three caudal
glands; gl monl, the moniliform glands; porus, exit pores
of the demanian system. Notice that in each case the
uvette empties through a minute pore, the uvette pore.
The moniliform glands in pristiurus are 64-fold; in
fuscus 8- or 16-fold.
Uterine Efferent. An examination of Met-
oncholaimus pristiurus (zur Strassen) furnishes
convincing evidence that the interesting female
organ described by zur Strassen is connected not
only with the intestine, as he discovered, but also
with the uterus by means of a tube (see eff ut,
Fig. 1) extending forward from the uvette, i.e.
from the "rosette" of zur Strassen. The evidence
is as follows: In many female specimens it is
possible behind the vulva to follow backward
from near the vulva a long, narrow, apparently
(not really) vacant space, reminiscent of the
uterine efferent of Oncholaimium appendiculatum
(see Fig. 3) which on more careful examination
proves to be a duct. This duct, however, is not
so refractive or of such uniform diameter as in
appendiculatum, and is even more difficult to see.
It varies slightly in diameter. Here and there
throughout its length it can be seen to have a thin,
double-contoured wall containing small but
definite, much elongated nuclei. This tube is
usually in a collapsed condition, more often pre-
senting its edge toward the observer, but some-
times not. When it is presented edgewise, one
may often detect in its thin wall the scattered
elongated nuclei, especially in specimens fixed
and stained in acetic acid methyl green; occa-
sionally nuclei can be seen also in other views.
Examining the requisite number of specimens
leads to the conclusion that from the uterus near
the vulva the duct arises dorsad as a broad tube,
directed backward, which narrows rapidly and ex-
tends along the right side of the nema, approxi-
mately along the right lateral chord though
not necessarily exactly opposite, and, expanding,
joins and envelopes the uvette. See Fig. 1.
UVETTE 427
Uvette*. The "warze" of deMan, i.e. the "rosette" of zur Strassen, is
the structure to which I apply what seems the more appropriate name
"uvctte." Comparisons show that, notwithstanding the very marked dif-
ferences in form, the various organs herein called uvettes are homologous;
the same is true of those called monil form glands.
The uvette of Adoncholaimus fuscus (Bastian) as illustrated by deMan
probably presents 32 elements (Kornchen, deMan's Fig. 29) as does that of
M . pristiurus; these elements have been outlined by deMan and figured some-
what more in detail by zur Strassen (deMan's Figs. 24, 29; zur Strassen 's
Figs. 13, 14).
In favorable specimens I have seen the uvette of fuscus to be a "radial"
structure made up of about 32 elements surrounding a minute pore, somewhat
as in the uvette of pristiurus, (See Fig. 1) but the elements here are far less
refractive. Rarely can one see the appearance illustrated by deMan in his
figure 29; whereas the appearance he does not satisfactorily illustrate, a
very complicated one, by the way, is the usual appearance; and when this
appearance is more pronounced, commonly the minute refractive "Kornchen"
that deMan figures are not to be seen, or only some of them faintly. DeMan's
"Kugel," figured by him as if nearly round, I find seldom round or ball-shaped;
frequently it is so "collapsed" (?) as to be difficult to see at all, and it is more
likely to be elongate or ellipsoidal, or perhaps flattish-ellipsoidal, than to be
equidiametral as shown in deMan's Fig. 29.
DeMan does not give a thoroughly satisfactory description or figure of
his "Warze." In one of his figures (Fig. 29) I count 33 minute, circular, dot-
like elements where he makes his "Verbindungsrohrchen" join the "Warze."
Occasionally I also see this appearance, and with about the same number of
elements (32?). It is difficult to say as yet what the exact function of the
uvette is, but it seems a regular, doubtless glandular, component of the
demanian system. In Oncholaimium appendiculatum the uterine vessel,
extending backward from the uterus, nearly as described for pristiurus,
finally expands a trifle into a small, often rather indefinite, ampulliform
uvctte of the very simplest character, which joins the right subdorsal of the
two longitudinal series of cells, the moniliform glands, by means of a
minute refractive pore, the uvette pore. See uv, Fig. 3. In Oncholaimus
nigrocephalatus the uvette, which in 0. appendiculatum appears as a simple
ampulla, becomes somewhat compound; that is to say, two additional or
subordinate elements occur, one on either side of the main "ampulla," so
that the whole is rather obscurely triplex.
In another oncholaim, Oncholaimus serpens n. sp., the uterine tube extends
backward just as definitely as in Oncholaimium appendiculatum and joins
the rest of the demanian system in the form of an expanded and much larger
* Uvette ; a diminutive cluster. From latin, uva, a cluster of grapes.
428
MALE ONCHOLAIMIUM. OSMOSIUM
uvette, rather closely resembling one of the uvettes of
* Adoncholaimus fuscus. In 0. serpens the elements are not
u nearly so refractive, and the somewhat pyriform whole is
so symmetrical ; but it is made up of radiating elements
" l * arr having some resemblance to those composing the uvette of
P (K pristiurus.
ili i nn isi not sfunct or sum .nit , sub ail Osmosium. Moniliform
..mesa glands. In addition, I
.din/M have established to my
satisfaction that the main
tube of the demanian sys-
tem in Adoncholaimus fus-
cus, which was described by
deMan as probably being
merely fastened anteriorly
to the intestine, and there-
fore regarded by him as
probably merely a holdfast,
is in reality in communica-
tion with the intestine by
means of what I have
called an osmosium.* It
has much the same struc-
ture as that described by
zur Strassen for Metoncho-
laimus pristiurus and M.
deMani (zur Strassen, Figs.
4 to 12), and which I
have examined in pris-
tiurus, except that there is
no open communication.
There are no essential differ-
ences in the structure of
& & the enteric junctions of the
arson silmit' 'tut nsrsm
Xig.2.Ma.leOnchclaimiumappendi- * Osmosium; that part of an
culatum n.g.,n.sp., drawn from a fixed emunctorium or analogous or-
and stained balsam specimen. The gan through which, mainly by
locus of the cross section drawing is osmotic action, soluble matter
ar shown at locusx-sec. ac gon, accessory is transferred from one organ to
to gonad; al'm'nt, food material; another. The osmosium is
appndl, appendicule; chrsm hap 14, here not emunctorial. It is
.one haploid number of chromosomes ; jnc still doubtful whether the os-
aasff ^ s '> J unc ti on f testes; ncll spmct, motic cells in this particular
nucleolus; ncl spmtd, nucleus of case are of enteric or deman-
srtaiha.L' spermatid; orginq, organs of uncertain ian origin. While the staining
function; os ac gon, mouth of accessory of these cells seems to favor de-
to gonad; spmct, sprmatocyte; tst manian origin, the structure
(175 ant, front testisjr, its cross-section, seems to favor enteric origin.
FEMALE ONCHOLAIMIUM. MONILIFORM GLANDS
429
various oncholaims I
have examined, except
minor ones in the more
or less, but very ob-
scurely, radiating part
that sets into the wall
of the intestine. This
part forms an "os-
motic" exit through the
the intestinal wall in
the shape of special,
presumably metabolic
and at least selective,
glandular tissue of the
osmosium.
In the species Oncho-
laimus nigrocephalatus
there are external lat-
eral exit pores in the
anal region much as in
pristiurus but they are
minute. Thus far, how-
ever, I have searched in
vain for these pores in
Oncholaimium appen-
diculatum.
In this latter species
there are two monili-
form subdorsal series of
24 cells each which I
propose to call monil-
iform glands. These
are rather close homo-
logues of the 64-fold rou-
leaux of zur Strassen;
less obviously, of the 8-
or 16-fold "Rothbraune
driisen" of deMan. The
uterine vessel joins the
right hand one of these
moniliforrn glands, as
is shown near the mid-
dle part of figure 3
on this page, at uv.
Fig. 3. Female of Oncholaimium
appendiculatum n.g., .n.sp., drawn
from living specimen under slight
pressure. The uterine efferent is
shown from where it joins the uterus
at ut eff to where it joins the right
moniliform gland at uv, the uvette;
gl monil, moniliform glands; gl
dxt, the right hand moniliform
gland; gl sns, left hand moniliform
gland; crystal, tetrahedroid (?) crys-
tals on the outer surface of the enteric
efferent; eff int, the intestinal or
enteric efferent; lum ut, lumen of the
uterus; del cdl, the three caudal ducts;
chrd lat, borders of the right hand
lateral chord; amph extr, external
amphid; spm, sperm ; ncl spm, nucleus
of one of the sperms; trm ov, blind end
of the single ovary; ov tegmt, shell of
the egg; div secnd, second division of
the nucleus of
female gamete; aa/i//ixtr..
plrcyt, polarcyte;
ov in dct, much
elongated egg op/to
passing through
the oviduct from a/raaipi .
the ovary to the /
uterus; pst, pus- '
tules due to uri- ,-////r
tis; grn bifr bire- /
fringent granules '"'
in intestinal cells. / ,
nap s/m
*175
430 ENTERIC EFFERENT
In 0. appendiculatum at the posterior end of the two 24-cell moniliform
glands, however, a number of the cells of each organ seem loosened from the
series; opposite these I am unable to find any outlet whatever; that is to say,
the organs appear as if in a deteriorated condition. See gl dxt, gl snst, Fig. 3.
Perhaps causally connected with this is the extraordinary fact that the
examination of hundreds of females of Oncholairnium appendiculatum over
a number of years has failed to disclose a single healthy specimen. Every
female is attacked by a disease that often results in necrosis of the posterior
portion of the nema. (See section Uritis, p. 240). The disease (uritis)
breaks out on the tail in the shape of minute pustules having an internal
radiated, or linear and "parallel-fibered,"' structure, pst, Fig. 3, sometimes
extending forward for a considerable distance into the nema, in extreme
cases, as far forward as the vulva. There may be one, two, three, or even as
many as a dozen of these pustules irregularly scattered on the posterior part
of the female. The pustules are minute, exude, inter alia, an insoluble
material, and frequently exhibit surface bacteria, though it seems doubtful
if the bacteria thus far seen are connected \vith the disease. The uniform
occurrence of this disease in females of Oncholaimium appendiculatum may
perhaps be connected with the deteriorated (?) condition of the demanian
system. On a later page attention will be called to the fact that other on-
cholaims possessing the demanian system have what appear to be similar
diseases of the posterior extremity; but in none of them is there any such
extraordinary condition as in 0. appendiculatum, where examination has
failed to disclose a single adult female free from uritis.
Enteric Efferent. Against the idea that in Adoncholaimus fuscus the
anterior junction of the demanian system with the intestine is merely a hold-
fast, as suggested by deMan, it may be urged that of other elongated organs
known to lie loose in the body cavity of nemas, none are secured in this
particular way to the intestine. Why an exception in this case? If it is
merely a matter of security, it would seem more in harmony with known
nemic anatomy that the attachment be to the body wall rather than to the
intestine, and especially that it be effected along a lateral chord. It is not
unheard of for a nemic organ of this general form to be attached to a lateral
chord.
From a mechanical point of view the idea that the connection of the
demanian system with the intestine is merely a holdfast seems to have all the
less to recommend it in the case of the monodelphic species, such as pristiurus
and serpens, where this connection is so far caudad that such a holdfast seems
rather needless.
DeMan's idea that his main tube is simply and only fastened to the intestine
seems not borne out by facts; and his figure 25, if I understand it, admits of a
different interpretation. I find his "main vessel" anteriorly to be hollow to
NO OPEN CONNECTION 431
its very end, the "blind end" of dcMan, and that the freely moving con-
tents of the tube are visible clear to what might be called the surface tissue
of the intestine (tissue of the intestine altered, to be sure). DeMan's figure
25 seems easily to admit of this interpretation. I find the cells of the wall of
the intestine (if they be really intestinal) are altered where the vessel is
attached, and this fact suggests that we have here modified selective tissue
the osmosium, the function of which is to extract from the intestine and
usher into the demanian system, presumably mainly by osmosis, a product
utilized by the latter.
May not the evidence offered by zur Strassen for an open communication
between the enteric efferent and the intestine in pristiurus, i.e. the evidence
of his microtome sections, be capable of a different interpretation? Could
zur Strassen's sections have been deceptive? The published figures of his
"open connection" between the demanian system and the intestine are not
satisfying, in that they appear to show a large portion of the cell walls missing.
Now pristiurus ingests mud, and, in consequence, its intestine normally
contains much fine grit. Is it not likely that this grit, acting as it naturally
would during the sectioning, would damage, or even destroy, delicate cells
that, before being broken, might have closed the aperture which zur Strassen
shows and describes as an open connection? The suggestion is that this might
occur, at the time the sections were cut, through the combined abrasive
action of the grit and the coincident dulling of the microtome knife. All
zur Strassen's figures show the intestinal lumen more or less open; but when
the intestine is entirely empty and free of grit it is collapsed, not open, so that
the lumen, in well made sections, is closed and difficult to see. May not this
indicate that the vacant lumenal spaces shown in zur Strassen's illustrations
probably did contain grit at the time of fixation, and hence, no doubt, at the
time of sectioning?
Pristiurus, fuscus and some other mud-inhabiting Oncholaims can be kept
alive in pure running sea water for days, or even weeks, and when so kept
evacuate the intestine very completely. Sections may then be made without
the interference of the grit normally present in the intestine. / have not found
such sections to present the appearance figured by zur Strassen.
In an examination of very many specimens, alive and sectioned, I have
never been able to convince myself of the existence of an open communication
between the intestine and the demanian system.
Any such open connection would seem a grave menace to the well-being
of the organism. For if the enteric intake were of the nature figured and
described by zur Strassen, there would seem to be little or nothing to prevent
the entrance into the demanian system of undigested detritus contained in
the intestine, together with numerous living microorganisms which normally
432 UTERINE EFFERENT
constitute a very appreciable part of the feces. No such detritus is ever
seen in the demanian system.
Furthermore, on examining living pristiurus &nd fuscus, both of which I find
to occur along Cape Cod, U. S. A., I find that when the food in the intestine
is moving rapidly back and forth opposite zur Strassen's supposed open
connection, no portion of it ever enters the enteric efferent. There is not
even the slightest corresponding disturbance of the contents of the lumen of
the enteric efferent close by, which, as zur Strassen also points out, can be
seen in the end portion of the demanian tube where it joins the surface of the
intestine.
Possibly the analogous connection with the uterus is hardly to be taken as a
very distinctly open one. True, I have seen cases in pristiurus where, when
the diseased uterus was filled with microorganisms (microorganisms causing
the disease*), the continuous mass of them also filled the nearby part of the
corresponding demanian vessel in such a way that there was a direct "tubular"
connection between the uterus and the vessel. Normally, however, the
conditions are as follows: One traces the uterine demanian vessel directly
forward to the uterus, where its lumen continues for a short distance into a
glandular tissue in the posterior end of the uterus, zur Strassen's so-called
"blind end, behind the vulva," and there ceases in the midst of a large
number of uterine cells somewhat similar to many of those constituting the
main portion of the wall, i.e. what seems to be a special collection of glandular
uterine cells. In fuscus this same thing occurs where the oviducts join the
proximal ends of the two uteri, not, as in pristiurus, at the posterior portion
of the single uterus close to the vulva; the histology of this junction, however,
is much the same in these two species. It is as if special uterine cells were
devoted to secreting material to be deli vered to the demanian system through
the uterine efferent, the "tube de communication" of deMan.
In pristiurus the long tubular vessel connecting the uterus with the de-
manian system, the uterine efferent, often is difficult to see, especially in
its entirety. No better proof of this could be required than that it escaped so
keen an observer as zur Strassen.
Even in Adoncholaimus fuscus, while the two short uterine efferents can
sometimes be followed from the uteri to the main vessel of the demanian
system, often it is practically impossible in a given specimen to follow them
throughout their course. Knowing their locality and structure, one can
usually determine how they lie and their probable limits, but that is about all.
Of course, in a small minority of favorable poecimens quite the contrary is
true; the entire tube can be made out satisfactorily as was first done by
deMan.
* This disease appears to have nothing to do with uritis (see p. 240) ; uritis seems an
entirely distinct disease.
NATURE OF THE DEMANIAN FLUIDS 433
Direction of Flow in the Demanian System. Evidently a considerable
amount of matter is contributed by the intestine to the demanian system.
Zur Strassen had no difficulty in assuming the entire amount to be so con-
tributed in pristiurus (for he appears to have been unaware of the connection
in pristiurus of the uterus with the uvette, and hence with the demanian
system).
However, quite frequently in the contents of the enteric efferent of living
Metoncholaimus pristiurus near and in front of the uvette pore, refractive,
curved, wave-like effects are seen such as would be produced by the gradual
mixing of two viscid fluids of unequal refractiveness, an appearance that
might readily be produced by the flowing of a liquid through the uvette
pore from the uterine efferent into the enteric efferent in such quantity that
some of it passed slightly forward, perhaps through cover glass pressure.
On various occasions, I have seen a considerable quantity of matter in
the main enteric vessel close to its junction with the intestine. While this
is no proof that this matter was actually derived from the intestine, it is
favorable to that conception. Such matter never contains intestinal debris,
nor sperms (see F. H. Stewart, 1906), nor pseudo eggs, "balls of finely gran-
ular substance," (see zur Strassen.)
If the demanian system emptied into the intestine, it is to be expected that
it would do so through an aperture, pore, similar to those of other affluent
enteric glands, those emptying into the oesophagus for instance. In nemas
such pores are extremely small, have a definite refractive lining, and are
adapted to check any "backwash" due to movement of the contents of the
enteron, e.g. just such a structure as occurs in the uvette of pristiurus.
But no such pore has been seen in connection with any enteric demanian vessel.
Moreover, against the flow of any of the demanian fluids being toward the
enteron, it may be urged that in pristiurus a special secretion is at times
actually seen issuing rather copiously from the pores near the tail, the
external outlets of the demanian system, and there is not the slightest
reason to suppose that in this region the flow is ever anything but backward
and outward. There is no evidence that the demanian system is, for in-
stance, a water- vascular system; or that sea water is taken in through the
antecaudal lateral pores.
Again, there is little if any reason to believe the demanian system accessory
to digestion, because whatever digestive function would be advantageous to
adult females would seem also to be advantageous to the young nemas; yet
there are no such organs in young oncholaims, for they come into existence
at the last moult. The same may be said of any supposable ordinary excre-
tory function.
But if it be supposed that, for some unexplained reason, adult egg-producing
females require to excrete (not secrete) matter peculiar to them, in other words
that the demanian system, or some part of it, be a sort of temporary mal-
434 FLOW OF THE UEMANIAN FLUIDS
pighian system, a rather violent supposition, it would seem that the
excretion, as such, if poured into the intestine at all, should be poured in
posteriorly. But in didelphs, -fuscus, panicus, such a supposition would
pour it in near the anterior end. Or, if it be supposed that the demanian
system is simply an emunctorium accessory to the intestine and emptying
outward and backward, then why the attachment to the fore part of the
intestine as in fuscus!
If the demanian system is excretory, then it is necessary to assume that
the necessities of adult females in the way of excretion are different from those
of the male or the young female. No reason has been advanced for such an
assumption.
Deduction by Elimination. In the demanian system of 0. pristiurns
three ducts come together at a single point, indicated by X in
figure 4, ducts in each of which a fluid may conceivably flow
in either direction; i.e., there are six different paths along
which fluid may be conceived to flow. The assumption is, of
course, that, when the organs are functioning normally, fluid
passes constantly in one direction only in each of the three
tubes, 1, 2, 3, Fig. 4.
Indicating the six possible paths by arrows lettered a, b } c,
d, e, f (Fig. 4), mathematically, there are twenty possible
combinations in groups of three as follows:
abc, abe, acd, acf, adf, Me, cde, cef, bef, bcf.
abd, abf, ace, ade, bed, bdf, cdf, aef, bee and def; O f the sixpos-
this is according to the formula for combinations, s ^'^ c currents.
n(n-l) (n-2) (n-r + 1) GX5X4
- =
Fig. 5. Diagram showing the direction of flow of the fluid in the demanian system.
The intestine and the posterior end of the uterus are shown near bde . The backward
flow of the fluid in the enteric and uterine efferents is indicated at b and d, and the
backward flow of their combined products at e. The outward flow of the fully elabo-
rated secretion after it has passed the moniliform glands is shown by the two oblique
black arrows.
It is evident that a combination containing a and 6 represents a physical
impossibility, i.e. represents opposite currents simultaneously in the same
duct, duct number 1 ; and so with combinations containing c and d, and e
FLOW OF THE DEMANIAN FLUIDS
435
and /. (It is theoretically possible, of course, that the same tube might have
a flow in one direction at one time and in the opposite direction at another
time, but, physiologically speaking, this is an unusual occurrence, and prac-
tically an unheard of thing in a tubular organ "open" at both ends). We
may therefore eliminate from the 20 possibilities, 12 of the combinations,
leaving eight, acf, adf, bcf, ade, bee, bde, bdf and ace.
But there are also two more combinations that obviously must be left out,
as involving physical and physiological impossibility, namely ace and bdf,
i.e., the cases where the three currents would simultaneously come to, or
radiate from, the point X; bdf, (no outlet, or reservoir), and ace, (no
obvious source of supply). This leaves six combinations possibly worthy of
discussion, acf, adf, bcf, ade, bee and bde. These six possibilities are dia-
grammed in figures 5 and 6. Five of these possibilities (Fig. 6) are rendered
I. No exit pore for a; pore of uvette indicates
reverse of c; / doubtful because entrance of
sea water is possibly involved, while outflow
of secretion is known from lateral pores, p.
II. No exit pore for a; f doubtful as in I; monili-
form glands are believed here to empty out-
ward because of their form and location in ().
fuscus; only outlet of d and / would be
through a.
III. c doubtful as in I; / very doubtful as in I
and II; the only outlet for/ and b would be If
through the uvette and c, reverse of direc-
tion indicated by structure.
IV. No exit pore for a; the only source of a would
be d and the uvette.
V. c doubtful as in I; c may also be reasoned
against on the basis of homologous structures
in O. nigrocephalalus and 0. appendicu-
lalum.
Fig.
Fig. 6. Five diagrams of supposed currents in^a demanian system,
h supposition are listed opposite its diagram. Compare with Fig. 5.
Objections to
exceedingly improbable by the physiological and morphological considera-
tions listed opposite their diagrams. We may therefore safely deduce, even
from this single discussion, that the flow is almost certainly as shown in Fig.5.
The significance of seven exit pores on each side in panicus (see Fig. 7) is
an interesting subject for speculation. It can hardly be said that the exist-
ence of seven pores is for the purpose of furnishing a large outlet; it would
seem much simpler to attain such a result by having a larger single pore. Nor
436
MULTIPLE OUTLETS IN THE DEMANIAN SYSTEM
does it seem that the multiple outlet would have anything to do with the
quality of the secretion that is prepared. The most reasonable supposition
is that, in use, the demanian secretion is rendered more effective through a
multiple delivery, and it is not difficult to reason out why this might be so.
Take, as a basis of reasoning, the fact that spiders have multiple spinneret
tubes. This plurality is an advantage in that if some tubes of the spinneret
apparatus do not act, or are restrained from acting, the remaining ones may
continue to act, an economy of a kind often seen in nature. Thus threads
of varying size and composition can be "spun." It seems not unlikely
that the multiple thread of the spider may have
dnldsf. effdlt fsc structural advantages; at any rate it is a fact that,
in some cases at least, the thread can be artificially
split into components harmonizing in number
with the elements of the spinneret apparatus.
If these be advantages, it is quite conceivable that
*** they may apply in some way to the multiporous
Adoncholaimus panicus, and this would harmonize
with the previous conclusions concerning the
function of the demanian system; for presum-
ably the secretion in panicus is like that of other
oncholaims, i.e. a copious, sticky, non-water-
soluble, elastic material; at least these arc its
properties after it is delivered into sea water by
pristiurus.
The location of the outlets of the demanian
system is always well caudad, and the oncholaims
having the system are agile and limber, all of which
harmonizes with the belief that the system elabor-
ates material used with some degree of "skill."
Fig. 7. Adoncnolaimus . , , . , ., ,
panicus n.sp. Side, ven- All oncholaims having the demanian system
tral and sectional views of have a habit of coiling and uncoiling and can with
the posterior portion of the , ij.i-i r,i
same female, eff prep, the the greatest ease place the exit pores of the system
principal efferent at the against any part of the body except the tail and
point where it forks to pro- ... ,. , . . ., , ,, . , , ., , , ,
duce the two deltic effer- its immediate vicinity, and this habit, no doubt,
ents, eff dlt; the seven-fold j s correlated with the function of the secretion,
delta is shown at delta and _. . , , i i . 7 7.77
the seven exit pores at exit. Females of such oncholaims have relatively short
tails, as if longer ones would perhaps be in the way.
Conceivably, of course, the demanian secretion might have properties
attractive to the other sex (odor, etc.), but the idea does not seem to appeal
so strongly as that of having something to do with other matters.
In this connection it may be recalled that, opposite the demanian exit
pores of Metoncholaimus albidus (Bastian), deMan described and figured a
persistent girdle of left-over yellowish brown secretion.
USES OF THE DEM AN IAN BECEET1ON
437
Oncholaims having the demanian system,
at least most of them, have a way of collecting
together in masses when artificially assembled
in sea water. Conceivably this habit may
have some connection with the demanian
secretion, but it is not obvious why only adult
females should secrete for this purpose alone.
The demanian system appears more dis-
tended when the uterus is full or nearly full of
eggs. For instance, at this time the uterine
efferent and portions of the uterus of pristiurus
may contain an abundance of colorless, trans-
parent, rather structureless-looking matter,
resembling, under the microscope, partially,
dissolved shavings of gelatin.
The question arises as to what becomes of the
secretion of the accessory gland of the male, Fi g- 8 - Profile of head end of male
which is possibly or probably a homologue of ^S^2?^Si
the demanian system in the female. No reply } eft ventral submedian is the
. , . , , . longest, see on dsl and on subm
to this question has occurred in connection (#). The sensilla and amphidial
with these investigations except that the "gum nery e are shown. Nuclei shown
,.,., . , . .. ,. mostly central nervous system;
arabic-like" mixture seen in the uterus of the scattered darker ones are.
pristiurus might possibly have been derived o^lei of the lateral chord, the
_, . , , ,, , ,, , , , width of which is pointed out
wholly or in part from the male. It should & tchrdlat.
perhaps be mentioned that
X350
Fig. 9. Tail, male Oncholaimium
appendiculatum. ppl, single ven-
tral papilla; del (3), caudal ducts
leading to spinneret; appndl,
ventral, erectile appendicule; an
set, anal setae ; set subm (12), sub-
median setae on male only.
in the nemic
genus Rhab ditis, glands accessory to the
male gonad are known that secrete a copu-
latory cement; but no such cement is yet
known in connection with any oncholaim.
Of course, the mere presence of this
material in the uterus and in the portion of
the uterine efferent nearby does not of
itself indicate the direction of the flow, but
the structure of the organs distinctly sug-
gests that the flow is caudad, i.e. from the
uterus toward the external openings near
the tail. Were the entire flow of the deman-
ian system toward the uterus, it would
seem strangely circuitous.
While the fact that no external exit
pores have been discovered in Oncholaimium
appendiculatum makes conceivable a flow
from its enteric vessel and the moniliform
glands through the uvette to the uterus, yet
the structure of the uvette pore seems as dis-
tinctly adapted to a flow in the opposite
438
DISEASE OF ONCHOLA1MS
direction, i.e. caudad, in this species as in the others. Moreover a different
explanation of this exceptional case seems more plausible, namely, that in
0. appendiculatum the demanian organs are in a deteriorated condition. The
fact that this species is the only one that almost invariably presents disease
in the posterior extremity of the adult females may harmonize with the
supposition that the demanian system of this species is in a deteriorating
and perhaps useless condition. The nonconsecutiveness of the posterior
cells of the moniliform glands in 0. appendiculatum, and the appearance
of crystals on the outer surface of the enteric efferent, (Fig. 3) suggest
decadence in this anomalous species.
In 0. appendiculatum the uvette is reduced to a mere ampulla; and is
almost as greatly reduced in nigrocephalatum. In neither of these is it at
all likely that the uvette itself could produce any very appreciable secretion
flowing into the uterus, and yet in both species the uterine tube is better
developed (or at any rate more obvious) than it is, for instance, in pristiurus,
where the uvette is strongly developed.
Uritis. It is interesting that the females of a number of oncholaims
shown to possess demanian vessels seem unusually subject to disease.
Among such oncholaims, allusion is made to the following typical cases:
Name
Location
Lesions
Regeneration
?
Woods Hole. Mass..
U. S. A.
"tailless"
Undoubtedly healed
over
0. appendiculatum
Woods Hole, Mass.
From tail end to half
of nema necrotic
No signs of regenera-
tion
M, pristiurus
Woods Hole, Mass.
Tail end gone; no
anal opening; no
spinneret
Merely healed over;
no openings
A. fuscus
1. Cape Cod, Mass.
2. Miss E. Horsman
Univ. College of
Wales
Former uritis (?)
Former uritis (?)
Terminus regener-
ated; no spinneret
New Oncholaim
Florida, U. S. A.
Former uritis (?)
Imperfect spinneret
and anal opening
regenerated
An interesting morphological problem is thus disclosed. As the table
indicates, one not infrequently finds oncholaims, especially females, with
highly peculiar caudal extremities, sometimes without spinneret or anus,
sometimes with these organs present but apparently abortive, or at least
peculiar in form, abnormalities probably due to specific disease. Ap-
parently the disease is sometimes combated by the nemic organization, so that
the posterior end of the nema heals over, and in some cases it seems as if a new
anus is formed, and possibly even a new spinneret ! Just how this occurs is
not yet clear,*but I have seen both deformed anal openings and deformed
spinnerets of female oncholaims that appeared to give evidence of having
been imperfectly regenerated after some accident, or, more likely, after uritis.
* Regeneration seems to be uncommon in nemas.
Additional articles consulted see zur Strassen's bibliographic list, 1896.
METONCHOLAIMUS PRISTIURUS (ZUR STRASSEN)
A Nema Suitable for Use in Laboratory Courses in Zoology 1
BY N. A. COBB
CONTRIBUTIONS TO A SCIENCE OF NEMATOLOGY XXV 2
Zur Strassen, who first proposed the species Metoncholaimus pristiu-
rus, alluded for the most part only to the organs whose forms served
to distinguish it from its nearest allies among the oncholaims. The
present attempt at a more complete understanding of its morphology
adds to our knowledge in a number of ways, especially with regard to
the remarkable demanian system.
At the same time the text and figures have been prepared with par-
ticular reference to requests of school, college and university instruc-
tors in invertebrate zoology, a course suggested by the fact that this
species has been used with some promise of success in the invertebrate
courses of a considerable number of universities.
Unfortunately few if any zoological textbooks treat nemas ade-
quately. It is believed that any progressive and well equipped in-
structor who will study carefully the following descriptions, with the aid
of good living as well as preserved specimens, will find himself all the
better equipped to instruct students concerning the morphology of
the important nemic phylum.
METONCHOLAIMUS PRISTIURUS (Zur Strassen)
[Meta, changed; Oncholaimus, tooth (in the) throat]
FEMALE. Fig. 1.
The cuticle and the body wall. olii "/" i.i \A i.s o.z* 5 - 6mm
The contour of the nema is plain. The thin, transparent, colorless, nearly
naked cuticle, 72, 96, about one micron thick, is traversed by plain transverse
striae; but these are very difficult of resolution except with high powers of the
microscope used skillfully under favorable conditions, ordinarily they will
1 Through the much appreciated courtesy of the United States Bureau of Fisheries a
considerable part of these investigations was carried out at its Laboratories at Woods
Hole, Mass. Received May 18, 1932.
2 Reprinted from the JOURNAL OF THE WASHINGTON ACADEMY OF SCIENCES, Vol. 22,
No. 12, June 19, 1932.
Warerly Press, Inc., Baltimore, Maryland, December, 1932.
440 JOUKNAL OF THE WASHINGTON ACADEMY OF SCIENCES VOL. 22, NO. 12
not be seen. These striae are not altered on the lateral fields; there are no
longitudinal wings. The subcuticle, 99, usually contains multitudinous
pebbly, i.e. roundish or slightly elongate, yellowish pigment granules, 34,
82, 95, one to two microns across, "paved" in longitudinal bands of variable
width; two broad lateral bands, one on each side of the body, about one-
third as wide as the nema and having narrower submedian bands on each side;
and three narrow ventral bands as well as even narrower dorsal bands. These
bands are better seen after staining over night in seawater-methylene-blue,
which may not only stain them but bring out the fact that the granules along
the edges of the two main lateral bands are of a somewhat different nature
from the rest. Longitudinal striations in the subcuticle, clue to the attach-
ment of the musculature, 4, 16, 77, are faintly visible at high magnification in
most regions of the body, especially the more translucent parts. The body
wall, including the cuticle, is about six microns thick.
