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1 !

Mi H

DEPARTMENT OP THE INTRRIOK

BULLETIN

OV THK

UNITED STATES

GEOLOGICAL SURVEY

i ■.*«•■ ■ ■ \

N^o. 30

WASHFNGTON

GOVERNMENT PUINTING OFFICE

L880

STUDJ

UNITED STATES GEOLOGICAL SURVEY

J. W. POWKLL, DIKECTOR

SECOND CONTRIBUTION

If '!,}<{

TO IHX

''ft.'' ■■>' 4 "

STUDIES ON THE CAMBRIAN FAUNAS

NORTH AMERICA

CHARLES r>OOLITTLE WALCOTT

WASHINGTON

GOVERNMENT PRINTING OFFIOB
1886

Letter of tri

Inti'otliictnrj

Review «

borizo]

Sniiimar.

On t\ui 11

Aeknowl

Description <

Fiicoidnl

Hjidngia)

I'icliiuodc

Hiachiup

LiiiiKtllib

(laNteropi

Ft(irop()(l

I'o'cilopoi

Description o

Index

Since the t<
used for a ge
ueric name wi

CONTENTS.

PaC«w

Letter of transmittal 7

Introductory observations 11

Review of tho strata and faunas referred to the Middle Cambrian or Georgia

horizon 12

Sninmury of I lie Caniliriau faunas of North .'.nierica 59

Oil thtt use of the name Taconic 65

Aclmowledgmonts 71

Description of the Middle Cambrian fauna 72

Fiicoidal remains, trails of annelids, &c 72

■Spongio) 72

Kdiinodermata 94

Itruchiopoda 9o

liiiincljibrnnchiata 123

CiaHteropoda 126

Ftrropoda 131

Pd'cilopoda 149

Description of n Ptfcropod from the Upper Cambrian or Potsdam horizon 223

Index 357

NOTE.

Since the text of this bulletin was written, the generic name BiUingsia has been
used for a genus of brachiopods (Amer. Jour. Sci., June, 1886, p. 466). Another ge-
neric name will be proposed for the name as used in this bulletin.

(731) 6

';!

5-fi ' f

Fig. 1.

ILLUSTRATIONS.

Platr I. SpongitB '. asn*

II. Spongiw 'J31

III. Spongise 835

IV. SpoDRiBB aao

V. S|M>ugi(e 243

VI. Spongiiu nnd Echinodermata 247

VII. BrachloiMMla 251

VIII. Brachiopoda aud Crustacea 255

IX. Brachiopoda 25»

X. Brachiopoda 26S

XI. Brachiopoda and Hydrozoa 267

XII. OaHteropoda and Pteropoda 271

XIII Pt«ropoda 275

XIV. Pteropoila 279

XV. Crustacea 283

XVI. Pojcilopoda 287

XVII. Pmcilopotl 291

XVIII. PoBcilopoda 295

XIX. Poecllopoila 299

XX. Pojcilopoda 303

XXI. Poscilopoda :m

XXII. Pcncilopoda 311

XXIII. PcBcilopoda 315

XXIV. Pfficilopoda 319

XXV. PoBcilopoda 323

XXVI. PoBoilopoda 327

XXVII. Pojcilopoda 331

XXVIII. PcBcilopoda 335

XXIX. PtBcilopoda 339

XXX. Pfficilopoda 343

XXXI. PcBcilopoda 347

XXXII. Pteropoda 351

XXXIII. Pteropoda 355

Fig. 1. Section from Lalce Chaniplain eastward across the town of Georgia,

Franklin County, Vermont Ifi

2. Ideal section of the strata resting against the east side of the Adiron-

dack Mountains, at the close of the deposition of the sediment-s of the

Utica shale formation 25

3. Section of the Cambrian rocks of Prospect Mountain, Eureka District,

Nevada 31

4. Section of the Cambrian rocks of the Wasatch Mountains, south of Big

Cottonwood CaDon, Utah 37

5. Section of the Cambrian rocks of the Qrand CaQon of the Colorado, Ari-

zona

ti. Ethmophyllum Minganensis (after Billings) 77

7. Ethmophyllum Minganensis (enlargement of surface) 77

8. Ethmophyllum Minganensis (spicule, enlarged to 50 diameters) 77

9. Obololla chromatica , 110

10, Obolella chromatica 110

(733) 7

:i\ i

ft- •.

LETTER OF TRANSMITTAL

' )

■ . ; , ' I • .

Department of the Interior,

UN-i^. States Geologicat, Survey,

Washington, 1). C, February 15, ISSfJ.
Sir: Herewith I have the honor to transmit the secotul of my prelim-
inary studies on the Cambrian Faunas of North America. The huger
portion of the report was reatly for ])nl)li(;ation July 7, 1885, but, havin;^
visited a number of localities in Utah and Nevada during the season of
1885, numerous additions have been made to both the text audthe plates.
Very respectfully,

CHARLES D. WALCOTT.
Hon. J. W. Powell,

Director U. 8. Geological Survey.

(736) •

Ml*

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i I

^ 4

l»

THE CAMBRIAN FAUNAS OF NORTH AMERICA.

By Charles D. Walcott.

INTRODUCTORY OBSERVATIONS.

jl
I

§ 1. In using the name Cambrian in this paper for the series of
strata characterized by the First or Primordial fauna of Barrande, I do
not forget the claims of the name "Upper Taconic," which Dr. E.
Emmons proposed for the strata now placed under the Middle Cambrian
or Georgia Formation. At the end of these introductory observations
the reader will find some remarks upon this subject which define my
position at the present time.

§ 2. The term Cambrian is used from the belief that in so doing I
approve of the view of those writers that hold that each of the distin-
guished authors, respectively, of the names Silurian and Cambrian
will be fairly recognized, and geologic nomenclature advanced by the
use of the names Cambrian and Silurian for the divisions of strata char-
acterized by the first and third faunas as defined by Barrande. This is
spoken of here as, in the second edition of Geikie's Manual of Geology,
1885, p. 651, the author has included the Cambrian as a subdivision of
the Silurian system. I do not wish at this place to question the wis-
dom of this; but of the presence of a well defined geologic system
beneath the strata characterized by the second fauna of Barrande or
the Trenton fauna (including the Chazy and most of the Calciferous)
of North America, on the North American continent, there is no
question. The geologic sections given in this paper show it to have
11 total thickness of over 18,000 feoi,, and that its middle division has
a known fauna of 43 genera, represented by 107 species. We also
know that the Lower Cambrian or I'aradoxides fauna has 32 genera
and 76 species ; that the Upper Cambrian or Potsdam fauna includes
52 genera and 212 species; that of the 393 species now 'known from
Cambrian rocks but very few pass up into the Calciferous horizon of
tlie Lower Silurian (Ordovician) ; and that the faunas of the two sys-
tems are so distinct in thei; general facies, and also in detail, that they
arc quite as re.idily separated as the Silurian and the Devonian or the
Devonian and the Carboniferous. There is no doubt that in certain

(737) U

l'f-'if:(i

r¥'

t* ' ,

CAMBRIAN FAUNAS OF NORTH AMERICA.

(BULL.30.

areas tbe faunas of the Cambrian and the Lower Silurian (Ordovician)
systems are intermingled; but the same is more or less true of all tbo
great div isions of tbe entire geologic series from above the great Arcbean
break to the Quaternary.

§ 3. A good illustration of the mixing of the Upper Cambrian and the
Lower Silurian (Ordovician) faunas is shown in tbe Eureka section of
Nevada, in the fauna described by M. Barrande from the environs of
Hof, in Bavaria, and still better in the Tremadoc of Great Britain ; but
all this mixing, at tbe boundary line, does not prevent tbe recognition
of tbe first and second faunas, as such, either above or below the ho
rizon where the great change in the faunas took place.

REVIEW OF THE STRATA AND FAUNAS REFERRED TO THE MIDDLE
CAMBRIAN ORGEORGIA HORIZON.

§4, I have long been of tbe opinion that the paleontologist should
become personally acquainted with the strata containing tbe faunas be
is to study, and, as far as it is practicable, collect the fossils or superin-
tend their collection in order to learn their exact stratigrapbic relations
to the geologic section and their relative position to each other in tbe
section ; but, in the study of the enormous thickness of strata in tbe
Rocky Mountain Paleozoic, it has often been impracticable to carry out
the work in tbe degree of detail that is desirable. I have, however,
studied in the field most of the sections mentioned in this article, and
know from which horizons tbe collections were obtained, and therefore
with considerable confidence express conclusions that differ from those
reached by geologists and paleontologists who have arrived at their re-,
suits through the accounts of the observations and collections of others
or from stratigrapbic or paleontologic data considered without giving
due weight to tbe importance of combining them.

§5. While not desiring, at this time, to enter into a general discussion
of tbe stratigraphy and paleontology of tbe Cambrian System as u
whole, it appears desirable to present sufficient evidence to show that
the Potsdam and Georgia horizons are well-defined stratigrapbic divi-
sions and distinguished by large and distinct faunas in tbe same geo-
graphic area and geologic sections.

§ 6. Tbe stratigraphy of tbe Cambrian System of North America has
not been well known up to a comparatively recent date, and tbe extent
and the character of its organic record are not yet appreciated. Dana's
Manual of Geology, edition of 1881, p. 163, places the Cambrian as a
subdivision of the Lower Silurian, as follows :

I. Primordial or Cambrian Period. (2)

1. Acadian Epoch (2a). Sbule and saudHtone at St. John, New Bmnswick,
the St. John gronp of Matthew and Logan, the Acadian gronp of Daw-
son; beds at St. John's and elsowliere, in Newfoundland; clay-slate and
silicious slate of Braintreo, Mass.; Ococo conglomerate and slates of East
Tennessee and North Carolina.

(738)

WALCOW

§10.

WAUxnt.J

INTRODUCTORY OBSERVATIONS.

I. PritGordial or Cambrian Period — Continued.

2. Potsdam Epoch {2b). SandHtone of Potsdam and other places in Northern
and Northeastern New York, Western Vermont, and Canada ; sandstone and
limestone of Troy, N. Y.; slate and limestone of Northwestern Vermont,
including the Oeorgia shales; limestone and sandstone of shores of the
Straits of Belle Isle; Chilhowee sandstone of East Tennessee ; sandstone
with some limestone in Wisconsin and Minnesota.

§ 7. On paleontologic evidence, Prof. R. P. Whitfield (Bull. Amer.
Mu8. Nat. Hist., vol. 1, p. 140, 1885) correlates all the Cambrian faunas,
practically ignoring the stratigraphic evidence then published. He says :

My own impression, at the present time, is that the New York typical Potsdam is
about equivalent to the lower portion of the Wisconsin areas, and that the Acadian
beds of Canada and Vermont, and perhaps the other Atlantic areas, are not appreci-
ably different in age, but that the difference in faunae is more the result of conditions
upon which life depended than a difference in time.

§ 8. Dr. T. Sterry Hunt has been a strong supporter of the view that
the Cambrian System exists in North America as a system distinct from
the Lower Silurian (Ordovician), and advocates the use of the name
Ordovician of Lapworth in place of Lower Silurian and the retention
of the term Cambrian for the strata of the first fauna. He placed the
Upper Taconic of Emmons in the Cambrian and gave a table showing
the nomenclature and classification of North American rocks (Can. Bee.
Sci., vol. i, p. 81, 1884).

§ I). The accompanying observations on the geologic sections of a
portion of the Cambrian System and their contained faunas are also
given that the. student may know the data upon which the writer pro-
l)Osed dividing the Cambrian system of North America into subdivis-
ions in 1883 (Cambrian Syst. U. S. and Canada; Bull. Phil. Soc. Wash-
ington, vol. vi, p. 98, 1883).

We will begin with an examination of the Western Vermont sections
of the borders of Lake Champlain, where the Georgia Formation first
yielded a portion of its characteristic fauna.

WW*,'

GEOEGIA FORMATION.

§ 10. The history of the Georgia Formation as we find it in the Geol-
ogy of Vermont, vol. i, pp. 357-8, 374, 18(J1, is as follows :

I'riinUive Argillaceotu Slate : Prof. Chester Dewey's Geological map of Berkshire, Mass.; Columbia

and Kensselaer Coantioa, New York ; American Journal of Science and Aits, 1st sor., vol. viii,

1824.
I'rimitive ArgiUaeeous Slate: Geological Report of Massachusetts, 1832.
Black Slate and Taconic Slate: Roofing slate of tiio upper part of the Taconic System ; Prof. B.Em-

nionH's works on the Taconic System, 1840-1860.
Jludsan River Group or Lorraine Shaleg : Geological roni> of Now York, 1842 ; also in the Paleontology

of Now York, vol. i, hy Prof. James Hall, 1847.
"Roofing Slate of the laconic Syitem" but confidered at of the Hudson Kioer Group; Ri'_>r,rt8 on the

Otology of Vermont, 1845-1847, by Prof. C. B. Adams.
Ui>])er part of the Hudtoji Jtiver Group, or a distinct group above the Hudson River Group: Quoted by

I'rof. James Hall, from tlie opinions of Sir William E. Logan ; Twelfth Annual Report of the Re-

Ktnts of tho University of tlie State of New York, 1859.
I'pper Hudson River Group: Elementary Oeology, thirty-flrat editiou, p. 411; by Bdward Hitohoook

and C. U. Uitohcook, 1880.

(739)

I '

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CAMBRIAN FAUNAS OF NORTH AMERICA.

[BULL. 36.

Slate* eontaining Vie Firtl FautM,or Uie Priituirdial Zone of Life : Letter froDi M. Joachim Bnrmndo to

Professor Bronn, of Heidelberg, July 10, 1860.
Belonging to the Primordial Zone of Life, and perhapi the equivalent of the PoUdam Sandetone : Letter

from Sir William K. Logan to M. Joachim Ban-ando, Janaary 3, 1861.

We use the term Georgia Group to designate this terrain from the town of (}eor{{ia
in Franklin County, Vermont, where it is developed in its full proportions and where
the most interesting fosHils have been found. It is a name also which does not involve
any theory and may be used by both parties in the controverKy respecting its age.

The name of Georgia Group or Georgia Slate is given to this group of rocks rather
than any other, such as Fairhaven Slate or Caatleton Slate, because it is a purely
geological designation and has no reference to the economical vahie of the slate.
Two reasons may be given for the preference of Georgia : First. The whole of the
group is developed in the town of Georgia, but is not in cither of the others men-
tioned. It is a rule of geological nomenclature that the whole series of rocks must
be developed in the town, mountain, or along the river from which the name is de-
rived. Second. Nowhere but in Georgia, in Vermont, are the characteristic fossils of
the group displayed. They have as yet been found only in the New York portion of
the southern terrain. The geological character of the group is best developed in
Georgia, and we are therefore compelled to use the name of this town in describing
the slates geologically.

Litlwlogical characters. — The Georgia slate includes all. the following varieties of
rock :

1. Clay slate.

2. Roofing slate.

3. Clay slate, approximating to micaceous sandstone.

4. Various kinds of limestone.
r>. Brecciated limestone.

6. Conglomerate, composed of pebbles of limestone.

The Georgia slate includes Avhat Professor Emmons has ranked as the black slate,
Taconic slate, and roofing slate; and yet not altogether, for we have iregarded all the
black slate beneath the red sandrock as belonging to the Hudson River Group. The
characteristic trilobites of the Georgia slate are represented by Emmons in his Ta-
coNtc •S'(/8tem, 1844, as found in the black slate. ' j.

There are three views respecting the age of the Georgia slate :

(1) Professor Emmons says it is the uppermost member of the Taconic System .uid
that the Taconic System is stratigraphically below the Potsdam sandstone — that is
to say, that the Taconic System is Cambrian. Upon pages 90, 91, of Part V of Amer-
ican Geology, the Taconic System is directly compared with the Skiddaw slates «f
Cumberland. In opposition to this view, we would say that the Georgia shit o rt'sts
conformably upon the Red Sandrock series, as is shown in Fig. iir)7, and its fossils r.iiik
it as Lower Silurian rather than Cambrian.

(2) M. Barrande and Sir W. E. Logan, judging from paleontological evidonco, n^-
gard the Georgia slate as equivalent to the Primordial Zone C of Bohemia, or very
nearly the Potsdam sandstone of North America. » * •

(3) The stratigraphical view of the Georgia slate, which has lieeu so ably defendcil
by Professor Hall, seems to demand for it a place either above or equivalent to tlio
Oneida conglomerate.