Ten widely spreading cephalic setae, 26, are arranged on the lateral surface
of the lip region in the usual way, i.e. a pair on each submedian line and one on
each lateral line; the longest of these are one-fourth as long as the correspond-
ing portion of the head is wide, the shorter member of each submedian pair
being about three-fourths as long as the longer. The members of the sub-
median pairs grow so close together as sometimes to appear as one. These
subcylindroid setae are nearly straight and are blunt at the end, where they
seem more or less open, not closed, indicating, probably, that they may also
be connected with some sense in addition to that of touch. There are a few
scattered subcephalic setae near the head, of nearly the same length (ten to
twelve microns) as the cephalic setae, but more slender. On the neck and on
the body there are also a few scattered setae, very inconspicuous and seldom
seen. There are also a few very short, very inconspicuous setae on the tail,
especially toward its extremity and on the spinneret, 24, 74. There are no
cuticular pores.
The neck and head. The head and neck occupy the anterior 11 to 13 per
cent of the body, i.e. the part in front of the prominent constriction, 13, be-
tween the nearly colorless oesophagus, 12, 36, and the darker intestine, 83, 94.
The slightly conoid neck ends in a subtruncate continuous head, the frontal
mouth opening in which is not depressed. In front the pharynx, 31, 48, 57,
is arched over by the six distinct and separate, flat and thin, fairly well
developed, mobile lips, 28, 49, which are not set off by constriction or in any
other way. As a rule the lips are not readily counted except when seen from
in front. Toward the margin of the head there is a circlet of six, innervated,
very minute and inconspicuous, forward-facing sensory papillae, 29, 45, one on
each lip. This circlet is about two-thirds as wide as the front of the head.
These papillae also are rather difficult to see except from in front, 45. The
rather simple subregular pharynx, 31, 35, 48, 57, about forty by twenty-three
microns, is somewhat cylindroid anteriorly and vaguely conoid posteriorly.
The posterior "chamber," 35, sixteen by nine microns, supports the three
acute onchia, 25, 33, 53, the forward pointing projection of the largest of which
is very readily seen. Taken as a whole the pharyngeal cavity might be
described as somewhat convex-conoid. Its refractive, cuticularized wall is
nearly two microns thick.
Its armature consists of three unequal, conoid, perforated, pointed onchia,
one dorsal, 25, two ventrally submedian, 33, 53. Of these the grooved left
ventral submedian, 27, 53, is much the largest, and reaches two-thirds the dis-
tance to the lips. The other two, e.g. 33, 25, nearly equal in size, reach only
about halfway to the lips. Each onchium is the outlet of a branched and
JUNE 19, 1932
COBB: METONCHOLAIMUS PRISTIURUS
441
ndittt .parsed dint, %
mcsmn
cnfmt
Fig. 1 Living
9 M. pristiurus.
Drawing, from
favorable speci-
men s, m o d i fi e d
from examination
of intra-vitam
methyl blue
staining, and, to a
very slight extent,
of carmine stain-
ing. Two views of
the same head, in
glycerine, are
shown. X 750.
The abbreviations
are self-explana-
tory; e.g., "pars
ext cl int," ex-
...:.v...-/.,...^*'-~ - ternal portion of
'-dM69 intestinal cell. Food occurs in the intestine
OT?7/from 92 to 101. Most of the features drawn
, can be seen in good specimens with a 4 mm^
objective; some, however, require a .good _2 or
'^3 mm. mmersion objective. Cuticulan*
mnarts eg of the head, may be favorably
- 7 vfewe'd in'5-10% KOH solution. Specimens
'UtslmeM jSen and instantly treated with acetic ac,d
' methylene green are useful.
mcsmioo
.dord MIDI
dintbhfnv
442 JOURNAL OF THE WASHINGTON ACADEMY OF SCIENCES VOL. 22, NO. 12
much elongated unicellular salivary gland, e.g. 43, and dot gl sal, located
along the corresponding sector of the oesophagus and reaching back even to
near the base of the neck, where the corresponding three nuclei, 41, may be
seen, about one body-width in front of the prominent constriction, 13, sepa-
rating the oesophagus from the intestine. Each gland empties through a
perforation, 27, in the corresponding onchium, by means of an inconspicuous
ampulla and a very fine duct, about one micron across. The distribution of
the salivary glands among the radial contractile fibers of the oesophagus may
be indicated by the granules, one micron or less in diameter, to be seen in
various parts of the glands, e.g. at dct gl sal. In favorable specimens the ducts
of these glands, when filled with this granular secretion, can be followed
throughout the length of the oesophagus, and the glands are then seen to have
numerous short lateral branches, (see from 43 forward). The much larger,
though inconspicuous pigment granules of the oesophagus are scattered through-
out the organ.
The external amphids, 32, 51, one on each side of the head, are somewhat
escutcheon shaped, being symmetrical only to a longitudinal line, and are
longer transversely than longitudinally. The anterior border of each amphid
is removed from the anterior extremity of the nema a distance about equal to
the radius of the head. They are much more obvious if looked at dorso-ven-
trally, when they are distinctly seen to be two pocket-like entrances to internal
sensory organs, the internal amphids, located laterad in the back part of the
head. Each of the external amphids is about one-fourth as wide as the corre-
sponding portion of the head and about two-thirds as long as it is wide. Each
outer amphid connects with a sensilla, 54, or receptor, close behind, by means
of an exceedingly narrow and very short (two and a half microns) but strongly
refractive, duct, shown in the figure. The sensilla is one-fifth as wide as the
head and lies opposite the basal part of the pharynx and is connected back-
ward with the central nervous system by a lateral nerve, 55, just beneath the
body wall. The details of the sensilla, 54, are usually difficult to see except
when specially stained. The amphids are held to be chemical sense organs.
The oesophagus, 12, 36, is cylindroid, enlarging very slightly posteriorly;
behind the pharynx it is three-fifths, at the nerve-ring one-half, and finally
two-thirds as wide as the corresponding portion of the neck. The refractive
membranous "triquetrous" lining of the eosophagus, mainly about one micron
thick, but two microns in the axial parts, is a distinct feature throughout the
organ, and finds main optical expression in what appear as two or three closely
approximated refractive, often slightly sinuous, axial elements, and, in the
ordinary closed condition of the oesophagus, seeming to occupy about one-
eighth of its width. The radial musculature of the eosophagus, to be seen
throughout its length, consists of fine strands and is accompanied by only a
slight amount of yellowish granular matter. There are no cuticularized
valves in the oesophagus.
The intestine. The intestine, 83, 94, which becomes at once two-thirds as
wide as the body, is thick-walled and is composed, as is usual in nemas, of a
single layer of cells, 69 and vicinity, here of such a size that about twelve are
required to complete the circumference. The walls of the cells are only
faintly visible except sometimes in the outer colorless part, 1, 76. Usually the
lumen of the intestine, (see just behind cardia, 14) can be seen only faintly,
since the lining of the intestine is not refractive. As the nema bends back
and forth, the food content of the intestine, e.g. at 92, may be seen to move
backward and forward in the lumen. This nema appears to swallow mud
JUNE 19, 1932 COBB: METONCHOLAIMUS PRISTIURUS 443
rather indiscriminately, and to extract its nutriment from a variety of organic
material contained in the mud. Large quantities of this food material in the
intestine may interfere with microscopic examination; hence the advisability
of keeping the nemas in clean cool seawater for a day or two before examina-
tion. The cardiac collum, or constriction, 13, between the oesophagus and
intestine, is about two-fifths as wide as the base of the neck, making a very
obvious demarcation between the oesophagus and the intestine. There is a
conoid cardia, 14, about two-fifths as wide as the base of the neck; this is the
very short extension of the oesophagus into the intestine, and is composed of
numerous smaller cells of a distinct kind, having to do, among other things,
with the prevention of regurgitation. Though small, the cardia is a very
important part of the alimentary canal. The outer portion of the intestine,
1, 76, is usually more or less destitute of granules, but the inner and greater
portion of each intestinal cell contains globular yellowish granules, 69, of
variable size, the largest of which are about three microns in diameter, and
the smallest less than one micron. These granules are varied and numerous,
sometimes are even packed close together, and may be so arranged in the cells
as to give rise to a faint, or sometimes a quite distinct, tessellated effect.
The intestine is made up of cells of different kinds, discharging different
functions. One of these various kinds is readily made out, especially with the
aid of polarized light, namely the cells, as many as one hundred in number or
even more, containing the exceedingly minute Urefringent granules. These
cells, 15, 81, 98, when examined by ordinary transmitted light, present a
finer texture internally, and usually are more distinctly yellowish. If a suit-
able specimen be allowed to remain in a concentrated solution of seawater-
methylene-blue a few minutes, a differential staining of the "birefringent"
cells will often occur, but the effect does not last. The "birefringent" cells are
everywhere less numerous than those that do not contain birefringents, and
there are none of them at all in the posterior part of the intestine. We may
therefore speak of two distinct intestinal regions, one fore, one aft. The
"birefringent" cells occur in early ovic embryos.
The rather prominent short rectum, 19, the rear part of the intestine, is
somewhat cuticularized, and is about as long as the anal body diameter; from
the somewhat depressed anus, 70, it extends inward and forward at an angle of
about forty-five degrees. Its structure in the female differs somewhat from
that of the male, which appears "helical." The anterior and posterior lips of
the anus are of about equal size. Small inconspicuous somewhat pear-shaped
unicellular anal glands can sometimes be seen, lying alongside the rectum with
their narrowed necks directed toward the anus.
Tail and spinneret. The slightly arcuate tail is first conoid, then cylindroid
in the posterior fourth, where it ends in a somewhat blunt, almost impercep-
tibly swollen, rounded spinneret, 73, armed only with three exceedingly incon-
spicuous setae, two ventrally submedian, 74, and a dorsal one, 24. Though
insignificant in appearance these sensory setae are important. The very
nearly symmetrical spinneret displays internally the three very slightly
swollen ampullae of the three caudal glands, 23. The spinneret valve, or plug, 75,
four microns across, almost at the very end of the tail, stains green with
methyl blue ("intra vitam") while other nearby parts stain blue. This impor-
tant valve is hemispherical posteriorly and tapers anteriorly to a fine contractile
element, shown white in the drawing, fastened in the midst of the three ampul-
lae (23). It is by the contraction of this minute fiber that the plug or valve is
pulled away from its seat, so as to permit the sticky, non-water soluble,
444 JOURNAL OF THE WASHINGTON ACADEMY OF SCIENCES VOL. 22, NO. 12
vglmal
/JffltSt'"
cement-like secretion of the three caudal glands to pour outward to be used in
temporarily cementing the nema by the tail to the substratum in a versatile
manner. The spinneret and associated glands are of vital importance to
aquatic nemas; and this apparatus is all but universal among them. The
three elongated ellipsoidal caudal glands, 84, 88, 90, the remotest of them
ten body-diameters in front of the anus, are scattered in a loose tandem in
the ventral part of the body cavity. Their ducts, 18, 86, leading to the spin-
neret, can be distinctly seen under some circumstances. Most of the caudal
setae on the female are reduced and inconspicuous.
It is the sticky nature of the secretion of the caudal glands that enables
these nemas to ensconce themselves so securely in the midst of the elements of
the mud in which they live. By its aid they attach themselves to the sub-
stratum, especially in times of danger, and to each other. By means of this
cement, they bind themselves together with mud etc. in almost inextricable
tangles.
The two very thin ribbon-
like lateral cords, 3, 93, of
Metoncholaimus pristiurus,
one on each side, imme-
diately under the cuticle,
are about half as wide as
the body, each cord consist-
ing of three regions, a me-
dian region composed of a
single broad row of quadrate
cells, and a row, less than
half as wide, on each side of
it. In the anterior part of
the body the quadrate cells
are usually a little longer
than they are broad, in the
posterior part a little shorter
than broad. As stated,
these median cells are
flanked by two much nar-
rower longitudinal series of
cells, having the same gen-
eral composition, i.e. a very
fine protoplasmic network
(meshes two microns to
five microns) in the inter-
sections of which are roundish or somewhat ellipsoidal yellowish granules,
usually not equidiametral. Even without staining, there are also to be
seen, at least in each of the cells composing the central row of the lateral
cord, faint indications of a nucleus; these indications in the living nema con-
sist in an almost entire absence of the reticulation which is to be found else-
where in the cell. These cells of the lateral cord are necessarily very flat;
that is to say, their depth (radially to the nema) is much less than their diam-
eter in either of the other two directions, i.e. longitudinally to the nema or
tangentially. The division line between the central row of cells and the
narrower ones on the margin is an almost invisible, very thin, somewhat
indirect cell-wall line. Around the outer margins of the two outer rows of
cells the granules are slightly differentiated from the other granules; so that in
IB mem
n jar Am
& rectum
u
Fig. 2 Tail of fe-
male M. pristiurus, X
325; showing the mi-
nute but important
spinneret valve, vlv
spn, and the muscular
strand leading from it
into the midst of the
3 ampullae of the
caudal glands; shown
light in the midst of
the spinneret. Note
the pylorus at pylor.
.spnn
spn 75
JUNE 19, 1932 COBB: METONCHOLAIMUS PRISTIURUS 445
seawater-methylene-blue the subcuticular pigment granules on the borders of
the longitudinal bands, already described in connection with the cuticle, mav
stain green at a time when the rest of the granules stain blue. This appear-
ance is similar to what is now being described for the unstained nema; so that
the structure of the lateral cords is now shown to be in harmony with that of
the longitudinal bands of subcuticular pigment. In other words, the arrange-
ment of the pigment granules of the cuticle is doubtless in some way correlated
with the arrangement of the cells in the lateral cords beneath. The proto-
plasmic network in the cells of the lateral cords is considerably finer than the
protoplasmic network in the outer part of the cells composing the intestine,
but nevertheless, has the same general appearance. The lacunae among the
strands of the network are of variable size, more or less equidiametral,
though never exactly so; polygonal, but not regularly so. The lateral cords
are wellsprings of the cuticle.
The granules of the subcuticle, 34, 82, 95, differ from the yellowish gran-
ules contained in the network of the cells of the lateral cord; in the specimen
under examination the granules in the subcuticle (a little under one micron)
are more nearly colorless and are round, whereas those in the lateral cord are
yellowish, and somewhat irregular in size and form.
Renette and excretory pore. The excretory pore, 58, is located about one-
fourth the distance to the nerve-ring on the ventral side of the neck. The
nucleated single renette cell, 68, about four body-widths behind the neck, is a
fusiform, granular, ventrad cell, about twice as long as wide, and nearly two-
thirds as long as the corresponding body diameter; the renette duct, 60, 67,
leads from it, somewhat meanderingly, forward to the excretory pore, and is
readily seen, as a rule, or at least some of it is. It is a slender tube about
one-twentieth as wide as the neck and ends anteriorly in a small ellipsoidal
ampulla, near 58, nearly one-third as long as the neck is wide, emptying
outward through the ventral excretory pore in the cuticle by means of an ex-
ceedingly narrow duct only three to four microns long. The excretory secre-
tion of this gland, as seen in its duct, and ampulla, is granular, the uniform,
spherical, colorless granules being about one micron in diameter. This
entire apparatus, the renette, is regarded as excretory in function.
Nervous system. An important part of the central nervous system is the
nerve-ring, 38, about ten microns wide, surrounding the oesophagus somewhat
obliquely in front of the middle. It consists of a compact network, or skein,
of exceedingly fine nerve fibers. Before and behind the nerve-ring are scores
of distinct nucleated ganglion cells, 11, 56, etc., mostly bipolar, those in frort
being arranged in eight obscure longitudinal groups, two lateral, one ventral,
one dorsal, and four submedian. The ganglion cells are variously connected
with each other and with the nerve-ring. Placing the nema over night in
seawater-methyl-blue discloses some of the elements of the ventral nerve
leading from the nerve-ring along the ventral line to the tail. Usually about
128 fusiform elements in the ventral series may be disclosed (stained blue)
in this way. These can be proved to be connected with each other. The
same treatment is likely also to reveal the nerve elements entering the bases
of setae, and papillae, especially in the tail of the male. See Fig. 4.
Female organs. From the slightly elevated vulva, 7, which is a transverse
ventral slit of moderate size, the medium sized vagina leads inward and
slightly forward about halfway across the body; the vagina is somewhat
cuticularized and is accompanied by small and very inconspicuous vaginal
glands, 9, fore and aft. About two dozen radiating muscles, 6, occur around the
446 JOURNAL OF THE WASHINGTON ACADEMY OF SCIENCES VOL. 22, NO. 12
vulva, together with an associated complicated nerve plexus. This muscula-
ture is least developed behind the vulva.
The straight uterus, 30, 8, extends forward, and is of such capacity as to
accommodate a maximum of about forty eggs, 10, 39, (i.e., many more than
shown in this drawing) arranged approximately single file, although this
large number of eggs is rarely seen except toward autumn. Under such cir-
cumstances the oblate eggs, seeming to nearly fill the body cavity in this region.
are more or less ellipsoidal in contour and half a body-width long, and twice
as wide as long. When deposited, or when not crowded in the uterus, the
eggs are ellipsoidal and longer than wide. The shells of the eggs, one and a
half microns thick, are smooth, and the eggs are deposited before segmentation
begins. Naturally, the length of the uterus varies according to the number
of eggs it contains.
The broad reflexed ovary appears more or less cylindroid, and when there
are, say, a dozen eggs in the uterus, the terminus of the ovary, 59, lies about
halfway back to the vulva. The narrow oviduct, 46, 52, leading from the
front end of the ovary back to the uterus, is usually nearly invisible, but when
a ripe ovum, 50, having passed round the bend (flexure) near 46, is being
forced backward through it from the front part of the ovary back to the
uterus, its presence is obvious. It is faintly visible at 52. The ova are
fertilized on first reaching the uterus, and soon after this it is not very un-
common to witness the early stages of the formation (mit, Fig. 1) of the polar
bodies, which appear later as small spherical bodies just under the eggshell.
A small collection of sperms is seen in the spermathecal region at 61.
The demanian system. In the adult female of Metoncholaimus pristiurus
there is a complicated double system of efferent tubes, the demanian vessels,
connecting, first, with the posterior part of the intestine through an osmosium,
87, and second, with the posterior end of the uterus by means of a very long
slender efferent duct, 79, 85. These two efferents join at a conspicuous
thirty-two-merous, special glandular gateway, the uvette, 40, and empty,
by way of the uvette pore, 62, thence backward and outward through two
separate narrow lateral ducts, 42, having attached to them, along their outer
sides, relatively large and long conspicuous moniliform affluent glands, 64,
seventeen microns wide, each consisting usually of sixy-four somewhat
discoid elements, 66, occasionally double (?) this number. These discoid
cells of the two moniliform glands are three microns thick and packed with
granules of the order of one micron; the flat ducts, along the inside of the
moniliform glands, lead to two exit pores, the right hand one shown at 17, five
by seven microns, laterad in the body wall one-half tail-length in front of
the anus. However, the caudad elements of the moniliform glands are
"pyriform," as shown in the illustration, not discoid. The demanian vessels
elaborate a copious, elastic, sticky, non-water-soluble, nearly colorless secretion,
possibly utilized during agglomeration and copulation, and also mayhap to
protect and preserve the batches of eggs after deposition and during seg-
mentation.
The uvette, 40, is a very striking organ consisting of thirty-two concen-
trically arranged, highly refractive, flask-shaped, glandular elements, all
concentric about a single minute central pore, 62, leading into the large duct
passing backward and dividing to form the two lateral efferent ducts each
accompanied by a sixty-four-fold moniliform gland, as already described.
The connection of the intestine with the demanian system at the osmosium
is not an open one; the nature of the connection with the uterus, however,
appears less certain.
JUNE 19, 1932 COBB: METONCHOLAIMUS PRISTIURUS 447
The osmosium, 87, of the enteric efferent is located about one-third the
distance from the anus to the vulva, and may usually be seen on the dorsal
side of the intestine, being mainly visible on account of the somewhat
greater transparency of its tissues. The narrow uterine efferent duct, ut.
eff., 79, 85, is very difficult to follow throughout its length, and usually can be
seen only in specially favorable specimens. Its connection with the posterior
end of the uterus is sometimes easy to see, near 30. Its connection with the
uvette is also nearly always easy to see, and it may be followed thence for-
ward a short distance, but to trace it far is usually a matter of some difficulty.
The thirty-two flask-shaped elements of the uvette have their necks con-
centrated at the pore. The wall of the uterine duct, as previously described,
spreads out over the uvette, and beneath it the thirty-two elements form a
craterlike affair leading to the uvette pore. This pore opens into the some-
what duplex (but really monoluminal) corridor of the caudad part of the
intestinal efferent. This latter efferent may show signs of forking at a dis-
tance in front of the uvette about equal to the corresponding body diameter,
but is seldom, if ever, really bifurcate until behind the uvette.
Or, following the demanian system from the rear toward the uvette: Where
the moniliform glands approach the uvette, they join to form a two-fold
structure, and the pore of the uvette is placed between the two parts of this
double structure. The structure of the tunic of the demanian system opposite
the uvette presents two sets of exceedingly fine symmetrically arranged
elements, one sloping 45 right, the other left, which continue forward.
This "spiral" structure can be seen throughout the duplex portion of the
demanian system now being described, namely that portion in the vicinity
of the uvette.
Sperms, 61, are to be seen at the cephalad end of the uterus i.e., the sper-
matheca, where the oviduct joins the uterus, sometimes in a mass comprising
scores of sperms, each about one-tenth as wide as the corresponding portion
of the body. They are rather difficult to see except when they are present
in considerable numbers.
MALE. Fig. 3.
0.8 53 11. SM_ &e. ^,
The spicula and other male organs, b.a "/" "ii ii " ' " iVs' ^ -^oi
The tail of the male is more or less like that of the female in form, but is
somewhat larger, more arcuate, and far more flexible, even prehensile, as Fig.
2 indicates. It diminishes a little more suddenly in size at the anus, and is
armed with special setae and papillae. The two, equal, colorless, long and
very slender, uniform spicula, 57, 58, seven times as long as the anal body
diameter, are almost imperceptibly cephalated by expansion. They are
simple and frail looking, their proximal ends lying more or less opposite the
body axis. A long slender, duplex, nucleated retractor muscle, 16, extends
forward from the proximal end of each spiculum to the body-wall in the cor-
responding subdorsal region, near 12; an antagonistic protrusor muscle, of
about equal size ensheaths each spiculum. The small inconspicuous guber-
naculum, 42, lying near the anus, is double and straight. Its two equal parts
are somewhat frail and simple, but are expanded internally so as to be visible.
They are only about half as long as the anal body diameter, and lie against
the tips of the spicula in such a way that their swollen and more visible
proximal ends, 42, lie nearly opposite the axis of the base of the tail.
There is a single inconspicuous preanal ventral papilla, 22, very close to the
anus, 21, but readily seen when searched for. There are about ten small
448 JOURNAL OF THE WASHINGTON ACADEMY OF SCIENCES VOL. 22, NO. 12
JESC SOS 69
Fig. 3 d* If. prisliurus,
from balsam specimens;
stain, acid carmen. Com-
pare with Fig. 1. Here the
nuclei are brought out more
distinctly. The renette and
caudal glands may be fol-
lowed throughout. Devel-
opment of the sperms can
be followed; reduction divi-
sion is shown at 2. The
long gland accessory to the
male gonads can be followed
from 23 to 33. One of the
exceedingly slender spicula
is shown, together with its
long duplex, nucleated re-
tractor muscle. The oblique
copulatory muscles of the
male extend forward to near
the vicinity of 74. The
minute but important spin-
neret valve is shown at 20.
The oesophageal glands
shown at 28, may be profit-
ably compared with the
larger drawings in Fig. 1.
conical supplementary organs, 19,
on the ventral and subventral pos-
terior two-fifths of the tail. These
are arranged in a sort of ventral
row, but the anterior ones are more
or less staggered; they are somewhat
unequally spaced, being wider apart
posteriorly. They give a serrated
appearance to the ventral contour of
the posterior part of the tail, hence
the specific name, pristiurus (saw-
tailed). There are also about thirty
ventrally submedian short setae, 18,
on the front portion of the tail,
about fifteen on each subventral
line. These two rows extend forward
to, and around, the anus, forming
there a sort of circlet of inconspic-
uous character. These conical sup-
plements and setae of the male are
special sensory organs; each is supplied with a
minute nerve readily demonstrable with seawater-
methylene-blue (See Fig. 4).
The internal male organs. The two slender,
straight testes, 7, 63, 70, 76, of about equal length,
but the posterior somewhat the longer, are out-
stretched in opposite directions, and extend along
the middle third of the body, each being about
sixteen body-widths long. The ejaculatory duct,
17, 59, toward the anus, is one-fifth; the vas
deferens, 14, 53, next farther forward and set
150
JUNE 19, 1932
COBB: METOXCHOLAIMUS PRISTIURUS
449
Fig. 4 Tail
end of M. pris-
tiurus, Male X
wnstrx
off from the ejaculatory duct by
a distinct constriction, 56, is one-
fourth; and the testes average
one-fourth to one-half; as wide
as the body. There is a con-
striction midway in the vas defer-
ens, 37. The blind end of the
anterior testis, 70, directed for-
ward, is about two neck lengths
behind the cardia, while the blind
end of the posterior testis, 76, di-
rected backward, is about five
tail-lengths in front of the anus.
Beginning between the renette
cell and the cardia (at 23) there
is a long, straight, tapering ac-
cessory gland, 51, emptying back-
ward into the beginning of the
vas deferens, i.e., at the point
where the two testes join it, 33. . ^.
This gland, accessory to the 22 fn '' 44TCt
gonads, is, no doubt, a re-
duced homologue of the demanian system of the female. A possible func-
tion is the production of cement (aseptic?) used in copulation.
The primary spennatocytes, 69, near the blind end of the testes are about
forty microns in diameter. About twenty of them would be required to
span the corresponding body diameter. Full grown spennatocytes, 4, 36,
occur farther along the testes in rouleaux, and are two-fifths as wide as
the body of the nema and one-third as long as wide. Nearly simultaneous
synapses and reduction divisions of a full grown sperm are often in progress in
one or the other testis, 2, 3, and the members of the resulting quartet, 2, of
smaller cells, that is the resulting spermatids, are somewhat equidiametral
and are about one-fifth as wide as the body.
.COP MM
X1000
Fig. 5 Cross sections of Metoncholaimus pristiurus through the regions of the
moniliform glands of the female and the spicula of the male respectively.
450 JOURNAL OF THE WASHINGTON ACADEMY OF SCIENCES VOL. 22, NO. 12
The three caudal glands, 15, 38, and their three ducts, as at 40, are shown
more clearly when stained, as in the male specimen figured.
Habitat: Stagnant marine mud, below low tide, often where there is a slight
overgrowth of eelgrass; harbor at Woods Hole, Massachusetts, U. S. A. at
all seasons. It also occurs in the Mediterranean Sea, near Naples, Italy.
This species is subject to autumnal (?) attacks of fungi and bacteria. The
resulting diseases are of a very interesting character, and sometimes give rise
to necrosis of the posterior part of the body. One of the common assailant
cyanophytes(?) gives rise to an extensive aigrette-like appearance.
Examination of the living specimens may very profitably be supplemented
by examination of temporary mounts in lactophenol, 5 per cent solution of
potassium hydrate, and (broken open) in acetic acid-methylene green, as well
as "intra-vitam" in seawater-methyl blue.
A KEY
TO THE GENERA
OF FREE-LIVING NEMAS
CONTRIBUTIONS
TO A SCIENCE OF NEMATOLOGY
XXVI
BY
N. A. COBB
BALTIMORE
1935
A KEY TO THE GENERA OF FREE-LIVING NEMAS
BY N. A. COBB
Division of Nematology, U. S. Bureau of Plant Industry
Checked, revised and prepared for the press by Margaret V. Cobb and Corinne Cooper
CONTRIBUTIONS TO A SCIENCE OF NEMATOLOGY XXVI 1
PREFACE
This key, which was built up and used by N. A. Cobb as a card
catalog during forty years of work in nematology, had been reorgan-
ized in rough manuscript form during the last two years of his life.
As Miss Cooper and I had previously worked with him on this draft,
it seemed best for us to carry it to completion. In essentials and
in general form it is his key, but we are responsible both for cor-
rectness of detail (an appreciable amount of the detailed work was
incomplete, in need of revision, or in need of change because of ad-
dition or omission of genera), and for such decisions as have to be
made in getting such a work printed. Our aim has been to follow his
ideas wherever they were known to us, or where we could infer them,
and to make as few changes as possible in his outline. Nearly a
hundred entries have been omitted, chiefly his own new genera
which it has not been possible to publish in advance of publication
of the key. In some cases genera have been dropped as not being
free-living. Index, glossary and list of abbreviations have been added.
The bibliography has been prepared by Mrs. Rowena R. LeHew
of the Division of Nematology. The definitions in the glossary
are not intended to settle the meaning of terms for other workers
in the field, but merely to indicate the terminology used in this key.
A few details in the form of the key stand in need of special explana-
tion. Parentheses have been used around generic names in the key
in two ways ; one, to indicate that the genus is better placed elsewhere
in the key, and two, with an equality sign, to indicate a synonym for
the accepted name of a genus. An example of this second use is given
by the first genus entry in the key. The symbols 9 for female, d" for
Received September 20, 1934.
1 Reprinted from the Proceedings of the Helminthological Society of Washington,
Vol. II, No. 1, January, 1935. Repaged without material alterations.
451
452
PROCEEDINGS HELMINTHOLOGICAL SOCIETY VOL. 2, NO. 1
male, and J for young or immature specimens are used throughout the
key as a means of saving space; "c? only," for instance, indicates
that only the male form is known. The % sign is used to mean per-
cent of body length, or, distant from anterior end, measured in percent
of body length.
In general the intention has been to include all synonyms, together
with the corresponding accepted generic names. The case of Di-
chromadora and Trichromadora, Kreis 1929, is an exception; these
designations seemed to cut across the accepted classification in such a
way as to make their inclusion impracticable.
Through the much appreciated courtesy of the United States Bureau
of Fisheries, a part of the work on the key had been carried out at its
Laboratories at Woods Hole, Mass. Needless to say, the work could not
have been completed or completion even attempted by us without the
resources and the expert advice of the Division of Nematology, of the
Bureau of Plant Industry, U. S. Department of Agriculture, within
which the work has been done. Dr. G. Steiner and Dr. J. R. Christie have
given never-failing aid. Dr. Maurice Hall and Dr. B. Chitwood of the
Division of Zoology have also given generously of their time, their
knowledge and their experience.
MARGARET V. COBB.