§ II. As we now know the Georgia Formation, it appears that Dr. Em
mous was correct in placing it below the rotsdani sandstone, as was
also done by Mr. Billings and later writers.

§ 13. The typical Georgia Formation, as developed in the town of Geor-
gia, Franklin County, Vermont, consists, as seen at the base, of a great

(740)

WALCOTT.]

INTRODUCTORY OBSERVATIONS.

thickness of magnesian limestones that pass, in their upper portions,
into an arenaceous magnesian limestone that is overlaid by a belt of
areuaceo-argillaceous shales, and this by a great thickness of a purer
argillaceous shale that, high up, carries a brecciated limestone con-
glomerate and lenticular masses of sandstone and limestone, from the
size of a bean to masses 2,000 feet in thickness and several miles in
superficial area.

§ 13. A carefully measured section (fig. 1, page 16), beginning at the
base of the westward-facing clitt' overlooking the level that reaches to the
shore of Lake Champlain, and extending southeastward through Parker's
quarry, and a little south of Georgia post office, gives the following :

Feot

1. Massive-bedded, bluish-gray dolomitic limestone with many inosculating •

threads and bunches of a yellowish-drab sandy limestone that weathers

in relief Uo

2. No. 1 ])asHes into a steel-gray dolomitic limestone that weathers to a dark ,

buff and bluish black, with angular fragments of bluish-gray limestone
appearing irregularly at the surface. At 160 feet from the base the first
band of mottled limestone, "Calico" or Winooski marble, is met with.
The latter grades into a reddish dolomite free from mottling, and then in
a gray limestone. (Fossils: Hyolithellust) 200

3. Gray dolomitic limestone in massive layers, some of which are mottled, red-

dish and white, but the larger part are gray and yellow. Many of the
gray layers break up into a columnar structure, the columns being at right
angles to the bedding. In a reddish-colored limestone, 200 feet from the
base, a slender elongate tube occurs, probably HyolUhellus micana 475

4. Reddish-pink dolomitic limestone weathering to a reddish brown and de-

composing, on the exposed edges, to an arenaceous, dark, brownish-red
rock that shows numerous fragments of fossils : Kutorgina Labradorica,
Oholella{f) sp., Salterella pulchella{i), Ptyohoparia Adamsi, OlcneUus
Thompsoni 100

5. Gray arenaceous limnsrone in rough massive layers, passing into more

evenly bedded light-gray arenaceous limestone. Fossils similar to those

in 4 occur in the lower portion 190

Total thickness of limestone 1,000

6. Georgia nhahs. — Argillaceo-micaceous and arenaceous shales containing

niunerous fossils at Parkf ' "'dge and showing deposition contact on No; 5. 200
Strike at Parker's qtiarry N. :{0° E., dip 8^ to 12« E.
Tilt; fos.siliferons shales at Parker's quarry contain : ralwophyciis iucipiens, I',
roiigrcgatua, DipJograptua (.') simplex, CHmacograptuH (?) Emmonsi, Kutor-
ghia ciiigiilata, Ortliinina Orientalis, O. festinata, <). trnitsverm, O. sp. (f),
MicrodiKCiia Parkcri, Mesonucia Vermontana, Olciiclhia Thompsoni, Olenoidea
Marcoui, ISathynotua holopyga, I'tychopavia Adamii, /'. I'lilcanus, I'rotypus
nUchcocki, P. sriirciiis, and /'. scnectiis var. parrulus.

7. Hast ol'tho Parker quarry the rocks are argillaceous shales with occasional

layers of hard gray limestone, one-half of an inch to two inches thick,

that carry nunicrous fraguieiits of a linguloid shell 3, fjOO

Strike of shales near top of 7 N. 40° to 60° E., dip 60° S. E. .

8. I.iglit-gray quartzite 50

(741)

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CAMBRIAN FAUNAS OP NORtH AMERICA.

(742)

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WALCOTT.J

INTRODUCTORY OBSERVATIONS.

Feet.

U. Gray liiiieNtono in innHsive layora, with ucc^aHionsl intercaliiMMl biiixlH of Iianl
ur^illaceouH shale siiiiilur to that beucath t\w liiiioAtoiio. Many of tho
beds of limoHtoDb appear to have been broken np into fra^nieutH and rece-

uientedin situ 1,700

Average strike of limestone beds N.50° E., dip SO" to 1)0°, avorngo dip

60OS. E.
In this limestone bolt, one mile north of where the section crossed, a
few fossils were found: Lingula, n. sp., Orthisina uudt. (fragment),
Caniarella undt. (probably new), Agnostus like A. Orion, and Ptycho-
paria like P. Adamsi.
10. Argillaceous shales, very similar to those in the Parker ledge, continue on
up to the opposite side of the line of tlio Vermont Central Railroad track.
At the base the shales rest conforniouly against the lihiestone of 9, and
above appear to be cut oft' by a fault.

Strike N. 50° E., dip 60° to 80° S. E, for a distance beyond the limestone;
the dip then decreases and does not exceed 20° for a long distance,
until within 1,000 feet of the railroad rack, where the shales become
coarser ami changed by addition of arenaceous material and the dip
increases.

Total thickness to fault line of No. 10, :?, 500 to 4, 500 feet.

§ 14. No. 8 of the section when traced on its strike to the south-
west increases in force very rapidly to tlie thickness of 500 feet or more,
and also changes from a quartzite to a more or less calcareous sand-
stone, containing irregular fragments of argilhiceous shale. Follow id
to the northeast, it soon disappears and the. limestones rest directly on
the shales. Continuing northeast on the limestone (9), it is ibund to
decrease rapidly, and a mile northeast or where it is over 1,500 feet in
thickness the width across the outcrop is not over 150 feet, and soon
the shales above it and those below it come together, the limestone
having disappeared. Southwest ot the line of the section the width of
the outcrop narrows, and north of Georgia IMains post office the entire
section is covered by beds of sand.

No. 9 appears to be a great lenticular nniss of limestone (lentile
of Marcou), with intercalated beds of argillaceous shale, and more rarely
with arenaceous beds imbedded in the argillaceous shales. The fauna
is (/umbrian in character, and, in the absence of Olenellus and other
typitial Middle Cambrian fossils, approaches that of the Upper Cam-
brian or Potsdam sandstone.

§ 15. On Mr. Noah Parker's farm a lenticular mass of calcareo-arena-
ceous rock is exposed on the edge of the first clitF facing west, where
trilobites are found: Olenellus, Bathynotus, &e. (G of the section). The
mass is small : 25 feet in thickness at the center and about 50 feet in
diameter, as seen in the section. Erosion has removed most of the
shale from above it, but in a second lenticular mass, just back of it, the
shales may be seen resting over and against the upper side of the cal-
careo-arenaceous rock, and in the shales numerous small masses of a
similar rock occnr that are not over s.x inches in diameter. On the
hill, still forther to the nortlieast, a hard cilciferous sandrock occurs
that appears to hf^ a rcsmnant of a diflferent formation from the shales
Bull.30 2 (743)

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18 CAMBRIAN FAUNAS OP NORTH AMERICA. [bull 3a

below ; but a close study shows it to be a portion of a lenticular oiatM
left by erosion, and resting conformably on the shales beneath, each
dipping 1(P eastward. Several other instances were observed where
erosion had left these masses resting on the shales; and it was not until
they were fouud to pass beneath the shales, to have imrlious of tiie
shale still preserved on their upper surface, and to contain the same
species of fossils as the shale, that the writer felt sure that they were
not fragments of the later formation deposited on the Cambrian beueath.
It is these masses that Prof. Jules Marcou referred to the Potsdam sand
stone (Bull. Soc. G^ol. de France, 3" ser., t. ix, p. 24, 1880). In a letter
to the write'', dateil December 20, 1885, Prof. Marcou states that the
sandrock at Parker's quarry was referred, by error, to the "Red Sand-
rock or Potsdam Sandstone," as his Held notes of 1801 place it in the
Georgia series as a " lentile."

§ 10. A section taken east of Highgate Springs, beginning on the line
of the same fault as the Georgia section, gave a slightly greater tliick-
uess and also more arenaceous matter in the limestone series beneath
the Georgia shales.

The section begins on the east side of the road running from St. Ar-
mand, Canada, to Swanton, Yt., near the house of Eldad Stearns:

Feet

1. Compact gray silicioiiH liiiiestone ill massive layers 20

2. Gray oalciforous limestoiK'. compact, bard, evenly bedded, breaking up into

sbaly layers in places, ^oiue of the layers decompose on exposure into a
reddisb saudy rock 180

3. Compact piirplisli, piukisb, or greenish colored silicious limestone in mas-

sive layers 30

4. Thick layers of buff and pi nkisb-colored silicious limestone with fragments

of Plijehoparia Adamsi 15

5. Heavy-bedded, reddish-purple, fine-grained magnesian limestone, breaking

into angular I'la^mcutH {I'tycho2)aria Adainni in nbuiiduiice) CO

Strike N. 30° E., dip 25° to 28° E.

6. Shaly and massive layers of g ly and purplish colored sandstones contain-

ing fragments of Plychoi)aria Idamsi, occurring at various horizons 175

7. Reddish-colored arenaceous limestone, with irregularly bedded massive lay-

ers of gray silicious limestone and a few more-ovenly-bedded layers carry-
ing fossils: Eutorgina Lahradorica, Orthinna ftel'mata, Orthisina ap.t, Sce-
nella varian8, Hyolithesfip.l, Salterellapulcluillaf, Olenellue Thompsoni, Ptycho-
paria Adamai, Ptychoparia Teiicer. Layers of gray and buff sandstone also
occur at intervals 700

Total 1,170

8. Georgia shales. — Argillaceons shale with interbedded masses of limestone,

layers of sandstone, and silicious limestone. In the limestone, Eutorgina
oingulata, Orthisina festinata, Olenellus Thompsoni, and Ptychoparia Adamsi
occur 1,000

9. Heavy layers of silicious limestone, with layers of sandstone midway, ex-

^. tending about 100 feet 850

Average dip, 20"^ ; distance, 2,500 feet. A fault line here cuts off the section.

§ 17. The section east of Swanton does not show as great a thickness
of the limestone beueath the Georgia shales, and a fault line crossing

(744)

muxm.]

INTRODUCTORY OBSERVATIONS.

Fc«t
20

160
30
15
60

176

700
1,170

.. 1,000

850
section.

the shales a littlo obliquely to the strike cuts out a portion of them.
On the east side of the fault two or three hundred feet of shales occur,
and then a layer of conglomerate limestone, the fragments of limestone
varying in size from pebbles to masses six feet in diameter. The fossils
in the limestone conglomerate have an Upper Cambrian aspect and
incUule Lingula sp. ?, Amphion ? sp. f, Bathijurua sp. ?, a fauiiii tiiut may
be compared to that obtained in itonw of the bowlders of the Point Levis
conglomerate. Below the horizon of the conglomerate and in situ in
tbe shales we found Lingulella^ Agnostun, IHychoparia, and Solenopleura.
With the exception of the Solenopleura the species appear to be iden-
tical with those in the limestone "lentilo" (9) of the Georgia section.

§ 18. A section taken east of Swanton by Sir William Logan (Geol.
Canada, 1863, pp. 281, 282) gave 520 feet of the limestone series; by
tracing the strata north nearly to the Canadian boundary, he found
1,410 feet in the section ; another series north of the Province line gave
790 feet, making a total of 2,200 feet, part of which is estimated.

That this portion of the Georgia Formation thickens rapidly to the
north there is little doubt; but, until further study is given to the cor-
relation of the horizons in the different sections, I should hesitate in
giving it a greater thickness than 1,500 feet within the limits of Ver-
mont.

§ 19. The fauna of the Olenellus horizon east of Swanton gives A'm-
torgina eingulata, K. Labradorica, Orthisina Onentalin, O.fetitinata, Ca-
marella antiquata, Salterella pulcJiella ?, Olenellus Thompsoni, Ptychoparia
AAnmai^ and Protypus senectus.

§ 20. The Georgia section is the most complete yet taken in Vermont.
At the base the great belt of dolomitic limestone, 1,000 feet in thickness,
rests against and, by a fault, overlaps the Trenton limestones of the
Ordovician (Lower Silurian). What was originally beneath the lime-
stone belt is yet undetermined.' In the Highgate section the limestone
belt is nearly 1,200 feet thick. The base is unknown, and it does not
appear, so far as I know, in the section between the boundary of the
United States and Canada and the outcrops in the town of Georgia;

Following the Georgia section up, a great mass of argillaceous shales,
3,500 feet in thickness, occurs before the great "lentile" is reache<l;
this adds 1,700 feet, and above it 3,500 feet of shales come in before a
probable line of faulting is met with.

§ 21. East of the supposed fault line, which is indicated by the dis-
turbed strata and a high ridge of hills, just east of the Vermont Cen-
tral Kailroad track, a great thickness of hard argillaceous shales or
iirgillites occurs, in which no traces of organic life have been discovered
to my knowledge. It may be that in taking the section eastward of
Parker's quarry faults occur that have duplicated the thickness of the

' It niiiy be that the great mass of shaly argillites east of the Vermont Central Rail-
road track, in the Georgia section, are older than the limestones at the base of the
Kction ; but until further evidence is obtained this is merely conjectural. (See $ 13.)

(746)

Im:'

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I I

CAMBRIAN FAUNAS OP NOBTH AMERICA.

(BULL 30

nIuiIch, but, on each Hide of the great ^Mentile," deposition contuctg
were seen and no evidenee of the presence of faults was observe*!. If
tbi.s is actually the case, we have nearly ten thousand feet of stmta
that we know to be of Cambrian age by its contained fauna. Of this,
I refer 4,500 feet to the Middle Cambrian or Georgia Formation, or 1
to 7, inclusive, of the Georgia section.

§ 22. The typical Georgia fauna, Kutorgina cingulata, K. Labrador-
ica, OlenelluH, MeHonads, Bathynotus, Ptychoparia Adamai, and ProUjpm
»enectuH^\B found in the upper portion of the great limestone seiies, in
the sandy and argillaceous shales resting on it, and in the masses of
interbedded calciferous sandrock which Prof. Marcou referred to the
Potsdam. (See § 15.) How far this fauna extends up into the shales
we do not know. One species, Ptychoparia Adamsiy Is represented in
the great "lentile" of the Georgia section; but I have drawn the pro-
visional upper line of the Georgia Formation at the base of the "lentile,"
as it is here that we meet with a decided change in the fauna, and the
deposit is unlike that found below. It will probably be found that the
limestone conglomerate, east of Swanton, occurs at about the same rel
ative horizon as the "lentile" of the Georgia section.

§ 23. In the group of sections, taken across New Hampshire and Ver
niont, by Prof. C. H. Hitchcock (Bull. Amer. Mus. Nat. Hist., vol. I,
pis. 16 and 17, 1884) we find the Georgia series called Potsdam and
Cambrian; and, in section XI, pi. 17, the Georgia shales (Cambrian of
section) are represented as resting conformably on the magnesian lime-
stones (Potsdam of section), in the town of Milton. This is the same
as we found it in the Georgia section a few miles to the north; and the
great "lentile" (8 and 9 of the Georgia section) corresponds in po-
sition to the mass of Cambro-Silurian limestone of Professor Hitch
cock's section XI, except that it is represented as let into the shales by
faulting. The Highgate section of Hitchcock, No. XIII, shows a fault
between the limestone and the shales, but my section crossed where
the succession was unbroken.

§ 24. The fauna of the Georgia shales is referred to the Lower Pots-
dam by Professors Whitfield and Hitchcock in the text accompauying
the sections, but, as is shown in this paper, there is very little reason
fop longer retaining- that name.

§ 25. The great mass of argillites, east of the railroad track, in the
Georgia section, is placed under the Cambrian by Professor Hitchcock,
and the reference may be correct ; but, as yet, we have no recc
Cambrian fossils from it.