ABBREVIATIONS USED IN KEY
abs, absent
lab, labial
absent, none
am'g, among
alt, alternative
lat, lateral
long, longitudinal
+ or more, plus
more or less, somewhat, about
amph, amphid
ant, anterior
mand, mandibular
med, median
% per cent of body length
cf male
card, cardiac
caud, caudal
no, number
nr, near
d" only only the male known
9 female
ceph, cephalic
oes, oesophagus
' 9 ' ovaries 2, reflexed
cerv, cervical
oesoph, oesophagus
~9~ ovaries 2. outstretched
circ, circular
onch, onchium
'9 ovary 1, anterior,_reflexed
conspic, conspicuous
opp, opposite
9 f ovarv 1 , posterior, reflexed
constrict, constriction
cutic, cuticular
cylind, cyUndroid
papill, papillae, papilloid
phar, pharynx, pharyngeal
pharyng, pharyngeal
"9 ovary 1, anterior, outstretched
9~ ovary 1, posterior, outstretched
dents, denticles
post, posterior
Bast, Bastian
devel, developed
pres, present
Btitsch, Biltschli
diam, diameter
prob, probably
Clap, Claparede
exc, except
prs, pairs
Dies, Diesing
excret, excretory
reg, region
Ditlev, Ditlevsen
ext, external
set, setae
gub, gubernaculum
gubernac, gubernaculum
inconspic, inconspicuous
indef, indefinite
stri, striae
subceph, subcephalio
sublat, sublateral
submed, submedian
Duj, Dujardin
Ehrenb, Ehrenberg
Fil, Filipjev
Leuck, Leuckart
intest, intestine
term, terminal
Linst, von Linstow
irreg, irregular
J, young, juvenile
undev, undeveloped
Metsch, Metschnikoff
Micol, Micoletzky
junct, junction
Strass, zur Strassen
COBB: A KEY TO THE GENERA OF FREE-LIVING NEMAS 453
GLOSSARY
adhesion tubes, hollow tube-like setae by means of which some nemas "walk" along a surface
ambulatory setae, setae, sometimes hollow and tube-like, by means of which some nemas "walk" along a surface
amphid, a paired lateral sense organ the opening of which is often conspicuous, near the anterior end
amphidial opening, the pore (or larger aperture) through the cuticle at which amphid opens exteriorly
amphidial pocket, a chamber, outline often cup-shaped, sometimes present just behind external amphid
ampulla, widening in canal, forming a reservoir
annulated, haying annules
annules, definite transverse rings of the cuticle
apophysate, having an apophysis
appendicule, a large single ventral pre-anal supplementary organ which is extensible
bursa, flap-like extensions of the lateral cuticle of the tail end of the male
calvarium, subcuticular cephalic framework
cardiac bulb, swelling of oesophageal wall, glandular or muscular, just anterior to beginning of intestine
cardiac valve, thickening or complication of oesophageal lining in cardiac bulb, functioning as a valve
caudal glands, 3 cells in or near tail, emptying by separate ducts into a common ampulla at spinneret
cephalated, having the head or anterior end set off in some way
cephalic setae, setae of the second or "outer" circlet around the mouth
cephaloboid, resembling (that of) the genus Cephalobus
cervical, on the neck
chromadoroid, resembling (that of) the genus Chromadora
cirri, elaborate cephalic appendages in front of the cephalic setae
cuirasse, a helmet-like appearance of cuticle of bead
cyatholaimoid, resembling (that of) the genus Cyatholaimus
demanian system, gonenteric system of vessels connecting intestine and uteri with each other, and posteriorly
with the exterior
dentate, bearing teeth
denticles, minute teeth or "prickles," usually numerous
denticulate, bearing denticles
diplogastroid, resembling (that of) the genus Diplogaster
dorylaimoid, resembling (that of) the genus Dorylaimus
enchelid, male form such as has been classified in the genus Enchelidium, male of Symplocostoma group
eurystomoid, resembling (that of) the genus Eurystomina
excretory duct, canal leading from renette to ampulla near excretory pore
excretory pore, opening through cuticle (usually cervical or cephalic), at which the renette empties
external amphid, the cuticular manifestation of the amphid
glottoid apparatus, valvular structure at base of pharynx
gubernaculum, grooved cuticularized piece, sometimes paired, through which the spicula slide
head, portion of nema anterior to base of mouth cavity
jaws, cuticular framework around the mouth, for grasping and holding; fundamentally 3-parted
labial setae, setae of the ' 'inner' ' circlet, on the lips or close to the mouth
male supplements, male organs, usually pre- or post-anal, usually a single ventral row, or paired, subventral
mandibles, hard, strong, biting or grasping organs around the mouth
mandibular, of the mandibles, resembling mandibles
median bulb, swelling of the oesophageal wall at or near the middle of its^length
monospiral, spiral of one wind or not much more
monospire, spiral, or a spiral, of one wind or not much more
mucron, a knob-like ending, shaped like that on the end of a lemon
multispiral, spiral of two or more winds
multispire, spiral, or a spiral, of two or more winds
neck, portion of nema anterior to base of oesophagus
odontium (odontia), labial tooth (teeth)
oesophagus, portion of alimentary tract between pharynx and intestine, sometimes surrounding pharynx
onchium (onchia), pharyngeal tooth (teeth)
"palps," special labial appendages, apparently for touching, grasping, or getting material to mouth
percent, percent of body length, or distant from anterior end measured in percent of body length
pharyngeal bulb, muscular swelling of the oesophageal wall around the pharynx
pharynx, the mouth cavity and its walls
phasmids, a pair of cuticular pores on the tail
plectoid, resembling (that of) the genus Plectus
posterior bulb, cardiac bulb, q.v.
probolae, prominent and elaborate specialized appendages encircling the mouth
pseudonchs, structures in pharynx which from some points of view resemble onchia
renette, a cell or group of cells emptying through the excretory duct(s)
rhabditoid, resembling (that of) the genus Rhabditis
sensory papilla, a structure in the amphidial area in which apparently nerves terminate
setae, hair-like structures on the cuticle
sole, the region of attachment of the special ambulatory setae or adhesion tubes
somatic setae, setae general on the surface of the body (opposed to cephalic, caudal, etc. setae)
spear, a long, rather slender oncbium, in adult usually axial
spicula, male intromittent organs, often paired each an elongate cuticularized framework, extrusible through anus
spinneret, outlet, usually terminal, of the caudal glands, enabling nema to attach itself
striae, fine transverse lines in the cuticle
striate(d), showing striae
stylet, a long slender spear
subcephalic setae, setae on the head but behind the cephalic circlet
supplementary organs, see male supplements
tooth, element of buccal armature, onchium, odontium, spear etc.
tylenchoid, resembling (that of) the genus Tylenchus
uvette, rosette or group of cells between uterine afferent duct and efferent duct of demanian system
vestibule, entrance to the mouth cavity, sometimes a distinct chamber
wings, longitudinal structures in cuticle, or projecting from it, usually lateral, but sometimes numerous and
evenly spaced around the nema
454 PROCEEDINGS HELMINTHOLOGICAL SOCIETY VOL. 2, NO. 1
PHARYNX ABSENT, or so obscure as easily to escape notice (for alternative see page 458)
Oesophagus with median or posterior bulb or swelling, or both (for alternative see next page)
Amphid not known or obscure
F oS5 1, anterioTl^fph. set. 0; oesoph. with med. bulb; spinneret 0; bursa pr^jm^iL^otonchium CobMgO
Spinneret'none- amphid a pore at lips; cepn. set. 2, minute; in beetle larvae (Neoapleetana Steiner 1929)
Spinneret present; oesoph. without median bulb; bursa none; marine
Cephalic setae 0; cuticle not annulated; spicula long, 18%. flexible. Molgolaimus Ditlev. 1921
Cephalic setae numerous, in circlets of 4; cuticle annulated, exc. on head (Stilbonema Cobb 1920)
Hemispherical cephalic cap suddenly wider than neck, edge set with dots Mitrepharus Linst. 1877
Hemispherical cephalic cap absent
Spinneret absent; cephalic setae 0; wings present; in soil; J Litonema Cobb 1920
Spinneret present (Xuadella ?); ceph. set. present; wings 0, striae uninterrupted; marine
Cuticle not annulated, striae none; cephalic setae small
Neck 8%; cardiac swelling slight, clavate Nuadella Allgen 1927
Neck under 4%; card, bulb broad; cepb. set. in 3 circlets of 4; am ph. small, near bps..(Catanema Cobb 1920)
Cuticle annulated, exc. on head; amphid near lips
Setae on head, labial 6, ceph. 10; contour of nema serrate; pores lateral (Leptonemella Cobb 1920)
Setae on head in circlets of 4; contour of nema crenate; pores 0; nema 10 mm (Laxonema Cobb 1920)
Amphid known
External amphid not spiral, circular nor elliptical
Head a hemispherical cap, suddenly wider than neck, edge set with dots Mitrepharus Linst. 1877
Head not suddenly wider nor cap-like
Habitat soil about roots
Spinneret present; lips 6, long, revolute, flower-like; amph. semicircular; wings 2; ' 9 ' Anthonema Cobb 1906
Spinneret absent; lips not long nor revolute; cephalic setae
Wings pres. ;oesoph. cephaloboid;striaecoarse;amph. transverse.i head-width; ' 9 lotalaimus Cobb 1920
Wings absent, striae not interrupted
Ceph. papill.6, conspic.;am ph. crescentic.head- width back; tail 3%, rounded; cf only Bolbinium Cobb 1920
Ceph. papill. tiny; amph. inconspic.,2 head-widths back;tail 6-12%, slender.conoid Alaimus de Man 1880
Habitat marine; cephalic setae and spinneret present
Ambulatory & body setae absent; nema not crooked
Wings pres.; amph. shepherd's crook; annules under 300, of tile-like elements; ' 9 ' Ceramonema Cobb 1920
(cf. Pselionema Cobb 1933)
Wings 0; amph. a tran verse slit, at lips; pores lateral; nema 2 mm.; d 1 only. ..Leptonemella Cobb 1920
Ambulatory & body setae pres.; amph. crook-shape to spiral; nema S-shaped; ' 9 '
Oesoph. region hardly swollen; card, bulb faint; cerv. striae alike Notochaetosoma Irwin-Smith 1918
Oesoph. region swollen, ovoid; oesophageal bulbs 1 or 2; band of cervical
striae accentuated, exc. Tristicochaeta falcatum
Ventral ambulatory adhesion tubes or setae in 3 or 4 rows Tristicochaeta Panceri 1878
( = DraconemaCobb 1913)
Ventral ambulatory adhesion tubes or setae in 2 rows Drepanonema Cobb 1933
( = Chaelosoma Clap. 1863)
External amphid spiral, circular or elliptical
Female not known; J only, exc. Bolbinium
Annules 90, prominent ;subdorsal setae 9 prs.;amph. saccate;nema 10%+ wide Eudesmoscolex Steiner 1916
Annules or not prominent; subdorsal setae 0; amphid not saccate; nema under 5% wide
Spinneret absent; cephalic setae 0; in soil
Cephalic papillae 6, conspicuous, each on circular base Bolbinium Cobb 1920
Cephalic papillae or inconspicuous; wings double; oesophagus icephaloboid Litonema Cobb 1920
Spinneret present
Wings single, projecting; amphid almost neck width, barely longer than broad Antomicron Cobb 1920
Wings 0, striae not interrupted laterally
Pharynx with basal cuticularized ring; amphid monospire (Cricolaimus Southern 1914)
Pharynx without basal cuticularized ring; cephalic setae in circlets of 4
Amphid spiral, of 2 winds (Alaimonema Cobb 1920)
Amphid circular or elliptical
Head set off by constriction, spherical; cephalic setae 4; amphid on neck Cinctonema Cobb 1920
Head set off by lack of annules, if at all; ceph. set. many; amph. small, at lips; neck 2%
Cuticle without annules; head not set off; pharnyx definite; nema 3-4 mm (Catanema Cobb 1920)
Cuticle with annules exc. on head; pharnyx obscure; nema 10 mm Laxonema Cobb 1920
Female known
Ovary 1 ; spinneret none; wings 0; cephalic setae or papilloid
Oonad 9 posterior, reflexed; amphid iobscure; cardiac swelling slight; in soil (Alaimus de Man 1880)
Gonad 9 anterior, outstretched
Habitat marine; anterior oesophagus fusiform, cardiac bulb massive (Solenolaimus Cobb 1894)
Habitat soil; oesophagus with median bulb; bursa present lotonchium Cobb 1920
Ovaries 2 ( = Hemic V cli P hora de Man mi)
Gonads 9 outstretched; cephalic setae present; marine (for alternative see next page)
bpmneret doubtful or absent; striae very fine or seen with difficulty
Cephalic setae 10, subcephalic 4: amphid multispire (Laimelli Cobb 1920)
Cephalic setae 4 or 8; amphid circular
Pharynx none; cardiac bulb broad, valvate; tail setaceous Terschellingia de Man 1888
Pharynx obconoid; cardiac bulb pyriform, sometimes valvate (Cryptolaimus Cobb 1933)
opinneret present
Length of oval monospiral amphid twice its width, equalling head width Disconema Fil. 1918
Length of amphid not much greater than its width
Gknd ducts cuticularized , pores ventrad , cerv. & pre-anal ; striae coarse Halaphanolaimus Southern 1914
Gland ducts and pores 0; striae fine, usually plain
COBB: A KEY TO THE GENERA OF FREE-LIVING NEMAS 455
Oesophagus narrowed from middle ; cephalic setae 4 ; amphid large ; head narrowed Cyartonema Cobb 1920
Oesophagus not narrowed; cephalic setae present; wings
Setae on head 10, 4 short specialized at tip; cardiac swelling slight ............ (Linhomoella Cobb 1920)
Setae on head 4-8, less than 1 head-width long, tip not specialized; amphid circular
Pharynx 0;nema small, tapered ; card, bulb broad, valvate; tail setaceous.. Terschellingia de Man 1888
Pharynx present though obscure
Ceph. set. 8-10; card, swelling none or clavate, non-valvate; nema not tapered Linhomoeus Bast. 1865
Ceph. set. 4;cardiac bulb pyriform, sometimes valvate; pharynx obconoid (Cryptolaimua Cobb 1933)
Gonads 9 reflexed; amphid circular, oval or monospiral (for alternative see preceding page)
Spinneret none; amphid a pore at lips; ceph. set. 2, minute; in beetle larvae. . . (Neoaplectana Steiner 1929)
Spinneret present; marine exc. Haliplectus
Ambulatory setae 0; nema not crooked; calvarium absent, or not truncate-conoid
Med. oes. bulb pres.; ceph. set. 0; pores in submed. rows; water & brackish soil.. (Haliplectus Cobb 1913)
Med. oes. bulb absent; marine
Gland ducts cuticularized, pores cerv. & pre-anal; striae coarse. .. (Halaphanolaimus Southern 1914)
Gland ducts and pores none or not cuticularized
Head expanded opposite monospiral amphid; cephalic setae 4 .................. Bolbonema Cobb 1920
Head not expanded
Cephaljc setae 0; wings 0; head narrowed from amphid forward ....... Aegialoalaim.ua de Man 1907
Cephalic setae present; often in coastal sand
Amphid oval, 1 head-width long; annules fine; wing single; ceph. set. 4..Eutelolaimus de Man 1922
Amphid iequidiametral, less than i corresponding neck width
Neck 21%; striae duplex; wings 2; ceph. setae 4; pharynx narrow, inconspicuous Aplectus Cobb 1914
Neck 7% or less; striae not duplex; wings
Cuticle annulated; amph. small, at lips; set. on head many, in circles of 4..(Stilbonema Cobb 1920)
Cuticle finely striated; amphid 1 to i head-width, often monospiral
Pharynx straight.closed.with pharyng.swelling; nema 4-7 mm.; width 0.3-0.8% Laxus Cobb 1894
Pharynx conoid, often with small onchium; nema 2-4 mm.; width 1.5-3.5% Spirina Fil. 1918
Ambulatory set. forming a ventral sole, midbody or pre-anal: nema crooked; calvarium unstriated
Nema narrowest in cardiac region, S-shaped; ambulatory setae hollow, pre-anal; annules finer
Oesoph. region hardly swollen; card, bulb faint; cervical striae alike. . . Notochaetosoma Irwin-Smith 1918
Oesoph. region swollen, ovoid; oesophageal bulbs 1 or 2; band of cervical
striae accentuated, exc. Tristicochaeta falcatum
Ventral ambulatory adhesion tubes or setae in 3 or 4 rows ................. Tristicochaeta Panceri 1878
( = Draconema Cobb 1913)
Ventral ambulatory adhesion tubes or setae in 2 rows ........................ Drepanonema Cobb 1933
( = Chaetosoma Clap. 1863)
Nema narrowest midway, epsilon-shaped; ambulatory setae not open at end; annules coarser
Sole apparently absent; amphid crescentic; annules 98 ...................... Epsilonella Steiner 1930
Sole present; amphid circular or monospiral
Oesophagus with median and cardiac bulbs .............................. Metepsilonema Steiner 1927
Oesophagus with cardiac bulb only
Annules 80-112; ambulatory setae slender, falcate ..................... Bathyepsilonema Steiner 1927
Annules 144-192; ambulatory setae straight or slightly arcuate
Body cylindroid, if crooked faintly so ............................... Archepsilonema Steiner 1927
Body epsilon-like, i.e. body arches well developed
Cuticular annules homogeneous in structure .............. Prochaetosoma Baylis & Daubney 1926
( = Rhabdogaster Metech. 1867)
Cuticular annules not homogeneous in structure
"Axial" part of the cuticular annules hollow ("frame rings") ........... Epsilonema Steiner 1927
"Axial" part of the cuticular annules vacuolated, etc .................. Epsilonoides Steiner 1931
Oesophagus plain, i.e. without median or posterior bulb or swelling (for alternative see preceding page)
Amphid not known or obscure (for alternative see next page)
Female not known
Habitat freshwater marshes ; setae 0; spinneret none; neck 15-25%; wings double Macroposthonia de Man 1880
Habitat marine
Neck 8%, cylindroid; cephalic setae 4(?); tail cylindroid ............................. Nuadella Allgen 1927
Neck 16-43%, itapering; tail conoid
Spinneret absent; eyes 0; neck 40%; cephalic setae 4 or 8 ................... (Halalaimoides Cobb 1933)
Spinneret present; eyes with lenses; neck 16-25%
Cep
phalic setae 4 ; head set off by cessation of very fine striation ...................... Nemella Cobb 1920
Cephalic setae 10; striae none; amphid and setae very large; adult cf only ..... Enchelidium Ehrenb. 1836
(=Lasiomitus Marion 1870
= Parasymplocostoma Schulz 1932)
Female known
Ovary 1, anterior exc. Antopus & Thalassoalaimus (for alternative see next page)
Gonad 9 outstretched; setae 4, papilloid ; amphid minute, open caudad; marine algae. . .(Litotes Cobb 1920)
Gonad 9 reflexed; spinneret none, exc. Antopus & Thalassoalaimus
Cephalic setae 6; posterior ovary longer than anterior; marine
Pores in dorso-lateral rows ........................................................... Antopus Cobb 1933
Pores none ................................................................ Thalassoalaimus de Man 1893
Cephalic setae 0; vulva near anus; spicula 2; in and around insects
Spear none or vestigial
Uterus not evaginated
Nema serpentine; oesophagus and intestine persisting; in beetles and weevils. . .Bradynema Strass. 1892
Nema saccate; organs degenerating exc. gonads ............................... Allantonema Leuck. 1884
( = TylenchomarphusFucbs 1914)
Uterus finally evaginated; oesophagus and intestine degenerating early
Evaginated uterus many times as large as nema .............................. Sphaerularia Duf . 1837
Evaginated uterus not much larger than nema .................................. Asconema Leuck. 1886
( = Atractonema Leuck. 1887)
Spear present, at least in larva or 9 ; organs degenerating in adult
Base of spear ibulbed ; oes. fusiform, glands abs. in a" ; bursa pre- and post-anal . . Scatonema Bovien 1932
Base of spear straight; spicula nearly straight
Vulva degenerating; 9 free living; bursa pre-anal; in Passalus. .Chondronema Christie & Chitwood 1931
(=Uracanthus Dies. 1861)
456 PROCEEDINGS HELMINTHOLOGICAL SOCIETY VOL. 2, NO. 1
Vulva remaining functional; adult 9 parasitic; gubernaculum small
Anus none or vestigial; in cucumber beetle, Diabrotica Howardula Cobb 1921
Anus persisting; in frit-fly, Oscinella (Tylenchinema Goodey 1930)
Ovaries 2; spinneret present exc. Micoletzkyia (for alternative see preceding page)
Gonads 9 parallel, posterior; wings 10-12, segmenting the annules Parocoma Cobb 1920
Gonads 9 opposed
The ovaries outstretched; marine
Annules few, very coarse; amphid saccate; cephalic setae 4; nema wide
Number of annules 17, secreted annules prominent, separated; head small Desmoscolex Clap. 1863
Number of annules 32-91 , secreted annules absent ; head concave-quadrate pyramidal. . Tricoma Cobb 1894
( = Quadricoma Fil. 1922)
Annules and striae 0; amphid not saccate; cuticle thick Phanodermella Kreis 1928
The ovaries reflexed
Habitat freshwater; lips 3, thick; pharynx narrow, deep; onchium minute, deepset (Tripyla Bast. 1865)
( = Promononchus Micol. 1923)
Habitat marine; pharnyx and onchium absent
Annules 17,secreted annules prominent ;amphid saccate;ceph. set. 4;nema wide Desmoscolex Clap. 1863
Annules not few nor coarse; amphid not saccate; nema slender
Odontia 6; lip region discoid; ceph. set. 4; gland ducts oft piercing cuticle. . Stephanolaimus Ditlev. 1918
Odontia 0; lip region not set off
Head set off by constrict.; ceph. set. 8; spicula long, slender; gub. complex Micoletzkyia Ditlev. 1926
Head not set off; cephalic setae 4 or 6
Setae on head 4 ; eyes with lenses ; amphid transverse-oval, at lips ; among algae (lonema Cobb 1920)
Setae on head 6 ; eyes none
Spicula short, 1 anal body-diam.; pores 0; longest cerv. set. J neck-width. .Paroxystomina Micol. 1924
Spicula long, several anal body-diameters
Cervical setae in 6 longitudinal rows; pores 0; ovaries equally long (Stenolaimus Marion 1870)
Cervical setae 0; pores in dorso-sublat. rows; ovary post., anterior a rudiment. . Antopus Cobb 1933
Amphid known (for alternative see preceding page)
External amphid not spiral, circular nor elliptical (for alternative i
5 see next page)
Female not known; marine
Neck 40%;amph. narrow, several head- widths long;tail setaceous ;spinneret oft Halalaimoides Cobb 1933
Neck not over 25%; amphid not linear; spinneret present
Wings absent
Odontia 6;lip papill. 6;ceph. set. 10(?) ; subceph. 4, jointed; amph. oval, flat caudad Apodontium Cobb 1920
Odontia 0; mouth & phar. vestigial; eyes, amph. & set. very large; adult cf only Enchelidium Ehrenb. 1836
( = Lasiomitus Marion 1870
= Parasymplocostoma Schulz 1932)
Wings conspicuous
Head mitreform, set off by constriction; striae 0; cephalic setae small, 4 or 6 Xennella Cobb 1920
Head not mitreform, set off by lack of annulation; annules of "tiles" ; amph. crook-shape
Annules over 700; ceph. set. conspicuous, 8, in 2 circlets; onchia 0; nema 3 mm.+ Pristionema Cobb 1933
Annules under 300; cephalic setae 4; onchium present (?); nema under 1 mm Pselionema Cobb 1933
( = Steineria Fil. 1922)
(cf. Ceramonema Cobb 1920)
Female known
Ovary 1
Gonad ? outstretched, anterior ;ceph. papill. 4;amph. minute, open caudad ;marine algae Litotes Cobb 1920
Gonad 9 reflexed
Spinneret present; ovary posterior, anterior branch short; wings 0; marine Thalassoalaimus de Man 1893
Spinneret absent; ovary anterior; in soil about roots
Wings present, striae icoarse; cephalic papillae 4; amphid 1 head-width back. ..lotalaimus Cobb 1920
Wings 0, striae 0; cephalic papillae minute; amphid 2 head-widths back Alaimus de Man 1880
Ovaries 2
Gonads 9 outstretched; spinneret present; marine
Annules 17, secreted annules prominent ;amphid saccate ;ceph. setae 4 ;nema wide Desmoscolex Clap. 1863
Annules not few nor coarse; amphid not saccate; nema slender
Mouth ventrad ; amphid huge, bent, dorsal limb the longer Campylaimus Cobb 1920
Mouth axial; amphid not huge
Amphid narrow, oft many head- widths long; eyes 0; cephalic setae 6, subceph. 4 Halalaimusde'M.a.n 1888
Amphid "folded," not over 1 head-width long; eyes 2, sometimes absent
Oesophagus and lumen widened between eyes and nerve ring; pharynx obvious (Coinonema Cobb 1920)
Oesophagus and lumen not widened; pharynx like oesoph. lining. . . . Araeolaimoides (de Man) Fil. 1918
Gonads 9 reflexed
Spinneret 0; tail 3%; ceph. set. 10, cervical long, 1 group at amphid; marine. . Platycomopsis Ditlev. 1926
( = DactylonemaFil. 1927)
Spinneret present
Habitat freshwater; lips 3, thick; pharynx narrow, deep; onchium minute, deepset (Tripyla Bast. 1865)
( = Promononchus Micol. 1923)
Habitat marine; onchia absent ex<5. Actinonema
Amphid narrow, several head- widths long; head set off, with colorless cuticle
Cephalic & subceph. setae 1 head-width apart; cuticle thin (to ,'j radius) . . . Halalaimus de Man 1888
Cephalic & subceph. setae near together exc. Nuada isaitshikovi ; cuticle thick, to J radius
The cuticle i to 1 radius in thickness Nuada Southern 1914
The cuticle i to i radius in thickness Tycnodora Cobb 1920
Amphid not narrow nor very long
Shape of amphid a shepherd's crook ; each annule of tile-like elements Ceramonema Cobb 1920
(cf. Pselionema Cobb 1933)
Shape of amphid not a shepherd's crook; annules not of tile-like elements
Annules 17, secreted annules prominent ;amph. saccate; ceph.set.4; nema wide Desmoscolex Clap. 1863
Annules not few nor coarse; amphid not saccate; nema slender
Cutjcle 4 radius; striae coarse; amphid transverse, J head-width ; setae (Actinonema Cobb 1920)
Cuticle not thick; amphid not a transverse slit; eyes with lenses; cephalic setae 4
Amphidial gland large, conspicuous; cephalic setae 4, j head-width long lonema Cobb 1920
Amphidial gland not evident; external amph. semicircular, internal elongate Nemella Cobb 1920
COBB: A KEY TO THE GENERA OF FREE-LIVING NEMAS 457
External amphid spiral, circular or elliptisal (for alternative see preceding page)
Female not known; spinneret present
Habitat brackish earth; wings faint; d" supplements on neck, ventral, papilloid Deontolaimus de Man 1880
Habitat marine
Annules 90, prominentjsubdorsal setae 9 prs. ;amph. saccate; nema 10% + wide Eudesmoscolex Steiner 1916
Annules none or not prominent; subdorsal setae 0; amphid not sacsate; nema under 5% wide
Wing small, distinct; amphid almost neck width, joined dorsad (Antomicron Cobb 1920)
Wings absent
Mouth and digestive system vestigial; setae strongly developed
Eyes absent Barbonema Fil. 1927
Eyes and amphid strongly developed ; adult cf only (Enchelidium Ehrenb. 1836)
( = Lasiomitus Marion 1870
=Parasymplocostoma Schulz 1932)
Mouth and digestive system functional
Odontia 6, minute; cephalic setae 10(7), subcephalic 4, jointed Apodonlium Cobb 1920
Odontia 0; cephalic setae or rather small
Annules rather coarse; setae minute; amphid transverse-oval (Zygonemella Cobb 1920)
Annules and striae none; amphid with internal pocket
Cephaljc setae 0; amphid long-oval, internal pocket conspicuous Schislodera Cobb 1920
Cephalic setae small, 10; cervical setae lateral; amphid small, round . . . . (Leptosomalides Fil. 1918)
Female known
Ovary 1 ; amphid not multispire
Gonad 9 outstretched
The ovary posterior; spinneret present
Amphid large, open caudad; spinneret sometimes doubtful; marine (Alaimella Cobb 1920)
Amphid round; anterior ovary rudimentary; ceph. set. 12, in 2 circlets; in salt marsh Litinium Cobb 1920
The ovary anterior; marine
Pharynx absent; setae 4, papilloid ;amph. small, open caudad; spinneret 0; among algae Litotes Cobb 1920
Pharynx present, often minute; setae not papilloid ; amphid larger, circular; spinneret sometimes
Onchia 0; nema small Monhystera Bast. 1865
( = Tacky hodites Bast. 1865)
Onchium dorsal; nema often several millimetres long Linhomoeus Bast. 1865
( = L. obtusicaudatus de Man 1907)
Gonad 9 reflexed
Habitat soil or fresh water, or in insects; amphid circular
The ovary posterior; spinneret absent; in marshy soil Alaimus de Man 1880
The ovary anterior
Spinneret present ; in fresh water Helalaimus de Cillis" 1917
Spinneret absent; in beetle, Passalus Chondronema Christie & Chitwood 1931
(=Uracanthus Dies. 1861)
Habitat marine; ovary posterior; spinneret present (Alaimella ?)
Cephalic setae
Amphid monospire; in sand about algae Nemanema Cobb 1920
Amphid long-oval, with posterior cuticularized pocket Schistodera Cobb 1920
(cf. Oxy stamina Fil. 1921)
Cephalic setae present
Setae on head 4, over 1 head-width long; striae coarse; amphid large, open caudad. . Alaimella Cobb 1920
Setae 10 or 16, 4 being subcephalic; striae or fine
External amphjd circular; cephalic setae 12, as long as head is wide Lilinium Cobb 1920
External amphid oval, pocket cuticularized; cephalic setae 6 (4?)
Amphidial opening small transverse-oval, or circular Nemanemella Fil. 1927
Amphidial opening large, long-oval Oxystomina Fil. 1921
( = Oxystoma Butsch. 1874)
Ovaries 2
Gonads 9 outstretched; marine
Spinneret absent
Pharyngeal bulb definite; ceph. setae 6, stout, jointed; amphid circular; in sand (Cytolaimium Cobb 1920)
Pharyngeal bulb absent
Tail 3%, eonoid; ceph. set. 10; cervical long, bunched; amphid transverse-oval Platycoma Cobb 1894
Tail over 12%, conoid then cylindroid; ceph. set. minute, 18, in 3 circlets (Anticyathus Cobb 1920)
Spinneret present
Gland ducts cuticularized, pores cervical & pre-anal ; striae coarse (Halaphanolaimus Southern 1914)
Gland ducts and pores absent
Annules few, very coarse; amphid saccate; cephalic setae 4; nema wide
Number of annules 17, secreted annules prominent, separated; head small. . .Desmoscolex Clap. 1863
Number of annules 32-91 , secreted annules none; head concave-quadrate pyramidal Tricoma Cobb 1894
( = Quadricoma Fil. 1922)
Annules if present not coarse; amphid not saccate
Ampbid multispire
Cephalic setae 10, shorter 4 specialized at tips; multispire faint; neck 5% Linhomoella Cobb 1920
Cephalic setae without specialized tips; multispire distinct; neck 9-16%
Male ventral pre-anal supplementary organs papilloid Parasabatieria de Man 1907
Male ventral pre-anal supplementary organs absent Sabatieria de Rouville 1903
Amphid circular (Southernia slightly irregular)
Oesoph. & lumen with ellipsoid enlargement behind eyes; eyes sometimes Araeolaimus de Man 1888
Oesoph. without median enlargement; eyes
Cephalic setae 4; amphid slightly irregular Southernia Allgen 1929
Lips distinct; pharyngeal bulb pres.; ceph. set. 6, stout, jointed; papillae 6. .Cytolaimium Cobb 1920
Setae on head 10, shorter 4 specialized at tips; multispire faint (Linhomoella Cobb 1920)
Setae on head without specialized tips; amphid circular Linhomoeus Bast. 1865
Gonads 9 reflexed
Spinneret absent; amphid circular, elliptical or monospiral; wings (for alternative see next page)
Habitat soil ; internal amphid conspicuous (Basliama de Man 1876)
Habitat marine
Tail 40%; vulva 33%; ceph. set. 6, subceph. 6; internal amphid conspicuous. ... Trefusia de Man 1893
458 PROCEEDINGS HELMINTHOLOGICAL SOCIETY VOL. 2, NO. 1
Tail under 10%; vulva 60%; ceph. set. 1 head-width long; internal amphid not conspicuous
Ceph. set 10, cervical long, bunched, in & 2 flat ones at amphid; tail 3%, conoid. .Platycoma Cobb 1894
Ceph. set. 4 (6?), other setae 0; nema cephalated by contraction; tail slender, 9%. . . Acoma Steiner 1916
Spinneret present (for alternative see preceding page)
Habitat not marine (Aphanolaimus ?); contour often crenate
Amphid obscure,small;pharynx narrow;onch.deepset;ceph.set. 6-10, oft papilloid. . .(Tripyla Bast. 1865)
( = Promononchus Micol. 1923)
Amphid distinct, circular or spiral; pharynx none or closed; ceph. set. 6, rarely 4 or
Position of amphid i-2 head-widths back Aphanolaimus de Man 1880
Position of amphid 3-4 head-widths back Bastiania de Man 1876
Habitat marine
Ambulatory tubes hollow; body setose, annulated
The amphid not saccate; ambulatory tubes ventral ; setae not dense. .Notochaetosoma Irwin-Smith 1918
The amphid saccate; annules coarse, 17-91; nema broad
Body setae not dense; secondary annules secreted, prominent (Desmoscolex Clap. 1863)
Body setae dense, set along annules; junction oesoph. & intestine indefinite. . . . (Greeffiella Cobb 1922)
( = Trichoderma Greeff 1869)
Ambulatory tubes absent; body not densely setose; not annulated exc. Stephanolaimus
Wings 50;nema broad, 16% ;neck "collared" ;amphid spiral ;pharynx small.. .Richtersia Steiner 1916
Wings if present not numerous; nema slender, under 5%
Odontia 6; ceph. set. 4, long; lip reg. discoid; gland ducts oft projecting. .Stephanolaimus Ditlev. 1918
Odontia 0; cephalic setae not longer than head is wide
Gland ducts cuticularized, pores cervical & pre-anal; striae coarse . . Halaphanolaimus Southern 1914
Gland ducts and pores none, or not cuticularized
The amphid multispire; cephalic setae 16, 1 head-width long; in sand . .Nannolaimus Cobb 1920
The amphid not multispire
Amphid at lips, transverse-oval, with large gland; eyes with lenses lonema Cobb 1920
Amphid not at lips; eyes none exc. Leptosomatum
Anterior part of oesoph. the wider; cervical setae 0; amphid irregular. . .Southernia Allgen 1929
Anterior part of oesoph. not wider; amphid with internal pocket
Oesophagus crenate posteriorly
Calvarium none; labial tubercles none Stenolaimus Marion 1870
Calvarium in front of ceph. set., margin irregular; labial tubercles 3 Klugea Fil. 1927
(=Phanodermopsis Ditlev. 1926, in part)
Oesophagus not crenate posteriorly
Cephalic setae 0; pores on anterior half of neck; tail rounded Leptosomatum Bast. 1865
Cephalic setae present; pores on neck absent
Setae on neck none; cephaljc setae 10, 1 head-width long Leptosomella Fil. 1927
Setae on neck in lateral series; amphid small
Gubernaculum present; c? pre-anal ventral supplement tubular Anticoma Bast. 1865
Gubernaculum none; cf pre-anal ventral supplement papilloid. .. (Anticomopsis Micol. 1930)
PHARYNX PRESENT (for alternative see page 454)
Wall of the Pharynx armed (for alternative see page 470)
Armature spear-like or apparently so (for alternative see page 461)
Spear bulbed; cephalic setae usually 0; amph. oft obscure; spinneret 0; not marine exc. Siphonolaimus (pg. 460)
Oesophagus plain, i.e. without median or posterior bulb or swelling; cephalic setae
Female not known spear with retrorse points midway, base 3-lobed ;bursalobed. .Ecphyadophora de Man 1921
Female known; ovary 1
Gonad 9 reflexed
Habit free-living; spear (dorso-ventral view) arrow-headed; ovary posterior. . Pharetrolaimus de Man 1921
Habit parasitic in beetles, etc.; ovary anterior
Nema saccate; mouth none, organs degenerated; vulva terminal (Allantonema Leuck. 1884)
( = Tylenchomorphus Fuchs 1914)
Nema not saccate; anus none or vestigial
Spear none; parasitic in beetles, weevils, etc (Bradynema Strass. 1892)
Spear present in young 9 only ; in cucumber beetle, Diabrotica Howardula Cobb 1921
Gonad 9 outstretched; mostly parasitic
Anus none or vestigial; spear vestigial; in cucumber beetle, Diabrotica (Howardula Cobb 1921)
Anus present; spear present, in Aphelenchulus reduced; traces median bulb sometimes present
Junction oesoph. & intest. definite; anterior oes. fusiform, isthmus at nerve ring; in or about plants
Habitat crop plants; head of 8 sectors; terminus of tail straight Neotylenchus Steiner 1931
Habitat bladders of Fucus, or among marine algae; head of 6 sectors; tail hooked. . Halenchus Cobb 1933
Junction oesophagus and intestine indefinite
Spear with 6 basal lobes; oesoph. isthmus at nerve ring; in decaying vegetation. . Hexatylus Goodey 1926
Spear with tripartite base; renette body length; parasitic in insects Aphelenchulus Cobb 1920
Oesophagus with median or posterior bulb or swelling, or both
Female not known ; spear tripartite at base
Cephalic setae 4, 1 head-width long; oesoph. swellings med. & card.; bursa striate. .Eutylenchus Cobb 1913
Cephalic setae or papilloid
Spear with retrorse points midway, 3-lobed at base; bursa small, lobed Ecphyadophora de Man 1921
Spear without retrorse points midway ; oesophagus without median bulb
Pharyngeal bulb O.cardiac i neck length ;ceph.set.0;nema 5% wide;bursa 0. . Tylencholaimellus Cobb 1915
Pharyngeal bulb pres.;ceph.set.6,papilloid;nema 9% wide;tail short .rounded. .Brachynemella Cobb 1933
( = Brachynema Cobb 1893)
Female known
Ovaries 2; cephalic setae 0; spear with tripartite base (for alternative see next page)
Gonads 9 outstretched (for alternative see next page)
Median oesophageal bulb absent ; spear 3-pronged at base ; in sandy soil . . . ( Tylolaimophorus de Man 1880)
Median oesophageal bulb present; spear 3-lobed at base
Junction oesoph.& intestine indefinite ;annules plain;tail rounded.with bursa. . Hoplolaimus Daday 1905
Junction oesoph. & intestine definite, exc. sometimes Tylenchus
Spear-guide wide as head, forming cuirasse or helmet; bursa none; testes 2..Nemonchus Cobb 1913
COBB: A KEY TO THE GENERA OF FREE-LIVING NEMAS 459
Spear-guide smaller, slighter, not forming cuirasse; bursa present
Nema cephalated by constriction, head idiscoid; spear long; bursa loba.te....Dolichodorus Cobb 1914
Nema cephalated by contraction or not at all ; bursa not lobate
Anterior end extensible.narrow & beak-like,inner framework cuticular. . Tylenchorhynchus Cobb 1913
Anterior end never narrowed & beak-like, without cuticular framework Tylenchus Bast. 1865
Gonads 9 reflexed (for alternative see preceding page)
Structure of pharynx obscure; oesophagus with cardiac swelling only
"Spear" 3 rods, ant. hinged to 2 U-shaped pieces, post. 2 stalked swellings. . (Tylopharynx de Man 1876)
"Spear" rods 2-3, base heavy, irreg.; setae or papill.; ovary obscure. . . Diphtherophora de Man 1880
( = Chaolaimus Cobb 1893
= Archionchus Cobb 1913)
Structure of pharynx obvious
Oesophagus without median bulb, cardiac bulb present
Cardiac swelling cylindroid (i.e. oesophagus dorylaimoid)
Oral spear large, over 5%, base 3-bulbed but not trif urcate
. large, over 5%, base 3-bulbed but not trif urcate Xiphinema Cobb 1913
Oral spear smaller, under 5%, base trif urcate (Tylencholaimus de Man 1876)
Cardiac swelling pyriform to clavate
Spear 3-bulbed at base, stout; amphid protrusile, tube cuticularized Triplonchium Cobb 1920
Spear 3-pronged; amph. J head-width, transverse-oval; labial papillae 6 Tylolaimophorus de Man 1880
Oesophagus with median bulb, often with cardiac swelling also
Body thick, not serpentine; 9 and larval forms Heterodera Schmidt 1871
( = Meloidogyne Goldi 1887
= Caconema Cobb 1924)
Body serpentine
Junction oesoph.& intestine indef . ;annules plain;tail rounded, with bursa. . (Hoplolaimus Daday 1905)
Junction oesoph. & intestine definite; bursa none; tf and larval forms
Spear really the apophyses of 3 movable onchia at base anterior pharynx Tylenchodon Fuchs 1930
Spear tylenchoid Heterodera Schmidt 1871
( = Mdoidogyne Goldi 1887
= Caconema Cobb 1924)
Ovary 1 (for alternative see preceding page)
Gonad 9 reflexed; setae
Spear trif urcate half its length, base swollen; oesoph. with cardiac bulb only. .Dory Ilium Cobb 1920
Spear furcate at base only; bulbs usually 3
Body thick, inert; parasitic 9 forms
Nema body swollen, head and neck narrow; vulva 90%; in citrus roots Tylenchulus Cobb 1913
Nema sausage-shaped ;organs degenerated exc.gonads; vulva term.; in insects Allantonema Leuck. 1884
( = Tylenchomarphus Fuchs 1914)
Body islender or serpentine
Oral spear vestigial; median bulb ireduced; cf and larval forms
Habitat in citrus roots and soil Tylenchulus Cobb 1913
Habitat in and around wood-boring beetles Allantonema Leuck. 1884
(=Tylenchomorphus Fuchs 1914)
Oral spear well developed
Median oesophageal bulb elongate; vulva over 70%, ovary anterior; bursa none
Spear 3-4%; annules 0; median bulb ireduced; anus not functional Tylenchulus Cobb 1913
Spear 8-23%;annules under 150,retrorse;median bulb oft valvate;vulva 70-95%. .Ogma Southern 1914
(=Iota Cobb 1913)
Median oesophageal bulb absent
"Spear" rods 2-3, base heavy, irreg.; setae or papilloid; vulva 5Q%... Diphtherophora de Man 1880
( = Chaolaimus Cobb 1893
= Archionchus Cobb 1913)
"Spear" of usual structure, shaft distinct, base tripartite
Tip of spear tapering, posterior prongs little swollen; vulva 33-72%. . Tylencholaimus de Man 1876
Tip of spear (dorso-ventral view) arrow-headed; vulva 25%, ovary post. Pharetrolaimus de Man 1921
Gonad 9 outstretched
Habitat marine;"spear" an evertible pharyng. lining ;amph. round ;neck 4% Siphonolaimus de Man 1893
Habitat not marine; median oesophageal bulb present (Neotylenchus ?)
Cephalic setae 4, li head-widths long; longitudinal striae 10; in cranberry bog. .Atylenchus Cobb 1913
Cephalic setae
Dorsal oes.gland emptying at med.bulb;junct.oes.&intest. indef. ;bursa A phelenchoides Fischer 1894
( = Seinura Fuchs 1931
=Parasitaphelenchus Fuchs 1930
= Pathoaphelenchus (Cobb) Steiner 1931)
Dorsal oes. gland emptying at base of spear; genera tylenchoid
Spear under 5%; junction oesoph. & intest. usually definite; nema under 5% wide; bursa present
Anterior oesoph. with median bulb; head of 6 sectors; tail without mucron. ...Tylenchus Bast. 1865
Anterior oesoph. fusiform to isthmus; median bulb not definite; in or about plants
Habitat crop plants; head of 8 sectors; terminus of tail straight Neotylenchus Steiner 1931
Habitat bladders of Fucus, &am'g marine algae;head of 6 sectors ; tail hooked Halenchus Cobb 1933
Spear 8-24%; oesoph. lining flexible, looping; nema 5%+ wide; bursa 0; vulva 72-94%
Base of spear bulbed, not fluked; annules over 100, not retrorse; junct. oes. & intest. definite
Oral area not raised; annulation fine Paratylenchus Micol. 1922
Oral area raised, surrounded by "fossa" ; annulation rather coarse Procriconema Micol. 1925
Base of spear anchor-shaped (fluked); annules under 150, retrorse; junct. oes. & intest. indef.
Scales, prickles and fringes absent from annules Criconema Hoff manner & Menzel 1914
Scales, prickles or fringes ornamenting the annules Ogma Southern 1914
(=Iota Cobb 1913)
460 PROCEEDINGS HELMINTHOLOGICAL SOCIETY VOL. 2, NO. 1
Spear plain, i.e. not bulbed at base (for alternative see page 458)
Oesophagus plain, i.e. without median or posterior bulb or swelling
Amphid known
External amph.reniform; dorsal pnch. small, at spear base; ovary ant.; not marine Enoplocheilus Kreis 1932
External amphid circular, elliptical or monospiral
Spinneret absent; anus reduced; parasitic in beetles
Pharyng.bulb strong.head swollen; spear 1.5%; junct.oesoph.& intest. indef. ;~9 (Rhabdonchus Cobb 1933)
Pharyng. bulb none; spear vestigial; in beetle, Passalus; '9 Chondronema Christie & Chitwood 1931
(= Uracanthus Dies. 1861)
Spinneret present; marine
Annules coarse exc. on head ; onch. spear-like, axial ; body set. in long, rows ; ~ 9 ~ Aculeonchus Kreis 1928
Annules none or fine; head not expanded; cephalic setae 4
Striae of dots, larger laterally; amph. multispire; spicula 2-jointed; ~9~. .Dorylaimopsis Ditlev. 1918
( = Xinema Cobb 1920)
Striae 0; amph. monospire; spicula entire; junct.oes. & intest. obscured by glands; eyes present
Spear 0.3%, a thickening of dorsal phsryngeal wall; ovaries 1 or 2, reflexed (Onchium Cobb 1920)
Spear more obvious, 1.5%; ' S ' Onchulella Cobb 1920
Amphid unknown or obscure
Female not known; spear a small prod at lips; marine Rhinonema Allgen 1927
Female known
Spinneret present; ovaries 2; marine
Calvariumsubcuticular; spear long, slender; set. on head long; nema 6 mm. Thoracostomopsis Ditlev. 1918
Calvarium none; head not suddenly narrowed; spear short; ovaries reflexed (Onchulella Cobb 1920)
Spinneret absent; ovary 1; not marine
The female saccate, sausage-shaped; vulva terminal, ovary reflexed; in beetles Allantonema Leuck. 1884
(=Tylenchomarphus Fuchs 1914)
The female ielongate, usually not slender; vulva posterior, ovary anterior
Ovary outstretched; anus present; spear a mere prod, reduced in a"; wings O...Iotonchium Cobb 1920
Ovary reflexed exc. Rhabdonchus; anus none or reduced; parasitic in insects
Spear long, slender, in muscular bulb, head swollen; junct. oes. & intest. indef. .Rhabdonchus Cobb 1933
Spear vestigial, minute or none; pharyngeal bulb absent
Mouth and spear absent; in beetles, weevils, etc (Bradynema Strass. 1892)
Mouth and spear present in young 9 only; in beetles, frit fly, etc.
' Vulva degenerating; 9 free-living ;bursa pre-anal;in Passalus Chondronema Christie & Chitwood 1931
(= Uracanthus Dies. 1861)
Vulva remaining functional; adult 9 parasitic; gubernaculum small
Anus none or vestigial; in cucumber beetle, Diabrotica Howardula Cobb 1921
Anus persisting; in frit-fly, Oscinella (Tylenchinema Goodey 1930)
Oesophagus with median or posterior bulb or swelling, or both
Amphid nc
r ._ not known or obscure
Spinneret present; cardiac swelling slight; spear a small prod at lips; J (Rhinonema Allgen 1927)
Spinneret absent; cephalic setae
Nema parasitic, saccate female; vulva terminal; in beetles, etc.; '9 (Allantonema Leuck. 1884)
(=Tylenchomorphits Fuchs 1914)
Nema free-living
Armature a minute labial prod; expanding headsuddenly truncate; vulva88%;~ 9 lotonchium Cobb 1920
Armature an obvious spear
Spear closed, bent dorsad at tip when extruded; '9 (Campydora Cobb 1920)
Spear open, a hollow passage; not bent at tip
Lips petaloid, lip reg. expanded, discoid ; oesoph. dorylaimoid ; spear small ; ' 9 ' Antholaimus Cobb 1913
Lips 0; median bulb valvate, with outlets of 3 glands; junction oesoph. & intestine indefinite; ~9
Gubernaculum and bursa present Aphelenchus Bast. 1865
(=*Isonchus Cobb 1913)
Gubernaculum and bursa absent Aphelenchoides Fischer 1894
( = Seinura Fuchs 1931
*=Parasilaphelenchus Fuchs 1930
=Pathoaphelenchus (Cobb) Steiner 1931)
Ampbid known
External amphid spiral, circular or elliptical (for alternative see next page)
Spinneret present; amphid labial, spiral; "spear" filling posterior pharynx; marine
Width of nema 3.5%; pharyngeal bulb definite; ' 9 ' Onyx Cobb 1891
Width of nema 7%; pharyngeal bulb faint; J Oistolaimus Ditlev. 1921
(cf. Onyx Cobb 1891)
Spinneret absent; amphid circular or elliptical
Anus none;setae 0; pharyng.bulb strong; junct.oes.&intest. indef.; in beetles; ~ 9 Rhabdonchiu Cobb 1933
Anus present; nema free-living
Cephalic setae 10, Siphonolaimus sometimes 0; amphid circular
Habitat marine ;"spear" evertiblephar.lining;nema5-10mm.;neck4%; ~ 9 Siphonolaimus de Man 1893
Habitat moist soil; spear tooth-like; nema 0.85 mm.; neck 16% Odontolaimus de Man 1880
(=Neonchus Cobb 1893)
Cephalic setae
Spear bent dorsad at tip when extruded; amphid small, oval, at lips; '9 Campydora Cobb 1920
Spear not bent at tip
Med.oes.bulb 0;nema dorylaimoid;lab.papillae 6,cepb.6;ovaries 2 (Tylolaimophorus de Man 1880)
Med. oes. bulb valvate; nema tylenchoid; papillae 0; amphid oval, near lips
Junction of oesophagus and intestine definite
Gubernaculum and bursa absent; tail often with mucron; ~9 Paraphelenchus Micol. 1925
Gubernaculum small; bursa without ribs; tail slender, long-conoid; ~9~ Psilenchus de Man 1921
Junction oesoph. & intestine indefinite; oes. gland outlets at med. bulb; tail short; ~9
Bursa and gubernaculum present Aphelenchus Bast. 1865
(=Isonchus Cobb 1913)
Bursa and gubernaculum absent Aphelenchoides Fischer 1894
( = Seinura Fuchs 1931
=Parasitaphelenchus Fuchs 1930
=Pathoaphelenchus (Cobb) Steiner 1931)
COBB: A KEY TO THE GENERA OF FREE-LIVING NEMAS 461
External amphid a transverse slit, oft at lip reg.; ceph. set. 0; fresh water or soil (from preceding page)
Ovary 1, reflexed; spinneret (Oionchus ?)
Spear a closed cutting or pricking organ, tooth-like; vulva 55-60%, ovary anterior
Spinneret (?) present; spear straight Oionchus Cobb 1913
Spinneret absent; tip of spear bent dorsad when extruded; amphid elliptical ...Campydora Cobb 1920
bpear open at end, a hollow passage, tip not bent; oesophagus dorylaimoid
Anterior f of oesophagus narrow; cardiac swelling set off by constriction (Doryllium Cobb 1920)
Anterior |-j of oesophagus narrow; both parts cylindroid
Narrow part of oesophagus set off behind by constriction Axonchium Cobb 1920
Narrow part of oesophagus iconfluent with wider posterior part; 9 ' (Dorylaimus Duj. 1845)
Ovaries 2, reflexed; 9esophagus idorylaimoid
Spear a closed cutting or pricking organ, tooth-like
The spear long, slender, flexible; cardiac swelling slight, basal, iclavate
Guide rings for spear absent; spear 30-40% of neck length Trichodorus Cobb 1913
Guide rings for spear present; spear 20% of neck length Leptonchus Cobb 1920
Ihe spear shorter, less slender, less flexible; cardiac swelling cylindroid, i-| oesophagus
Tip of ventral spear oblique, ventrad when extruded; nema 6-10 mm Sectonema Thome 1930
Tip of submedian spear straight; nema under 4.5 mm Nygolaimus Cobb 1913
Spear open at end, a hollow passage
Pharynx with cup-shaped anterior portion
Cup-shaped portion with 6 ribs; spear with guiding ring Actinolaimus Cobb 1913
Cup-shaped portion without ribs ; spear without guide ring ; lip region discoid . . Antholaimus Cobb 1913
Pharynx without cup-shaped anterior portion
Oesophagus with fusiform "bulb" behind spear Dorylaimellus Cobb 1913
Oesophagus without swelling behind spear
Lip region discoid, much expanded Discolaimus Cobb 1913
Lip region usually not discoid, expanded little or not at all
Labial papillae 0, cephalic 6; circumoral ridge present; vulva 34% Chrysonema Thome 1929
Labial papillae 6, cephalic 6; circumoral ridge absent Dorylaimus Duj. 1845
Armature of one or more teeth (odontia or onchia) (for alternative see page 458)
Tooth (onchium) 1 (for alternative see page 465)
Oesophagus plain, i.e. without median or posterior bulb or swelling; amphid occasionally obscure (pg. 463)
External amphid not spiral, circular nor elliptical (for alternative see next page)
Female not known
Habitat soil;spinneret 0;phar.i neck-length ;onch.outward-acting;oes.dorylaimoid. .Nanonema Cobb 1905
(=Cephalonema Cobb 1893)
Habitat marine
Annules coarse, elements tile-like ; amphid crook-shape ; ceph. set. 4 ; nema 0.7 mm . Pselionema Cobb 1933
(=Steineria Fil. 1922)
Annules not coarse; amphid not crook-shape
Onchium small, a labial prod; cephalic setae 6 Rhinonema Allgen 1927
Onchium pharyngeal
Labial set. 6, cephalic 10; onchium dorsal; nema 0.5% wide; amphid transverse Trileptium Cobb 1933
( = Trilepta Cobb 1920)
Labial set. 0, cephalic 6; onchium ventral; nema over 4% wide Doryonchvs Kreis 1932
(cf. Symplocostoma Bast. 1865)
Female known
Ovary 1 ; habitat not marine
Median onchium spear-like, dorsal onchium minute, basal Enoplocheilus Kreis 1932
Median spear-like onchium absent; ovary reflexed; Enoplidae
Pharynx tubular, depth 10 times width ; tooth basal ; cephalic setae Cryptonchus Cobb 1913
( = Ditlevsenia Micol. 1925)
Pharynx conoid when open, depth not over 3 times width
Tooth minute, basal, deep-set; denticles 0; spinneret terminal Trischistoma Cobb 1913
Tooth large, subventral; denticles present; other onchia 2; spinneret ventr&d(Mononchulus Cobb 1918)
Ovaries 2
Gonads 9 outstretched; spinneret present; striae plain; marine Mononcholaimus Kreis 1924
Gonads 9 reflexed
Spinneret absent; amphidial opening oval or a transverse slit
Base of tooth without "flukes"; cephalic setae 6; onchium large, acute; in soil. .Onchulus Cobb 1920
Base of tooth anchor-shaped, "flukes" dorsad and ventrad Diphtherophora de Man 1880
( = Chaolaimus Cobb 1893
=Archionchus Cobb 1913)
Spinneret present, exc. sometimes Eurystominae
Habitat not marine; Trilobinae
Pharynx closed; lips 3 ; onchium minute, basal, deepset Tripyla Bast. 1865
(=Promononchus Micol. 1923)
Pharynx open, domed, larger; lips 6; onchia often more than 1 Trilobus Bast. 1865
Habitat marine
Striae conspicuous, resolvable into dots or rod-like elements; Chromadoridae
Amphid at lips, lenticular, oft obscure; cuticle of "basket-work" on neck Euchromadora de Man 1886
(=Graphonema Cobb 1898)
Amphid not at lips, of even width, conspicuous, reaching nearly across head
Cephalic setae 0; annules of obscure rod-like elements; spicula entire Actinonema Cobb 1920
Cephalic setae 10; annules on neck of "basket-work"
Spicula entire; amphid a wide transverse oval Pareuchromadora Stekhoven & Adams 193
Spicula of 2 sections ; amphid a narrow slit of even width R hips Cobb 1920
Striae 0, or plain and very fane
External amph. bent or crook-shaped, plate oval, 1 head-width ;"tooth" minute Diplopeltis Cobb 1905
( = Dipeltis Cobb 1891
=Discophora Villot 1875)
External amphid not crook-shaped, plate absent; Enoplidae
Head with elaborate, ornate calvarium Deontostoma Fil. 1916
Head without calvarium
Pharynx of single chamber; cephalic setae 10
462 PROCEEDINGS HELMINTHOLOGICAL SOCIETY VOL. 2, NO. 1
Mouth cavity iquadrate; onchium minute, close against wall; eyes Anoncholaimus Cobb 1920
Mouth cavity twice as deep as wide; dorsal qnch. bent in over pharynx Asymmetrella Cobb 1920
Pharynx of more than 1 chamber; large onchium sub ventral
Onchium conoid to base of short stylet; phar. quadrate; cf supplements eurystomoid
Bulbs of oesophagus 5-8, serial, contiguous Bolbella Cobb 1920
Bulbs of oesophagus none
Cervical setae long, about 30; cf supplements weakly developed Ledomtia Fil. 1927
Cervical setae or minute; cf supplements well developed Ewystomina Fil. 1921
(=Eurystoma Marion 1870
=Marionella Cobb 1922)
Onchium a long stylet; phar. much deeper than broad; cf an enchelid
Anterior oesophagus (pharynx ?) narrower, lumen wide Calyptronema Marion 1870
( = Catalaimus Cobb 1920)
Anterior oesophagus not differentiated
Vestibule set off by row of "comma" markings; pharyng. rings 3 Symplocostomella Micol. 1930
Vestibule not set off by a ring or rows of denticles or markings. . Symplocostoma Bast. 1865
External amphid spiral, circular or elliptical (for alternative see preceding page)
Female not known; marine
Amphid multispire,big;phar.ribbed,complex;onch.3;cf supplements chromadoroid Pomponemo Cobb 1917
Amphid circular or oval (Rhinonema, Doryonchus?)
Annules of dots & rods.altered laterally ;amph. trans verse-oval Pareuchromadora Stekhoven & Adams 1931
Annules none or not ornamented; cephalic cuticle not thickened
Cephalic setae 6
Onchium a minute labial prod Rhinonema Allgen 1927
Onchium ventral, pharyngeal, slender, lance-like Doryonchus Kreis 1932
(cf. Symplocostoma Bast. 1865)
Cephalic setae 8 or 10
Oesophagus surrounding phar.; onch. opposed by denticles; amph. long-oval Anaxonchium Cobb 1920
Oesophagus ceasing at base of pharynx; denticles 0; amphid smaller, circular; Enoplidae
Pharynx of 1 chamber; onchium digitate Cophonchus Cobb 1920
Pharynx of 2 chambers; onchium a slender, subventral stylet Isonemella Cobb 1920
Female known
Ovary 1, anterior; onchium dorsal
Striae of dots; pharynx cyatholaimoid; '9 Dentatonema Kreis 1928
Striae none or plain; pharynx not cyatholaimoid
Pharynx large, open; onchium large, apex far forward; amphid with pocket Pseudodilaimus Kreis 1928
Pharynx small or closed, onchium basal or deepset, small
Gonad 9 reflexed; striae 0; spinneret small; vulva 80%; in soil Trischistoma Cobb 1913
Gonad 9 outstretched; onchium dorsal; amphid circular
The pharynx very small; oesophagus strongly developed Prosphaerplaimits Fil. 1918
The pharynx } head-width, as deep as wide; onch. central; in warm salt springs. . .Anticyclus Cobb 1920
Ovaries 2
Gonads 9 outstretched; spinneret present; marine
Amphid not known; striae plain Mononcholaimus Kreis 1924
Amphid multispire; striae of dots
Head setose; striae not altered laterally; spiculalong; apophysis absent Comesoma Bast. 1865
Head less setose; spicula short; gubernaculum with apophysis
Male ventral pre-anal supplementary organs small, papilloid Parasabatieria de Man 1907
Male supplementary organs absent Sabatieria de Rouville 1903
Gonads 9 reflexed
Habitat soil or fresh water; cuticle without pores; wings
Amphid multispire; pharynx conoid; spinneret present; cf supplements none Nannonchus Cobb 1913
Amphid elliptical, with internal pocket; pharynx not conoid
Cephalic setae 0; labial papillae in 2 circlets; spinneret usually present Mononchus Bast. 1865
Cephalic set. 6, jointed; labial papillae 1 circlet; spinneret 0; about roots Cyathonchus Cobb 1933
Habitat marine and brackish waters
Nema broad, 16%; wings 50; neck region "collared" ; pharynx narrow (Richtersia Steiner 1916)
Nema slender, not over 5%; wings exc. Rhinema 12
Amphid multispire; striae of dots; cuticular pores pres.; vestibule with 12 (6 double ?) ribs
Large cf supplement tub ular.anteriorto smallsupplements;nema viviparous Acanthonchus Cobb 1920
( = Seuratia Ditlev. 1918
= Seuratiella Ditlev. 1922)
Large cf supplement absent, others if tubular small; nema usually oviparous
Phar. tubular behind onch.; gubernacula not serrate; cf papill. setose Paracyatholaimus Micol. 1922
Phar. cyathiform; gubernacula serrate distally; cf setose papillae none
Dorsal onchium large, acute, projecting; striae altered laterally Paracanthonchus Micol. 1924
Dorsal onchium or not projecting; pharyngeal ribs extending to base
Tail setaceous; onchium small; cf papillae present or not Longicyalholaimus Micol. 1924
Tail not setaceous
Dots larger laterally; cf supplements tubular; gubernac. oft joined Praeacanthonchus Micol. 1924
Dots not larger laterally; cf tubular supplements 0; gubernacula joined Cyatholaimus Bast. 1865
( = Necticonema Marion 1870)
Amphid circular, elliptical or monospiral
Wings 12, markings V-shaped; pharyng. bulb stronger dorsad ; amphid circular Rhinema Cobb 1920
Wings 0; striae plain
striae pi
Dorsal pharyng. wall thick, tooth-like; amph. monospire at lips; ceph. set. 4; renette far back
Oesoph. glands obscuring junct.intest.;dorsal phar.element uniform, slighter Onchium Cobb 1920
Oesoph. glands not prominent; dorsal pharyng. element not uniformly thick, but heavy
Tooth-like thickening parallel to axis Camacolaimus de Man 1889
( = Digitonchus Cobb 1920
= Acontiolaimus Fil. 1918)
Tooth-like thickening bent outward from beginning of vestibule
Point of "onchium" single Acmaeolaimus Fil. 1918
Point of Y-shaped "onchium" duplex Ypsilon Cobb 1920
COBB: A KEY TO THE GENERA OF FREE-LIVING NEMAS 463
Dorsal pharyngeal wall not thickened; onchium a distinct projection (from preceding page)
Cephalic setae 20-30; cardiac glands conspicuous
Male supplementary organs complex; copulatory muscles conspicuous .... Xanthodora Cobb 1920
Ce a ha!ic PI et ementS Simp ' P a P illoid : copulatory muscles not conspic. Acanthopharynx Marion 1870
Head with elaborately ornate calvarium; striae 0; spinneret present ....... Deontostoma Fil. 1916
Head without calvarium; cuticular pores absent
Plate round.with "bent" amph.;phar.smaU;ceph.set.4,cerv.oft long.many Diplopeltis Cobb 1905
(=Dipeltis Cobb 1891
. A = Discophora Villot 1875)
Plate absent; pharynx large, complex, of more than 1 chamber; onchium large, sharp
Onchium conoid to base of short stylet; pharynx iquadrate; d" supplements eurystomoid
Long cervical setae 30; <? supplements weakly developed ....... . , . . . Ledovitia Fil. 1927
Long cervical setae
Tail rounded; spinneret oft present; d 1 supplements well developed.. .Eurystomina Fil. 1921
( = Eurystoma Marion 1870
=Marionella Cobb 1922)
Tail spicate; spinneret 0; d" supplements weakly developed ...... Pareurystomina Micol 1930
Onchium a long stylet; phar. much deeper than wide; d 1 an enchelid
Oesophageal bulbs 5-8, serial, contiguous ......................... Polygastrophora de Man 1922
Oesophageal bulbs
Anterior oesophagus (pharynx ?) narrower, lumen wide ........... Calyptronema Marion 1870
( = Catalaimus Cobb 1920)
Anterior oesophagus not differentiated
Vestibule set off by row of "commas," pharyng. rings 3; eyes Symplocostomella Micol. 1930
Vestibule set off by rows of denticles or markings, or by a ring
Pharyngeal chambers behind vestibule more than 2 ............. Symplocostoma Bast. 1865
Pharyngeal chambers behind vestibule 2; eyes 2 ........................ Dilaimus Fil. 1927
( = Amphistenus Marion 1870)
- Oesophagus with median or posterior bulb or swelling, or both (for alternative see page 461)
^- Amphid not known or obscure (for alternative see next page)
Female not known
Habitat soil;phar.tubular,i neck;onch.outward-acting;oes.dorylaimoid;spinneret Nanonema Cobb 1905
( = Cephalonema Cobb 1893)
Habitat marine; pharynx not over ,' neck-length; spinneret present (Rhinonema?)
Pharyngeal bulb stronger dorsad; onchium pharyngeal; cephalic setae small or 0. . ..lotadorus Cobb 1920
Pharyngeal bulb absent; onchium a mere prod at lips; cephalic setae 6 ......... (Rhinonema Allgen 1927)
"" Female known
Ovary 1
Gonad 9 outstretched ;spinneret pres.;wings 10, marks V-shaped;ceph.set.4;marine (Nudora Cobb 1920)
Gonad 9 reflexed; spinneret absent; not marine
Onchium (spear) bent dorsad at tip; amphid small, oval, at lips; in soil ...... (Campydora Cobb 1920)
Onchium not bent obliquely at tip
Cardiac bulb not valvate; median bulb strong
Tooth recurved outward; long, striae present; c? supplements papilloid. .Diplogaster M. Schultze 1857
Tooth forward-pointing, deepset; long, striae none; d" supplements setose ---- Acrostichus Rahm 1928
Cardiac bulb valvate; median bulb absent, oesophagus cephaloboid
Posterior pharynx muscular, lumen closed; vulva 75%; tail blunt ........ Plectonchus Fuchs 1930
Posterior pharynx open; vulva 53-65%; tail conoid, usually slender
Vagina directed inward, not heavily muscular; not viviparous ........... Macrolaimus Maupas 1900
Vagina directed forward, heavily muscular; viviparous or ovoviviparous ...... Turbatrix Peters 1927
' Ovaries
Gonads 9 outstretched ; pharyngeal bulb globular ........................... (Bolbolaimus Cobb 1920)
(=B U lbopharyngiella Allgen 1929)
- Gonads 9 reflexed, exc. perhaps Demaniella.