STRATIGBAPHIC RELATIONS OF THE GEORGIA TO THE POTSDAM

§ 26. Across Lake Ohamplain from Vermont in New York the typ
leal Potsdam sandstone rests against the Archean of the Adirondaci; j
Mountains. At the Au Sable Chasm there have been found Lingal

(746)

wAtcorrl INTRODUCTORY OBSfiRVAtlONS. 21

minima, Obolella prima, Palwacmea typica, CUmaeiichnitCft np. f and
Ptychoparia minuta. Following tlio Handstoiic Hoiitli from Au Sublo
Cba«m, it is seen outcroppiug all along tbo base of tbe mountains; at
the Falls in the Hudson at Corinth, a good section is shown ; in the
town of Greenfield, Saratoga County, the calcareous layers begin to
uppear resting on the sandstone, and a little west of Saratoga Springs
numerous fossils are found that correspond in character to the higher
Potsdam sandstone faunas of Wisconsin; they are associated with
others of a more distinctive type. The species now known are:

Cryptozoa proliferuiu. BilliugBia Sarntoffouaia.

Lingulepis acuminnta. Matthevia variabiliH.

Platyceras ntinutiHsimam. Dioelloceplialna Hartti.

Platyceras Hoyti. Dicellocephalus specioaus.

Metoptoma comutiforme. Ptychoparia calcifera.

Metoptoma simplex. Ptychoparia (A.) Baratogenais.

§ 27. This fauna was first noticed in a paper printed in advance of
the Thirty-Second Annual Report of the New York State Museum of
Natural History. It was there referred to the Calciferous horizon,
January, 1^79. The fauna was referred to as Potsdam in 1883 (Amer.
Jour. Sci., 3d ser., vol. xxvi, p. 439, footnote), and the reference to the
Calciferous corrected in 1884 (Science, vol. iii, p. 136, February, 1884),
and attention again called to the relations of the fauna to that of the
PotHdam sandstone of Wisconsin, and a list of species given.

Prof. Jules Marcou refers to the latter reference and uses the dala
in Lis work on the "Taconic System and its position in Stratigraphic
Geology" (Proc. Amer. Acad. Sci. and Arts, new ser., vol. xii, p. 222,
1885).

§ 28. The means of comparison now at hand show the Saratoga Pots-
dam fauna to be still more closely related to the Wisconsin Potsdam
sandstone fauna.

NEW YORK. WISCONSIN.

Cryptozoa proliferum

Lingulepia acumiuata Lingulepia piunajformia.

Platyceraa minutisaimuui Platyceras iniDutissimum.

Platyceras Hoyti

Metoptoma comutiforme Metoptoma comutiforme.

Metoptoma simplex

Billingaia Saratogeusis

Matthevia variabilis

Dicellocephalus Hartti Dicellocephalus Pepinensis.

Dicellocephalus speciosus Dicellocephalus Lodensis.

Ptychoparia calcifera Ptychoparia Wisconsensis.

Ptychoparia (A. ) Saratogeusis Ptychoparia Oweni (of Hall).

Platf/ceras minuiissimum and Metoptoma comutiforme occur at Osceola
Mills, Wisconsin, and Dicellocephalus speciosus appears to be identical
with D. Lodensis.

(747)

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3d CAMBRIAN FAUNAS OP NORTH AMERICA. (»t>ii.3o

§ 29. The sectiou, jih detormincd north ninl west of Bnrntogii Spi iiijfH
and north as fur oh Corinth, Nuw York, huM, at the baNO, about L'OO Ihi
of evenly-bedded, compact, grayish to yellowiHli colored HandHtoiie, tlni*
restti unconformably against or upon H\mrn or ridges of Archean ^'iieisN.
Including the upper beds of sandstone, the section throe miles noitli nt
Saratoga village gives in ascending order:

Keet.

1. Samlatone 40

2. Oulitio limestone 'M

l\. Dark-gray, evenly-bedded lininHtonfl 50

4. Unfoasiliferous, impure, compact, more or lew* silicioiiH limo8tone %

r>. MaHsive- bedded, Hlightly magueHiau, gray and dove colored limeHtoues with

numerous small, narrow-cbanibered cepliulopods near tbe snmuiit 'X>

6. Macsive layers of steel-gray, more or less arenaceous limestone 125

7. Bird's-eye limestone li

8. Black River limestone 4

9. Trenton limestone 40-f

§30. The passage from the Potsdam fossil bearing limestone (3) of tlie
section to the dove-colored limestones (5) carrying the cephalopcxls is
through a considerable thickness of more or less impure, sligiitly avtMin
ceous limestone that has been known as the Calciferous sandrock iii
this region, but at Rock City Falls the Bird's-eye limestone rests di
rectly on similar beds, and from a study of the strata to the uortliciLst,
in the vicinity of Glens Falls, I am inclined to think that it is impos
sible to recognize, by lithologic characters, the Calciferous formation as
distinct from the Chazy limestone horizon ; and at Glens Falls Machim
magna and great numbers of an Ophiiita like 0. compacta are found in
the same stratum of rock but a little distance beneath the Trenton lime
stone, an occurrence that renders it very difficult to state what is to be
assigned to the Calciferous horizon in this region and also in the valley
of Lake Champlain, as our section at Chazy, N. Y., gave 700 i'cet of
limestone with Chazy fossils to the base, where the limestone rested on
the sandy, fucoidal layers just above the Potsdam sandstone. These
fucoidal layers have been referred to the Calciferous on but very slijjlit
evidence.*

§ 31. The limestone (2,3) capping the sandstone (1) of the section is also
found at Whitehall and at Comstock's Lauding, Washington County,
New York, where it has been, as was the limestone (2, 3), referred to
the Calciferous. The limestone 2 and 3 appears to have been, on tlie
southwestern side of the Adirondack Mountains, the closing deposit ol
the Cambrian ; and there is but little doubt 1 hat if we could tind ii
fauna in the limestone (4) of the section it would serve to connect the
Cambrian and Lower Silurian (Ordovician) faunas.

' This nonconformity by non-deposition, noticed by Logan, is nowhere better illus-
trated than in this section ; the entire Calciferous or Phillipsburg ibrmation, so near
at hand, is absent. The same irregularity of deposits, indicating varying levels iu
the sea bed, is noticeable around the Adiroudavks to the southern side.

(748)

\s f

fAUrOTT.)

INTRODOCTOKY OBShKVATlONS.

§32. The beds 2, 3, 4 till in, to a curtuin de^cc, tliu gu\y M'hidi oxiNtM
iM'tweoii the PotHdiviu aud theChazy, in the (Jhazy Hectiun. In tho Mo-
Imwk Valley, at Little Falls and at Fort IMaiii, the Chazy formation i.s
ubsuiit, a considerable development of tli<^ Caluifi>roiis, 'MM feet or more,
rtlliiig in the space between the Archean and the Trenton (Hinl'M-eye
liint'Htone) ; the Potsdam and older Cambrian formations being absent
except at the " Little Nose," on the New York, West Shore and Buf-
falo Railroad, Montgomery County, New York, where a band of decom-
posed gneiss aud lenticalar masses of shale, that occuis between the
({neisH and Calciferous sandrock, is referred to the Potsdam horizon.
(Prof. James Hall.)

§ 33. In the February number of the American Journal of Science (.{d
ser., vol. xxxi, pp. 125-133), Prof. W. B. Dwight des(!ribes a belt of lime-
stone near Poughkeepsie, New York, containing fossils of the Potsdam
fauna that, from the references made to them, appear to be identical
with the fauna of the Saratoga Potsdam limestone, even to an identity
of species. The limestone is described as over 300 feet in thickness,
and 12 or more species of fossils have been recognized. This discovery
is of great interest and importance, as it shows the ))resence of the
i'otsdam fauna of the Adirondack region 100 miles farther south and in
the line of a series of sediments that, 50 miles north, curry the fauna
of the Middle Cambrian. The inferenct^ is plain that we may expect to
find the two faunas in the Sii ue section, somewhere along the line of the
Upper Taconic of Emmons.

§ 34. From what has already been given, it is evident that the Pots-
dam formation has not been observed by the writer in Northern Ver-
mont as it exists in New York, but the inference is that the upper mem-
bers ot the Georgia section, or those carrying the lenticular and brec-
ciated masses of limestone, are near the Potsdam horizon, or, as Sir
William Logan said, in speaking of the equivalents of the Potsdam
(Geol. Canada, 1803, p. 235), " out in deep water the deposit may have
been a black, partially calcareous mud, such as would give rise to the
shales and limestones which come from beneath the (Quebec group."
This view is illustrated by the ideal diagrammatic section, fig. 2, page 25.

§ 35. Accepting the conclusion that the matrix of the. conglomerates
at Point Levis is of Calciferous age, whicl was Sir William Logan's view,
as expressed on page 233 of the Geology of Canada, the above view of
the origin of the Georgia shales and the included cahiareous beds, and
their equivalency to the Potsdam Sandstone, is, to a certain extent, cor-
rect; the error consisted in considering the entire deposit as equivalent
to the Potsdam, whereas it appears from the faunas that the limestone
series of the Georgia Formation, including the " Wiuooski marble" and
"Red sandrock," was a deposit antedating the Potsdam Sandstone of the
New York series ; that a considerable portion of the Georgia shales also
antedated the latter, and that strata of an age equivalent to the Pots-
dam Sandstone were deposited in a continuous series, and conformably

(749)

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CAMBRIAN FAUNAS OP NORTH AMERICA.

IBUU. M.

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on the deposits beneath. Such appears to be the deduction from tJje
Georgia, Swanton, and Highgate sections when compared with those of
the Potsdam about the eastern and southeastern base of the Adirondack
Mountains.

§36. The view expressed by the section, fig. 2, page 23, is that there
was a practically conformable deposition of sediments, against and over
the Archean area of the Adirondack Mouutains. from early Cambrian
times up to the close of the deposition of the sediment forming the Utica
shale, except in the case of the unconformity by non-deposition between
the Potsdam and the Chazy. The writer has seen the deposition contact
of tlie Utlca shale, against the granite, on the eastern side of the Adiron-
dack Mountains, in Essex County, New York, and takes that as the up-
per line of the ideal section, although lie has little doubt that the forma
tioiis overlying the Utica shale, even through the Silurian, were depos-
ited against and over the Archean of the Adirondacks and subsetiuently
removed by denudation. Numerous minor iaults now bring the strata of
the ideal section in various relations to one another, e. g., the Potsdam
sandstone resting against the Cha/y and the Trenton, as at Cliazy, N. Y.;
the limestone of the Middle Cambrian of the Georgia section thrust over
on the Trenton series, &c.

§37. In Fig. 2, the Potsdam formation, near the Adirondacks, is rep
resented as a sandstone ; to the eastward, as an arenaceous argillaceous
shale; and beyond, as an argillaceous slate with irregular masses of lime-
stone (lentiles) and thin beds of limestone intercalated in the slate or
shales. This succession shows shore, offshore, and deeper water de-
posits. The Trenton, Ohazy, an«l Georgia limestones are represented as
deposited directly against the Archean. We know this was the case witli
the Utica shale, and it appears to point to the submergence of the Adi-
rondacks in the vicinity of the contact observed in Essex County, so as
to prevent the disintegration and deposition of the materials composing
the Archean, the mud, forming the Utica shale, being deposited against
the ledges of granite that were entirely below atmospheric or wave ac-
tion.

ST. LAWRENCE VALLEY.

§ 38. The conglomerate limestones of Bic Harbor, St. Simon, and up
ihe St. Lawrence to the island of Orleans, and thence southwest toward
Lake Champlain, do not appear to have been derived from pre-existing
strata where they were deposited, as appears to be the case with tlie
brecciated limestone in the vicinity of Troy, N. Y., but to have bcon
transported and deposited as a portion of formation of a later geoli)}>i(
age. Dr. Selwyn has shown this to be the case with the Point Levis
beds which contain bowlccrs, some of which carry Georgia fossils, others
Potsdam fossils, and others Calciferous fossils, the last being uoarl\
contemporaneous with the matrix of the conglomerate, the noted grap
tolitebeariug shales.

(760)

WAI.COTT.]

IKTRODUCTORY OBSERVATIONS.

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§ 39. Sir William Logan, in describing the section at Trois Pistoles,
says : ''At Trois Pistoles, in a section of 700 feet of strata, 150 feet at
the base consist of gray calcareous sandstones and coarse liinestoue
conglomerates, the latter comprising one-third of the amount, in nine
separate layers of from two to sixteen feet thick. The matrix of the con-
glomerates is a gray calcareous sandstone; and the rounded masses im-
bedded in it, in addition to limestone, Qonsist of quartz, and occasionally
of amygdaloidal diorxte. Of the limestone and the diorite, there are
masses weighing from a pound to a ton, while the quartz pebbles seldom
exceed an ounce." (Geol. Canada, 1803, p. 260.) This mode of occur-
rence compels us to refer to the faunas as from strata of which we have,
as yet, no positive information.

§ 40. From Bic Harbor, Trois Pistoles, and St. Simon the following
species have been found in the conglomerate limestone, as observed in
the collection of the Canadian Geological Survey :

Lingalella cslata.
Iphidea bella.
Kntorgina ciugulata.
Obolella crassa.
Obolella Circe.
Obolella gemma.
Orthis 2 n. sp.
Platyceras primsBVum.
Hcenella retusa.
Stenotheca rngosa.
HyoUthes Americanua.
Hyolithes communis.
Hyolithes princeps.
Hyolithellus micans.

AgnoBtao sp. T.
Microdiscus lobatus.
MicrodiBciis Hpecioeus.
Olenellus Tbompsoni.
Olenoidcs Marcoui.
Olenoides levis.
Ptycboparia Adamsi.
Ptycboparia Teucer.
Ptycboparia f triliueata.
Ptycboparia sp. undt.
Ptycboparia (Agraulos) strenaas.
Protypus sonectus.
Protypus senectus var. parvalua.

§41. On the island of Orleans, Dr. Selwyn found in the conglomerate
limestone:

Obolella crassa.
Ortbisina sp. f .
C'amerella sp. T.
Hyolitbes Aiuericanns.
Hyolitbellus micaiis.
Olenellus Tbompsoni.

Ptycboparia Adaiusi.
Ptycboparia Vulcanua.
Solenopleura sp. t.
Protypus senectus t.
Olenoides Marcoui.
Olenoides levis.

§ 42. At Point Levis, Dr. Selwyn also discovered a pebble of lime-
stone, in the conglomerate beds, filled with beautifully preserved speci-
mens of SalUrella pulchella.

TROY, NEW YORK.

§43. Passing to the locality which Mr. S. W. Ford has made so well
known by his researches, we find that the conglomerate limestone is of
the same geologic age as the limestones with which it is interbeddod in
the argillaceous shales, as both carry the same fauna ; and the conglom-

(752)

WALCOtt.]

I^JTP.ODUCTORY OBSERVATIONS.

erate is brecciated, although showing evidences of wear in most in-
Btances. The limestone appears to have been consolidated and then
subjected to wave action. In some instances great masses of the
evenly-bedded layers remain intact, while a little distance away they
are broken up and buried in arenaceous and argillaceous sediments.

§44. The section as described by Mr. Ford (Amer. Jour. Sci., 3d ser.,
vol. ii, p. 33) consists, "for the most part, of coarse red and yellow
weathering slates and shales, with occasional thin-bedded sandstones;
but most of them are supposed, and four of them are known, to hold
subordinate limestone deposits. Of these deposits the two westernmost
individually consist of a few courses of thick-bedded limestone, and of
irregular, sometimes lenticular, sparry and frequently pebbly masses,
varying from one pound to several hundred pounds in weight, imbedded
iu a coarse, dirty-looking arenaceous matrix; while the others form tol-
erably compact even-bedded limestones, with an abundance of scattered
black nodules, from 25 to 30 feet in thickness. The same species of
fossils, with a few exceptions, have been found in both the even-bedded
and conglomerate limestones."

§ 45. The following list is made from the species in Mr. Ford's collec-
tions and those of the Dnited States Geological Survey :

lie

Ethmophyllum raram.
Ethmophyllom Rensselaericnm.
Lingulella cselata.
Obolella orassa.
Obolella gemma.
Obolella nitida.
Orthis sp. T.
Fordilla Troyensis.
Scenellaretasa.
Stenotheca ragosa.
Platyceras primeevnm.
HyolitheH Americanus.
Hyolithes cummunia.

Hyolithes communis var. Emmonsi.
Hyolithes impar.
Hyolithes sp. T.
Hyolithellus micans.
Leperditia Troyensis.
Agnostus Dobilis.
Microdiscus speciosus.
Microdiscus Meeki.
Microdiscus lobatus.
Oleuellus asaphoides.
Ptychoparia trilineata.
Soleuopleura Nana.

§ 46. South of Schodack Landing, in Columbia County, New York, Mr.
Ford obtained a better section than at Troy (Amer. Jour. Sci., 3d aer.,
vol. xxviii, p. 36). The base is cut ott" by a funlt and the upper limits
are unknown. It shows the varied character of the strata and the
position of the brecciated limestone (in 7 of section), carrying twelve
species of fossils identical with those at Troy, viz :

:%'m

^SJItil

p '-M

I <n

Palffiophycus incipiens.
Tdngulella cislata.
Obolella crassa.
Stenotheca rngosa.
Hyolithes .V.mericanas.
Hyolithes impar.

Hyolithellus micans.
Fordilla Troyensis.
Microdiscus lobatus.
Microdiscus speciosus.
Olenellus asaphoides.
Ptychoparia trilineata.

(753)

■ ■ f*!

!"■■'

hi?'- '

:ii'

\'^■ •'

J'-^ 1

1*'

ill:;'

28 CAMBRIAN FAT7NAS OP NORTH AMERICA. tiTOLL.a).

The following is the section measured by Mr. Ford :

8. Bluiah-gray nlato, about 10 feet.

7. Even-bedded limestona, becoming brecciated at top 5 feet.

6. Green calcareoutt slate 10 feet.

5. Reddish quartz rock 9 inches.

4. Green calcareous slate 6 inches.

3. Reddish quartz rock Ifoot.

2. Dark-blue compact limestone, in regular courses, with slight shaly part-
ings • 13 feet.

1. Bluish-gray slate 80 feet.

Total thickness about — -. 120 feet.

Two species are known from No. 2, LinguIeUa ccelata and Microdiscm
speciosus, and Syolithellus micans ? occurs in No. 1.

§ 47. A section that I hurriedly examined with Mr. S.W. Ford, on Kin-
derhook Creek, above Stockport, Columbia County, New York, gives a
greater thickness than the sectioas to the north, and is more like the
sections given by Dr. Emmons as occurring in Washington County,
New York.

All the thicknesses are estimated from the base up:

Feet.

1. Greenish-drab argillaceous or silico-arglllaceous shale 2, 000

2. Gray limestone, evenly bedded, shaly, and also brecciated fjO

3. Bluish-gi'ay silico-argillaceous shale, with compact arenaceous layers at

irregular intervals 800

4. Evenly-bedded and brecciated limestone, with Olenelhis and TAnf/uleUa cwlata. '2;')

5. Dark and grayish shale, changing into slaty shale towards the summit 1,200

4, 075

The section shows the Olenelhis horizon underlaid by a great thick-
ness of shaly beds and that the massive limestone of the Georgia sec-
tion is absent at this point. It is dangerous, however, to correlate in
this way, as the shales may have been deposited to a much greater
thickness than to the north in Vermont and the Oknellns fauna given a
greater vertical distribution.

§ 48. Stratigraphically we cannot now connect the sections of Frank-
lin County, Vermont, and those of Eastern New York with those of
the Straits of Belle Isle or Newfoundland. I think it is only a ques-
tion of careful field work to connect the Vermont and New York sec-
tions; the Vermont section will probably be traced northward into
Canada, and the source of the conglomerates of the island of Orleans,
Bic Harbor, &c., discovered. The presence of almost simihir conglom-
erates in the Troy section, in connection with evenly-bedded stratn cur
rying the same fauna, points to one condition under whicli the conglom-
erates may occur, but it is hazardous to consider that this is the method
of its origin along the St. Lawrence, as Jit Point Levis, where the de-
bris derived from three geological formations was buried in a common
matrix.

' (754)

♦ ■■

§49
vicinit
St. La
Bay oi
of Bel
St. Jo
thorou
Geolos

f ■

WALCOTT.]

INTRODUCTORY OBSERVATIONS.

NEWFOUNDLAND.

§ 49. As we have already noticed, the Georgia fauDa is found in the
vicinity of Quebec, Canada, and eastward along the south shore of the
St. Lawrence Kiver, in conglomerates of a later group; but at Bonne
Bay on the west coast, L'Anse au Loup on the north side of the Straits
of Belle Isle, and at Topsail Head, the extreme eastern locality, near
St. John's, it occurs in situ. The Topsail Head locality has not been
thoroughly worked, but I recognized, in the collections of the Canadian
Geological Survey :

Iphidea be] la.

Protypiis senectns var. parvulns.

Scenella reticulata.
Stenotheca riigOBa. •

Of these Stenotheca rugoaa and Protyptis senectus are found at L'Anse
au Loup, and Bic Harbor, below Quebec.

§ 50. The section given by Logan (Geol. Canada, 1863, pp. 865-867)
of the strata holding the Georgia fauna at Bonne Bay gives over 2,000
feet in thickness ; but, as the section was not taken by him and as there
is confusion in relation to the fossils collected from it, a doubt remains as
to its value. The species mentioned (Geol. Canada, 1863, p. 866) include
Kutorgina Labradoricn, Obolella ehromatica, Salterella sp., Olenellus sp.f
Ptijchoparia sp.? Keference is made to a species of Bathyurus like B.
extans, and, from an examination of the specimens and also associated
fossils, I have no doubt that it is Bathyurus extans of the Trenton. The
other species mentioned I did not sec when looking over the collection
of the Geological Survey of Canada. The section at L'Anse au Loup,
as given in the Geology of Canada, p. 288, shows 231 feet of arenaeeous
beds at the base, ov*erlaid by 143 feet of gray,, reddish, and greenish
limestones. I recently examined the collections from these limestones,
now in the Canadian Geological Survey collection, and found the fol-
lowing species, most of which had been recognized and described by
Mr. Billings:

PaliBophycns incipiens.
Ethmophyllum profiiiMlnin.
Archicocyathus Atlauticus.
ArchiPocyathiiM Billiii^Hi.
Iphidea bella.
Kutorgina ciugulata.
Kutorgina Labradorica.
Obolella clironiatioa.
OrthiH, 2 sp.

Stenotheca elongata.
Stenotheca rugosa.
Hyolithes Billingsi.
Salterella pulchella.
Salterella rugosa.
Olenellus Thoinpsoni.
Ptychoparia miser.
ProtypuH senectus.
Solenoploura (like S. Nana).

§ 51. In passing from the eastern to the western side of the continent
the Georgia horizon is not met with, as far as known, until we reach
into the heart of the liocky Mountains, in the great Wasatch Range of
Utah.

Prof. N. H. Winchell has described Paradoxides Barheri from so called
Potsdam strata (Geol. and Nat. Hist. Survey Minnesota, Thirteenth Ann.
Rep., 1885, p. 67), but after examining the sjjecimen I am led to doubt

(755)

^Ku

CAMBRIAN FAUNAS OF NORTH AMERICA.

[BULL. 30.

whether it is organic at all; even if it were, the reference to the genus
is conjectural, as such a trilobite might belong to the genus Olenellm,
Olenoides, ]>icellocephalu8, or even CrepicephulitH, as we have specimens
of the latter from the Potsdam of Alabama 20 ceutiu' iters in length, in-
cluding terminal spines of the pygidium. The brachiopod from the Cat-
linite quarry, described as Lingula calumeU looks very much like an
Obolella. It is therefore evident that the fossils of the Oatlinite beds do
not fix the geologic horizon so that we can correlate them, although the
section is much like that of the Grand Canon of the Colorado, and the
Catlinite beds are probably Pre-Cambrian. Geographically, we should
speak of the Wasatch section first, but, as the section and fauna are
more thoroughly known in Kevada, that area will now be considered.

X, •'■

\m: ■■•■ ■
If,.;

. NEVADA.

§ 52. The Georgia horizon, in the Cambrian section of the Eureka
mining district of Central Nevada, is shown in the accompanying sec-
tion, taken from Mr. Arnold Hague's Report on theGeology of the Eureka
District, p. 253 (Abstract in Ann. Rep. Director U. S. Geol. Survey,

1881-'82):

[Cambrian, 7,700 l'<^et.]

350

Yellow nrgiUaceous shale ; layers of chert
notlnles throughout the bed, but more
abundant near the top.

1,200

Dark-gray and granular limestone; sur-
face weathering, rough and ragged;
only slight traces of bedding.

•

1,600

Tellow and gray argillaceous shales, pass-
ing into shaly limestone near the top;
intorstrntifled layers of shale and thinly
bedded limestones.

Prospect Mountain limestone. . .

3,050

Gray compact limestone, lighter in color
than the Hamburg limestone, traversed
with thin seams of calcite; bedding
planes very imperfect.

Prospect Mountain qnartzite . . .

1,500

Bedded brownish-white quartzites, weath-
ering dark brown ; ferruginons near the
base; intercalated thin layers of arena-
ceous shales ; bods whiter near the sum-
mit.

Total section

7,700

if-'1 iJ

§ 53. At the summit of 1 the quartzite becomes more thinly bedded
and passes into an arenaceous shale which is more or less calcareous
and, in its extension northward, is replaced by limestone. This belt of

(756)

[BULL. 30.

WALfOTT.]

INTRODUCTORY OBSERVATIONS.

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CAMBRIAN FAUNAS OP NORTH AMERICA.

[BULL. 30.

shale and limestone \n from 100 to 200 feet in tbickness aud carries nu-
merous fraf^mentH of fossils, among which we have determined six spe-
cies, viz : Kutorgina ProspeetenHis, Scenelta conula, Olenoides quadriceps,
OlenelluH Gilberti, 0. Iddingsi, Anomocareparvum,fi,rn\Ptych<ypariaBii. 1

§ 54. The Prospect Mountain limestone is practically a continuation
of the limestone of the upper portion of No. 1, aud 500 feet up in it
we find, in a baud of shale, Scenella conula, Agnoatits inter atrictv^t 1,
Olenoides quadriceps, Ptychoparia Prospectensia. All but the last are
closely related to species from ihe Georgia horizon, in either Vermont
or Canada. One other species, Stenotheca elongata, which is found as-
sociated with Olenellua Thompaoni, Protypua aenectus, &c., at L'Anse an
Lonp, is found 2,000 feet higher up in the limestone. Another species,
Olenoides apinoaus, is found in association with species characteristic of
a lower horizon than the typical Potsdam of Eureka, at Pioche, Nevada.

§ 55. Within a short distance of the summit of the limestone (-) we
foupd a fauna that is more readily referred to the Upper Cambrian or
Potsdam horizon, although Stenotheca elongata, Protypua aenectus, and
Olenoidea apinoaus are elsewhere found in the Middle Cambrian. This
fauna includes representatives of both the Georgia and the Potsdam
faunas, and is, in a measure, the passage fauna between them. The
species are:

Obolella (liko O. pretiosa).
Lingula nianticulu,
KntoFf^ina Whitlielrti.
Orthis Eurekensis.
Stenotheca eluugata.
AguoHtus communis.
Agnoatns bidona.
AgnoHtus Neon.

Protypus senectus.
Protypus expansus.
Dicellncephalns ? nasutns.
Ptycboi)aiia Oweni.
Ptychoparia Hagiiei.
Ptychoparia occidentalis.
Ptychoparia dissimilis.
OleuoideH Hpiuosua.

Agnostus Richmondeusis.

§ 50. At the summit of No. 3 the fauna is without traces of the spe-
cies found in theOlenellus horizon at any known locality. It includes:

Protonpongia fonestrata.
Lingulepis Mmia.
Lingnlepis minuta.
Lingnia I uiauticula.
Ipbidca depressa.
Acrotreta gemma.
Kutorgiua miuutissima.
Hyolithes primordialis.
AgnoBtus communis.
Agnostus bideus.
Agnostus Neon.
Agnostus seclusus.
Dicellocephalus ? nasutus.

Dicellocepbalus Richmondensis.
Ptychoparia pernasnta.
Ptychoparia laticeps.
Ptychoparia bella.
Ptychoparia Linuarssoni.
Ptychoparia Oweni.
Ptychoparia Haguei.
Ptychoparia similis.
Ptychoparia unisulcata.
Ptychoparia Iseviceps.
Cbariocephalus tumifrons.
Ogygia t problematica.

§ 57. Seven of the species pass up from the top of No. 2 and unite
with five more from No. 3 and pass to the summit of the Upper Cam-
brian or Potsdam horizon in No. 5 of the same section.

(758)

!-| i

WALCOTT.]

INTKODUCTORY OBSERVATIONS.

In No. 6 we find :

Lingulopis Macra.
Lingulepis luinuta.
Lingula T manticula.
Obolella discoidea.
Acrotreta gemma.
Kutorgina miniitissima.
AgnostuH communis.
Agnostus bidona.
Agnostus Neon.
Agnosias prolongaa.
Agnostus tnmidosus.
Agnostus tumifrons.
Dicellocephalus ? nasutus.

Dicellocoplialns augustifrons.
DicellocopLalus Marica.
Dicellocephalus Lilobus.
DtcoUocoplialns Oaccola.
Ptychopivrid afflnis.
Ptyclioparia Owoni.
Ptychoparia Haguei.
Ptychoparia granulosa.
Ptychoparia simulata.
Ptychoparia unisulcata.
Ptychoparia brevicops.
Arcthusina Americana.
Ptychiispis minuta.

Three of these species, HyoUthes primordiali8,Dicellocephal'Us Osceoltty
and Ptychaspis minuta., are identical with forms from the Potsdam sand-
stone of Wisconsin,

§ 58. The above section and details are given to show the relation
of the Georgia, or Olenellus, to the Potsdam liorizon. The section of
7,700 feet of strata is coutinuons and entirely visible throughout its ex-
tent, as it forms the summit and eastern slope of Prospect Peak ahd
crosses the Hamburg ridge. Hammer in hand I examined it, and col-
lected fossils at all places where they could be found. The Olenellus
horizon is separated by 3,000 feet of limestone from a fauna that can
be correlated with the Potsdam fauna of New York and the Missis-
sippi Valley, and 1,600 feet of calcareous shale intervene before a
typical Potsdam fauna is reached at the summit of No. 3. This section
is typical, as it Axes the horizon of the Georgia iauna below that of the
Potsdam, without the shadow of suspicion thrown on it, which there is
on the Georgia section, as the latter may be defective through faulting
iu the shaly argillites above the Olenellus horizon.

§ 59. A section taken in the Highland Itange, 125 miles south of the
Eureka section, gives a greater variation of sedimentation in the lower
portion and less in the ui»per, and we find that the variation was more
favorable to the development and i)reservation of the fauna, as is shown
by the Highland liange section, having an abundant and more varied
fauna in the lower 1,500 feet above the quartzite, whih; in the Eureka
section the upper or Potsdam fauna is much larger than in the High-
laud section.

The section was measured on the west side, half way between Ben-
nett's Spring and Stampede Gap. The base of the section begins at
the (Quaternary, on the western slope, and the summit forms the high-
est point of the range.

1. Dark reddish-brown quartzite, evenly bedded, and ripple-marked in some

places .*. 350

2. Blnish-gray limestone 35

(769)
Bull.30 3

Feet

''Ml

Vft:

l.M'J. ,

lilt,

1 >' \ ; '

■f "! !■

Mil

84 CAMUniAN FAUNAS OF NORTH AMERICA. tBUi.L.30.

T'oHsils: OleiivUiiH Gilhfrll. Font.

:?. Bull' jirgillaceouH mid nfienacooiiH sliiiles, more or Ichh solid n»!ur tho bane and

lainiiiati'fl in tin- niiitcr i)<)rti(>ns 80

FoshUs: Amiiiiid trails aii(H'ra;i;riuint.s of Olenolliin iu tho lower part.
Higher u|), tlio heads of OJenMm Gilhtrli aii<l O. lddUnj»l occur in abundance.

4. Lipht-colortMl ^;ra.v liino.stonc! and bluish-ljlack liuicstono 10

5. Sandy, bult'-colorod Hlial(^ 40

FohsIIh: Annilid trails, Criiziana »\>J
(5. Dark bluitsh-black limestone 4(i

7. Finely laminated bull' iU'^inacoous shale 80

Fossils: Jfjiolilhin JiiUhij/Hi tind I'tiicltojiaria riovlwntis.

8. Gray to bluish-blnck (tomjiaet limestone Ifl

•J. liuirareuiici'ous shales 64

10. Ooniimet cherty liniestone I'lO

11. Compiiet shaly sandstoin! in massiv<! layers 40

12. Hard silieious f^ray limestone, almost quartz at base 1::'

1:5. Yellow to biitr sandy shale 70

14. Bluish-black iimcslonc 1(1

1.'). Vi.'lloAV to budVsaudy shales 40

IC), Ijluish-bhiek, haid, eomjiaet limestoue \i

Fragmeuls of fossils.