.
Spinneret absent; oesophagus with muscular median bulb, usually valvate
Cardiac bulb valvate
( = Diploscapteroides Rahm 1928)
Lip region not set off; odontia absent Poikilolaimus Fuchs 1930
Lip region set off by constriction; curved odontia 2 or 4 Rhabditis Duj. 1845
Cardiac swelling not valvate, oesophagus diplogastroid
Onchium small, anterior; median bulb wide as long, wider than oesophagus Neodiplogaster Cobb 1924
Onchia larger, basal; "prod" at lips; median bulb not wider than oesophagus Demaniella Steiner 1914
( = Demania Steiner 1914)
- Spinneret present; oesophagus without median bulb; wings often present; marine exc. Punctodora
Lip reg. protrusile; ceph. set. 4; renette long; excretory pore opp. pharynx. .Ptycholaimellus Cobb 1920
Lip region not protrusile
Pharyngeal swelling stronger dorsad; d* supplements chromadoroid exc. Odontonema
Striae altered laterally; onchium large, dorsal, apex ventral Hypodontolaimus de Man 1886
Striae not altered laterally
Onchium solid, inward-pointing Prochromadora Fil. 1922
Onchium with internal cavity, forward-pointing
Tooth small . .V. Chromadorita Fil. 1922 f
Tooth very large, apex ventral; d" supplements papilloid Odontonema Fil. 1930
Pharyngeal swelling not stronger dorsad
Cardiac bulb long, 2- or 3-parted; striae altered laterally; tooth large, forward-pointing
The bulb with dilated lumen Spilopharella Fil. 1918
The bulb with lumen not dilated; d 1 supplements chromadoroid Chromadorissa Fil. 1917
Cardiac bulb short, not divided
Striae altered laterally, several rows of dots larger Chromadora Bast. 1865
Striae not altered laterally
Onchium solid, inward-pointing; d" supplements chromadoroid Prochromadora Fil. 1922
Onchium with internal cavity, forward-pointing
Tooth small, sharp; d" supplements chromadoroid Chromadorita Fil. 1922 r
Tooth large, irregularly rectangular; cardiac bulb very large, simple Punctodora Fil. 1930
464 PROCEEDINGS HELMINTHOLOGICAL SOCIETY VOL. 2, NO. 1
Amphid known (for alternative see preceding page)
External amphid not spiral, circular nor elliptical, but a transverse slit
Female not known; amphid large
Pharyngeal bulb not stronger dorsad; ceph. set. 10; cutic. "basket-work" on neck Nygmatonchus Cobb 1933
Pharyngeal bulb stronger dorsad; striae of dots
Denticles in pharynx numerous; cephalic setae 4; in humus near sea coast Denliculella Cobb 1933
Denticles 0; cephalic setae if present almost invisible; marine lotadorus Cobb 1920
Female known
Ovary 1, reflexed; habitat soil about roots
Tooth short, closed, not bent at tip; ovary anterior, vulva 57%; spinneret(?) present Oionchus Cobb 1913
Tooth (spear) bent obliquely dorsad at tip when extruded; spinneret absent Campydara Cobb 1920
Ovaries 2, reflexed; spinneret present
Oesophageal bulbs 5-8, contiguous ; amphid with pocket ; c? supplements eurystomoid Bolbella Cobb 1920
Oesophageal bulbs not more than 2, not contiguous
Tooth small, near lips; setae 0; pharynx long, tubular; in fresh water Rhabdolaimus de Man 1880
Tooth not small; pharynx 1 head- width deep; amphid usually at lips
Onchium curved, solid, apparently mobile radially Prochromadara Fil. 1922
Onchium forward-pointing or irectangular, motion apparently iparallel to axis
Lipreg. protrusile; ceph. set. 4 ; renette long ; excretory poreopp. pharynx.. Ptycholaimell us Cobb 1920
Lip region not protrusile
Neck with cuticular "basket-work"; 4 sublat. scales opp. phar.; spicula 2 sections Rhips Cobb 1920
Neck without "basket-work," or laterally only ; scales 0; spicula entire
Striae of rod-like elements, exc. towards extremities, changing to large dots laterally
Cardiac bulb broad, well set off, valvate Punctodora Fil. 1930
Cardiac bulb not very broad, confluent, non- valvate Neochromadora Micol. 1924
Striae of dots, altered laterally
Pharyngeal bulbstrongerdorsad;onch.large;card.bulb2-3-zoned . . Hypodontolaimus de Man 1886
Pharyngeal bulb if present not stronger dorsad; cardiac bulb not zoned. . . .Chromadora Bast. 1865'
External amphid spiral, circular or elliptical
Female not known; marine or salt marsh (exc. Amphispira ?) ; wings none
Habitat soil (possibly marine) ; amphid spiral; cephalic setae 0; spinneret present Amphispira Cobb 1920
Habitat marine or salt marsh
Amphid multispire, large, on front curvature of head
Striae altered laterally Neotonchus Cobb 1933
Striae not altered laterally Amphispira Cobb 1920
Amphid not multispiral
Onchium spear-like, free at tip Oistolaimus Ditlev. 1921
(cf. Onyx Cobb 1891)
Onchium not spear-like
Cephalic setae minute; pharyng. bulb stronger dorsad; amphid narrow, transverse lotadorus Cobb 1920
Cephalic setae 0; amphid circular or monospiral
Tooth ventral Crassolaimus Kreis 1929
Tooth dorsal; nema cephalated by expansion and by cessation of striae Micromicron Cobb 1920
Female known
Ovary 1
Gonad 9 outstretched; amphid circular; cephalic setae 4; spinneret present; marine
Wings 10, of V-shaped marks; phar. bulb long, set off by constrict. ; lab. papill. setose Nudora Cobb 1920
Wings 0; phar. bulb very slight; labial papillae 0; renette large, of 6 cells Synonema Cobb 1920
Habitat not marine; amphid round or oval; spinneret m
Median oesophageal bulb present, usually valvate; tail
Pharynx narrow, post, part 6 times width; ceph. set. 0; <
Habitat marine; amphid round; spinneret pres.; wings 6-20, marks V-shaped Monoposthia de Man 1889
none exc. Udonchus
il conoid, then setaceous; bursa none
; onch. small, basal Diplogasteroides de Man 1912
Pharynx not more than twice as deep as wide; cephalic setae usually present
Onchium anterior, recurved, outward-acting Diplogaster M. Schultze 1857
Onchium deepset, forward-pointing Acrostichus Rahm 1928
Median oesophageal bulb absent; striae fine, plain
Pharynx occupying i neck-length; habitat decaying bulbs (Odontopharynx de Man 1912)
Pharynx occupying J neck-length or less
Tooth (spear) bent obliquely dorsad at lips when extruded; soil near roots. . (Campydara Cobb 1920)
Tooth not bent
Spinneret present; external amphid oval; pharyng. bulb absent; in fresh water Udonchus Cobb 1913
Spinneret absent; amphid circular
Pharyngeal swelling absent; cardiac bulb valvate Macrolaimus Maupas 1900
Pharyngeal swelling clavate; in moist soil Odontolaimus de >Ian 1880
( = Neonchus Cobb 1893)
Ovaries 2
Gonads 9 outstretched; spinneret present; habitat marine or brackish soil
Amphid not multispire; onehia several, often minute
Pharyngeal bulb none, or slight, confluent; ceph. setae 4; labial papillae 6. .Microlaimvs de Man 1880
Pharyngeal bulb almost globular; cephalic setae 6; labial setae 6 (Bolbolaimus Cobb 1920)
(=Bulbopharyngiella Allgen 1929)
Amphid multispire; striae finely dotted; pharyngeal bulb absent
Head setose; striae not altered laterally; spicula long; apophysis none Comesoma Bast. 1865
Head less setose; spicula short; gubernaculum with apophysis
Male ventral pre-anal supplementary organs small, papilloid (Parasabatieria de Man 1907)
Male supplementary organs absent (Sabatieria de Rouville 1903)
Gonads 9 reflexed
Spinneret absent (for alternative see next page)
Habitat marine; cephalic setae 4; pharyngeal bulb absent, pharynx small Spirina Fil. 1918
(=Spira Bast. 1865)
Habitat not marine; tail isetaceous exc. Neodiplogaster
Cardiac bulb valvate Poikilolaimus Fuchs 1930
Cardiac bulb not valvate
Pharyngeal bulb clavate, ,'0-} neck-length ; median bulb none;ceph.set.lO Odontolaimus de Man 1880
Pharyngeal bulb none or short, not tapering; oesoph. diplogastroid; onchium a projection
COBB: A KEY TO THE GENERA OF FREE-LIVING NEMAS 465
Median oesophageal bulb not swollen; ceph. set. 0; striae plain (Odontopharynx de Man 1912)
Median oesophageal bulb swollen; cardiac swelling non-valvate
Pharynx i wide as deep; ceph set. present; tail setaceous; bursa 0. . ..Diplogaster M. Schultze 1857
Pharynx narrow, posterior tubular portion not over 1 as wide as deep; ceph. set.
Onchium basal; tail conoid then setaceous; bursa none Diplogasteroides de Man 1912
Onchium anterior; striae of dots; tail conoid; bursa rhabditoid Neodiplogaster Cobb 1924
Spinneret present, exc. sometimes Spirina (for alternative see preceding page)
Oesophageal bulbs 5-8, serial, contiguous; cf an enchelid; marine Polygastrophora de Man 1922
Oesophageal bulb 1
Anterior oesophagus narrow, lumen wide; marine Calyptronema Marion 1870
( = Catalaimus Cobb 1920)
Anterior oesophagus not differentiated
Wings present
Pharyngeal bulb set off by constriction; wings 12, bristles retrorse; marine. . .Rhinema Cobb 1920
Pharyngeal bulb none or confluent
Nema cephalated by cuticular change & by expansion; cardiac bulb short, not divided
Head "punctate" ; wings 12-18; ceph. set. 6; denticles pres. ; amph. spiral Desmodorella Cobb 1933
Head plain;wing l;ceph.set.0;denticles 0;amph.round;caud.gl'nds pre-anal Xenonema Cobb 1920
Nema not cephalated; cardiac bulb long, 2- or 3-zoned; amphid spiral
Striae of dots; wings scalariform; cf supplements Spilophorium Cobb 1933
(-SpOopkom Bast. 1865)
Striae plain
Cephalic setae many, jointed; c? pre-anal cuticle thickened Neonyx Cobb 1933
Cephalic setae 4, short; wing 1; cf supplements post-anal Metachromadara Fil. 1918
( = Ckromadoropsis Fil. 1918)
Wings 0; striae not altered laterally, exc. sometimes Desmodora
Habitat freshwater; minute subordinate onchia usually present
Pharynx behind onchia parallel-sided; pharyngeal bulb definite Elhmolaimus de Man 1880
Pharynx behind onchia iconoid; pharyngeal bulb absent
Amphid spiral; cephalic setae usually 10; pharynx open, irregular Achromadora Cobb 1913
Amphid circular; cephalic setae 4; pharynx often obscure Prodesmodara Micol. 1923
Habitat marine
Dorsal pharyngeal wall thickened, onchium-like; amphid monospire
at lips; cephalic setae 4; renette far back
Oesoph. glands obscuring junction of intest.; dorsal phar. element iuniform Onchium Cobb 1920
Oesoph. glands not prominent; dorsal pharyng. element not uniformly thick, but heavy
Tooth-like thickening parallel to axis Camacolaimus de Man 1889
( = Digitonchus Cobb 1920
= Acontiolaimus Fil. 1918)
Tooth-like thickening bent outward from beginning of vestibule
Point of "onchium" single Acmaeolaimus Fil. 1918
Point of Y-shaped "onchium" duplex Ypsilon Cobb 1920
Dorsal pharyngeal wall not thickened; onchium a distinct projection
Cephalic setae 12-26; cardiac bulb elongate; amphid spiral
Striae of dots, on head also; labial papillae setose; ceph. set. 12 Bradylaimus Stekhoven 1931
Striae plain, absent on head; cephalic setae 24-26; amphid monospire
Pharynx denticulate; onch. sigmoid ventrally ; of 1 supplements sigmoid Sigmophora Cobb 1933
Pharynx not denticulate; onch. not sigmoid; cf supplements papilloid Xanthodora Cobb 1920
Cephalic setae 4
Striae of dots
Dorsal onchium large, basal; pharyngeal bulb stronger dorsad Odontonema Fil. 1930
Dorsal onchium anterior; pharyngeal bulb isymmetrical Chromadorina Fil. 1918
Striae plain
Head set off by lack of striae; pharynx & onchium inconspic. ; marine. . Desmodora de Man 1889
Head not set off; striae extending to lips
Pharyngeal bulb 0; cardiac bulb short; onchium minute; neck 6-7% Spirina Fil. 1918
(=Spira Bast. 1865)
Pharyngeal bulb present; cardiac bulb long, massive, 2- or 3-zoned; neck over 12%
Onchium spear-like; head rounded Onyx Cobb 1891
Onchium not spear-like; head truncate Metachromadora Fil. 1918
( = Chromadoropsis Fil. 1918)
Teeth (onchia or odontia) 2 or more (for alternative see page 461)
Oesophagus with median or posterior bulb or swelling, or both (for alternative see page 467)
The teeth equal in size, usually mobile radially (for alternative see next page)
Stroke of teeth outward; amphid often obscure (for alternative see next page)
Spinneret absent; '9 or ' 9 '
Cardiac bulb valvate; cuticle without longitudinal striae Diploscapter Cobb 1913
Cardiac bulb not valvate, median bulb valvate; cuticle with longitudinal striae
Posterior pharyngeal chamber behind onchia; lips with radiate framework Mononchoides Rahm 1928
Posterior pharyngeal chamber absent; lips without radiate framework Diplogaster M. Schultze 1857
(=Pristionchus Kreis 1932)
Spinneret present; median oesophageal bulb absent
Pharynx tubular, 4-6% of body length
Amphid long, reaching base of pharynx or mid-body ; odontia 6, minute ; - 9 ~ Pseudolella Cobb 1920
Amphid small, at lips, with pocket; odontia 3, massive; tail oft striate; ' 9 ' Syringolaimus de Man 1888
Pharynx conoid, not over 2% of body length
Odontia ;onch . 3 , at base shallow phar. ;amph . round ; card, swelling obvious r 9 A ponchium Cobb 1920
Odontia 6 or 12;onch. 0;amph. bent or crook-shape;card. bulb or weakr9~ Odontophora Butech. 1874
( = Trigonolaimus Ditlev. 1918
= Conolaimus Fil. 1918)
Striae of dots; cardiac swelling obvious
Amphid spiral ;onch.3,curved; cf 1 supplements or papilloid; gubernac.O; cf only. . Statenio Allgen 1930
Amphid a transverse slit, near lips; ' 9 '
Lateral fields marked by longitudinal rows of larger dots Chromadorella Fil. 191:
Lateral fields without longitudinal rows of larger dots Prochromadorella Micol. 1924
466 PROCEEDINGS HELMINTHOLOGICAL SOCIETY VOL. 2, NO. 1
Stroke of teeth inward; amphid occasionally obscure (for alternative see preceding page)
Spinneret 0; phasmids present; odontia 6; oesophagus cephaloboid; ovaries reflexed
Nema usually cephalated; cirri 0; amphid round; soil & fresh water; '?'... . (Teratocephalus de Man 1876)
Nema not cephalated; cirri 6; amphid oval; tail hooked; in bark, etc.; '9 (Chambersiella Cobb 1920)
( = Diastolaimus Rahm 1928)
Spinneret present
Mandibular jaws 2 or 3; pharyngeal and cardiac bulbs strong; marine
Jaws 3; amphid not known; c? only Fusonema Kreis 1928
Jaws 2, lateral, dentate; amphid multispire Cheironchus Cobb 1917
( = DignathonemaFil. 1918)
Mandibular jaws absent
Amphid multispire; lips flat, confluent; pharynx rather narrow; marine
Striae very fine; wings 0; labial papillae not seen; d" only (Alaimonema Cobb 1920)
Striae icoarse, of dots; wings pres.; labial papillae 12; -?-, or reflexed at tip (Mesonchium Cobb 1920)
( = Pepsonema Cobb 1920)
Amphid not multispire
Habitat soil;amph.monospire to crook-shape ;phar. 6%;nema small,0.2 mm.;J (Pycnolaimus Cobb 1920)
Habitat marine; pharynx under 2%, not tubular; ovaries not reflexed
Vulva 15%; odontia 12, minute; amphid "folded"; 9~ Synodontium Cobb 1920
Vulva 81%; odontia 0; onchia 3; pharyngeal swelling slight; ~9 (Aponchium Cobb 1920)
The teeth unequal in size, usually not mobile radially; amph. usually not obscure (from preceding page)
External amphid not spiral, circular nor elliptical; ovaries 2; spinneret present
Gonads 9 outstretched ;amph. long, reaching sometimes to mid-body ;odontia6r?~PseiioW/a Cobb 1920
Gonads 9 reflexed; amphid a transverse slit
Striae fine, plain; onchia dorsal and ventral Deltanema Kreis 1929
(cf. Metalinhomoeus de Man 1907)
Striae resolvable into elements; dorsal onchium usually the largest
Spicula of 2 joints; striae forming "basket-work" on neck; amphid opp. base pharynx Rhips Cobb 1920
Spicula entire; striae of dots ; amphid near lips Chromadora Bast. 1865
External amphid spiral, circular or elliptical
Female not known; spinneret present; marine
Amphjd multispire ;head conoid;onch. minute;ceph. & subceph. setae in sets of 4 Alaimonema Cobb 1920
Amphid circular, elliptical or monospiral
Pharynx surrounded at base by cuticularized ring Cricolaimus Southern 1914
Pharynx not surrounded by cuticularized ring
Striae of dots, interrupted laterally; pharynx cyatholaimoid, onchium large Endolaimus Fil. 1922
Striae unaltered laterally; pharynx small; cf supplements tubular, post-anal Catanema Cobb 1920
Female known
Ovary!
Gonad 9 outstretched ;spinneret pres. ;cf supplements numerous,complex;marine Aponchium Cobb 1920
Gonad 9 reflexed; amphid small, circular, obscure; spinneret 0; not marine
Cardiac bulb valvate, median bulb absent; bursa small, ribs stout Myolaimus Cobb 1920
Cardiac bulb not valvate; oesophagus idiplogastroid
Oesophagus without (or with non-valvate, clavate) median swelling Odontopharynx de Man 1912
Oesophagus with median valvate bulb Diplogaster M. Schultze 1857
(=Pristionchus Kreis 1932)
Ovaries 2
Gonads 9 outstretched, Mesonchium reflexed at tips; marine
Amphid spiral; dots larger laterally; onchia equal; spinneret present (Mesonchium Cobb 1920)
(=Pepsonema Cobb 1920)
Amphid circular; striae when present not altered laterally; onchia unequal
Striae desmodoroid, coarse, plain; amph. behind pharynx, open caudad Paracothonolaimus Schulz 1932
Striae none, or not desmodoroid
Pharyngeal bulb iglobular, set off by constriction; spinneret present Bolbolaimus Cobb 1920
(=Bulbopharyngiella Allgen 1929)
Pharyngeal swelling slight, confluent; base of pharynx denticulate Linhomoeus Bast. 1865
(i.e. subg. Eulinhomoeus de Man 1907)
Gonads 9 reflexed (Mesonchium at tips only)
Habitat marine; spinneret present; amphid spiral
Striae of dots; amphid opposite pharynx, of few winds
Subventral onchium small, dorsal acting out; dots unaltered laterally. .. .Chromadorina Fil. 1918
Subventral & dorsal onchia dhequal, apices axial; dots larger laterally Mesonchium Cobb 1920
(=Pepsonema Cobb 1920)
Striae none or plain
Head set off by cessation of coarse annulation ; amphid usually multispire . . . Desmodora de Man 1889
Head not set off; striae none or very fine
Male ventral pre-anal supplements tubular, sigmoid, in 2 rows Polysigma Cobb 1921
Male ventral pre-anal supplements simple, in 1 row Chromaspirina Fil. 1918
(=Mesodorus Cobb 1920)
Habitat not marine
Spinneret present; amphid spiral, behind pharynx; in fresh water Achromadora Cobb 1913
Spinneret absent; phasmids present; amphid circular; usually in soil
Cardiac bulb valvate, oesophagus cephaloboid; onchia 4 Seleneella Rahm 1932
Cardiac bulb not valvate; oesophagus diplogastroid
Anterior oesophagus (corpus) without (or with clavate, non-valvate) swelling
Cephalic setae 6 or 10; dorsal onch. opposed by ventral onchium or ridge. . . .Butlerius Goodey 1929
Cephalic setae 6; dorsal onchium opposed by denticles Odontopharynx de Man 1912
Anterior oesophagus (corpus) ending in valvate median bulb
Lips with radiate framework; post, pharyngeal chamber behind onchia. . .Mononchoides Rahm 1928
Lips without radiate framework; post, pharyngeal chamber none Diplogaster M. Schultze 1857
( = Pristionchus Kreis 1932)
COBB: A KEY TO THE GENERA OF FREE-LIVING NEMAS 467
Oesophagus plain, i.e. without median or posterior bulb or swelling (for alternative see page 465)
The teeth equal in size, usually mobile radially (for alternative see next page)
Stroke of teeth outward; amphid usually not obscure
External amphid spiral, circular or elliptical; spinneret present (Eleutherolaimus ?)
Armature of 2 teeth ;ceph. set. 4 ;amph. monospire.in front of setae;d" only Diodontolaimus Southern 1914
Armature of 6 or 12 odontia
Odontia 3-jointed, heavy ;phar. cylind.;onch. dorsal ;am ph. round-multispire; ~9 Scaptrella Cobb 1917
Odontia not jointed
Amphid "folded" or shepherd's crook; ~9~ Odontophora Butsch. 1874
( = Trigonolaimus Ditlev. 1918
= ConolaimusFil. 1918)
Amphid circular or elliptical, sometimes obscure; cephalic setae 4
Pharynx obscure; odontia small; lab. set. 6, setae long; striae coarse; ' 9 ' Stephanolaimus Ditlev. 1918
Pharynx obvious; odontia larger; labial and subcephalic setae 0; cf only
Striae of dots; amphid transverse, open caudad Apodontium Cobb 1920
Striae plain; amphid circular Eleutherolaimus Fil. 1922
External amphid not spiral, circular nor elliptical; spinneret pres. exc. Ironus and Parironus
Cardiac bulb slight ; striae of dots ; amphid a transverse slit near lips ; ' 9 '
Dots of striae larger laterally, in longitudinal rows (Chromadarella Fil. 1918)
Dots of striae not altered laterally (Prochromadorella Micol. 1924)
Cardiac bulb none; striae none, or plain and very fine
Odontia 6, sometimes dentate; amphid "folded" or crook-shaped; ~9~
Amphid opposite basal portion of pharynx; odontia less developed Axonolaimus de Man 1889
Amphid opposite anterior portion of pharynx; odontia more developed Odontophora Butsch. 1874
( = Trigonolaimus Ditlev. 1918
= ConolaimusFil. 1918)
Odontia or onchia 3; amphid transverse, with internal pocket; ovaries reflexed
Armature 3 awl-shaped onchia, protrusile forward; pharynx 0.5%; ' 9 ' (Fimbrilla Cobb 1905)
( = Fimbria Cobb 1894)
Armature 3 heavy odontia; pharynx tubular, l-4 ( : ' c ; Ironinae
Lips expanded, denticulate, 6; tail 2% ; spinneret ventrad; 9 ' Trissonchulus Cobb 1920
Lips not expanded; tail 5% or more; spinneret not ventrad; ' 9 '
Spinneret none; pharynx 2-4%; dorsal tooth duplex; in fresh water and soil Ironus Bast. 1865
Spinneret present (in Parironus rudimentary or none); marine
Cephalic setae or papilloid; odontia not duplex; pharyngeal swelling slight
Pharyngeal wall thin; pharynx 3%; nema 3 mm Dolicholaimus de Man 1888
Pharyngeal wall thick; pharynx 1.1%; nema 2-7 mm Thalassironus de Man 1889
Cephalic setae present
Odontia duplex; phar. 2.7%, bulb set off by constriction; ceph. set. 6,subceph.4../roneifa Cobb 1920
Odontia not duplex; pharynx 1-1.6%, swelling slight; cephalic setae 10 Parironus Micol. 1930
Stroke of teeth inward; amphid known, in Enoplidae with internal pocket and often obscure
External amphid not spiral, circular nor elliptical; ovaries reflexed
Ovary 1, post.; phar. bulb strong; "palps" labial ;onch. 3, at summit of apophyses Gammanema Cobb 1920
Ovaries 2; wings absent; amphid with internal pocket; Enoplidae
Calvarjum a band with undulating margins; glands lateral; odontia large Fiacra Southern 1914
Calvarium absent
Onchia 3, awl-like, protrusile forward, like bristles around open mouth Fimbrilla Cobb 1905
( = Fimbria Cobb 1894)
Onchia not awl-like
Lips confluent, bearing 6 (or 3 duplex) odontia
Pharynx narrow; onchia 0; odontia probaby 6 Tubolaimella Cobb 1933
Pharynx conoid; onch. 3, midway , alternating paired odontia . . Rhabdodemania Baylis & Daubney 1926
( = Demania Southern 1914)
Lips distinct, 3; armature heavy
The lips large, conoid, as high as broad; jaws 3
Mandibles 2-clawed; lips radially striate; spicula long, striate Enoploides Saveljev 1912
Mandibles absent; lips not striate; tooth midway on onchial framework . . . Enoplolaimus de Man 1893
The lips not conoid, nor as high as broad
Armature 3 short flattish acute onchia, doming the ismall pharynx .... Triodontolaimus de Man 1893
Armature of 3 jaws within the pharynx, anteriorly 2-pointed Enoplus Duj. 1845
( = Enoplostoma Marion 1870)
External amphid spiral, circular or elliptical
Female not known
Amphid monospire, transverse; lips 4; cephalic setae 4; c? supplements 8-12, tubular
Striae very fine; pharynx conoid; onchia 3; labial papillae 2 Dagda Southern 1914
Striae coarse; phar. cylind.; onch. 2, lateral orsubventral; lab. papill. 4 Diodontolaimus Southern 1914
Amphid multispire; d* supplements ichromadoroid
Pharynx unarmed; lips 6, grasping organs, with longitudinal cuticular ribs Dispira Cobb 1933
Pharynx armed, bulb strong; often nemativorous; cf supplements chromadoroid
Mandibles 3, split exc. at tips, distal hooks 3, subordinates 2; phar. 1 chamber. .Synonchium Cobb 1920
Mandibles 0; phar. 2 chambers; onchia 3, midway, with backward apophyses. . Trogolaimus Cobb 1920
Female known
Ovary 1 ; amphid circular or monospiral (for alternative see next page)
Gonad 9 post.;pnch.3, on apophyses ;phar.bulb strong ;spinneret pres.;marine Gammanema Cobb 1920
Gonad 9 anterior
Spinneret none; wings none; labial "palps" 6, small; marine; ~9
Amphid large, raised centrally; tail with thorn-like setae (Zanema Cobb 1920)
Amphid small, not projecting; tail without setae (Crystallonema Cobb 1920)
Spinneret present
Cephalic setae usually or papilloid; ovoviviparous or viviparous; in gills of land crabs
Pharynx small, of 2 chambers; cephalic setae 10, often papilloid. (Monhystrium Cobb 1920)
Pharynx large, open, of 1 chamber; cephalic setae 0; wings none Tripylium Cobb 1920
Cephalic setae present; ovary outstretched; marine
Lips thick, with 3 projecting finger-like "odontia"; wings up to 32 on head (Xyala Cobb 1920)
Lips 6, very thin, each with 3 parallel-sided cuticularized ribs (Daptonema Cobb 1920)
(cf. Theristus Bast. 1865)
468 PROCEEDINGS HELMINTHOLOGICAL SOCIETY VOL. 2, NO. 1
Ovaries 2 (for alternative see preceding page)
Gonads 9 outstretched; spinneret present; marine
Amphid "folded" or crook-shaped; pharynx conoid; striae plain (Axonolaimus de Man 1889)
Amphid multispire; striae of dots, altered on lateral fields
Spicula 2-jointed ; nema 2% wide Dorylaimopsis Ditlev. 1918
( = Xinema Cobb 1920)
Spicula entire; nema 4% wide Mesonchium Cobb 1920
( = Pepsonema Cobb 1920)
Gonads 9 reflexed; spinneret present
Amphid large, multispire; striae resolvable into elements; often nemativorous
Pharynx 2 chambers; mid-pharynx denticulate, apophyses forward & backward; striae of dots
Circular muscles about anterior pharynx; phar. small; denticles irregular. . Cobbionema Fil. 1922
Circular muscles none; pharynx capacious; denticles regularly placed H alichoanolaimus de Man 1886
( = Smalsundia Allgen 1929)
Pharynx not of 2 chambers; denticles absent (Demonema ?)
Mandibles none
Dots of striae not larger laterally; jaws with many horny teeth anteriorly. . ..Demonema Cobb 1894
Dots of striae larger laterally; onchia equal, apices axial Mesonchium Cobb 1920
( = Pepsonema Cobb 1920)
Mandibles 2 or 3; Selachineminae
Dorsal mandible a mere rod, developed mandibles 2 Selachinema Cobb 1915
Dorsal mandible developed, making 3, split; subordinate hooks pres. ; cutic. pores pres.
Central mandibular prong 1, no. hooks odd ; striae of dots ; c? supplements 2 Synonchium Cobb 1920
Central mand. prongs 2,no. hooks even;stri.dots, dashesic? supplements 20 Synonchiella Cobb 1933
Amphid small, opening circular, obscure; lips 3, large; Enoplinae
Lips not conoid, nor high as broad; labial papillae seldom setose; jaws 2-pointed. .Enoplus Duj. 1845
( = Enoplostoma Marion 1870)
Lips large, conoid, often as high as broad; labial papillae 6, setose
Mandibles 2-clawed; lips radially striate; spicula long, striate Enoploidex Saveljev 1912
Mandibles absent; lips not striate
Basal onchia large, reaching lips %
Framework of jaws absent Sai-eljevia Fil. 1927
Framework of jaws present Filipjeria Kreis 1928
Basal onchia absent; "jaws" 3. without hooks
Jaw framework bearing 3 equal mid-pharyngeal teeth Enoplolaimus de Man 1893
Jaw framework without teeth Parenopius Fil. 1927
^The teeth iunequal in size, usually not mobile radially; amph., in Enoplidae, oft obscure (from pg. 467)
Female not known
Cephalic setae 0; spiculum 1, gubernaculum absent Dioncholaimus Kreis 1932
Cephalic setae pres.; spicula 2, gubernac. pres. (Hyptiolaimus, Cacolaimus, Convexolaimus, J only)
Amphid multispire, head width; striae of dots, wings 2; labial "palps" 12, jointed Pomponema Cobb 1917
Amphid circular, elliptical or monospiral
Pharynx with denticles, or many subordinate onchia ; labial pa pill. 6, setose; amph. round or oval
Labial"palps"12, tips large; onch. dorsal, denticles not basal; wingscalariform Anaionchium Cobb 1920
Labial "palps" 0; base of pharynx filled with subordinate onchia Polydontus Schulz 1932
Pharynx without denticles or numerous subordinate onchia
Bulb around pharynx set off by sudden constriction Hyptiolaimus Cobb 1930
Bulb around pharynx none or not set off by constriction
Striae coarse; onchia 2, lateral or subventral; labial papillae 4 DiodonMaim us Southern 1914
Striae none or very fine; onchia 3
Lips 4, 2 of them bearing papillae; cephalic setae 4; cf supplements tubular . .Dayda Southern 1914
Lips 6, papillae 6, setose; cephalic setae 10, short; J
Head set off by thicker cuticle; wall of pharynx thin Cacolaim us Kreis 1932
Head not set off, its cuticle thin; wall of pharynx distinct Conrexolaimus Kreis 1928
Female known
Ovary 1 , anterior (Pseudoncholaimus ?)