17. Shaly sandsroiie in massive layers Tyi

IH. flray arena<'e(ms limestoue 2

li). (a) Butf, sandy .-.liale 40

(/;) Gray arenaceous limestone 30

20. («) Massive-bedded, bliiish-j;ray limestone 200

Fraj^ments of fossils.
(&) Comi>aet gray silieious limestoue, almost quartzite in some

jilaees 400

(i06

Strike N. .lOO W., dip HP E.

21. Buff to ])inkish arifiliaoious shale, with fossils, and a few interbedded layers

of limestone from 15 t" !.'» iuelies tliick 125

Fossils: Jiocynlilcnf? hnujhlacljihifs, Linguldla Ella, Kiitorghia pannnla,
ffi/oUllien lHUini/iii, riychoparia Fiocheiisin, OU'noich>ityi)Undi8, Bathy-
nrixoiH Hou-vW, and II. [iroducla.
28. Massive-bedded, silieious limestone; weathering rongli and broken into
great belts, iJOO to 300 feet thick, by bands of color iu light-gray, dark-
lead to bluish-blaclc; ou somo of the clitf faces tho weathered surface is

reddish 1,570

23. Bluish-black limestone iu massive strata, that break up into «haly layers
on exposure to the weather, Th<! latter feature is less distinct 850 feet
up, and the limestoue be(U)nu's more silieious, with occasional shaly beds. 1, lliO
Fossils: Neai" the summit specimens were found that are referred to
riijclioparia minor.

Quite a fauna occurs in 23, as fouud one mile farther south ou the hue

of the sectiou.

Simunari/ of section. Feet.

1. Quartzite :!50

2. Limestoue and shales (argillaceous and arenaceous) 1,450

3. .Massive limestones 3,000

Total 4,800

(760)

WAi.corr.]

INTRODUCTORY OUSKRVATlOl^S.

§ 00. The Enroku Cambrian section gives 750 feet more strata be-
tween the quartzite at the base and the base of the Lower Silurian
(Ordoviciim) above; a variation not unexpected, as both the latter and
the Devonian strata decrease in thickness between the Eureka and the
Southern Nevada sections.

§ 61. The shales above the lower quartzite carry two species in the
Uifjhland Range that oc(;ur at the same horizon in the Eureka district,
viz, Olenelluft Oilherti and 0. Iddingai.

§ 62. The great thicikness of strata between the shales carrying Ole-
iieilus and division 21 of the section contains more or less remains of
trilobit^s, mostly fragments of the genus Ptychoparia.

§ 63. On the east side of the anticlinal arch at Pioche, 20 miles east
of the Highland section, the strata resting on the quartzite (2, 3 and
4 of section) contain the following species, four of which are found in
the two localities :

Eocyatitesn longidactyluH.
Lingalella Ella.
Kutorgina puniiiila.
Acrotliele siibsidua.
Acrotreta goiiiiua.
Ortbis Hisjlilamlonsis.

Hyolithes Billingsi.
Oleuollns Gilbert!.
OlenoidoH levis.
Cropicopbalus Augusta.
Cropicepbalus Liliaua.

§04. The second strongly marked faunal liorizon (21 of the section), or
tlie Olenoides fauna, is better shown in the Ely Mountains, just east
of the Highland Range, owing to mining opei'ations which have cut into
and thrown out large masses of the shales. The same species occur at
eacli locality. The list is given in the section.

§ 05. Tlie fauna of the great limestone belt, above 21, is so obscured by
the character of the matrix that only a few specimens were found on
tlie line of the section. One of the species is a small Ptychoparia with
an occipital spine; and, from the head, it is identified with Ptychoparia
minor of the Wisconsin Potsdam fauna. Two other species of Ptycho-
paria occur that are not yet specifically identified. A mile south, on
the strike of the strata, an anticlinal, accompanied by a fault, has thrown
the limestone down so that a partial section is given; and here a strongly
marked Upper Potsdam fauna occurs.

§ 00. The following species are identified:

Dicellocepbalus sp. t
Ptycbopiiria (Euloma?) dissimilis.
Ptycboparia ap. f
Aretbusiua Americana.
lUiBUurus sp. f

Bolleropbon antiquatus.
Pleurotoinaria, 3 undt. sp.
Hyolitbes, 3 ii. sp.
Dicellocepbalus Pepiuensis.
Dicellocepbalus (typo of D. Minue-
sotensis).

Of this fauna two species are identical with those from the higher
Potsdam fauna at Eureka, viz : Ptychoparia [E. f) dissimilis and Arethu-
sina Americana; and Bellerophon antiquatm and Dicellocephalus Pepin-
cmis occur in the upper Potsdam sandstone of Wisconsin. The pres-
ence of the Pleurotomaria-like shells and the species just mentioned

(761)

il'I'' ■''■
I 1^! i U

CAMnRTAN FAUNAS Op N(mTlr AMKRtCA.

|Diit.i..ao.

coriclatws the fauim with that of the upper horizon of the Potsdam
faunas of WiHConsiri aii<l Nevada.

§ 07. At the Moutli end of the Tiiiipahiite JIange, in Bonthern Nevada,
Mr. G. K. Gilbert collected Olenellm GUberti and 0. Iddingsi from fillets
of limestone in u yellow argillaceouH shale occurring above a niassive
quartzite, the equivalent of 1 of the JJighland Kange section.

§(58. In comparing the Highland Range section with the Enreka hoc;-
tion, we tlnd that the stratigraphic and faunai succession, up to the
base of the Trenton limestone horizon of the Eureka section^ is much
alike in each. The Highland Kange section was not measured in de-
tail above 23 of the section, but, continuing north along the crest of
the range and crossing Stampede Gap, the higher strata, above 23,
begin to appear dii)ping to the southeast, the dip increasing towards the
north, and higher beds coming in until at the low pass just north of
Bristol the white quartzite just below the Trenton horizon appears.
An estimate, made while riding along the eastern base of the range,
gave 2,500 feet as the thickness above the highest beds of the section
and the (piartzite. I think this is less than the actual thickness.
Adding 2,500 feet to the 4,800 feet of the measured section, we have
7,300 feet of limestone between the (Cambrian and Silurian quartzites,
or the Prospect Mountain and Eureka quartzites of the Eureka section.

§ 09. At Pioche, on the Ely Mountains, just east of the line of the sec;
tion, the lower quartzite (1) gives 1,200 feet. Adding 850 feet to divis
ion 1 of the Highland section, we have over 5,500 feet for the Cambriiin
and 2,500 feet for the Silurian. The hiatus between the two is prob
ably considerable, as at White Pine, 100 miles nt *^h, the Lower Silurian
(Ordivician) limestone, below the quartzite, is ovCi ^'^> feet thick.

§ 70. On the west side of the Highland Range, wesi *" the highest
l)oint, the upper (Eureka) quartzite is shown in a hill north of the ntad
leading from Rennet's Springs to Hiko. Fossils are very abundant.
No strata overlying the upper quartzite were observed in the Highland
Range between Rennet's Springs and two miles Morth of Bristol; but
in the Pahranagat Range, both Trenton and Silar San (Niagara) fossils
occur within 500 feet above the quartzite.

§ 7^. West of the Highland Range, at Silxaf Peak, Nevada (long.
117°, 20' W., lat. 380 N.), Mr. J. E. Clayton collected a few fossils to
which Prof. J. D. Whitney called the attention of the California Aciid-
emy of Sciences, in 1860, referring to them as probably Upper Silurian
or Devonian (Proc. Cal. Acad. Sci., vol. iii, p. 270, 1866).

§ 72. Mr. F. B. Meek subsequently studied the fossils, referring to
them as Silurian, and describing Ethmopliyllum Whitneyi and E. gracilc
(Amer. Jour. Sci., 2d ser., vol. xlv, p. 62, 1868) as corals, and then, in tlie
same year, referring (ibid., vol. xlvi, p. 144) them to the genus Arclite-
ocyathns of Billings. No other species were mentioned by Mr. Meek.

§ 73. The original collection from Silver Peak, or a portion of it, was
found in the Suiithsonian Institution collections, and proved to be-

<762)

WALCOTT.)

INTRODUCTOKY ODSEUVATIONS.

nan

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38 CAMBRIAN FAUNAS OF NORTH AMERICA. [bull. 30.

lonpf to the Middle Cambrian fanna which is so extensively developed
iu Central Nevada. We have no description of the section, but the
fossils are from a limestone and silico-arj^nllaceous shale, and identical
with species fouud elsewhere. The most noteworthy occurrence is that
of ArchoEocyathvs Atlanticus and a large brachiopod like Kutorgina cin-
gulnta, both of v/hich occur over 3,000 miles to the east-northeast on the
Labrador coast. The abundant and peculiar typ,^ ol" sponge Ethmophyl-
Inm profundnm, of the L'Anse au Loup locality, is represented by the
nearly identical species E. Whitneijl at Silver Peak, and the trilobite
Olenvllus Gilberti is scarcely distinguishable from 0. Thompsoni as it
oc(!urs at L'Anse au Loup.

The species now known from Silver Peak are:

Arcbtoocyathus Atlauticiis, Kutorgina (liko K. eingalata).

ArdiiPocyiiMins iukU. sp. llyolithes princi4)H.

Fithniophylluiu Whitneyi. Oleuclliis Gilherti.

Strepbocbetus ? sp. ?.

UTAH.

§74. The writer visited P>ig Cottonwood Ciifioii, in the Wasatch
Mountains, during the summer of 1885, and examined the great Cam-
brian section described by the geoh)gists of the Fortieth I'arallel Sur-
vey (Geol. Expl. Fortieth Par., vol. i, p. 2L'f); vol. ii, p. .'!06) more in
detail than they ha<l the ojjportunity of doing. The section was meas-
ured from the base near the mouth of Big Cottonwood Canon, uj) the
caiion to its summit J'bout one mile below Argenta. Owing to the
irregularity of the line of outcrop, the thickness of some of the ditfeivnt
divisions of the sections was obtained by careful measurement and that
of the others by estimates based on partial measuremeuts.

Wasatch or Big Cottonwood section.

Feet.

1. Black arenaceous Hbale 1*00

(Miul inaiking,s and cracks, and ripple marks.)

2. Massive-bedded, liglit-gwiy quart? ite 1, f'Ofl

3. Puiplisb, tbin-bedcb'dsandstoue, tvi th bauds of greeni.sb-yeHow, argillaceous

slialo near tbe Nuuiinit 700

4. Light-gray (lUiirtzite and (|uartzitie sandstone in biycrs varying from lOlVet

down toSincbes, tbe tbin layers occurring as partings between tbe more
massive bands of layers. In some plates tbe quartzitie sandstone sbows
grains, and in otbers tbey are lost. Stains of ptirple, iron-rnst, reddisli-
brown, and buff color occur, with bands of purplisb artMiaeioMs sbale
near the base 70('

5. Hard, black, arenaceous sliale, witb specks of mica on tlic surfaces. Qnartz-

ite and sbab • intercalated near tbe base 1, 000

1). Light-gray (jnartzite and quartzitic sandstone in layers varying from 10
feet down to 2 inches, tbe tbin l.'iyi-rs ocenirinfr as ))ar(ings between the
more nnissive bands of layers. In some places the (inartzitic sandstone
shows grains, and in otbers they are lost. Stains of purple, iron-rnst,
reddish-brown, and buiF color occur "00

(704)

nv'

WALCOTT.] IR-ntODUCTORY OBSERVATIONS. |f9

Teet

7. Arenaceous and iirftilliiccoiis sljifos, lilncli, hliiisli-hliick, <ltiib, i)n«l yel-

lowish-j^roen. This cxixi.sini) is i-xlciisivc, iLe opportiiiiity lor liuding
fossils excellent, and the slates afford a lieautifiil matrix for tbcir pres-
ervation, but none were olisorvcd 700

8. Light-gray quartzito and qiiarrzitlc sandstone in layers varying from 10

feet to 2 inches, tlio thin layers occurring as }>artings lictween the more
massive bands of layers. In some places the ((uartzitic sandstone shows
grains, and in otluM's fhey are lost. Stains of purplis iron-rust, reddish-
brown, and hutf color occur 2,700

9. Black, sandy, arenaceous, slightly micaceous shal 'S 75

10. Gray, compact, (juartzitic sandstone 700

11. Purplish and reddish-brown quartzitic sand.stone 75

12. Gray, compact, (|uartzitic sandstone 3, 000

13. Hard, Hilico-argilhicoous shales, a little sandy in places iiSO

Fossils : Cruxiana sp. ?, Lhi(/iilcHa Ella, Kutorfjina patniuhi, Jli/dUtluH Jtil-
Ungvi, Lcperditia Argcnta, Olcnellus Gilbcrti, I'hjvJioparia qnudrmiH, aud
Baihyvrhms prodncta.

Total 12.000

§ 75. A band of mixed sandy and calcarooibs rocks rests confornialViy
on 13 of the section, and carries a fauna wiiich I'cfers it to the Lower
Silurian (Ordovici^n).

§ 76. Tlie fauna! Jiorizon of the fauiui contained in the sliales of 13 is
ill once kicated by a comparison with tho faunas of tlie TIi<?ldand Eange
section. Five out of the eiglit sjiecies are identical, and tlieir strati-
graphic positi(m in relation to the f;reat underlying' quartzite is the same
in both sections; Olenellus comes first, and then Linguldla EUa, Bnthy-
urimus prodneta^ &c.

§ 77. T!ie 250 feet of sediment of 13 of the section r(^i)resent the en-
tire 1,000 feet of Cambrian strata above the qiiarlzile of tlio JIi<;hlaiul
Kanfje section that I have included in the Georgia horizon; and the 2,000
to 3,000 feet of the Tipper Cantbrian of tlie Eureka aud Highland l'an},'e
sections have no equivulenr in the Cuiiihiian svction of the Wasatch
Mountains. The same condition appears in tiie Uqiiirri; rcaiij;e. next
west of the Wasatch, and, from the conformity of the overlyinjj Silu-
rian strata, it appears that durinj;' llie later (Jainbriau times there
was an area of non-deposition, aud as Car as known a period of slijjht
or total non-erosion of the Cambrian. The latter .statement i.s liir<;e]y
(|ualified by the small amount of detailed information we have on the
line of contact between the Cambrian and Silurian. That there is a
great unconfo- nity, '''' "i'bseiu!e of strata, liicre is r,o doubt. ()n< of
the most important i^oults of the study of the shah>s of 13 of th<^ ic"-
tion is the locating; of a horizon by which we can comi)are the section.
At Eureka, High land Hange, aiulTimpahutelbmge, Xevada, the quartz-
ite of 12 te'-'Muated the section below, but now we have 11,750 feet of
strata in a conformable series that extend down to the granite (prob-
a])ly Archean).

§78. The section iu the Oquirrh Eange, above Ophir City, shows a

(705)

'Iff

■iv I

|.v'.;

■A-

■i^'^i

■> ' ' EJ

•i

40 CAMblilAN FAUNAS OF NORTH AMERICA. [bulu3o.

quartzitc with .shales ijbove it carryiug IjhujuleUa Ella, Olemllm Gil
herti, and liutliyuriscus ]noducta, and at Antelope Spring, in the House
liauge, Western tltah, Mr. G. K. Gilbert measured the following sectiou
(Geog. and Geol. Expl. and Surv, West 100th Merid., vol. iii, p. 1G7),
from the top downward:

I'eet

1. Gray, inaHsivo limestoiio 2(K)

2. Bl;ie-gray, calcareous Hlialo SJUO

Fossils (as corrected by C. D. W): Acrothele suhsidua, Jgnostus inter-
striclus, Olenoides Nevadensls, Ftyohoparia Kingi, P. Housensin^ and
Aaaiihiscua WheelerL

3. Gray limestone, light and dark, chiefly massive 900

4. Vitreous sandstone, nmbor-hrowu on weathered face; base not seen 1,000

Total ..'. '. '2,:iOO

§ 79. No. 4 of this section may be correlated with No. 1 of the Eureka
and Highland sections or No. 12 of the Wasatch section ; and the fos-
sil-bearing shale No. 2 is the stratigraphic, lithologic, and i>aleontolo{;ic
equivalent of No. 13 of the Highland liange section ; and although theic
is but one species in common, Acrothele subsidua, the general facies of
the fauna is comparable to that of the fauna of division 13 of the High-
land Eange section.

CORRELATION OF SECTIONS.

§ 80. The foregoing sections show that the Middle Cambrian fauna has
a distinct stratigraphic position in the Cambrian System and that it is
widely distributed over the North American continent. When study-
ing the faunas we found that of the Vermont section to be similar to
that of the Bic Harbor and L'Anse au Loup first determined by Mr.
Billings; and that tho Bic Harbor and the Troy fauna were united by
twelve species common to each locality, first determined by Mr. S. W.
Ford and Mr. Billings. With llie Nevada area there is a greater differ-
ence r but the presence of a pre-Potsdam fauna, characterized by the
gene"..'a Olenellus, Olenoides, iind Frotypiis — all of which are found in tlio
typical Georgia section — serves to unite them.

§ 81. Throughout the Mississippi Valley, including the areas of Uj)-
per Cambrian in Llano County, Texas, a)id in Wisconsin, nothing is
known of the Georgia fauna ; l)ut to tho nortliwest, on the eastern slope
of the Bocky jMountains, Dr. George M. Dawson discovered a species of
Olenellus like 0. Gilhcrti, also Proli/puH scni'dus, tluis showing tho ex-
tension of the fauna north from Southern to Central Nevada, and north-
east to Kicking Horse Lake in British Columbia.

§ 82. In the accompanying table an attempt is made to correlate the
principal sections herein mentioned . The Georgia or Olenellus fauna of
the Middle Cambrian and the Potsdam or Dici.»Mo'"'pl»alus fauna of ilio
Upper Cambrian au taken as the two horizons to locate the local sec-
tions on the line of the great section, as their relations are known iu

(7G(i)

WAI.COTT.l

INTRODUCTORY OBSERVATIONS.

the unbroken stratigrapliic sections of the Eureka District and the
lliyhland Eauyo.

§ S3. The first section, that of Big Cottonwood Cafion in the Wasatch
Mountains, is repveaouted as resting on pre-Canibiitiu rocks, and ex-
ti'iiding ui> to the IMiddle Cambrian horizon. The Lower Sihirian (Or-
(lovician) strata rest directly on tlie top of tliis section in nature: but
we h'ave the hiatus between the MiddUi and Upper Cambrian horizons
to show the unconformity, by non- deposition, in this section, as com-
piiied with tlie Eureka section, where the hiatus of the Big Cotton-
wood section is filled in by several thousand feet of limestone strata
containing the fauna that, to a great extent, bridges over the break in
the fauna between the toj) of the Big Cottonwood Cambrian and the
Silurian strata.

§ S4. The Eureka section (2) is correlated at its base with section (1)
l)y the sti{i'iir''a])hy and contained faxiua. A dark mussive quartzite,
ovorIn,ic' l\v 'vies, occurs in each; and this horizon is traced across
the int-'M' T!i;(, ^ouu try between the two sections by its occurrence in
the Oquia!); intic, and House lianges, and also south of Eureka in the
llif^iiland Kange. It is only in the Wasatch section that the great quartz-
itic series is ti-aced down towards its base, the uj>lifts of Nevada not hav-
ing brought it up, except, possibly, at one point — White's Peak, in the
Sc'liell Creek Eange of Eastern Nevada — where Mr. G. K. Gilbert meas-
ured a section 11,580 feet thick, thatis very much like that of the Wasatch.
Unfortunately no fossils were found (Geog. and Geol. Ex])l. and Surv.,
West lOOth Alcrid., vol. iii, pp. 107, 171). The Eureka section extends
iiljfioni theOIenellus horizon (j,'J(K) feet to where the n])])er limit of the
Ciiinbrianis drawn. In the table it is represented on the same scale in
its extension up to tlu Tienton horizon of the Lower Silurian (Ordo-
vi(Man).

§ 85. The Ilighlaii (lat' .;« section is essentially n reduplication of
tile Eureka sectioi. ji"\', i:ke it, joins on the Wusatch section in the
same manner at the oa, < it is not represented in the table.

§80. The Grand Cafion >' i'iian and pre-('anibriaii strata (see fig. 5)
liave been roughly described by the writer (Anier. Jour. Sci., vol. xxvi, p.
4.")8, 1883). At the top it consists of 1,000 feet of strata cariying a strong
and characteristic Upper Cambrian or I'otsdani fauna. Then a great un-
conformity occurs by the erosion of an entire cross-section of the 13,000
feet of strata below that rest unco:iforniably on the underlying highly
iiic'Hned strata, which, where the section terminated, belong to a system of
Htrata between tlv-, 'vand Canon Series and the Archean. In the table
tiie period of eru^ !"• i •. represented as having removed all the strata
between the Uppei mbriaii and the Lower Cambrian horizon, but I
now think it would have been better tu classify all the pre-Tonto strata
'!< 'ire-Cambrian.

i) *7 This to a certain extent is hypothetical, but we know from the

(767)

'■ii

■m

CAMBklAN FAUNAS OF NORTH AMERICA.

[UL-LI,. 30.

■ V' ■

U:'

•»

■1

tt o

'A i

''. ST

■3

? *

i,)

F- St

cC "

»-*

•= £

o
p.

i J

WAICOTT.]

(768)

WALCOTT.]

INTRODUCTORY OBSERVATIONS.

])hy8ical conditions of the unconformity that a great period of erosion
existed whose duration might readily have permitted of the deposition of
tlie great series of strata that occur below the Upper Cambrian, over
the area of Utah and Nevada. I now think that in the Grand Canon
section the Middle Cambrian and the Lower Cambrian were periods
of erosion, and not represented in the section, and that the 4,000 or
5,000 feet of limestone of the Eureka and Highland sections and the
(letrital sediments of the Wasatch section are the deposits accumu-
lated in the sea of the Great Basin area when the area of the Grand
Canon was a land surface. The latter was of considerable extent, as
essentially the same section as that of the Grand Canon of the Col-
orado occurs in Llano County, Central Texas, and in Minnesota and
Wisconsin.

§ 88. The strata of the older series of the Grand Caiion section are
in a remarkable condition of preservation, considering their geologic
<age. In the Chuar formation, or the upper 6,000 feet, limestones and
argillaceous shales alternate, that lithologically resemble the Trenton
limestone and Utica shales of the New York section. The party colored
shales of the lower 700 feet recall the friable clays of the Permian. In
fact, there is no evidence of the great age of these strata in their physical
aspect, as they might be taken quite as readily for the friable and uii-
clianged strata of the Trias and Cretaceous series of Southern Utah.
The lower 6,000 feet are sandstone, with iuterbedded lava flows toward
the upper portion. Eipple marks and mud cracki* abound in many of
the layers, but not a trace of a fossil or the trail of a moUusk or annelid
was seen.

§ S9. Midway of the lower portion of the shales and limestones of the
overlying Chuar strata the presence of a fauna is shown by a minute Dis-
cinoid or Patelloid sh'ell, a small Lingulalike shell, a species of Ilyolithes,
and a fragment of what appears to have been the pleural lobe of the seg-
ment of a trilobite belonging to a genus allied to the genera Olenellus,
Olenoides, or Paradoxides. There is also an obscure Stromatopora-like
form that may or may not be organic. The fauna, as given above, is very
unsatisfactory, but it shows the i)resence of a fauna that is Cambrian
in character, as far as we know, although it may be a trace of a fauna
preceding that of the Lower Cambrian of the Atlantic border; and as
the stratigraphic evidence favors this view I do not think we can con-
sider it of Cambrian age.

§ 90. The fourth section of the table is that of Georgia, Vt. While
the Potsdam horizon is probably present, it is not certainly known in the
section. The section is represented on the same j>roportional scale as
Nos. 1, 2, and 3, although we fully appreciate the fact that a much thin-
ner series of strata in one locality may represent the same relative
period of deposition in another area where the accumulation of sedi-
ment was very much greater. When we attempt in the future to corre-

(769)

"' 'I

I'-'

CAJIliUIAN FAUNAS OF NORTH AMERICA.

liiri.l..30

f'"

■■v

It'-'*. , ■■

■|v.:, ,

Table showing the correlations of tsrpical Cambrian Sections with

reference to the Potsdam and Georgia faunas of the Cambrian.

1 ORDOVIGIAN- or

X 2 .

3 4 5

LOWER SILURIAN.

1 1
1 /
1 /
1 /
! . /

1 1 1

^ Upper Limit of -^

I .

' ---''■'

Upper Cambrian or Potsdam horizon.

—

t \

O 1

{

UPPER CAMBRIAN

§ 1 Mt^

= POTSDAM OR

1 ! ^

DICELLOCEPHALUS.

/ -1

tin

MIDDLE CAMBRIAN

"" (3

Central horizon of Middle Cambrian

__-

= GEORGIA OR OLENELLUS.

^ •

•

LOWER CAMBRIAN

= ST. JOHN SERIES.

NEWFOUNDLAND AND

o
o
o

BRAINTREE, MASS,, OR

o
o
o

PARADOXIDES.

CO"

V , «"

Base of Cambrian.

— S-

PRE- CAMBRIAN cUidARCHEAN.

1 <

Palseophyona
Cruziana sp.C

(770)

lmu..3o

WAIX-OTT.)

INTKODUCTOftY OBSERVATIONS.

H
":^:

late the various sections and fiiunas of the entire Cambrian System of
North America, all the sections will be drawn on a plan, so that the
divisions of each section will show their relations to each other as far
as practicable. The Vermont section is placed on the Middle Cambrinu
line by the evidence given by its contained fauna.

§ 91. Section 5 shows the Upper Cambrian horizon and the Lower Silu-
rian section up to the top of the Trenton limestone as developed in Xew
York State. The Middle Cambrisin is unknown to me in New York ex-
cept east of the Hudson River, although it may occur in the southeastern
portions of the State. The Troy and other sections of the Middle
Cambrian on a line south of the Georgia section are included under
section 4 of the table; also, that of the Straits of Belle Isle.

§ 92. The object ( ' the table being to show the stratigraphic rela.
tionsof the three divisions of the Cambrian fauna, many details are
omitted that may be expected when a review of the Di)per Cambrian or
Potsdam fauna is completed.

■m:^

TABLE OF THE MIDDLE CAMBRIAN FAUNA.

§ 93. In the following table the extent and character of the fauna are
sbown and also its geographic distribution.

Under the head of Highland Range we include the fauna at Pioche, in
the Ely Range, and the species from the Timpahute Range and Silvfir
Peak, Nevada, as they are all from the same geologic horizon and geo-
graphic area.

Table of distribution of Middle Cambriiin fauna.

Kxam.

X
X
X

....

Cru7.iaDasp,(?)

SPONGI^.
Arclia'ocvftthuw AtlaBticus Billings..

X
X

S.P.

BiUiosai Walcott

sp.? .... .. --..-

8.P.

Edininnbvllura Tjrofandnm Billinfffl

KfinRHelaericnni Ford

X
X

▼"arum Ford .. .. ... .........

Whltneyi Meek

8.P

^qitoniilus Zitteli Walnntt

I'lotdHpongia Tenestrata Salter

X
X

Stripliochotn8»8p.t

S.P.

.■Jjj",

(771)

i . J

" ' %l

ii^^^ ;■■,

::*V.:

CAMBRIAK FAUNAS OP NORTH AMERICA.

Table of dinMbution of Middle Cambrian fauna — Continued.

[bum. 30.

HTDKOZOA.

Diplograptns ? Rlmplex EnunonB

Cliiuacugruptu8?1 Emmonai Walcott.

CKINOIDEA.

EoisyBtiteg?) longidactylns Walcott .
Jap.?

ANNELIDA.

Areiilirolitns sp.f .

BRACKtOPODA.

Liiignlella ca3lata Hall (ap.)-
Ellan.&W

Kntorgina cinij^lata Billings

Labrartorica Billings . .
pannula Whitti (sp.) ...
Prospectensis Walcott.

Ipliiilea bflla Billings

Aciotrota gemma Billtuga

Aiirothelo Hiibsidua White

Ubolulla chroniatica Billings ...

Ciruo Billings

crassa Hall (sp.)

gemma Billings

nitida Ford

Orthis Bighlaudensis Walcott

Orthisiua fostinata Billings

oriontulis Whitfield

1 transTersa Walcott

? (sp. undetermined)

28p.?

sp.?

CamaroUa? nntiqnata Billings

Jsp.?

LAMELUBRANCHIATA.
Fordilla Xroyonsis Barrande

GASTEROPODA.

Stenotheca 1 olongata Walcott

rugosa Hall (sp.)

Sconclla conula Walcott

reticulata Billings

retuaaFord

! vaiians Walcott

Platycerns pvlmwvura Billings

8.P,
»

a u
M

^!«

Lcperditia Arjj

Tro

I'rotocaris Mat

(772)

•J

BUI.U 50.

WALCOTT.]

INTRODUCTORY OBSERVATIONS.

Table of disttihuiion of Middle Camliriaii fauna — Continued.

(' i 5

. i Georgia, Vt.

•6

-a

.a
u

•3

PTEROPODA.

HvolitliBH Amf^ricunufl BilliiiiTM . . ... .....

Bi1liui;8i WiUcott

x»

cotniiiQDiH I3illitiirs ...............

X
X
X

var. KniiuoDHi Ford

•

1 DrinconH Billin^H ....... ...................

S.P.

....

Hp, (uiidotorniunMl)

X
X

CRUSTACEA.
Leperdilitt Argent a Walcott

Trovenais Ford -.

I'mtofuris Murnbi Walcott ....

PCECILOPODA.
A li^noHtufl intcratrictus Whito .. .

•

iiobiliH Ford .. .

HI).? .

X
X

MicrodiscuH lobutus Hull (sp.) -

Meeki Ford

Parked "Walcott

Meflonjicis Vomioiitaiia HalWflT) ) . .

Gilberti Meek

X
X

—

Itldingsl Walcott ...

Thoiiipsoni Hall .. . .. ....•..-•

Olenoides Uafiricaiulus White (sp.)

X
X

lovi» WiUcott

'( Marcoui Wliitfleld (sp.)

quadriceps Hall & Whitfield (sp.)

....

tvpicalis Walcott

X
X

Wabsatchensis Hall & Whitfield

Until vnotus holopvga Hall

I'tyclioparia Adanisi Billings

Hou.seuBis Walcott

X
X

KingiMeek (sn.)

raiser Billings (sp.)

Piocliensis Walcott

? I'nwpecten.sis Walcott

qiuidians Hall & Whitfield (.sp.)

X
X

subcoi'onata Hall & Whitfield (sp.)

(A) stienuus Billings

....

■ • ••

(773)

■4 'tf »|

>.<i m-

:*'i

iii

t.R,

a ^i

CAMBRIAN FAUNAS OF NOllTIl AMIMilCA.

IBULL. ,'!0.

■i

f: ,x.|

■ m

;!*

"'V

w ^

i.;: li.S

Table of distribution of Middle Cambrian

fauna ■

— Contiiiuud.

•

1
I.

a3
G

a
43
,a
u

•PH

a
a
«
M
.a
fc

s
c
O

PCECILOPOD A — Continued.
Ptyoboparia Teocer Billings (up.)

X
X
X
X

VulcannR Billini?ft (f^n.)

•

2 8P.t

Croi>icophaln8 Augusta AValcott

X
X

Llliana Wnlcott

Orv*'^0(;epliJiluH piimiin Wttlcott

AnoniiH'art) parvutn AValcott i

Protypufl Ilitclicocki Whitfield (sp. )

X
X

sonectus BUIId^b (sp.) ...

X
X

BiLibviiriaGUS IlowoUi AValcott

X
X

productus H. & "W, (sp.)

8UMMAUY OF FAUNA.

§ 94. The total fauna, as known to me, includes 43 genera, 107 spe-
cies, and 2 varieties:

AlgOQ

Spongiaj

llydrozoa

Crinoidea

Annelida

Hracliiopoda

Lamellibranchiata

Gasteropodii

I'teropoda (1 variety)

Crustacea

PtBcilopoda (1 variety)

Total

a
O

I)
14

I
1

KIT

§ 95. Of the above, 14 species are not described in the text. Five ot
these are from ('anada and have not yet been named or described, \ iz:
2 species, Orthis; 1 species, Pt.vclio]>.'iria; 1 .species, Ciiiiiarella; ini<l 1
species, Agnostus. The 3 spe(;ies of rianla' are Wit to be studied witli
the Upper Cambrian iiuuia. A fragment of a species of Orthisiiia or
Orthis occurs at Troy, New York, and also one at Parker's quarry, Vci-

^ (774)

^T^'^

WAIfOTT. I

INTKODUCTOTIY OBS/^.RVATIONS.