Median onchium spear-like, dorsal onchium minute, basal Enoplocheilus Kreis 1932
Median spear-like onchium absent
Gonad 9 outstretched; amphid circular or monospiral
Onchia 2, like vertical plates, subventral; amphid monospire. longer than wide. .Gonimichus Cobb 1920
Onchia not plate-like, basal, outlets of oesoph. glands; amph. round; tail isetaceous Cobbia de Man 1907
Gonad 9 reflexed
Spinneret absent; phasmids present
Cardiac bulb iglandular, not valvate; median swelling often present (Odonto pharynx de Man 1912)
Card, bulb valvate, oes. cephaloboid; vagina directed forward, muscles heavy Turbatrix Peters 1927
( = Anguillula auctores)
~ Spinneret present; phasmids absent; amphid with internal pocket, usually small
Cephalic setae 0; papillae in 2 circlets; in soil and fresh water
Pharynx large, open, d= parallel-sided; spinneret terminal Mononchus Bast. 1865
Pharynx narrow, iconoid; spinneret ventrad Mononchulus Cobb 1918
: Cephalic setae present; papillae 1 circlet; marine or in brackish waters; Oncholaiminae
Demanian system absent
Ovary posterior; vulva 73-77%; gubernaculum none Pseudoncholaimus Kreis 1932
Ovary ant.; vulva 70-75%; gubernaculum pres.; spicula rttail length. . Prooncholaimus Micol. 1924
Demanian system present
Uvette and exit pores present Metoncholaimus Fil. 1918
Uvette ampulla-like, exit pores absent
Male with pre-anal appendicule Oncholaimium Cobb 1930
Male without pre-anal appendicule Oncholaimus Duj. 1845
Ovaries 2
Gonads 9 outstretched; striae of rods.exc. laterally; amph. a slit. . . .Dicriconema Steiner & Hoeppli 1926
Gonads 9 reflexed
Habitat soil and fresh water (for alternative see next page)
Spinneret 0; anterior oesoph. (corpus) with or without non-valvate med. bulb ; amph. round or oval
"Spear" none; dorsal onch. opposed by ventral tooth or ridge; ceph. set. 6-10 . . .Butlerius Goodey 1929
COBB: A KEY TO THE GENERA OF FREE-LIVING NEMAS 469
"Spear" a minute prod between lips; cephalic setae ..................... Demaniella Steiner 1914
( = .Demania Steiner 1914)
Spinneret present, exc. sometimes in Mononchue
Amphid spiral; pharynx iconoid ........................................... Nannonchus Cobb 1913
Amphid circular or oval, often small, with internal pocket
Pharynx irregularly conoid ; onchia small ........................................ Trilobus Bast. 1865
Pharynx not conoid; one or more onchia large
Lips thick; papillae 12, in 2 circlets; renette not known ................... Mononchus Bast. 1865
Lips thin; papillae 6, ceph. set. 10; renette pres., ampulla conspicuous ..... Adoncholaimua Fil. 1908
Habitat marine; spinneret usually present (for alternative see preceding page)
Cuticle annulated
Annules not resolvable into dots or rod-like elements
Head truncate; annules interrupted; ceph. set. 4 ; phar. ribs long. , serrate . . Rhabdotoderma Marion 1870
Head rounded; annules plain; setae many, short, iirregular on calvarium. . . .Croconema Cobb 1920
Annules of rod-like marks; pharynx cyatholaimoid, vestibule ribbed; amphid a transverse slit
Ceph. set. 4, labial papillae setose; annules plain laterally ..... Dicriconema Steiner & Hoeppli 1926
Ceph. set. 10; annules with V-shaped marks laterally, "basket-work" on neck. . ..Rhips Cobb 1920
Cuticle not annulated; striae if present very fine
Head wjth subcuticular calvarium; amphid with internal pocket; Enoplidae
Calvarium complex, ornate, long-conoid .................................. Thoracostoma Marion 1870
Calvarium relatively simple, a band with undulating margins; glands lateral
Pharynx wide; lips with denticles; odontia present(?); nema 20-34 mm.. .Cylicolaimus de Man 1889
Pharynx narrow, filled by onchia, dorsal largest; cervical setae many; nema 8-17 mm.
Odontia present; cephalic setae long ........................................ fiacra Southern 1914
Odontia absent; cephalic setae short or medium ............................. Synonchus Cobb 1894
( = Jagerskioldia Fil. 1916)
Head without calvarium
Amphid spiral; pharynx small, irregularly conoid, vestibule ribbed ........ (Chromaspirina Fil. 1918)
( = Mesodorus Cobb 1920)
Amphid with internal pocket; pharynx large, open, squarish, ribbed vestibule absent
Pharynx not divided, walls ithick; amph. small ; excretory pore oft not at lips; Oncholaiminae
Demanian system present, with exit pores and developed uvette ........ Adoncholaimus Fil. 1918
Demanian system absent, or gonenteric duct only
Subventral onchia equal in size; amphidial opening longer than wide
Tail 33%, filiform, spinneret none; gubernaculum none ................. Filoncholaimus Fil. 1927
( = Pseiidoi>aroncholaimus Kreis 1932)
Tail short, rounded ; gubernaculum present ............................... Pontonema Leidy 1855
^=Paroncholaimus Fil. 1916)
Subventral onchia unequal in size; pharynx depth twice its width or more
Cuticle not viscous; phar. bulb clavate; lip reg.set off by coastriction . .Steinvriella Allgen 1932
( = Steineria Ditlev. 1928)
Cuticle viscous; pharyngeal bulb none; nema under 3 mm.; tail 6-10%
Pharynx very deep, ifilled by subventral onch.; bursa present Oncholaimellus de Man 1890
Pharynx not over twice as deep as wide, not filled by onchium; bursa none
Dorsal wall of pharynx well developed ............................ Viscosia (de Man) Fil. 1918
Dorsal wall of pharynx rudimentary, an extension of dorsal tooth ---- Meroviscosia Kreis 1932
xcretory pore oft at lips; large onch. subventral
Pharynx 2-5 chambers, wall thin; amph. large; exc
Oesophageal bulbs 5-8, serial, contiguous
Amphidial opening transverse, slit-like; a" s
supplements eurystomoid ...... Bolbflla Cobb 1920
Amphidial opening ^circular; cf an enchelid, supplements simple. .Polygastrophora de Man 1922
Oesophageal bulbs none
External amphid transverse, slit-like; pharynx usually square; caudal glands before anus
Denticles forming a broad mid-pharyngeal band; d" supplements simple. . . Thoonchus Cobb 1920
Denticles in 1-3 rows; d" supplements complex, "fluked" ............. Eurystomina Fil. 1921
( = Eurystoma Marion 1870
= Marionella Cobb 1922)
External amphid round; pharynx deep; onch. spear-like, exc. Ditlevsenella; cf oft an enchelid
Anterior oesophagus narrower, lumen wide .......................... Calyplronema Marion 1870
( = Ca(aIaimiu Cobb 1920)
Anterior oesophagus not differentiated
Large onchia 3 ...................................................... fenestrolaimus Fil. 1927
Large onchium 1, other onchia 2
The large onchium conoid; nema 4-6 mm ............................. Ditlevsenella Fil. 1927
The large onchium long, slender, spear-like
Pharyngeal chambers behind vestibule 2; eyes 2 .......................... Dilaimus Fil. 1927
( = Amphistenus Marion 1870)
Pharyngeal chambers behind vestibule more than 2
Chambers separated by 2-4 rings or by dots or denticles ............ Symplocostoma Bast. 1865
Chambers (first 2) separated by "commas"; rings 3; eyes 6 ..... Symplocostomella Micol. 1930
470 PROCEEDINGS HELMINTHOLOGICAL SOCIETY VOL. 2, NO. 1
Wall of the Pharynx unarmed (for alternative see page 458)
Cavity not cylindroid nor prismoid, i.e. cavity conoid or irregular in long, section (for alt. see page 474)
Oesophagus with median or posterior bulb or swelling, or both (for alternative see next page)
Amphid not known or obscure
Female not known; spinneret present; cephalic setae present; nema 1% wide; marine
Cuticle with distinct, anastomosing annules; amphid a transverse slit (Leptonemella Cobb 1920)
Cuticle without annules; amphid minute, at lips (Catanema Cobb 1920)
Female known; spinneret none, exc. Dasylaimus
Ovaries 2, reflexed; wings present
Spinneret pres.;phar. denticulate ;oes. without med. bulb ;post. ovary undev.;marine Do0ytotmtu Cobb 1933
Spinneret 0; post, pharynx concave-cylind.; oes. with med. bulb; in sheep dung Rhabditoides Goodey 1929
Ovary 1
Gonad 9 outstretched, anterior; cephalic setae 4 Walcherenia de Man 1921
Gonad 9 reflexed; cephalic setae or minute
Spinneret present; pharynx denticulate; striae of dots; post, ovary undev. : marine Dasylaimus Cobb 1933
Spinneret 0; pharynx not denticulate; oesophagus cephaloboid; not marine
Probolae present; amphid at lips; in soil
Cephalic appendages in 2 circlets Acrobeles Linst. 1877
Cephalic appendages in 1 circlet Cephalobvs Bast. 1865
( = Acrobeloides (Cobb) Steiner & Buhrer 1933)
Probolae absent; cephalic appendages none or in 1 circlet
Pharyngeal wall a long, series of elements; onch. 0; vagina directed inward. .Panagrolaimus Fuchs 1930
Pharyngeal wall not of serial elements; onch. oft pres. ; vagina directed forward; Turbatricinae
Posterior pharynx closed; vulva 75%; vagina less muscular; tail iblunt. . . .Plectonchus Fucbs 1930
Posterior pharynx open; vulva 65%; vagina muscular; tail slender Turbatrix Peters 1927
( = Anguillula auctores)
Amphid known
External amphid not spiral, circular nor elliptical
Habitat not marine
Spinneret present; cephalic setae 4; in fresh water; '9 Chronogaster Cobb 1913
Spinneret none; ovaries 2
Tail setaceous, 19%;amph. semicirc.;oesoph. with med. bulb;vulva 21%;' 9 ' (Aulolaimoides Micol. 1915)
Tail not setaceous, 9-15%; amphid inconspicuous, small or slit-like
Med. oesoph. bulb confluent in front; post. phar. closed; in decaying matter; ' 9 "... (Cheilobus Cobb 1924)
( = Rhabdi<ophanes Fuchs 1930)
Med. oesoph. bulb none; pharynx ovoid; wings 0; amphid a slit; in soil; ~9~. . .Monhystera Bast. 1865
( = M. dintheriana de Man 1885)
Habitat marine; cephalic setae present; spinneret present
Ambulatory tubes forming ventral pre-anal sole; nema S-shape, narrowed in card, reg.; marine; ' 9 '
Oesoph. region hardly swollen; card, bulb faint; cerv. striae all alike. . Notochaetosoma Irwin-Smith 1918
Oesoph. region swollen, ovoid; oesophageal bulbs 1 or 2; band of cervical
striae accentuated, exc. Tristicochaeta falcatum
Ventral ambulatory adhesion tubes or setae in 2 rows Drepanonema Cobb 1933
( = Chaetosoma Clap. 1863)
Ventral ambulatory adhesion tubes or setae in 3 or 4 rows Tristicochaeta Panceri 1878
( = Draconema Cobb 1913)
Ambulatory tubes absent; nema not crooked, not narrowed in cardiac region
Amphid transverse; pharynx minute; annules plain ;ceph. set. 10, jointed; o* only Leptonemella Cobb 1920
Amphid large, folded or shepherd's crook; pharynx obvious; ovaries outstretched
Pharynx 4-5%, heavy ,tubular;amphid 4-50% body;ceph.set.4,subceph.l2r9~ (Pseitdolella Cobb 1920)
Pharynx under 2%, conoid, not heavy; cephalic setae large, long; odontia 6 or 12
Ovary 1, posterior; cephalic setae 6; odontia 12; vulva 15% (Synodontium Cobb 1920)
Ovaries 2; cephalic setae 4 ; odontia 6; vulva 45-67%
Tail clavate; nema shorter, stouter; amphid larger Axonolaimus de Man 1889
Tail conoid; nema long, slender; amphid smaller Ascnlaimus Ditlev. 1919
( = Bathylaimus Ditlev. 1918)
External amphid spiral, circular or elliptical
Female not known
Habitat soil (possibly marine); spinneret present; amphid spiral; ceph. set. 0. . . .(Amphispira Cobb 1920)
Habitat marine
Amphid multispire; wings 0; annules very fine
Pharyngeal bulb none; lip region not set off; head truncate-conoid; onch. 3, small Alaimonema Cobb 1920
Pharyngeal bulb present
Head cylindroid; lip region discoid, set off by constriction (Choniolaimus Ditlev. 1918)
Head hemispherical; lip region not discoid (Amphispira Cobb 1920)
Amphid circular or monospire; spinneret present
Nema cephalated, striae ceasing at constriction
Pharynx none; head spherical; amphid behind head; nema slender, 1.4%. . . .Cinctonema Cobb 1920
Pharynx definite; head hemispherical; amphid on head; nema wider, 3.8% (Micromicron Cobb 1920)
Nema not cephalated
Annules strong, each of 8 tile-like elements; oesphagus compound Dasynemella Cobb 1933
( = Dasynema Cobb 1920)
Annules none; oesophagus not compound
Cephalic setae 8 or more; onchium minute; amphid minute, at lips Catanema Cobb 1920
Cephalic setae 4; onchia 0; amphid large, not at lips
Wing single; amphids on head, large, double, circular, joined dorsally Antomicron Cobb 1920
Wings 0; amphids behind head, not joined
Base pharynx faintly cuticularized, without ring; amphid circular Monhysteriella Kreis 1929
Base pharynx with cuticularring, prongs 2, vertical; amphid monospire. .Cricolaimux Southern 1914
Female known
Ovary 1 (for alternative see next page)
Gonad 9 outstretched, anterior ; amphid circular; striae 0, or fine and plain; wings
Pharynx quadrate; neck under 5%; crystalline bodies lateral; marine (Crystallonema Cobb 1920)
Pharynx long-conoid; neck 17%; spinneret oresent; in fresh water (Monhystera Bast. 1865)
(i.e. subg. Monhystrella Cobb 1918)
Gonad 9 reflexed ; cephalic setae or minute
COBB: A KEY TO THE GENERA OF FREE-LIVING NEMAS 471
Spinneret present; striae of dots; phar. denticulate; post, ovary undev.; marine Dasylaimus Cobb 1933
Spinneret absent; pharynx not denticulate; not marine
Head with 6 biting odontia; amphid round; nema cephalated exc.
Teratocephalus palustris ........................... Teratocephalus de Man 1876
Head with entire or 3-parted lip region; amphid small, at lips; nema not
cephalated, exc. Acrobeles insubricus
Probolae absent ; cephalic appendages or in 1 circlet ....................... Panagrolaimus Fuchs 1930
Probolae present; in soil
Cephalic appendages in 2 circlets .............................................. Acrobeles Linst. 1877
Cephalic appendages in 1 circlet ............................................. Cephalobus Bast. 1865
( = Acrobeloides (Cobb) Steiner & Buhrer 1933)
Ovaries 2 (for alternative see preceding page)
Gonads 9 outstretched
Amphid multispire; striae fine; pharynx small, cup-shaped
ale ventral pre-anal supplementary organs small ....................... (Parasabatieria de Man 1907)
Male supplementary organs none ...................... ." ................. (Sabatieria de Rouville 1903)
Amphid circular
Pharynx obconoid, cutic. rings 1 or more; spinneret pres.; brackish soil. . . (Desmolaimus de Man 1880)
Pharynx without transverse cuticularized rings; spinneret present or not
Habitat not marine; cephalic setae
Spinneret present; head with 4 circular "warts" ; in fresh water ......... Pseudochromadora Daday 1901
Spinneret absent; head without "warts"; bursa present; in moss .......... Himatidiophila Rahm 1925
Habitat marine; striae fine; cephalic setae present
The pharynx obconoid, with cylindroid vestibule
Base pharynx cuticularized; head icylindroid; cardiac bulb valvate. . Metalinhomoeus de Man 1907
(cf. Deltane.ma Kreis 1929)
Base pharynx not cuticularized; head conoid; lips if everted knob-like Cryptolaimus Cobb 1933
The pharynx minute or none
Cardiac swelling not strongly developed; ceph. set. 8-10; nema not tapering Linhomoeus Bast. 1865
Cardiac bulb broad, valvate; ceph. set. 4; nema tapering, tail setaceous Terschellingia de Man 1888
Gonads 9 reflexed
Habit parasitic, in insects; oesophagus without median bulb ............. Neoaplectana Steiner 1929
Habit free-living
Spinneret absent; cephalic setae 0; in soil and fresh water
Nema cephalated, exc. T. palustris; lip reg. lobed, with 6 biting odontia. . Teralocephalus de Man 1876
Nema not cephalated; lip region not lobate; bursa present ................ Himatidiophila Rahm 1925
Spinneret present
Cephalic setae 0; head with 4 circular "warts"; in fresh water ............ Pseudochromadora Daday 1901
Cephalic setae present; head without "warts"
Habitat fresh water or soil; amphid circular to monospiral ...................... Plectus Bast. 1865
Habitat marine
Lips 2, mouth a dorso-ventral slit; "pseudonchs" dorso- ventral ridges. . . . (Pseudonchus Cobb 1920)
Lips more than 2. mouth not a slit; "pseudonchs" absent
Amphid multispire
Pharynx irregular, with tooth-like projections .............................. Zalonema Cobb 1920
Pharynx simply conoid, regular, without tooth-like projections
Head set off by absence of striae .................................. Heterodesmodora Micql. 1924
Head not set off; striae extending to lips; neck 6-7%; onchium minute ....... Spirina Fil. 1918
( = Spira Bast. 1865)
Amphid circular or monospiral
The pharynx denticulate ; post, ovary undev. ; stria* of dots; wings pres. . . (Dasylaimus Cobb 1933)
The pharynx not denticulate; both ovaries developed
Dorsal pharyngeal wall not thickened; amphid not at lips
Neck 14-21%; wings present; amphid long-oval; head set off by groove at 4 cephalic setae
Length of neck 14-16%; amphid large, head-width back .......... Eutelolaimus de Man 1922
Length of neck 21%; amphid 2 head-widths back .......................... Aplectus Cobb 1914
Neck under 7%; wings 0; amphid spiral
Nema 4-7 mm.; width 0.3-1%; phar. straight, closed, with pharyng. swelling Laxus Cobb 1894
Nema 2-4 mm.; width 1.5-4%; pharynx conoid, oft with small onchium ...... Spirina Fil. 1918
(=Spira Bast. 1865)
Dorsal pharyng. wall thick, tooth-like; amph. monospire at lips; ceph. set. 4 ; renette far back
Oesoph. glands obscuring junct. of intest.; dorsal phar. element dbuniform Onchium Cobb 1920
Oesoph. glands not prominent; dorsal pharyng. element not uniformly thick, but heavy
Tooth-like thickening parallel to axis .............................. Camacolaimus de Man 1889
( = Digitonchvs Cobb 1920
= Acontiolaimus Fil. 1918)
Tooth-like thickening bent outward from beginning of vestibule
Point of "onchium" single ......................................... Acmaeolaimus Fil. 1918
Point of Y-shaped "onchium" duplex .................................... Ypsilon Cobb 1920
Oesophagus plain, i.e. without median or posterior bulb or swelling (for alternative see preceding page)
Amphid not known or obscure (for alternative see next page)
Female not known
Habitat marine; lip region discoid; odontia 6; ceph. set.4; amphid small ..... (Stephanolaimus Ditlev. 1918)
Habitat fresh water, marsh or sand
Hemispherical "cap" wider than neck, edge setose; phar. conoid; spinneret pres. Diplolaimus Linst. 1876
Hemispherical cap none; setae 0; spinneret 0; wings double; bursa striate. . . .Macroposthonia de Man 1880
Female known; spinneret present
Ovary 1; marine
Gonad 9 reflexed; ceph. set. 0, pharynx denticulate; post, ovary undev.; wings pres. Dasylaimus Cobb 1933
Gonad 9 outstretched ; cephalic setae 4
The ovary anterior; nema 3 mm.; neck 12%,; vulva 75% ........................ Krampia Ditlev. 1922
The ovary posterior; nema 1 mm. ; neck 19%; vulva 35% ....................... Asymmetrica Kreis 1929
Ovaries 2, reflexed
Habitat fresh water (for alternative see next page)
Lips 3, rounded; pharynx small, closed; onchium minute, deepset .................. (Tripyla Bast. 1865)
( = Promononchus Micol. 1923)
472 PROCEEDINGS HELMINTHOLOGICAL SOCIETY VOL. 2, NO. 1
Lips 6, thin; pharynx larger, domed; onchia in posterior chamber (Trilobus Bast. 1866)
Habitat marine (for alternative see preceding page)
Wings conspic. ; striae of dots ; ceph . set. ;pharynx denticulate ; post .ovary undev . . Dasylaimus Cobb 1933
Wings 0, striae plain, not altered laterally; cephalic setae present; Enoplidae
Calvarium elaborate, ornate; onchia often present Deontostoma Fil. 1916
Calvarium not elaborate, sometimes absent
Oesophagus crenate towards base; calvarium simple or reduced
Eyes 0; neck rttapering; calvarium reduced; cervical setae in several rows Stenolaimus Marion 1870
Eyes with lenses
Pharynx simple ; calvarium reduced ; neck tapering Nasinema Fil. 1927
Pharynx with tooth-like processes; calvarium simple; neck icylindroid Phanoderma Bast. 1865
( = Heterocephalus Marion 1870)
Oesophagus not crenate; calvarium absent
Jaws 3, without mandibles or onchia (Parenoplus Fil. 1927)
Jaws absent
The pharynx tapering into oesophagus; cephalic setae 6, cervical small. .Paroxy stamina Micol. 1924
The pharynx broad.thin-walled.base truncate with mound ;amph. with pocket Pelagonema Cobb 1894
(cf. Vasculonema Kreis 1928)
Amphid known (for alternative see preceding page)
External amphid not spiral, circular nor elliptical ; female known
Ovary 1 ; amphid not linear
Gonad 9 outstretched; lips 6, thin, each with 3 parallel-sided cutic. ribs; marine Daptonema Cobb 1920
(cf. Theristus Bast. 1865)
Gonad 9 reflexed
The ovary posterior; spinneret absent; marine (Rhabdocoma Cobb 1920)
The ovary anterior, vulva 80%; spinneret present; soil about sugar cane Trischistoma Cobb 1913
Ovaries 2
Gonads 9 outstretched; marine exc. Monhystera
Habitat soil among roots; amphid a transverse slit; pharynx ovoid Monhj/stera Bast. 1865
( = M. dintheriana de Man 1885)
Habitat marine
Amphid large, long-oval, on triangular plate, as wide as head; spinneret none. . . .Didelta Cobb 1920
Amphid not on special plate
Mouth ventrad of axis; amphid large, long, "folded 1 Campylaimws Cobb 1920
Mouth axial; amphid shorter
Odontia absent; amphid flattened, more or less reniform Margonema Cobb 1920
Odontia, if present, 6 or 12; amphid crook-shaped or "folded"
Tail clavate; body less slender; amphid larger Axonolaimus de Man 1889
Tail conoid; body slender; amphid smaller Ascolaimus Ditlev. 1919
( = Bathylaimus Ditlev. 1918)
Gonads 9 reflexed
Habitat freshwater
Pharynx larger, domed; lips 6, thin; onchia small, in posterior pharynx (Trilobus Bast. 1865)
Pharynx small, closed; lips 3, rounded; onchium minute, deepset (Tripyla Bast. 1865)
( = Promononchus Micol. 1923)
Habitat marine
Wings present; amphid a transverse slit almost as wide as head Actinonema Cobb 1920
Wings absent; amphid with internal pocket (Rhabdocoma ?); Enoplidae (Rhabdocoma ?)
Oesophagus crenate towards base
Pharynx without tooth-like processes; cervical setae in longitudinal rows. . .Stenolaimus Marion 1870
Pharynx with 2-3 forward-pointing tooth-like processes; calvarium pres.. .(Phanoderma Bast. 1865)
( = Heterocephahis Marion 1870)
Oesophagus not crenate
Calvarium present; onchia often 1-3
The calvarium elaborate, ornate, relatively short Deontostoma Fil. 1916
The calvarium a mere band, margin wavy ;external amphid transverse-oval Cylicolaimus de Man 1889
Calvarium absent
Lateral series of setae on neck absent; spinneret absent (Rhabdocoma Cobb 1920)
Lateral series of setae on neck of few members
Excretory pore on projection; pharynx definite, iquadrate; testis 1. .. .Paranticoma Micol. 1930
Excretory pore not raised; pharynx conoid, often obscure; testes 2
Gubernaculum present; cf pre-anal ventral supplementary organ tubular Anticoma Bast. 1865
Gubernaculum none; cf ventral pre-anal supplementary organ papilloid Anticomopsis Micol. 1930
External amphid spiral, circular or elliptical
Female not known; marine exc. Dintheria (for alternative see next page)
Spinneret none;ceph.set.4,long;amph.transverse-oval,| head- width, open caudad Dintheria de Man 1921
Spinneret present (Neurella, Bognenia ?)
Nema broad, tapering from head to tail; wings 12-24; amphid spiral Pteronium Cobb 1933
Nema slender, not widest at head; wings none or few
Amphid multispire
Wing single; cephalic setae 4; amphid broad, of few winds; spinneret(?) Neurella Cobb 1920
Wings absent; striae not altered laterally
Onchia 3,at tops apophyses;ceph.set.papilloid;pharynx complex.bulb strong Trogolaimus Cobb 1920
Onchia 0; cephalic setae longer; lips flap-like, at least distally
Lip supports thickened; phar. cyathiform; cf supplements many, chromadoroid Dispira Cobb 1933
Lip supports none; pharynx spheroid, on front of head; cf supplements 0. .Dispirella Cobb 1933
Amphid circular, elliptical or monospiral
Wings strong; amphid circular or monospiral
Oesoph.compound.wide anteriorly .card.bulb faint ;amph. spiral jannules wide Daaynemella Cobb 1933
( = Dasynema Cobb 1920)
Oesoph. not compound; amphid circular
The wings.12, of spine-like markings Xenolaimus Cobb 1920
The wing single, with subordinate lines; amphids joined dorsally (Antomicron Cobb 1920)
Wings 0; striae not altered laterally
Onchium spear-like; cephalic setae 10; cephalic cuticle thickened; eyes 2 (Cophonchus Cobb 1920)
Onchium none (Nudolaimus ?)
COBB: A KEY TO THE GENERA OF FREE-LIVING NEMAS 473
Nema 9-10 mm.; striae 0; pharyngeat walls heavily cuticularized; amphid small
Amphid labial, spiral; phar. large, processes basal; ceph. set. 4; eyes . . (Niidolaimiw Allgen 1929)
Amphid 1 head-width back, oval; phar. small; ceph. set. 10; eyes 2 Leptoxomatides Fil 1918
Nema under 3 mm.; cephalic setae 4-6
Cephalic setae at least 2 head-widths long
Lip region discoid, set off; odontia 6; amphid small, oval Stephanolaimus Ditlev. 1918
Lip region not discoid; odontia none; amphid large, circular Cenolaimus Cobb 1933
Cephalic setae not over 1 head- width long; lip region not discoid; odontia
Pharynx a wide tube; head strongly conoid; width of nema 6% Tubolaimus Allgen 1929
Pharynx shallow; head not strongly conoid
Cutjcle annulated; amphid oval, near lips; lips 3, massive, low Zygonemella Cobb 1920
Cuticle with fine striae or none; amph. circular, 1 head-width back; lips confluent
Ribs of pharynx 6, cuticularized, parallel to axis Rhadinema Cobb 1920
Ribs of pharynx none; pharynx conoid Bognenia Allgen 1932
Female known (for alternative see preceding page)
Ovary 1; amphid not multispire
Gonad 9 reflexed; amphid circular or elliptical
The ovary posterior; marine
Spinneret none; cephalic setae 4; tail usually about 40% Rhabdocoma Cobb 1920
Spinneret present; cephalic setae 0; tail about 3% Nemanema Cobb 1920
The ovary anterior; cephalic setae present (in Monhystrium sometimes papilloid)
Habitat not marine; spinneret present
Pharynx deep; onch. small, basal; lips massive, with flaps; vulva 80%; soil (Trischistoma Cobb 1913)
Pharynx less deep, vestibule definite; onchia 0; in gills of land crabs (Monhystrium Cobb 1920)
Habitat marine
Spinneret 0; ceph. set. 10; caudal setae thorn-like; amphid large, center raised (Zanema Cobb 1920)
Spinneret pres.; ceph. set. 4, small; thorn-like setae 0; phar. cylind. .(Conolaimella Allgen 1930)
CSonad 9 outstretched, anterior; usually marine
Spinneret none; wings 0; amphid circular; marine
Amphid large, with central mound; caudal setae thorn-like; nema 0.9% wide. .(Zanema Cobb 1920)
Amphid not raised centrally; caudal setae if present not thorn-like
Labial palps 6; pharynx iquadrate; tail conoid, 4% Crystallonema Cobb 1920
Labial palps 0; pharynx conoid then spheroid; tail long, filiform. .. .(Diplolaimella Allgen 1929)
Spinneret present; marine exc. Monhystrium, and sometimes Monhystera and Theristus
Lips 3, each with finger-like odontium; striae coarse; wings 32, fewer towards tail Xyala Cobb 1920
Lips without finger-like processes; wings or few
Mouth cavity large, complex, of several chambers, the first of radial elements; carnivorous
Base pharynx unsymmetrical, meeting oesoph. ;middle chamber denticulate Sphaerolaimus Bast. 1865
Base pharynx symmetrical.oesoph. surrounding 2 chambers ;dents.O Parasphaerolaimus Ditlev. 1918
Mouth cavity smaller, of 1 or 2 chambers, walls relatively simple
Lips 6, conoid, twice high as broad, with hook-shaped set. ; amph. monospire Dactylaimus Cobb 1920
Lips not as high as broad, without hook-shaped setae; mostly Monhysterinae
Caudal glands pre-anal, reaching vulva; excret. pore nr. phar.; ceph. set. 4 Conolaimella Allgen 1930
Caudal glands post-anal; excret. pore nr. nerve ring, when seen; ceph. set. oft many
Labial ribs 18, cuticularized, parallel-sided; testes 2 Daptonema Cobb 1920
(cf. Theristus Bast. 1865)
Labial ribs absent or (Monhystrium) reduced ;genera resembling Monhystera.exc.Sphaerocephalum
Margin of transverse-oval amphidial area not definite, sensory papilla at posterior margin
Intestine narrow, J body-width; gubernaculum tubular Leptogastrella Cobb 1920
Intestine wider(?); gubernaculum not tubular(?) Paramonhystera (Steiner) Fil. 1918
Margin of amphidial area definite, sensory papilla not obvious
Habitat gills of land crabs; cephalic setae 10, sometimes papilloid Monhystrium Cobb 1920
Habitat aquatic; marine exc. sometimes Monhystera and Theristus
Pharynx conoid, then spheroid; striae fine or 0; eyes oft present. .Diplolaimella Allgen 1929
Pharynx without spheroid chamber; amphid circular exc. Sphaerocephalum
Amphid monospire; neck 5-9%; spinneret wide, plug striated. . .Sphaerocephalum Fil. 1918
Amphid circular; neck 10-27%; spinneret without striated plug
Oesophagus wide in post, half ; spicula hamate distally; gubernaculum Austronema Cobb 1914
Oesophagus not wider posteriorly; gubernaculum present
Setae on head 8-fold; somatic set. oft long. .Steineria (Micol.) Stekhoven & de Coninck 1933
Setae on head not 8-fold; long paired somatic setae absent
Gubernaculum tubular, barbed, apophysis none Fernanda (de Man) Fil. 1918
Gubernaculum not tubular
Spicula not much bent; gubernac. apophysate; mostly freshwater. . .Monhystera Bast. 1865
( = Tachyhodites Bast. 1865)
Spicula much bent or sickle-shape; gubernac. plate-like, dorsad Theristus Bast. 1865
( = Allomonhystera Micol. 1923)
(cf. Daptonema Cobb 1920)
Ovaries 2
Gonads 9 outstretched; marine (for alternative see next page)
Nema 12-16% wide; neck "collared"; amphid spiral; wings many; spinneret present
Wings over 50; pharynx narrow; spicula 2, equal... Richtersia Steiner 1916
Wings 16-20, in pairs; pharynx capacious, open; spicula unequal, or but 1 . . (Kichtersiella Kreis 1929)
Nema under 3% wide; neck not "collared"; wings if present not numerous
Spinneret absent; amphid circular exc. Didelta
Setae none; amphid ihalf as wide as head Metalaimus Kreis 1928
Setae present; amphid small exc. Didelta
Amphid very large, long-oval, on triangular plate; cephalic setae 4 Didelta Cobb 1920
Amphid small, not on plate; cephalic setae 6 or more
Pharyngeal bulb distinct; cephalic setae 6, stout, jointed Cytolaimium Cobb 1920
Pharyngeal bulb none; setae on head 18, small; amph. with faint multispire. . Anticyathux Cobb 1920
Spinneret present; cephalic setae present exc. Margonema
External amphid multispire
Male ventral pre-anal supplementary organs papilloid Parasabatieria de Man 1907
Male supplementary organs none Sabatieria de Rouville 1903
External amphid not multispire (Linhomoella faintly so)
474 PROCEEDINGS HELMINTHOLOGK'AL SOCIETY VOL. 2, NO. 1
Amphid wider than long, reniform; lips 3, double, with papillae Margonema Cobb 1920
Amphid circular or monospiral
Lips distinct, with distal flaps; ceph. set. 6, stout, jointed; papillae 6. . . .Cytolaimium Cobb 1920
Lips absent or confluent
Oesoph. &lumen with oval enlargement behind eyes ;eyes sometimes none Araeolaimux de Man 1888
Oesoph. without median enlargement; eyes 0; cephalic setae 6-10
Setae on head 10, shorter 4 specialized at tip; amph. faint multispire. . (Linhomoella Cobb 1920)
Setae on head 6-8, without specialized tips; amphid circular Linhomoeus Bast. 1865
Gonads 9 reflexed (for alternative see preceding page)
Habitat not marine exc. sometimes Aphanolaimus
Spinneretabsent; amphid multispire; setae 0; striae of dots; in sand dunes. .Choanolaimus de Man 1880
Spinneret present
Wings present; contour crenate; glands lateral, serial ; amphid monospire. . Aphanolaimus de Man 1880
Wings 0, striae not altered laterally; contour not erenate; amphid circular or oval
Lips, papillae & setae 0; amphid round; pharynx small, conoid, unarmed Diplohystera de Cillis 1917
Lips, papillae & small setae pres.; amph small, oval; phar. closed; onch. basal Tripyla Bast. 1865
( = Promononchus Micol. 1923)
Habitat marine
Amphid spiral ; spinneret present
Pharynx with apophyses forward and backward from mid-region
Mid-pharyngeal region not denticulate; wings numerous, markings V-shaped. . . .Nunema Cobb 1933
Mid-pharyngeal region denticulate Halichoanolaimus de Man 1886
( = Smalsundia Allgen 1929)
Pharynx without forward apophyses; mid-pharyngeal region not denticulate
Wings numerous; neck region "collared"; nema 12-16% wide
Spicula 2; wings over 50; pharynx narrow Richtersia Steiner 1916
Spicula unequal, or 1 only; wings 16-32; pharynx capacious, open (Richtersiella Kreis 1929)
Wings absent, striae if present not altered laterally
Jaws 3, with backward apophyses and numerous horny teeth anteriorly Demonema Cobb 1894
Jaws absent, pharynx without apophvses
Pharynx 2 chambers; ceph. set. 10. oft jointed, tips specialized; striae fine Tripyloides de Man 1886
Pharynx 1 chamber; tips setae unspecialized; striae less fine; eyes present
Cuticular pores none; pharynx with definite bulb Nannolaimus Cobb 1920
Cuticular pores present; pharvnx without definite bulb Cyatholaimus Bast. 1865
( = Necticonema Marion 1870)
Amphid circular, elliptical or monospiral
Spinneret absent; cephalic setae 4. stout; tail usually 40% Rhabdocoma Cobb 1920
Spinneret present
Oesophagus crenate towards base; calvarium reduced
Cervical setae in long, rows; pharynx none; ext. amph. semi-circular (Stenalaimus Marion 1870)
Cervical setae Phanodermopsis Ditlev. 1926
( = Galeonema Fil. 1927)
Oesophagus not crenate
Calvarium present; onchia often 1-3
The calvarium elaborate, ornate Deontostoma Fil. 1916
The calvarium a wavy band; often denticles at lips; amphid transverse. .Cylicolaimus de Man 1889
Calvarium absent
Jaws 3, with simple supporting framework Parenoplus Fil. 1927
Jaws absent
Pharynx of 2 chambers
Chambers of pharynx equal. small; cephalic setae Pseudopelagonema Kreis 1932
Chambers of pharynx unequal, anterior large; setae 10. often jointed, tips specialized
Both chambers conoid or irregular in shape Tripyloides de Man 1886
Both chambers parallel-sided Bathylaimus Cobb 1894
( = Macrolaimus Ditlev. 1918
= Cothonolaimus Ditlev. 1919)
Pharynx of 1 chamber; setae without specialized tips
Dorsal pharyng. wall thick, tooth-like; amph. monospire at lips; ceph. set. 4; renette far back
Oesoph. glands obscuring junct. of intest.; dorsal phar. element uniform Onchium Cobb 1920
Oesoph. glands not prominent; dorsal pharyng. element not uniformly thick, but heavy
Tooth-like thickening parallel to axis Camacolaimus de Man 1889
( = Digitonchus Cobb 1920
= Acontiolaimus Fil. 1918)
Tooth-like thickening bent outward from beginning of vestibule
Point of "onchium" single Acmaeolaimus Fil. 1918
Point of Y-shaped "onchium" duplex Ypsilon Cobb 1920
Dorsal pharyngeal wall not thickened; amphid not at lips; Enoplidae, exc. Aphanolaimus
The pharynx open, capacious, walls usually heavily cuticularized; amphid with pocket
External amphid circular; wall of pharynx irregularly thick (Pandolaimus Allgen 1929)
External amphid small, transverse;pharyng. wall thin. base with mounds Pelagonerna Cobb 1894
(cf. Vasculonema Kreis 1928)
The pharynx small or very narrow
Cervical setae absent; cephalic setae 4, in front of amphid Aphanolaimus de Man 1880
Cervical setae lateral, in short longitudinal series; amphid with pocket
Gubernaculum present; cf supplementary organ tubular Anticoma Bast. 1865
Gubernaculum none; cf supplementary organ papilloid Anticomopsis Micol. 1930
Carity more or less cylindroid or prismoid, i.e. parallel-sided in long, section (for alt. see page 470)
Oesophagus with median or posterior bulb or swelling, or both (for alternative see page 477)
Amphid not known or obscure (for alternative see next page)
Female not known
Spinneret none;ceph.set.0;phar.closed;oesoph.cephaloboid;neck over 20%;in swamp Litonema Cobb 1920
Spinneret present; setae on head numerous; neck under 5%; amphid small, near lips; marine
Pharyngeal bulb present; striae none; length 3-4 mm. ; onchia(?) 6, minute (Catanema Cobb 1920)
Pharyngeal bulb none; striae annulating the cuticle; length 10 mm (Laxonema Cobb 1920)
Female known; spinneret none exc. Rhabdolaimus; not marine; phasmids usually present
Spi
C
COBB: A KEY TO THE GENERA OF FREE-LIVING NEMAS 475
Ovary 1, anterior; cephalic setae or minute
Gonad 9 outstretched
Pharynx long, tubular, base halfway to nerve ring: spear none; median bulb . . Gymnolaimus Cobb 1913
Pharynx base J distance to nerve ring; spear reduced; oes. bulb strong (Aphelenchoides Fischer 1894)
( = Seinura Fuchs 1931
=Parasitaphelenchus Fuchs 1930
Gonad 9 renewed -Pathoaphelenchus (Cobb) Steiner 1931)
Median oesophageal bulb present
Pharynx wide as long; cardiac bulb not valvate, median valvate; bursa none. .Lycolaimus Rahm 1928
Pharynx much longer than wide; cardiac bulb valvate; bursa present ............. Rhabditis Duj. 1845
( = Diploscapteroides Rahm 1928
=Pseudorhabditis Kreis 1929)
Median oesophageal bulb absent; in soil and fresh water
Cardiac swelling long, non-valvate; pharyng. rods heavily cuticular ____ Diphtherophora de Man 1880
( = Chaolaimus Cobb 1893
= Archionchus Cobb 1913)
Cardiac bulb valvate, preceded by isthmus, i.e. oesoph. cephaloboid; pharyng. rods none
Head end lobed by 6 large biting lips or odontia; carnivorous ........... (Teratocephalus de Man 1876)
Head end not lobed, exc. in Acrobeles insubricus
Pharynx wall simple.forming 2 chambers ;onchium oft present;ceph.set.O-4 Macrelaimus Maupas 1900
Pharynx wall of a longitudinal series of elements, i.e. cephaloboid
Probolae on head none ................................................... Panagrolaimus Fuchs 1930
Probolae on head in 1 or 2 circlets
Circlets of probolae 2, elements often elaborate ................................ Acrobeles Linst. 1877
Circlet of probolae single ..................................................... Cephalobus Bast. 1865
( = Acrobelmdes (Cobb) Steiner & Buhrer 1933)
Ovaries 2; cephalic setae 0, exc. in Teratocephalus minute
Gonads 9 outstretched; ceph. set. 0; phar. tubular, reaching oesoph. bulb; in soil Aulolaimus de Man 1880
Gonads 9 reflexed
Spinneret present; wings absent; in fresh water and moist soil ............... Rhabdolaimus de Man 1880
inneret absent
uticle with prominent tubercles; lip reg. set off by constrict.; ceph. set. with saccate bases
Tubercles encrusting dorsal surface; wings broad, thin; in moss .......... Craspedonema Richters 1908
Tubercles in longitudinal row(s), right lateral; oesophagus rhabditoid ..... Bunonema Jagerskiold 1905
( = Rhodolaimus Fuchs 1930)
Cuticle without tubercles
Pharynx a long straight tube, \ neck length or more
Oesoph. short, a muscular bulb only; <? supplements few, ventral, pre-anal Aulolaimus de Man 1880
Oesoph. long, of 2 parts; cf supplements paired, post-anal, i.e. diplogastroid
Male papillae 9 pairs; gubernaculum sigmoid; labial papillae 16 ............. Myctolaimus Cobb 1920
Male papillae 10 pairs ; gubernaculum straight ; bursal membrane narrow . . Cylindrogaster Goodey 1927
Pharynx not a simple tube, much shorter
Oesophagus without median bulb
Cuticularized rods supporting pharynx; shed cuticle surrounding nema Diphtherophora de Man 1880
( = Chaolaimus Cobb 1893
= Archionchus Cobb 1913)
Cuticularized pharyngeal rods none
Head end lobed by 6 large biting lips or odontia; carnivorous ........ (Teratocephalus de Man 1876)
Headend n&t lobed; bursa present ............................................. Rhabditis Duj. 1845
Oesophagus with median and cardiac bulbs
Cardiac bulb valvate; median bulb well set off; glottoid apparatus present
Wall of pharynx cylindroid; bursa present; cf tail rhabditoid .................. Rhabditis Duj. 1845
Wall of pharynx convex inward; bursa much reduced; cf tail long, spicate Rhabditoides Goodey 1929
(=Rhabditella (Cobb) Chitwood 1933)
Cardiac bulb without valve; median bulb valvate; d" tail setaceous, diplogastroid
Pharyng. rods 3, basal bulbs 2, stalked; tail 25-41%; long, striae fine ...... Tylopharynx de Man 1876
Pharyng. bulbed supporting-rods none; Diplogasterinae
Nema with evident longitudinal striation ........................... Diplogaster M. Schultze 1857
Nema without longitudinal striation
Pharynx wide as deep, wa}l of several elements; d" papillae 0(?) ....... Peronilaimus Rahm 1928
Pharynx tubular, wall entire; d 1 papillae usually 5 pairs ............... Rhabditidoides Rahm 1928
Amphid known (for alternative see preceding page)
External amphid not spiral, circular nor elliptical (for alternative see next page)
Habitat marine; cephalic setae and spinneret present; amphid crook-shaped, sometimes =tspiral
Ambulatory & somatic set. 0; nema not crooked, not narrowed in card. reg. ; ventral arm amph. pr
Phar. wide.heavy, 4-5% ;amphid long,4-50% body ;ceph. setae 4,subceph.l2; -9-. - .Pseudolella Cobb
Phar. narrow,inconspic.;amph. under 2%;ceph.set.6,subceph.4;annules tiled; '9' Ceramonema Cobb 1920
(cf. Pselionema Cobb 1933)
Ambulatory set. forming ventral pre-anal sole; nema S-shape, narrowed in card, reg.; marine; '9'
Oesoph. region hardly swollen; card, bulb faint; cerv. striae all alike. . Notochaetosoma Irwin-Smith 1918
Oesoph. region swollen, ovoid; oesophageal bulbs 1 or 2; band of cervical striae
accentuated, exc. Tristicochaeta falcatum
Ventral ambulatory adhesion tubes or setae in 2 rows ......................... Drepanonema Cobb 1933
( = Chaetosoma Clap. 1863)
Ventral ambulatory adhesion tubes or setae in 3 or 4 rows .................. Tristicochaeta Panceri 1878
( = Draconema Cobb 1913)
Habitat not marine
Spinneret present; ' 9 ', exc. Chronogaster
Li ps 6, distinct, revplute; pharynx 9%; amphid semicircular; soil about cane roots Anthonema Cobb 1906
Lips not revolute; in fresh water
Cephalic setae 4; pharynx wider, under 1.5%; '9 ............................... Chronogaster Cobb 1913
Cephalic setae 0; pharynx long-tubular; tail 25-30% ......................... Rhabdolaimus de Man 1880
Spinneret absent; cephalic setae or papilloid
Tail setaceous, 19%;oesoph. with2 bulbs; amph. semicircular; vulva 21%; '9' Aulolaimnidex Micol. 1915
Tail not setaceous, under 15%; oesophagus without median bulb, exc. Cheilobu?
476 PROCEEDINGS HELMINTHOLOGICAL SOCIETY VOL. 2, NO. 1
Amphid transverse, curved, wide as head; phar. 7.6%; tail 2%; fresh water; cf only Colpurella Cobb 1920
Amphid inconspicuous, small or slit-like; tail over 9%; in soil or decaying material
Median oesoph. swelling before isthmus; cardiac bulb valvate; wings single; ' 9 '. .Cheilobus Cobb 1924
( = Rhabditophanes Fuchs 1930)
Median oesoph. bulb absent
Pharynx closed; amphid a pore, with internal cuticularized tube; wings 2; J Litonema Cobb 1920
Pharynx open, or with anterior open chamber; wings 0; cf 1 only
Tail 15%, terminus setaceous; pharynx without cuticularized rods (Monhystera Bast. 1865)
( = M. dintheriana de Man 1885)
Tail 8%, conoid; cuticularized rods in pharynx; shed cuticle retained. . . Diphtherophora de Man 1880
( = Chaolaimus Cobb 1893
= Archionchvs Cobb 1913)
External ampbid spiral, circular or elliptical (for alternative see preceding page)
Female not known; spinneret present
Habitat soil; ceph. set. 0; ceph. cuticle thick, flaps doming vestibule; amph. spiral Pycnolaimus Cobb 1920
Habitat marine; cephalic setae present
Amphid multispire; annules not coarse; wings absent
Head cylindroid; lip reg. set off by constriction; pharyng. bulb present. .(Choniolaimus Ditlev. 1918)
Head truncate-conoid ;lip reg. not set off ;pharyngeal bulb none;onch.3, minute Alaimonema Cobb 1920
Amphid circular, elliptical or monospiral
Wings 8; annules coarse; oesoph. to isthmus wide, muscular; card, swelling slight Dasynemella Cobb 1933
( = Dasynema Cobb 1920)
Wings
Cutilarized pharyng. ring basal; ceph. set. 4; <? supplements tubular, 14 Cricolaimus Southern 1914
Cuticularized pharyngeal ring none
Spiculum 1, gubernaculum absent; cephalic setae 10; amphid large, oval. .Pelagonemella Kreis 1932
Spicula 2, gubernaculum present (Chloronemella?); cephalic setae in circlets of 4
Striae coarse; amphid minute; length 10 mm. ; width 0.8% Laxonema Cobb 1920
Striae fine; length under 4 mm.
Pharyngeal bulb present; amphid at lips; onchia 6, minute Catanema Cobb 1920
Pharyngeal bulb none; amphid behind pharynx; onchia Chloronemella Allgen 1929
Female known
Ovary 1
Gonad 9 outstretched, anterior; amphid circular; wings absent
Spinneret present; pharynx long-conoid; neck 17%; in fresh water Monhystera Bast. 1865
(i.e. subg. Monhystrella Cobb 1918)
Spinneret absent; neck not over 5%; marine
Pharynx wide as deep; cardiac swelling faint, elongate; intestine not dark . . Crystallonema Cobb 1920
Pharynx tubular; posterior }-J oesoph. a massive bulb; intestine dark colored (Solenolaimus ?)
Cephalic setae minute; neck 1.4%; anterior oesoph. fusiform; tail rounded. .Solenolaimus Cobb 1894
Cephalic setae often as long as mitreform head is wide; neck 2-5%
Anterior oesoph. not fusiform; pharynx not eyertible; cf supplements Chromagaster Cobb 1894
Anterior oesoph. fusiform;phar. "spear" evertible; cf supplements pres..Siphonolaimus de Man 1893
Gonad 9 reflexed; wings often present; not marine exc. rarely Rhabditis
The ovary posterior, vulva 21%;med.bulb not valvate;amph.semicirc.;mud.. Aulolaimoides Micol. 1915
The ovary anterior
Spinneret pres.; ceph. set. 4; card, bulb or faint; amph. monospire; fresh water (Anonchus Cobb 1913)
Spinneret none; setae none, cephalic papillae sometimes setose
Oesophageal bulbs median and cardiac; pharynx simple; setae
Cardiac bulb valvate; amphid at lips, obscure; wings & bursa pres.; ubiquitous Rhabditis Duj. 1845
Cardiac bulb not valvate, median valvate; amph. transverse-oval, not at lips; phar. cylindroid
Dorsal onchium none; bursa present; ectoparasitic on beetle borer Rhabditolaimus Fuchs 1915
Dorsal onch. small, deepset; bursa 0; in exudate chestnut blight. .(Diplogasteroides de Man 1912)
Oesophageal bulb cardiac only, preceded by isthmus; phar. of serial plates; bursa or reduced
Head with 6 large odontia; amphid not obscure, often large
Nema mostly cephalated; cirri 0; amphid circular; soil & fresh water. .Teratocephalus de Man 1876
Nema not cephalated; cirri 6; amph. transverse-oval; tail hooked; in bark Chambersiella Cobb 1920
( = Diastolaimus Rahm 1928)
Head entire or 3-parted at lips; nema not cephalated, exc. Acrobeles insubricus; amph. small
Probolae absent; onchium 0, or 1 inward-pointing Macrolaimus Maupas 1900
Probolae on head in 1 or 2 circlets
Circlets of probolae 2, labial and cephalic; amphid a pore near lips (Acrobeles Linst. 1877)
Circlet of probolae single; amphid often obscure Cephalobus Bast. 1865
(= Acrobeloides (Cobb) Steiner & Biihrer 1933)
Ovaries 2
Gonads 9 outstretched; cephalic setae present; marine or in brackish soil
Amphid multispire; cephalic setae 10, unequal
Cardiac bulb ellipsoid; 6 of ceph. set. short; subcephalic setae 4; tail 30%, fine . . Laimella Cobb 1920
Cardiac bulb slight; 4 of ceph. set. short, tips specialized; tail 7% (Linhomoella Cobb 1920)
Amphid circular or monospiral; tail not over 18%, not setaceous
Gland ducts cuticularized, piercing cuticle, yentrad, cerv. & pre-anal. . Halaphanolaimus Southern 1914
Gland ducts and pores absent; pharynx minute or none
Pharynx inone; ceph. set. 10, 4 short, tips specialized; tail 7% (Linhomoella Cobb 1920)
Pharynx obconqid, when open J-J as wide as head; spinneret sometimes present
Cuticularized rings in pharynx 1-3; neck 8-14%; marine & brackish soil (Desmolaimus de Man 1880)
Cuticularized pharyngeal rings absent; ventriculus present; marine
Base pharynx not cuticularized; cardiac bulb oft valvate; head iconoid Cryptolaimus Cobb 1933
Base pharynx cuticularized; cardiac bulb valvate; head cylindroid Metalinhomoeus de Man 1907
(cf. Deltanema Kreis 1929)
Gonads 9 reflexed
Habitat not marine, exc. rarely Rhabditis and Haliplectus (for alternative see next page)
Oesophageal bulbs median and cardiac; cephalic setae 0; pharynx tubular (for alt. see next page)
Vulva21%;anus81%; amph. semicirc., \ head-width; wings & bursa none (Aulolaimoides Micol. 1915)
Vulva 40-94%; in soil etc., in fresh water, and marine
Spinneret pres.;amph.monospire,protruding;wings & bursa 0;pores lateral. .Haliplectus Cobb 1913
COBB: A KEY TO THE GENERA OF FREE-LIVING NEMAS 477
Spinneret none; cardiac bulb valvate; amphid obscure; wings and bursa present Rhabditis Duj. 1845
Oesophageal bulb cardiac only (for alternative see preceding page)
Spinneret absent; ampbid circular, elliptical or monospiral
Head without odontia; nema not cephalated; setae 0; spear minute; in soil (Triplonchium Cobb 1920)
Head with 6 large odontia; bursa none or much reduced
Nema mostly cephalated; cirri 0; amph. circular; in soil & fresh water. . . Teratocephalus de Man 1876
Nema not cephalated; cirri 6; amphid transverse-oval ; tail hooked; in bark Chambersiella Cobb 1920
( = Diastolaimus Rahm 1928)
Spinneret present
Pharynx simple; oesophagus not plectoid; neck 15-20%
Cephalic setae 0; wings 0; pharynx long; amphid with pocket; tail 27% (Rhabdolaimus de Man 1880)
Cephalic setae 4; pharynx short; tail 15%
Wings present; amphid monospire Paraphanolaimus Micol. 1923
Wings absent; amphid circular; onchium minute, not at lips Prodesmodora Micol. 1923
Pharynx compound-elongate; oes. oft with isthmus to card, bulb (plectoid); wings pres.
Labial region not expanded; cephalic setae usually 4, sometimes or 6; neck 12-30%
Cardiac bulb not valvate; pharynx long; neck 14-15%; in fresh water & mud Paraplectus Fil. 1930
Cardiac bulb valvate; amphid circular or transverse-oval Plectus Bast. 1865
Labial region expanded, with complicated appendages; pharynx 4-9%; neck 27-31%
Lips 6, distinct, revolute; striae fine; amphid semicircular; pharynx 9% (Anthonema Cobb 1906)
Lips not revolute; head with dorso- ventral bladders; striae coarse; amph. round; phar. 3-6%
Cephalic appendages elaborately palmate Wilsonema Cobb 1913
Cephalic appendages forming a closed, striated dome or cupola. .Bitholinema de Coninck 1931
Habitat marine or brackish (for alternative see preceding page)
Ambulatory set. forming a ventral sole, midbody to pre-anal; nema crooked; calvarium unstriated
Nema narrowest in card, reg., S-shaped; ambulatory set. hollow, pre-anal; annules finer
Oesoph. region hardly swollen; card, bulb faint; cerv. striae alike Notochaetosoma Irwin-Smith 1918
Oesoph. region swollen, ovoid; oesophageal bulbs 1 or 2; band of cervical
striae accentuated, exc. Tristicochaeta falcatum
Ventral ambulatory adhesion tubes or setae in 2 rows Drepanonema Cobb 1933
( = Chaetosoma Clap. 1863)
Ventral ambulatory adhesion tubes or setae in 3 or 4 rows Tristicochaeta Panceri 1878
( = Draconema Cobb 1913)
Nema narrowest midway, epsilon-shaped; ambulatory setae not open at end; annules coarser
Sole apparently absent; amphid cresentic; annules 98 Epsilonella Steiner 1930
Sole present; amphid circular or monospiral
Oesophagus with median and cardiac bulbs Metepsilonema Steiner 1927
Oesophagus with cardiac bulb only
Annules 80-112; ambulatory setae slender, falcate Bathyepsilonema Steiner 1927
Annules 144-192; ambulatory setae straight or slightly arcuate
Body cylindroid, if crooked faintly so Archepsilonema Steiner 1927
Body epsilon-like, i.e. body arches well developed
Cuticular annules homogeneous in structure Prochaetosoma Baylis & Daubney 1926
( = Rhabdogaster Metsch. 1867)
Cuticular annules not homogeneous in structure
"Axial" part of the cuticular annules hollow ("frame rings") Epsilonema Steiner 1927
"Axial" part of the cuticular annules vacuolated, etc Epsilonoides Steiner 1931
Ambulatory setae 0; nema not crooked; calvarium absent, or not truncate-conoid
Lips 2,mouthaslit;amph.faintmultispire;"pseudonchs"dorso-ventral ridges Pseudonchus Cobb 1920
Lips not 2, mouth not a slit; "pseudonchs" absent
Amphid multispire; neck 9-13%
Pharynx deeper than head width, wall irregular, with projections; striae plain Zalonema Cobb 1920
Pharynx tubular, less deep, wall straight; striae of dots Kreisia Allgen 1929
Amphid circular, elliptical or monospiral; neck 14-25%, exc. Bolbonema 8%
Wings present; anterior end set off by groove at 4 ceph. set. & usually by lack of annulation
Neck 20-25%
Species marine; striae duplex; wings 2; phar. tubular, inconspic., prob. double Aplectus Cobb 1914
Species in brackish soil & marsh; lip reg. discoid; ceph. set. papilloid. .Leptolaimus de Man 1876
Neck 14-16%; marine
Gland ducts cuticularized, piercing cuticle, cerv. and pre-anal. . Halaphanolaimus Southern 1914
Gland ducts & pores 0; pharynx of several long chambers; amphid round Polylaimium Cobb 1920
Wings absent
Median bulb present; ceph. set. 0; amph. protruding: neck 12%; pores lateral Haliplectus Cobb 1913
Median bulb absent; pores none; marine
Nema cephalated by expansion opposite large monospiral ampbid; neck 8% Bolbonema Cobb 1920
Nema not cephalated by expansion
Setae on head 6-10, long, flexible; neck under 5%: pharyngeal bulb present. . (Laxus Cobb 1894)
Setae on head 0-4; neck 6% or over; pharyngeal bulb absent
Head constricted at cephalic setae, not at amphid; amphid 2 head-widths back
Chambers of pharynx several, long; neck 10-11%; cephalic setae 0(?) Polylaimium Cobb 1920
Chamber of pharynx single; neck 19%; head conoid; cephalic set. 4 Dermatolaimus Steiner 1916
Head not constricted at setae; amphid near lips or not over 1 head-width back
Ceph.set.0;phar.a tube reaching card. bulb ;amphid conspicuous. . Aegialoalaimus de Man 1907
Amphid small.monospiral.at lips;neck 19%;dorsal phar.wall thickened (Onchium Cobb 1920)
Amphid conspicuous, round, not at lips;neck 6%;phar.wall not thick. .Linolaimus Cobb 1933
Oesophagus plain, i.e. without median or posterior bulb or swelling (for alternative see page 474)
Amphid not known or obscure (for alternative see next page)
Female not known; marine (for alternative see next page)
Neck over 40%; amphid a long, slit; ceph. setae 4 or 8, fine; spinneret oft none. . (Halalaimoides Cobb 1933)
Neck 10-30%; amphid not longitudinal; spinneret present (Trileptium, Fimbriella ?)
Cephalic setae 0; onchia 3, awl-shaped, almost parallel to axis (Fimbrilla Cobb 1905)
( = Fimbria Cobb 1894)
Cephalic setae 8 or more
Onchium dorsal,anterior,inward-pointing;neck 12%;nema0.5% wide;amph. asht (Tnleptium Cobb 1923)
( = Trilepta Cobb 1920)
Onchium none; neck 22-30%; nema 2-3% wide; cephalic setae usually 8, in 2 circlets
478 PROCEEDINGS HELMINTHOLOGICAL SOCIETY VOL. 2, NO. 1
Calvarium present; setae 8, near base of pharynx; eyes present Gullmarm'.a Allgen 1929
Calvarium absent; setae minute, around mouth; eyes 0; pharynx small, tubular. .Fimbriella Allgen 1929
Female known (for alternative see preceding page)
Ovary 1, anterior
Ceph. set. 4; pharynx large, open; spinneret present; spicula 2-jointed(?); marine. ..Filipjeva Ditlev. 1928
Ceph. set. or papilloid; pharynx none or narrow; spinneret usually none; ~9
Pharynx a tube reaching halfway to nerve ring; in soil Gymnolaimus Cobb 1913
Pharynx closed, or marked by reduced spear, not over J distance to nerve ring
Nema free-living, marine; spinneret doubtful; pharynx none or closed Litotes Cobb 1920
Nema parasitic in insects; spinneret 0; adult spear reduced, base 3-parted. . (Aphelenchulus Cobb 1920)
Ovaries 2
Gonads 9 outstretched; spinneret present; marine
The ovaries extending backward; winge 10-12; vulva 45% Porocoma Cobb 1920
The ovaries opposed; wings
Annules none or not coarse; amphid not saccate, far back; nema not wide. . . . Anoplostoma Butsch. 1874
Annules coarse; amphid saccate; nema wide; cephalic setae 4
Number annules 17, secreted annules prominent, separated; head small .. Desmoscolex Clap. 1863
Number annules 32-91, secreted annules 0; head concave-quadrate pyramidal. .Tricoma Cobb 1894
( = Quadricoma Fil. 1922)
Gonads 9 reflexed
Spinneret none; wings 0; pharynx 2.5-3%, tubular; tail rounded, under 2%; in soil. .Isolaimium Cobb 1920
Spinneret present
Habitat freshwater; lips thick; pharynx closed; amphid small; onch. small, deepset (Tripyla Bast. 1865)
(=Promononchus Micol. 1923)
Habitat marine
Annules 17,secreted annules prominent;amph.saccate;nema wide;ceph.set.4. .Desmoscolex Clap. 1863
Annules none; amphid not saccate; nema less than 5% wide
Dorsal pharyngeal wall bent inward at lips,onchium-like;ceph.setae 10. .(Asymmetrella Cobb 1920)
Dorsal pharyngeal wall not onchium-like; cephalic setae Angustinema Cobb 1933
Amphid known (for alternative see preceding page)
External amphid not spiral , circular nor elliptical (for alternative see next page)
Female not known; Enoplidae (Trileptium ?)