1
1

a
«

....

III

1.")

Ill,

nioiit, that iiidicato spiTicH (lifli-r. 'it (Voui tlioso dosrvibctl. Tlio uiido-
Hcribed specio.s of Ilyolitlu's is .. uii Troy iiiul uill i iithjiliiy bo de-
scribed by 'Mv. Ford. The siu'cits ol Ptyc!ioi);iiiii, from Nc\ii(Ui, is
known oiwy by imni'rlcct tVaj'iueiil.s, and Om' Nc'va<la spccii's of .Vrchae-
ocyathus is not rcprcsonted by sections that yivc anytiiin^ of the exte-
rior form or snrlaci'. The Eocystites, IVoni Vermont, is represented
only by a few detached plates.

STRATIGIIAPIIIO POSITION OF THK I'AUNA.

§ 00, The relations of the Geor^na and the rots<lani launas have been
ii(tti(^ed in si)eakin^ of the Nevachi sections, where tliey are sho\vu to
bo stratigraphically sei>arated by .'),(UI() feet or more of limestone. Bnt
three species, Protospovfjiafevcairaia, Stcnothcca ehwfjdta, and Acrotreta
gniDiia, are known to pass np to the l'i)per C^ambrian or Potsdam hori-
zon. In the tieorjiia section, Vermont, one t)f the si)ec!es, I'tt/chopdria
Adamni, appears to ])ass np into liie hori/on of the "h-ntile" (!)) of the
section, where the faniia is more like that of the Potsdam; and, of
the other 8i)ecies, Orthisiua oriexfolis is mnch like 0. r<pina of the
Potsdam sandstone of Wisconsin; bnt liie lamia as a wliole is so clearly
distinct from the tyi)ical Potschim of New Yoik, Wisconsin, Tennessee,
A'abama, Texas, Arizona, Xevada, and Montana, that, even withont
any section to show their relations to each other, 1 wonld not think of
correlating thero as possible faunas of the same seolo^ic hoii/on.

§97. The stratigraphic relations of the fauna of the Parado.xides
liorizon of St. John, Braintree, and Newfoundland are not so clearly
l)roven as those of the rj])per ('amln-ian fauna. Tiie t)nly I(M;ality known
where the two famias are in the same geograi>hi(! area is about Con-
ception Bay, Newfoundland. At Topsail Head about KM) feet of lime-
stone is exposed, overlaid by a dark shale. AH stratigraphic coujiectiou
with other sections in the vicinity is broken. The fossils in the lime-
stone are not numerous, but j\ir. Billings pronounced them Potsdam
(Gcol. Newfoundland, }). bj7; reprint of report for IS(iS), and identi-
fied Salterella and Crania {Kutorijina) Lahradorica, and I found in the
collections of the Geological Survey of Canada Sveiiella ntlcnlaia, Ste-
nofheca rugoso, Iphidea hella, and Frotypm acncctm yar.parrnhis, whi(!h
S'ives six species that are also known from the JMiddle Cambrian h(ni/on
of L'Anse au Louj).' Special stress is i)laced by the writer on the occur-
rence of these fossils at To])sail Head, as it is in the midst of the Par-
adoxides basin. ]\Ir. Alexander ]Muiray correlated the Toi)sail Head
limestone with that of other localities, and ])laces it beneatli the Para-
•loxides-bearing shales of St. Mary's Bay (on the page cited above),
hui without paleontologic or stratigra])hi(! evi<lence that authorized
liiui to say more than that a supposed connection is indicated.

' Mr. Billings called all tho Middles Caiiiliriau lauiia Lower Potsdam, wbich ex-
Iiliiiiis Ills referring Mio Topsail Head fossils to the Potsdam.

Bull. 30 4 (775)

m^A

iiii

ll?

.-' I ,

CAMBRIAN FAUNAS OF NORTH AMERICA.

ImiLL.30.

J 98. Not having 8tratigrai)Uic ovidotuie of the relation of the GeorKia
or Middle Cambrian fauna and tlie ParadoxideH or Lower Caniluiun
faui.a, other than that tliey occur in the same area and are not in the
same stratum of rock, we turn to the fauna to aid in tlie settlement ol'
the question.

Of the 32 genera of the American Paradoxidcs horizon, 15 pass up
into the Oleuellus horizon, viz : Arenicolites, Protospoiigia, Archicocy
ttthusT, Eocystites??, Lingulella, Acrotreta,Acrotliele, Kiitorjjina,Ortliis,
Stenotheca, Flyolithea, Agnostus, MicrodiscuH, Solenoplcura, andPtyclio
paria. Of these, Arenicolites, Protost>ongia, Lingiilclla, Kutorfjina,
Acrotreta, Orthis, Hyolithes, Stenotheca, Agnostus, MicTodiscus ?, and
Ptyohopariacontinueon up into the Potsdam orUpper Cambrian horizon,
leaving but four genera that are common to the Middle antl Lower Cam-
brian horizons. One genus, Dendro^raptus, is doubtfully identified in
the Paradoxides horizon of New Brunswick, and occurs in the Ui)i)er
Cambrian, but is, as yet. unknown in the Middle Cambrian. The geiins
Agraulos is also found m tlie Lower and Upper, but not in the Middle
Cambrian. Of species, not one of the Gl of the Ameiictan Lower Cam
briau fauna are known to occur in the Middle Cambrian fauna, whicii,
with its 107 spcicies, stands out clearly from the older fauna and also
from the more rectit Potsdam fauna, as but 3 of its species, iVo/«
apongiafcnestrata, Stenotheca. eUmgata, and Acrotreta gemma, are known
to be common to them ; and ^.0 of the genera in the Middle Cambriiui
are not known to i)ass up into the Potsdam or into the Lower Silurian
(Ordovician) fauna. Not one species is known to be ctmimon to tlic
Lower and Uj)per Cambrian horizons.

GENP.TIAL PALEONTOLOGIO CHARACTEUS OF TUE FAUNA.

§t)9. Owing to the obscure cliaraeter of the two species of Palicoi)Ii,y-
eu8,it is difticnlt to say that tlio> were not formed by tilling in of worm
borings or the trails of some annelid or moUusk. Cruziana 1 now \w-
lieve to have been a ftntoid, and hope soon to present the reasons for tiie
belief, as a beautiful series of specimens was obtained from theUi)i)er
('ambrian strata of the section in the Grand CaSon of the Colorado,
Arizona.

SPONGIiE.

§ 100. The sponges r^f the Middle Cambrian bid fair to form one of
the important elements of the fauna, as they now include 5 genera and
10 species, and the collecting at Silver Peak, one of the most prolific
localities in Nevada, has been of a supexficial character. Ethmophiilhm
profundum grows to a large size and is, as describe*! by Prof. Alpheiis
Hyatt, the reef builder of its time. (Science, vol. vi, p. 380, 1885.1
Archaoeyathus Atlanticus, another prolific ibrm, has a wide geographic
range, as we find it both in Labrador and Nevada.

(776)

li^l

"mw

flkVCOTT.]

INTBODUCTORY OBSERVATIONS.

Tho genus Ethmophyllum is a very intereHtiiifj form, for in it wo oh-
8('rvo tbe septa, vesicular striictnrt', and porilrrons .system liiat Ijitor,
in Paleozoic time, appear in the vaiious divisions of tlie Zoantliaria
brunch of tho .\ctinozoa (Zaphn'ntis, Cystiphylhim, I'avositcs, &c.);
to ini!lndo Arcliaiocyathns and allied {^cncia, I>i'. IWnneniann lias pro-
poHi'd a new (dass of the Cddentcrala, which he calls Ardiieoeyatliinie.

Li'ptomitus Zitteli in the only r('i)r('senfative we have in the Cambrian
ehowing the base or root of tin- " an(rhorin}ir sponji;es."

I'rotOHpongia fencHlrnta ranpss nearly thronf;h the Candnian of Wales,
iiccording to Dr. Uicks; and in America (he genns, if not the species,
is now known from both the jjower Cand)rian of New Unmswick and
the upper portions of the Middle Canduian of Nevada, the great ver-
tical range being accompanied by a corresjjondingly wide geogra])hic
distribution. Like most of the other Cambrian sponges (here is not
enough known of its structure to accurately place it in the ciassitica-
tlon of the Hexactinellidce. The minute structure of Arelueocyathus ami
Ethmophyllum is not well shown in the Cand)rian si)eciinens, owing,
in all probability, to the destruction of the spiouhe in the replacement
by calcite. In the one sihcified species, Efhmophnllnm Mingnnemift^
from the Lower Silurian, tho spiculai are preserved, aiul in Archo rya-
thuH r'Uingui w^e observe what appear to be spicuhe in the cup and iu-
ters*^ spaces, but not in the walls or septa.

IIYDROZOA.

§ 101. BipJograptiis ? simplex is a form allied to the leaf-like grai)to-
litt's of the Lower Silurian (Phyllogra])tus), but we know too little of
the species to even give it a proi)er generic reference ; the same may
be said of the species referred to Climacograptus ? Emmonsi. All we
can say of them is that they represent the graptolida^ at the horizon of
tho Middle Cambrian. Matthew recogni/es two getiera of grai)(olites in
the St. John Group, Dendrograptus and Protogniptus; the former
being found in the Upper Cambrian (Potsdam) horizon shows that the
type ranges through the Cambrian System.

t?}

'^■4

^§

.'' .UK'

ECniNODKllMATA.

§ i(Yl. A giance at tho figures illustrating Eocy^tltesff lotigidacti/lus
shows that we have not yet reached a simple type of the Cystoidea in
this Cambrian fauna, although, in the irregular size and groat number
of the plates, the pore-like openings at their margins, and (he long
simple arms, a general looseness of organization is indicated that is
wanting in the comi)act, regular forms of the siqierior fauna.

The genus was founded on single plates from the St. John Group;
ami s;>incwhat similar plates occur iu the Wisconsin Potsdam sandstone.
Until entire or nearly entire specimens are I'ouml from these horizons,
've cannot compare tho E.ff lonf/hlactijtKs with what these plates repre-
sent.

(777)

S>!.

I M

iii

~M\

CAMBRIAN FAUNAS OP NOT?TH AMERICA.

BUACHIOPODA.

( BULL, 80.

§ 103. Nine geiieni and 24 species from the Middle Cambrian, and 6
genera, with 12 specios (Matthew), from the Lower Cambrian of Aiiierica,
show a total of 10 genera an<l 3(5 species for this class, from below the
Upper Cambrian (Potsdam of xVmerica, Olenus Zone of Enrojje).

§ 104. The family Liugulidie is represented by 1 genus and 2 species,
each of which presents the high tissured area of the genus Lingiilella
and also its delicately sculptured surface ; and L. FAla affords a glimpse
of the muscular scars of the interior of the dorsal (?) valve that places
the genus near the genera Obolella and Lingiila.

§ 105. The Oholidaj has the largest <level»)pment of the Middle Cam-
brian families of the Brachiopoda, and includes .'i g«niera and 12 species,
viz: Kutorgina, 4 species; Iidiidea, 1 sj»ccies; Acrotrota, 1 species;
Acrothele, 1 sj)ecies; Obolella. 5 species. The genera Obolella and Ku-
torgina represent the Obolida- pr(>;)er, and the 3 remaining genera the
Siphonotretida', if we may use the latter as a subfamily. Obolella first
appears as O. maculata Hicks in the Paiadoxides horizon (Lower Cara-
bri'.iii) of Wales, and reaches its greatest development in the Middle
Can\biian horizon of America, fioin which 5 well detined species have
been recognized. From the Upper Cambrian we at present know of but
2 sjiecies that will be retained in ihe genus. The chara(;ters of the genus
are well shown by the figures on ])lat"S iy and x. The genera Aero-
treta, Iphidea, and Acrothele belong to a natuial group having a conical
ventral valve ])ei ."orate at the a])ex, wit li more or less of a false area and a
dejjressed dorsal valve. Acrothele is considered by its author as most
nearly related to the genera Obolella and Acrotreta, but, from the in-
forn'ation >V'^ now ha-, e, I would place it nearer to the latter and still
nearv^r to the geiius S(diiza!id>()n (Monographs United States (leolog-
ical fciurvey, vol. viii, j). ()!»).

Tl'.e genus Kutorgina has a wide geographic distribution and a vertical
range from the Lowei- Ca nbrian of Sweden and New Urunswiek up
thro igh tlie MidV.e Cambrian, where it reaches its greate«L (levc'<>i>
nient as now known, into the U})per (Jandjrian of Nev.ida and Montana,
<ui tie west<'rn side of the American contineirt. It is not certain that
the genus may not be divided, as the type K. ciiujuUUa is a large calca-
reous shell and the other si)ecies aresnniller and horny or corneo-calca-
reous. We find tiaces of the nni^cnlar scars o:i the interior of thi
valves of the A', cinfjidata, but not of the othei spetaes.

§ 100. The Strophomenida' has 2 genera and 8 s])ecies, 4 of which
are not yet described. The generic reference to Orthisina is doubiful
in most instances, as the condition of the si)ecimeMs is too imper-
fect to give the characters of the interior of the valves. O. fcslinata
appears to be a true Orthisina, and the otiieis are considered as pro-
visi(uially referred to the genus. The 1 sjieiiies referred to Orthis if*
apparently not an Oithisina, but, at the same iinie, its surface chai-

(778)

i:l' '::i

WALCOTT.]

INTRODUCTORY OBSERVATIONS.

actcrs and the interior of the ventral valve tend to remove it from the
ty|)i<!id foinis of the genus Orthis.

§ 107. The Rhynchonellida; appears thus far iu be restricted to the
genus Camarella, which makes its first appearance in the JMiddle ('ani-
briaii of I^abrador and Vermont. The Vermont species is somewhat
doubtfully referr«;d to the genus, and 1 ho Labrador species is yet uude-
scribed. It is very much lik«' Triplcmt prhnqrtJlaJis of the Up])er Cam-
brian (J'otsdam) horizon of Wisconsin and Texas.

LAMELUUHANC IllATA. '

§ 108. M. I>arrande suggests that tiie little shell Fordilla Troj/ensis
may be the valves of a crustacean, but, at the same time, calls attention
to its resemblance to shells ot the genus Xucula; and 3Ir. Ford noticed
the resemblance of the single valves to a small Modiolopsis. I think
tiiat it is a laniellibranchiate shell, but there is an element of uncer-
tainty owning to the obscure (sharacter of the muscular, impressions.
If a true lamellibranch it is tiie earliest now known, and the recoid of
the class is not taken uj) again until the passage beds between the C!am-
brian and Lower Silurian (Ordovician) are met with. Jt cannot be tluii
Euvha,s»u( BJumenhadd Billir.gs of the Calciferous formation ((ieol.
Can., Pal. Foss., vol. i, p. 3Gi, tig. ^^48) is the first of its class, judging
from its size and its relation to the genus Conocardiuni. Eopteria
typica, E, Bichardsoni, and J'J. ^ ornata Billings (Ibid., i)p. 221, liOG, .SOT)
conijjlete the list of the Calciferous sj)e(!ies, and, like E. Blumenbachi,
arc far in advance of what one would anticipate of the first of the
family to which they are referred (Aviculidie).

GASTERf)PODA.

§ 109. The type represented by Stenotheca ruffOfid ranges through-
out tlie Cambrian, ami is ioan<l on botli sides of t'.ie Atlantic basin in
the Lower Cairdirian aiid from Labrador to New York in the Mitldle
Cambrian. Its rei)resentative in the Wisconsin I'otschim sandstone has
not yet been described. F)Oth the genera Stenotheca '^1(1 Scenella are
Patella-like shells, with unbroken margit; ami surface and with the
apex turne<l forward, as far as we now know from the Midtlle Cam-
brian species.

Mv. Cr. F. iSlatthew considers Stenotheca Icadini as nearer the gen-, s
Parmophorus of the Fissurellidu' than to the Fattlli<la' (Canadian Kec.
Sci., vol. ii, p. 10, 1880).