Head mitreform, set off by constriction; wings 6-8; spinneret doubtful; marine Xennella Cobb 1920
Head not mitreform; spinneret often absent
Ceph. set. 0: ext. amph.wide,curved;phar.tubular,halfway to nerve ring ;fresh water Colpurella Cobb 1920
Ceph. set. present; amphid small, or long and narrow; marine
Amphid narrow,many head-widths long ;neck 40% ;ceph.set.4-8;tail setaceous Halalaimoides Cobb 1933
Amphid small, transverse-oval; neck 25% or less
Neck 25%;onchium no ne;ceph. setae 6 .small, inconspicuous ;spinneret present. . Vasculonema Kreis 1928
(cf. Pelagonema Cobb 1894)
Neck 12%; onchium dorsal; cephalic setae 10, conspicuous; labial setae 6 . . . . Trileptium Cobb 1933
( = Trilepta Cobb 1920)
Female known
Ovary 1 ( anterior
Gonad 9 outstretched ;pharynx closed;ceph.set.papilloid;spinneret doubtful ;marine. .Litotes Cobb 1920
Gonad 9 reflexed; spinneret present; external amphid a transverse slit, not at lips; not marine
Onchia 0; amphid far behind the quadrate pharynx; in fresh water Prismatolaimus de Man 1880
Onchium minute, deepset; amphid opposite pharynx; in soil about roots
Pharynx conoid when open; amphid opposite base of pharynx (Trischistoma Cobb 1913)
Pharynx a long tube, amphid opposite its anterior end, with pocket Cryptonchus Cobb 1913
( = Dilletsenia Micol. 1925)
Ovaries 2; marine exc. Monhystera
Gonads 9 outstretched
Spinneret absent
Habitat marine; amphid long-oval, on large triangular plate Didelta Cobb 1920
Habitat not marine; amphid a transverse slit; in soil about roots Monhystera Bast. 1865
(=M. dintheriana de Man 1885)
Spinneret present
Mouth opening ventrad;wing duplex ;amph. big, bent, dorsal arm the longer (Campylaimus Cobb 1920)
Mouth opening axial, terminal; wings none exc. sometimes Pseudolella
Annules coarse; amphid saccate; nema wide; cephalic setae 4
Number of annules 17, secreted annules prominent, separated; head small. . Desmoscolex Clap. 1863
Number of annules 32-91, secreted annules 0; head concave-quadrate pyramidal . . Tricoma Cobb 1894
( = Quadricoma Fil. 1922)
Annules none, striae fine; amphid not saccate; nema slender
Amphid small, opening transverse with internal pocket, far back (Anoplostoma Butsch. 1874)
Amphid shepherd's crook, dorsal arm the longer
Length of amphid extreme, sometimes exceeding neck; eyes (Pseudolella Cobb 1920)
Length of amphid not over 1 head-width, loop-shaped; eyes 2, sometimes none
Oesophagus & lumen widened between eyes and nerve ring;pharynx obvious Coinonema Cobb 1920
Oesophagus & lumen not widened; pharynx like oesophagus. . . Araeolaimoides (de Man) Fil. 1918
Gonads 9 reflexed
Spinneret absent; amphid with internal pocket
Cephalic setae 0; pharynx 2-3%, tubular; tail rounded, under 2%; in soil Isolaimium Cobb 1920
Cephalic setae 10, subcephalic many; marine Platycomopsis Ditlev. 1926
( = Dact V lonema Fil. 1927)
Spinneret present
Habitat freshwater; amphid usually small or inconspicuous
Pharynx wide.domedby thin lips ;onch.0;amph.transverseslit,far back. .Prismatolaimus de Man 1880
Pharynx closed, lips thickionch. minute, deepset ;external amphid round or oval. .(Tripyla Bast. 1865)
( = Promononchus Micol. 1923)
Habitat marine
Cephalic setae none or papilloid; external amphid narrow, transverse (for alt. see next page)
Amphid J head-width; cuticle i radius, annules coarse, markings rod-like. .(Actinonema Cobb 1920)
Amphid f head-width or less, with internal pocket ; cuticle less thick ; phar. with lumen ; Enoplidae
Eyes 2; protrusile pharyngeal ribs none Illium Cobb 1920
COBB: A KEY TO THE GENERA OF FREE-LIVING NEMAS 479
Eyes 0; protrusile pharyngeal ribs 3, straight Fimbrilla Cobb 1905
, .. ( = Fimbria Cobb 1894)
Cephalic setae present, not papilloid (for alternative see preceding page)
Amphid shepherd's crook
Annules not of tile-like elements Parachromagaster Allgen 1929
Annules coarse, each of 8 tile-like elements Ceramonema Cobb 1920
(cf. Pselionema Cobb 1933)
Amphid not shepherd s crook
Nemawide;annules17,secreted annules obvious ;amph.saccate;ceph.set.4. .Desmoscolex Clap. 1863
Nema slender, under 5%; amphid not saccate; annules 0, striae fine or 0; Enoplidae
Onchium dorsal; labial setae 0; cephalic setae 10, near lips
Tooth vestigial, on wall; external amphid a small slit; eyes (Anoncholaimus Cobb 1920)
Tooth a bending inward of dorsal pharyng.wall;amphid larger.faint. . (Asymmetrella Cobb 1920)
Onchia none; labial setae 6, obvious; cephalic setae 10 or more, length 1-5 times head width
Pharynx narrow,closed;odontia (?) minute;ceph.set.3 times head width (Tubolaimella Cobb 1933)
Pharynx wide, open; odontia none
Lips 3, deep-cleft, with frame work; ceph. set. 2-5 times head width Chaetonema Fil. 1927
Lips without framework; ceph. set. 1 head-width; excret. pore raised. . (Paranticoma Micol. 1930)
External amphid spiral, circular or elliptical (for alternative see preceding page)
Female not known; spinneret present; marine
Nema wide, 14-32%, widest at lip region, tapering to terminus; wings numerous. .Pteronium Cobb 1933
Nema slender, not over 5% wide, widest near middle
Amphid multispire; wings 0; cephalic & labial setae 18; labial framework present. . . .Dispira Cobb 1933
Amphid circular, elliptical or monospiral
Odontia 2, large, lateral or subventral (Diodontolaimus Southern 1914)
Odontia absent(in Stephanolaimus 6 minute?)
Onchium ventral ; cephalic setae 10; am ph. i head-width, with internal pocket. . (Isonemella Cobb 1920)
Onchium absent (Nudolaimus ?)
Calvarium reduced to submed.plates;phar.large,wall strong/'onchia" basal. .Nudolaimus Allgen 1929
Calvarium absent; cephalic setae present
Wings present; cephalic setae 6 or 10
Ceph. set. 6; wings 8; annules coarse, elements tile-like; oesoph. compound.. Dasynemella Cobb 1933
( = Dasynema Cobb 1920)
Ceph. set. 10; wings 2; oesophagus simple; pharynx iquadrate Pulchranemella Cobb 1933
Wings absent; cephalic setae 4-8
Lip region discoid, set off by constriction; odontia(?) 6 Stephanolaimus Ditlev. 1918
Lip region not discoid; cephalic setae 4 or 6
ng. vestibule with rod-like supports; head cylindroid; striae 0; ceph. set. 4
6, straight, parallel to body axis; cephalic setae 4, jointed Rhadinema Cobb 1920
Rods more than 6, curved, meeting axially Eleutherolaimus Fil. 1922
Pharyng. vestibule without supports; striae pres. exc. Vasculonema & Bathylaimella
Amphid transverse-oval, near lips; head slightly conoid; setae small
Setae labial, cephalic and subcephalic, minute Zygonemella Cobb 1920
. Setae cephalic only, 6, small, inconspicuous Vasculonema Kreis 1928
(cf. Pelagonema Cobb 1894)
Amphid circular, near base of wide-tubular pharynx
Head cylindroid; setae on head 16, longest 4 times head width Cenolaimus Cobb 1933
Head conoid, narrowing 50% from base; setae on head 4, short
Cuticle striated; width (compressed ?) 6% Tubolaimus Allgen 1929
Cuticle not striated; width 3% Bathylaimella Allgen 1930
Female known
Ovary 1 (for alternative see next page)
Gonad 9 reflexed
Amphid multispire; ovary posterior; pharynx linear; spinneret doubtful; marine Alaimella Co,bb 1920
Amphid not multispire; ovary anterior
Spinneret none; amph. round, with central mound; caudal setae thorn-like, 2 rows (Zanema Cobb 1920)
Spinneret present; tail without thorn-like setae
Habitat marine; pharynx tubular; cephalic setae 4; nema 2% wide (Conolaimella Allgen 1930)
Habitat not marine; pharynx open, not small nor narrow; nema 2-5% wide
Cephalic setae 4 ; pharynx with supporting pieces; amph. monospire; fresh- water Anonchus Cobb 1913
Cephalic setae 6 or 10, papilloid in Tripylium
Amphid monospire; in gills of land crabs (Tripylium Cobb 1920)
Amphid small, circular, transverse-oval or slit-like
Onchium 0; pharynx quadrate; amphid far back; in fresh water Prismatolaimus de Man 1880
Onchium minute, deepset; pharynx conoid; amphid opp. pharynx; in soil (Trischistoma Cobb 1920)
Gonad 9 outstretched
Habitat not marine
Spear minute; spinneret none; bursa present; parasitic in beetle (Aphelenchulus Cobb 1920)
Spear absent; bursa absent; in fresh water Cylindrolaimus de Man 1880
Habitat marine
External amphid multispire; pharynx linear; tail 10%; spinneret doubtful (Alaimella Cobb 1920)
External amphid circular, pocket elongate; tail 34%; spinneret none Halanonchus Cobb 1920
The ovary anterior
Cephalic setae 4, papilloid; pharynx obscure, linear; amphid faint, open caudad Litotes Cobb 1920
Cephalic setae not papilloid
Spinneret absent; labial appendages ("palps") present; amphid circular
Tail with 2 rows of thorn-like setae; amphid with distinct central mound Zanema Cobb 1920
Tail without thorn-like setae; amphid without mound; cardiac bulb faint Crystallonema Cobb 1920
Spinneret present ; amphid circular or monospire
Pharynx 7%, tubular ,halfway to nerve ring; head narrow ; amphid far back Rhynconema Cobb 1920
Pharynx less than 2%, not a long tube
Depth of pharynx much greater than width, pharynx small
Oesophagus almost surrounding conoid pharynx Conolaimella Allgen 193
Oesophagus meeting base of obconoid pharynx Sphaerocephalum Fil. 1918
Depth of pharynx not much greater than width, pharynx large, open
480 PROCEEDINGS HELMINTHOLOGICAL SOCIETY VOL. 2, NO. 1
Amphid 1 head-width; vulva 59%; caudal set. stiff, 8 prs.; post, ovary small Halinema Cobb 1920
Amphid i head-width; vulva 80^85% ; caudal set. 0; lips 6, conoid, separate
Labial setae 6, hook-shaped, on tips of lips; amphid spiral; in mud (Dactylaimus Cobb 1920)
Labial setae 6, not hook-shaped nor at tips; amphid round; cepb. set. 18. .Omicronema Cobb 1920
Ovaries 2 (for alternative see preceding page)
Gonads 9 outstretched: usually marine
Spinneret absent; marine exc. Pseudoaulqlaimus
Habitat mud, rice fields; wings 16-32, fusing to 4 on 4-pronged tail Pseudoaulolaimus Imamura 1931
Habitat marine
Amphid long oval, on wide triangular plate, almost as long as head is wide Didelta Cobb 1920
Amphid smaller, not on triangular plate
Cervical setae bunched; 2 flat setae in front of transverse-oval amphid (Platycoma Cobb 1894)
Cervical setae if present not bunched; amphid circular
Pharynx long, simple, tubular; cephalic setae 6 Southerniella Allgen 1932
Pharynx minute; ceph. set. 18, minute, in 2 circlets; amphid faint multispire Anticyathus Cobb 1920
Spinneret present; marine exc. Cylindrolaimus
Habitat freshwater; ceph. set. 4; ovaries usually unequal; pharynx tubular Cylindrolaimus de Man 1880
Habitat marine
Annules few, coarse; amphid saccate; cephalic setae 4; nema wide
Number annules 17, secreted annules prominent, separated; head small. . Desmoscolex Clap. 1863
Number annules 32-91, secreted annules none; head concave-quadrate pyramidal Tricoma Cobb 1894
( = Quadricoma Fil. 1922)
Annules if present not few nor coarse; amphid not saccate
Gland ducts cuticularized, pores cervical & pre-anal ; striae coarse Halaphanolaimus Southern 1914
Gland ducts and pores absent
Cephalic setae 10 or more
Pharynx with transverse cuticularized ring
Cavity of pharynx simple, capacious, cylindroid, J head-width. . . .Eumorpholaimus Schulz 1932
Cavity of pharynx small, cup-shaped, rings sometimes 2 or more (Linhomoeus Bast. 1865)
(i.e. subg. Paralinhomoeus de Man 1907
= Paradesmolaimus Schulz 1932)
Pharynx without transverse cuticularized rings
Longest ceph. set. 4, total 16, tips simple;phar. quadrate ;amph. neck-width Halinema Cobb 1920
Longest ceph. set. 6, 4 short specialized at tip; phar. 0(7); multispire faint Linhomoella Cobb 1920
Cephalic setae 4
Nema wide, 10-16%; wings numerous; neck region "collared" ; amphid spiral; Richtersiinae
Wings 50; pharynx narrow; spicula 2, equal Richtersia Steiner 1916
Wings 16-32; pharynx capacious, open; spicula unequal, or 1 only Richtersiella Kreis 1929
Nema slender, under 5%; wings if present not numerous
Eyes absent; amphid circular; pharynx truncate at base Bathylaimella Allgen 1930
Eyes often present; setae behind head usually long, numerous, conspicuous
Oesophagus lumen not enlarged; amphid loop-shaped (Araeolaimoides (de Man) Fil. 1918)
Oesophagus and lumen widened between eyes and nerve ring; pharynx obvious
Shape of amphid loop-like ("folded") (Cmnonema Cobb 1920)
Shape of amphid circular or monospiral; eyes sometimes absent(?) . . . Araeolaimus de Man 1888
Gonads 9 reflexed
Spinneret absent; amphid circular, elliptical or monospiral
Habitat not marine; pharynx long, tubular, half as long as oesophagus
Wings 16-32, conspic., fusing to 4 on 4-pronged tail; in rice fields Pseudoaulolaimus Imamura 1931
Wings 0; end of tail not 4-parted; in soil Isolaimium Cobb 1920
Habitat marine; pharynx short
Pharynx narrow; amphid flattened, preceded by 2 flat setae Platycoma Cobb 1894
Pharynx or linear; amphid transverse-oval, with pocket, 4 set. posterior. . Platycomopsia Ditlev. 1926
( = Dactylonema Fil. 1927)
Spinneret present
Habitat freshwater
Mouth cavity absent or obscure, closed
Amphid monospire; gland cells lateral; d" supplements protrusile tubes. . Aphanolaimus de Man 1880
Amphid circular or elliptical; cf supplements not protrusile Tripyla Bast. 1865
( = ProwononcAusMicol. 1923)
Mouth cavity definite, open, obvious
Pharynx narrow, compound; amphid monospire, J head-width; cephalic setae 4 Paraplectus Fil. 1930
Pharynx simple, i.e. of 1 chamber
The amphid small, transverse-oval or a slit; cephalic setae 6 or 10. . .Prismatolaimus de Man 1880
The amphid monospire, opp. pharynx; cepb. setae 4; gland cells lateral Paraphanolaimus Micol. 1923
Habitat marine
Nema wide, over 10%
Annules few, coarse; amphid saccate
Body setae not dense; secreted annules prominent, separate; head small. .Desmoscolex Clap. 1863
Body setae dense, set along annules; junct. oesoph. & intestine indefinite. . .Greeffiella Cobb 1922
( = TTichoderma Greeff 1869)
Annules if present many ; longitudinal ridges or wings 16-50; neck "collared" ; Richtersiinae
Wings 50; pharynx narrow; spicula 2, equal Richtersia Steiner 1916
Wings 16-32; pharynx wide, capacious; spicula unequal, or 1 only Richtersiella Kreis 1929
Nema slender, not over 5%
Calvarium present as a band or plates
Oesophagus not crenate ; calyarium of plates ; gland cells lateral Cylicolaimus de Man 1889
Oesophagus crenate; calvarium a band (Phanodermopsis Ditlev. 1926)
( = Galeonema Fil. 1927)
Calvarium absent
Gland ducts cuticularized, pores cervical & pre-anal; striae coarse. . (Halaphanolaimus Southern 1914)
Gland ducts and pores none, or not cuticularized
Denticles mid-phar., apophyses forward & back; amph. multispire (Halichoanolaimus de Man 1886)
(=Smalsundia Allgen 1929)
Denticles none: amphid not multispire
COBB: A KEY TO THE GENERA OF FREE-LIVING NEMAS 481
Pharynx open, wide, icapacious
Amphid round ; anterior pharyng. chamber large, posterior small ; setae 10 Bathylaimus Cobb 1894
( = Macrolaimus Ditlev. 1918
= Cothonolaimus Ditlev. 1919)
Amphid small, with internal pocket (Pandolaimus ?); pharynx of 1 chamber
Depth pharynx iequalling width; dorsal onch. small, ant., appressed Anoncholaimus Cobb 1920
Depth pharynx nearly twice width
Wall of pharynx irregularly thick; amphid apparently circular Pandolaimvs Allgen 1929
Wall of pharynx thin; amphid small, transverse-oval, with pocket Pelagonema Cobb 1894
(cf. Vasculonema Kreis 1928)
Pharynx narrow, often tubular or with closed lumen
The amphid behind level of cephalic setae
Cephalic setae 0; pharynx $ head-width, with 3 refractive elements. . . Angustinema Cobb 1933
Cephalic setae present
Nema over 3 mm. long Cynwa Cobb 1920
Nema 0.6 mm. long Aplectus Cobb 1914
The amphid in front of level of cephalic setae; cephalic setae 4
Dorsal pharyng. wall not thicker; ampbidial glands large, conspic.; eyes 2 . . .lonema Cobb 1920
Dorsal pharyng. wall thick, tooth-like; amph. monospire at lips ; re net te far back
Oesoph. glands obscuring junct. of intest. ; dorsal phar. element uniform. . .Onchium Cobb 1920
Oesoph. glands not prominent; dorsal pharyng. element not uniformly thick, but heavy
Tooth-like thickening parallel to axis Camacolaimus de Man 1889
(^Digitonchus Cobb 1920
= Acontiolaimus Fil. 1918)
Tooth-like thickening bent outward from beginning of vestibule
Point of "onchium" single Acmaeolaimus Fil. 1918
Point of Y-shaped "onchium" duplex Ypsilon Cobb 1920
482 PROCEEDINGS HELMINTHOLOGICAL SOCIETY VOL. 2, NO. 1
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INDEX
page
Acanthonchus 462
Acanthopharynx 463
Achromadora 465, 466
Acmaeolaimus 462, 465, 471,
474, 481
Acoma 458
Acontiolaimus 462, 465, 471,
474, 481
Acrobeles 470, 471, 475, 476
Acrobeloides 470, 471, 475, 476
Acrostichus 463, 464
page
Bolbinium 454,454
Bolbolaimus 463, 464, 466
Bolbonema 455, 477
Brachynema 458
Brachynemella 458
Bradylaimus 465
Bradynema 455, 458, 460
Bulbopharyngiella . . .463, 464. 466
Bunonema . . 475
Butlerius 466,468
page
Cylindrolaimus 479, 480
Cynura 431
Gytolaimium 457, 457, 473, 474
r)actium 466
*f Dactylaimus 473 , 480
Dactylonema 456, 478, 480
Dagda 4 6 7, 468
Daptonema 467, 472. 473, 473
Dasylaimus. .470, 470, 471, 471, 471,
Actinonema 456, 461, 472, 478
Aculeonchus 460
Adoncholaimus 469, 469
Aegialoalaimus 455, 477
Alaimella 457, 457, 479, 479
Alaimonema. .. .454, 466, 466, 470,
476
Alaimus 454, 454, 456, 457
AJlantonema. . . .455, 458, 459, 459,
460,460
Allomonhystera 473
Amphispira 464, 464, 470, 470
Amphistenus 463, 469
Anaxonchium 462, 468
Anguillula 463, 468, 470
Angustinema 478, 481
Anoncholaimus 462, 479, 481
Anonchus 476, 479
Anoplostoma 478, 478
Antholaimus 460, 461
Anthonema 454, 475, 477
Anticoma 458 472 474
Caconema 459,459
Calyptronema . . .462, 463, 465, 469
Camacolaimus 462, 465, 471,
474, 481
Campydora 460, 460, 461. 463,
464, 464
Campylaimus 456, 472, 478
Catalaimus 462, 463, 465, 469
Catanema 454, 454. 466, 470,
470, 474, 476
Cenolaimus 473, 479
Cephalobus 470, 471, 475, 476
Cephalonema 461, 463
Ceramonema. . . .454, 456, 456, 475,
479
Chaetonema 479
Chaetosoma. .454, 455, 470, 475, 477
Chambersiella 466, 476, 477
Chaolaimus....459, 459, 461, 475,
475, 476
Cheilobus 470, 476
Dasynemeila 470', 472', 476', 479
Deltanema 466, 471, 476
Demania Southern 467
Demania Steiner 463, 469
Demaniella 463, 469
Demonema 468,474
Dentatonema 462
Denticulella 454
Deontolaimus 457
Deontostoma. . . .461, 463, 472, 472,
Dermatolaimus 477
Desmodora 465, 466
Desmodorella 465
Desmolaimus 471, 476
Desmoscolex. . . .456, 456, 456, 456,
457, 458, 478, 478, 478, 479,
480, 480
Diastolaimus 466, 476, 477
Dicriconema 468. 469
Didelta 472, 473, 478, 480
Anticomopsis 458, 472, 474
Anticyathus 457, 473, 480
Anticyclus 462
Antomicron 454, 457, 470, 472
Antopus 455, 456
Aphanolaimus...4S8, 474, 474, 480
Aphelenchoides 459, 460, 460,
475
Aphelenchulus 458, 478, 479
Aphelenchus 460, 460
Aplectus 455, 471, 477, 481
Apodontium 456, 457, 467
Aponchium 465, 466, 466
Araeolaimoides 456, 478, 480
Araeolaimus 457, 474, 480
Archepsilonema 455, 477
Archionchus 459 459 461, 475,
Chloronemella 476
Choanolaimus 474
Chondronema 455, 460
Choniolaimus 470, 476
Chromadora 463, 464, 466
Chromadorella 465, 467
Chromadorina 465, 466
Chromadorissa 463
Chromadorita 463, 463
Chromadoropsis 465, 465
Cbromagaster 476
Chromaspirina 466, 469
Chronogaster 470, 475
Chrysonema 461
Cinctonema 454, 470
Cobbia 468
481
Dignathonema 466
Dilaimus 463,469
Dintheria 472
Diodontolaimus....467, 467, 468,
Dioncholaimus 468
Dipeltis 461, 463
Diphtherophora....459, 459, 461,
475, 475, 476
Diplogaster 463, 464, 465, 465.
466, 466, 475
Diplogasteroides 464, 465, 476
Diplohystera 474
Diplolaimella 473, 473
Diplolaimus 471
475, 476
Ascolaimus 470, 472
Asconema 455
Asymmetrella 462, 478, 479
Asymmetrica 471
Atractonema 455
Atylenchus 459
Coinonema 456, 478, 480
Colpurella 476, 478
Comesoma 462, 464
Conolaimella. . . . 473, 473, 479, 479
Conolaimus 465, 467, 467
Convexolaimus 468
Cophonchua 462 472
Diploseapter !"!!!'.'.... 465
Diploscapteroides 463, 475
Discolaimus 461
Disconema 454
Discophora 461, 463
Dispira 467,472,479
Aulolaimoides....470, 475, 476, 476
Aulolaimus 475, 475
Austronema 473
Cothonolaimus 474, 481
Craspedonema 475
Crassolaimus 464
Ditlevsenella. . . . ... 469
Ditlevsenia 461,478
Axonchium 461
Axonolaimus 467, 468, 470, 472
Barbonema 457
Bastiania 457,458
Bathyepsilonema 455, 477
Bathylaimella 479, 480
Bathylaimus Cobb 474, 481
Bathylaimus Ditlevsen. . .470, 472
Bitholinema 477
Bognenia 473
Bolbella 462,464,469
Cricolaimus 454, 466, 470, 476
Criconema 459
Croconema 469
Cryptolaimus. . . .454, 455, 471, 476
Cryptonchus 461, 478
Crystallonema 467, 470, 473,
476, 479
Cyartonema 455
Cyatholaimus 462, 474
Cyathonchus 462
Cylicolaimus 469, 472, 474, 480
Cylindrogaster ... 475
Dolicholaimus 467
Dorylaimellus 461
Dorylaimopsis 460, 468
Dorylaimus 461, 461
Doryllium 459, 461
Doryonchus 461, 462
Draconema. .454, 455, 470, 475, 477
Drepanonema. . .454, 455, 470, 475,
477
T^cphyadophora 458, 458
& Eleutherolaimus 467, 479
INDEX
489
page
Enchelidium 455, 456, 457
Endolaimus 466
page
Leptolaimus 477
page
Odontophora 465, 467, 467
Enoplocheilus 460, 461, 468
Leptonemella. . . .454, 454, 470, 470
Oionchus 461 ' 464
Enoploides 467, 468
Enoplolaimus 467, 468
Enoplostoma 467 468
Leptosomatides 457, 473
Leptosomatum 458
Oistolaimus 460, 464
Omicronema 480
Enoplus 467,468
Epsilonella 455,477
Epsilonema 455, 477
Epsilonoides 455, 477
Ethmolaimus 465
Euchromadora 461
Linhomoella. . ! .' .'455,' 457, 457,' 474,
476, 476, 480
Linhomoeus 455, 457, 457, 466,
471,474,480
L. obtusicaudatus 457
Linolaimus 477
474, 477, 481
Oncholaimellus 469
Oncholaimium 468
Oncholaimus 468
Onchulella 460, 460
Onchulus 461
Eudesmoscolex 454, 457
Litinium 457, 457
Onyx 460 460 464 465
Eulinhomoeus (subgenus) 466
Eumorpholaimus 480
Litonema 454, 454, 474, 476
Litotes. .455, 456, 457, 478, 478, 479
Oxystoma 457
Oxystomina . . 457, 457
Eurystoma 462, 463, 469
Eurystomina 462, 463, 469
Longicyatholaimus 462
Lycolaimus 475
"panagrolaimus 470 471 475
Eutelolaimus 455, 471
Eutylenchus 458
T7enestrolaimus 469
-Tpiacra 467,469
Filipjeva 478
Macrolaimus Ditlevsen 474,
481
Macrolaimus Maupas 463, 464,
475, 476
Macroposthonia 455, 471
Paracanthonchus. ..... ! .... . . .' 462
Parachromagaster 479
Paracothonolaimus 466
Paracyatholaimus 462
Paradesmolaimus 480
Filoncholaimus ... 469
Fimbria 467, 467, 477, 479
Fimbriella 478
Marionella 462, 463, 469
Meloidogyne 459, 459
Meroviscosia 469
Mesodorus 466, 469
Paramonhystera 473
Paranticoma 472, 479
Paraphanolaimus 477, 480
Fusonema 466
Mesonchium . . . .466, 466, 466, 468,
Paraplectus 477 480
468
Metachromadora 465, 465
Parasabatieria 457, 462, 464,
Gammanema 467, 467
Gonionchus 468
Graphonema 461
Metalaimus 473
Metalinhomoeus 466, 471, 476
Metepsilonema 455, 477
Parasitaphelenchus 459, 460,
460, 475
Parasphaerolaimus 473
Gullmarnia .' 478
Gymnolaimus 475, 478
Micoletzkyia 456
Microlaimua 464
Paratylenchus 459
Parenoplus 468, 472, 474
Mitrephorus 454 454
Pareuchromadora 461,462
ij - Halalaimus 456, 456
Halanonchus 479
Halaphanolaimus 454,455 457,
Molgolaimus 454
Monhystera 457, 470, 470, 472,
473, 476, 476, 478
Parironus 467
Paroncholaimus 469
Paroxystomina 456 472
458, 476, 477, 480, 480
Halenchus 458, 459
Halichoanolaimus. . . .468, 474, 480
Halinema 480,480
Haliplectus 455, 476, 477
Helalaimus 457
M. dintheriana. . .470, 472, 476, 478
Monhysteriella 470
Monhystrella (subgenus). .470, 476
Monhystrium 467, 473, 473
Mononchoides 465, 466
Mononcholaimus 461, 462
Mononchulus 461 468
Pathoaphelenchus 459, 460,
460, 475
Pelagonema 472, 474, 478, 479,
481
Pelagonemella 476
Penzancia 473
Mononchus 462, 468, 469
Peronilaimus 475
Heterodera 459, 459
Heterodesmodora 471
Hexatylus 458
Himatidiophila 471, 471
Hoplolaimua 458, 459
Howardvua 456, 458, 458, 460
Hypodontolaimus 463, 464
Monoposthia 464
Myctolaimus 475
Myolaimus 466
Nannolaimus 458, 474
Nannonchus 462,469
Nanonema 461, 463
Nasinema 472
Phanoderma 472, 472
Phanodermella 456
Phanodermopsis 458, 474, 480
Pharetrolaimus 458, 459
Platycoma 457, 458, 480. 480
Platycomopsis 456, 478, 480
Plectonchus 463,470
Plectus 471 477
I Ilium 478
lonema 456,456,458,481
Iota 459,459
Nemanema 457, 473
Nemanemella 457
Nemella 455,456
Poikilolaimus 463, 464
Polydontus 468
Polygastrophora 463, 465, 469
Polylaimium 477,477
lotadorus 463, 464, 464
lotalaimus 454, 456
lotonchium 454 454 460 460
Neoaplectana 454, 455, 471
Neocnromadora 464
Polysigma 466
Pomponema 462, 468
Pontonema 460
Ironella 467
Porocoma 456 478
Praeacanthonchus 462
Isolaimium 478, 478, 480
Isonchus 460,460
Isonemella 462 479
Neotonchus 464
Neotylenchus 458, 459
Prismatolaimus. .478, 478, 479, 480
Pristionchus 465, 466, 466
Pristionema 458
Jiigerskioldia 469
Notochaetosoma 454, 455, 458,
470, 475, 477
Nuada 456
ProchaetoBoma 455, 477
Prochromadora 463, 463, 464
Prochromadorella 465, 467
T^lugea 458
J*- Krampia 471
Nuadella 454,455
Nudolaimus 473, 479
Nudora 463, 464
Prodesmodora 465, 477
Promononchus...456, 456, 458.461,
Kreisia 477
Laimella 454, 476
Lasiomitus 455, 456, 457
Laxonema 454, 454, 474, 476
Laxus 455,471,477
Ledovitia 462,463
Leptogastrella 473
Nunema 474
Nygmatonchus 464
Nygolaimus 461
Hdontolaimus 460, 464, 464
^ Odontonema 463, 465
Odontopharynx 464, 465, 466,
466, 468
471, 472, 474, 478, 478, 480
Prooncholaimus 468
Prosphaerolaimus 462
Pselionema 454, 456, 456, 461,
475, 479
Pseudoaulolaimus 480, 480
Pseudochromadora 471, 471
Pseudodilaimus 462
490
page
Pseudolella. .465, 466, 470, 475, 478
Pseudoncholaimus 468
Pseudonchus 471, 477
Pseudoparoncholaimus 469
page
Siphonolaimus 459, 460, 476
Smalsundia 468 474 480
page
Triplonchium 459, 477
Tripyla 456, 456, 458, 461, 471
472, 474, 478, 478, 480
Tripylium 467, 479
Tripyloides 474,474
Trischistoma. .. .461, 462, 472, 473,
478, 479
Trissonchulus 467
Tristicochaeta 454, 455, 470,
475, 477
Trogolaimus 467, 472
Tubolaimella 467 479
Solenolaimus 454, 476
Southernia 457, 458
Southerniella 480
Sphaerocephalum 473, 479
Sphaerolaimus 473
Sphaerularia 455
Spilophora 465
Spilophorella 463
Pseudorhabditis 475
Psilenchus 460
Pteronium 472, 479
Ptycholaimellus 463, 464
Pulchranemella 479
Punctodora 463, 464
Pycnolaimus 466, 476
Quadricoma ....456, 457, 478, 478
Rhabditella 475
SpUophorium 465
Spira 455, 464, 465, 471, 471
Spirina 455, 464, 465, 471, 471
Statenia 465
Tubolaimus 473, 479
Turbatrix 463, 468, 470
Tycnodora 456
Tylenchinema 456, 460
Tylenchodon 459
Tylencholaimellus 458
Tylencholaimus 459, 459
Tylenchomorphus...455, 458, 459,
459, 460, 460
Tylenchorhynchus 459
Tylenchulus 459, 459, 459
Tylenchus 459,459
Tylolaimophorus 458, 459, 460
Tylopharynx 459, 475
TTdonchus 464
U Uracanthus 455,460
\7asculonema 472, 474, 478,
" 479, 481
Viscosia 469
Walcherenia ... 470
Wilsonema 477
Xanthodora 463,465
Xennella 456 478
Steineria Filipjev 456, 461
Steineria Ditlevsen 469
Steineria Stekhoven and
de Coninck 473
Steineriella 469
Stenolaimus..456, 458,472, 472, 474
Stephanolaimus 456, 458, 467,
471, 473, 479
Stilbonema 454, 455
Symplocostoma 461, 462, 462,
463, 469
Symplocostomella. . . .462, 463, 469
Synodontium 466, 470
Synonchiella 468
Synonchium 467, 468
Synonchus 469
Rhabditidoides 475
Rhabditis 463, 475, 475, 475,
476, 477
Rhabditoides 470 475
Rhabditolaimus 476
Rhabditophanes 470, 476
Rhabdocoma . . . .472. 472, 473, 474
Rhabdodemania 467
Rhabdogaster 455, 477
Rhabdolaimus. . .464, 475, 475, 477
Rhabdonchus 460, 460, 460
Rhabdotodenna 469
Rhadinema 473, 479
Rhinema 462 465
Rhinonema 460, 460, 461, 462,
463
Rhips 461, 464, 466 469
Syringolaimus 465
Tachyhodites 457, 473
* Teratocephalus. . . .466, 471, 471,
475, 475, 476, 477
Terschellingia 454, 455, 471
Thalassironus 467
Thalassoalaimus 455, 456
Theristus 467, 472, 473, 473
Thoonchus 469
Rhodolaimus 475
Rhynconema 479
Richtersia 458, 462, 473, 474,
480,480
Richtersiella 473, 474, 480, 480
Qabatieria..457, 462, 464, 471, 473
Saveljevia 468
Xenolaimus 472
Xenonema 465
Xinema 460,468
Xiphinema 459
Xyala 467,473
YPsilon . .. .462, 465, 471, 474, 481
Zalonema 471,477
Zanema..467, 473, 473, 479, 479
Zysonemella 457, 473, 479
Thoracostoma 469
Thoracostomopsis 460
Trefusia 457
Trichoderma 458, 480
Trichodorus 461
Tricoma 456, 457, 478, 478, 480
Trigonolaimus 465, 467, 467
Trilepta 461, 477, 478
Trileptium 461,477,478
Trilobus 461, 469, 472, 472
Triodontolaimus 467
Scaptrella 467
Scatonema 455
Schistodera 457, 457
"Sectonema 461
Seinura 459, 460, 460, 475
Sela/ihinema , ,468
Seleneella 466
Seuratia 462
Seuratiella 462
Sigmophora 465
/
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