The minute shell referred to riatyciya,sprhu(vvum is, as far as known,
tlu' lirst representative of the genus Capulus. which, increasing in nom-
bers very slowly through the Lower Silurian (Ordovician), reacheh a
great development in the Devonian, and, diminishing in the Carbonifer-
ous, comes down to the present with a few widely-distributed species

All thegasteropo'.isa))p(\ir to have been shadow-water forms, although
we now tiud them preserved in compact limestones.

(779)

■^l

■■■»'.■•;■

■ml

■4

, I-.;

)■•"'

111

.Pill

■)'i ■

i^'

CAMBRiAK FAUNAS OF NOtlTR AMEHICA.

(bull. 30.

PTEKOPODA.

§ 110. Three geuera and nine species, with numerous specimens, give
this class a prominent position in most localities of the Middle Cambrian
strata, although in several instances but few specimens sre met with-
This is noticeable at Georgia, Vermont, and in the Highland Range of
Nevada. Specimens occur abundantly in the silico-argillaceous shale.s
of the Wasatch Cambrian, in the clear limestone of the Ely Mountains
of Nevada, in the conglomerate limestones of Troy and Bic Harbor, and
in the silicious magnesian limestones ("Red Sandrock") of Vermont,

The extended range of the species Hyolithes Billingsi and H. princepit
from Labradorto Nevada is in accord with the free habits of the young,
if not of the older, individuals. The presence of transverse diaphragms
in the tubes of H. communis and II. impar allies the species to the types,
in the St. John series, that have been so well described by Mattbew
under the genera Diplotheca and Camarotheca. A noticeable feature
of the presence of the diaphragms is their almost total absence in tbe
species of the Upper Cambrian, Silurian, and Devonian.

The slender tube of Hyolithellus recalls the Dentalidsej and its operc-
ulum, which is one of the prettiest fossils of the Troy Cambrian rocks,
might belong to a shell allied to Dentalium and also to Hyolithes.

Although it is stated, under the description of the genus Salterella,
that I agree with M. Barrande that the relations of the genus are with
Tentaculites and Hyolithes, th.-^re is an element of doubt so strong that,
until more evidence is brought forward, the genus is left in a doubtful
position in relatioa to its affinities to other genera of the Pteropoda.

CRUSTACEA.

§ 111. The strongly-marked Leperditia Troyensis is not unexpected at
this horizon, as the genus is present in the Lower Cambrian of Wales.
In / \rgenta one of the largest species of the genus is found, if tbe
shell referred to Leperditia truly belongs to it and is not one side (tf
the carapace of a phyllopod crustacean allied to Hyraenocaris or Proto-
caris. The latter is possible, but, from a careful study of the specimen,
does not appear probable. Protocaris Marshi is one of the earliest, if
not the earliest, phyllopod crustacean now known, and is closely allied to
the Upper Cambrian Hymenocaris verm'waiida.

POSCILOPODA.

§ 112. I prefer to use Pcecilopoda, as the class name includes the
Trilobita, for reasons given in 1881 (lUill. Mus. Comp. Zoology, vol.
viii, pp. 208-211). The class is represented by the Trilobita in the
Cambrian, with the exception of the liniuloid-like Aglaspis of the Wis-
consin Potsdam sandstone. The Euryjiterida presents its earliest form,
as at present known, in Uohinognafhvn Clrvelandi of the Middle Lower

(780)

WlMOTT.]

INTRODUCTORY OBSERVATIONS.

Silurian (Ordovician) of New York (Anier. Jour. Sci., 3d ser., vol. xxiii,
p. 213, 1882).

§ 113. The Trilobita, with 14 genera and 45 species, so far outranks all
the other orders that without the latter the stratigraphic position of the
Middle Cambrian could be readily determined, although the SpongisB,
Brachiopoda, and Pteropoda present a facies distinct from that of the
some classes in the Lower and Upper Cambrian.

§ 114. The AgnostidaB is represented in the Lower Cambrian of Amer-
ica by 2 genera and 10 species: Agnostus, 8 species; Microdiscus, 2
species. In the Middle Cambrian, by Agnostus, 3 species, and Micro-
discus, 4 species. Several species of Agnostus occur in the Upper
Cumbrian, 10 or more ; and Microdiscus is represented by the curious
Pemphigaspis bullata of the Wisconsin Potsdam sandstone (Sixteenth
Rep. K Y. State Cab. Nat. Hist., p. 221, pi. 5A, figs. 3, 4, and 5, 1863).

Agnostus interstrictus belongs to the widely-distributed A. pisiformis
type, of which A.Acadicus is the representative in the St. John series of
New Brunswick, and A. Joscpha in the Wisconsin Potsdam sandstone.
A. nobilis is not unlike A. parilin of the Wisconsin Potsdam sandstone.
(Sixteenth Eep. N. Y. State Cab. Nat. Hist., p. 179, pi. x, figs. 24 and
25, 1863).

In Microdiscus there is a slight advance on the typical form of Agnos-
tus with two segments, and I think the genus should be included in
the family Agnostidse. The 4 species of Microdiscus have a somewhat
similar appearance, and differ from the Lower Cambrian (St. John)
species M. Dawsoni and M.pulchellus {=M. punetatus, U. S. Geoi. Sur-
vey, Bull. No. 10, p. 24, pi. ii, figs. 1, la-c), the former having ahi :hly
ornamented surface and the latter a strong nuchal spine.

§ 115. The genera of the Olenidfe of the American Middle Cambr)an
fauna known at present are: Meson acis, 1 species ; Olenellus, 4 species;
Olenoides, 8 species; and Bathyiiotus, 1 species. The genus Mesonacis
is the connecting link between I'aradoxides of the Lower Cambrian and
Olenellus of the Middle Cambrian; in the development of Olenellus, the
genetic relation of that genus to Paradoxides is shown more clearly.
Mesonacis is confined to one locality, as far as we noM know, and its
value in stratigraphic geology is thus limited.

The two geneva. Olenellus and Olenoides have a wide geographic range
and occur together in most localities. Olenellus is more limited in verti-
cal range, having been found through about 500 feet of strata, while
Olenoides extends up 1,200 feet or more in the Highland Eange section
of Nevada, and probably, into the Upper Cambrian horizon. The genus
Olenellus, wherever found in a well-defined section, is characteristic of
a horizon far below that of the typical Upper Cambrian or Potsdam
horizon of North America. Its relations to other genera are discussed
under the remarks on the remarkable species 0. Oilberti.

Olenoides, with its 8 species, is nearly as characteristic of the

(781)

i^;:-

lip^ i

f'. ■■'

CAMBRIAN FAUNAS OP NORTH AMERICA.

(nutt. 30.

Middle Cambrian fauimas Olonelhis. 0. tijpicalisi» a strongly-marlvorl
type and appears to be one of the forms that carried the Paradoxides
typo up through the Cambrian to the Dicellocephalus type of the Uppor
Cambrian. 0. Jl/arcomis also allied to Dicelloceph.ilus ; and thegemi.s
Olenoides, as a whole, is tlie representative of Dicellocephalus of the
Upper Cambrian. Bathynotus holcpyga is anotlicr curious form, re-
stricted, so far as known, to one locality and hoiizon. Its relations
appear to be with Olenoides and Dicellocephalus.

§ 116. The Conocephalida; family predominates in the trilobitic portion
of the fauna in having 6 genera and 21 species.

Ptychoparia Piochensis, with its 19 thoracic segments, adds to tlic
genus Ptychoparia a greati^r range in the number of segments of the
thorax, 14-15 being changed to 14-19. The other species of the genus
are essentially of the same gencMal type as the typical forms.

Crepicephalus is hardly of generic value, although so used in this
paper. The study of the Upper Cambrian species will assist in the
determination of its generic position.

Ory otocephalus adds another genus to the Conocephalidae, and it ap-
pears to be warranted by the combination of cfiaracters observed in
the head and pygidium. The peculiar glabellar furrows and the strong
spinous pygidium are unlike any other known to me.

The genera Anomocare and Solenopleura are not sufficiently well
represented. to demand special notice.

In Protypus there is a combination of characters recalling Ptychoparia ;
at the same time, the glabella and head point to Angelina and Batiiy-
urus. The genus has a wide geographic range and is, as far as we kno-y,
confined to the Middle Cambrian.

C 117. There is a group of genera intermediate between the Conoce-
phalidae and the Asaphidae that, as yet, have not been arranged in any
defined family. They include the genera Bathyurus, Bathyuriscus, and
Asaphiscus, and may be defined as the family Bathyuridie, as follows:
Trilobites of an oval form; medium sizj; capable of rolling v.p. Head
a little longer than the pygidium ; glabella distinctly defined, with or
without distinct glabellar furrows ; facial sutures terminating posteriorly
within the genal angles and anteriorly on the frontal margin; eyes
medium -size to large, semilunar. Thorax with 7-9 segments; pleurae
furrowed. Pygidium somewhat smaller than the head, formed of nu-
merous (6, 8 + ) closely united segments; border flattened, smooth.
Doublure of head and pygidium thin and well developed. The general
assemblage of characters places the Bathyuridie close to the Asaphida',
but I do not think we should include its get era under the typical gioup
of the latter.

§ 118. AsnpMscun WJuehri suggests forms placed under the genus
Asaphus, but the glabella and the direction of the facial suture in front
of the eyes are those of the ConoceidialidiB. Tiie .species and genus is
known from only one locality and Irorizon. Bathyimscm Ilowelli and

(782)

WAL OTT.]

INTRODUCTORY OBSERVATIONS.

B. prodncta appear at the same geologic horizon as Asaphiscus Wheeleri,
but not at the same localities. In the presence of well-marked glabellar
furrows and the general appearance of the entire body, Bathynriscus
is allied to Ogygia. With the fragmentary material of the Upper Cam-
brian still unstudied, we will not attempt comparisons; but from the
resemblance between this group of trilobites and the Asaphida? of the
Lower Silurian (Ordovician) there is probably a group of genera and
species corresponding to them in the Upper Cambrian or Potsdam
horizon.

§ 119. Reviewing the Middle Cambrian fauna as a whole, we find that
it combines the characters of both the Lower Cambrian and the Upper
Cambrian faunas, and yet is distinct from either of them. There does
uot appear to be an equivalent fauna in tlie Cambrian system of Europe,
either in Bohemia, the Scandinavian area, or in Wales. The nearest
approach to it is on the island of Sardinia. (See close of remarks on
the genus Ethmophyllum, p. 80.)

§ 120. The conditions that developed the Middle Cambrian fauna ap-
pear to have been largely peculiar to the American continent. During
the deposition of the St. John series of the Lower Cambrian or the
Paradoxides strata, we learn from the European and the eastern Ameri-
can sections that tiie fauna was essentially of the same type over the
entire basin (Atlantic), and, from the evidence known to date, that the
fauna did not extend west of a line passing northeast through Eastern
Massachusetts to New Brunswick and Newfoundland.

§ 121. That there were deposits of sediments to preserve the fauna, if
it extended wtistward, is shown by the thousands of feet of sediments
below the Middle Cambrian faunas of Utah and Nevada.

§ 122. From the evidence we now have it appears to me that during the
existence of the greater portion of the Lower Cambrian (Paradoxides)
fauna a barrier existed that j^revented its extension westward of the line
mentioned (§ l20) ; that towards the close of the time of the Paradoxides
fauna the barrier was removed to the northeast, and its descendants
entered the westward seas a i'! spread over the entire interior basin and
formed the middle Cambrian fauna. In the Atlantic basin the Para-
doxides fauna persisted to a greater or less extent, and mingled with
the types of the Upper Cambrian fauna, as in the Tpper Lingula Flags
of Wales.

k il?3. If the strata of the Grand Cation, Llano, and Keweenaw groups
are of pre-Cambrian age or older than the strata carrying the Paradox-
ides fauna on the eastern side of the continent, and also older than the
strata of the lower portion of the Wasatch section, another explanation
is offered for the absence of the Paradoxides fauna in the central and
western portions of the continent. During the period of erosion of the
Grand Canon, Llano, and Keweenaw Formations, a land surface probably
extended from north of Lake Superior south to Central Texas and
west, on the south, to the Grand Canon region of Northern Arizona.

(783)

. i.

CAMBRIAN FAUNAS OF NOllTH AMERICA.

IBULL. 30.

How much larger it was we do uot know, but the orograpliic movetncMit
that brought the Grand Canon, Llano, and Keweenaw Formations above
sea level probably extended all along the central line of the continent,
leaving the Atlantic area and the Great Basin of Utah, Nevad.a, Arizona,
&c., areas of deposition during the existence of the Paradoxides launa,
and probably during the existence of the Middle Cambrian fauna, a
break on the north or south permitting the latter fauna to pass into tiie
western basin now covered by a portion of the Eocky Mountain area.
At the time of the Middle Cambrian fauna the central land area of the
IMiddle and Lower Cambrian epochs, or the Keweenaw land, was de-
pressed beneath the sea and a series of strata deposited that now con-
tains the Upper Cambrian fauna in all the localities where the strata of
the Keweenaw land and of the Upper Cambrian show their relations to
each other.

If this is a correct interpretation of the evidence now known, we may
look in vain in the interior basin for the Paradoxides fauna of the At-
lantic basin.

§ 124. That there was life in the older Cambrian or possibly in the pre-
Cambriau seas of the interior basin there is no doubt, as we have found
traces of it in the Grand Caiion Formation of Arizona ; and the develop
ment of that fauna is one of the problems yet awaiting solution.

§ 125. During the Upper Cambrian (Potsdam of America, Upper
Lingula Flags of Wales) the faunas of the two basins appear to have
had free communication with each other, and we now find them with
a more similar facies.

§ 126. The above views are more or less theoretical, but the facts de-
mand an explanation other than that the faunas of the Lower, Middle,
and Upper Cambrian were contemporan/^.ous, but in different geographic
areas. That the Upper and Middle faunas were separated by a great
interval is shown by the sections, and that the Middle and Lower faunas
were not contemporaneous is shown by the biologic evidence and the
indirect evidence of the absence of the Lower fauna in association with
the Middle fauna in the Newfoundland area, where they are now found,
in different sections, a short distance from each other, but separated by
faults and valleys of erosion, now filled by the sea.

§ 127. With the given facts there is little hesitancy in claiming for
the Middle Cambrian (Georgia or Oleuellus) fauna a distinct horizon in
the Great Cambrian System of the American continent. That firrther
research will result in discovering many connecting links between the
Lower and Middle and Middle and Upper faunas of the system there is
little, if any, doubt ; but that the three faunas are not of the same geo-
logic age appears to be now well established.

§ 128. Analytic comparisons with the Cambrian faunas of Europe are
omitted until the study of the Upper Cambrian fauna is further ad-
vanced.

§ 129. If students discover errors in these preliminary studies of the

WALCOtT.)

INTRODUCTORV OBSERVATIONS.

Middle Cambrian fannas, I will be glad to have nay attention called to
them. I also wish to obtain information of the occurrence of Cambrian
fossils and of the places where perfect or rare specimens may be seen
or obtained for study and illustration. Any information will be accept-
able, and the completeness of the work and its value to the student will
be increased by such assistance.

SUMMARY OF THE CAMBRIAN FAUNAS OF NORTH AMERICA.

§ 130. In the accompsinying table a summary is given of the Cam-
brian faunas of North America, as far as known to me, up to the pres-
ent date. A critical study of the Upper Cambrian faunas will eliminate
some of the genera and species, and also add others. The study of the
Lower Cambrian fauna of New Brunswick is now being carried forwaid
l>y Mr. G. F. Matthew, and that of the Upper Cambrian by myself, and
probably within two years the Cambrian fauna of North America will
be known to include more than 100 genera and 400 species, as to-day
tliere are 92 genera and 393 species published that I have included in
tiio fauna. Besides these there are a number of genera and species not
included that may not be based on organic remains or are synonyms of
some of those that are included.

■.

'! A' i

Summary of the Cambrian faunas of North America, by genera.

Lower.

Middle.

Upper.

No. of
Cenera.

Ko.of
species.

AI.QM.

x-1

x-1
x-1
y-4

1
1

x-2

Totals

2-3

3-0

SP0NGI2B.

Ai'cliffiocvatliiift ..... .... ...............

1 1
X 1

X 3

1
1
1

Kocorvnfi . ..... .... ...............

KllinionhvUnm ... .....................

X 4
X 1
X 1
X 1

X 1

Si riipljocliottis

Totals

3-3

5-10

1-1

HTDROZOA.

X 1

1
1

X 1

DinloffrantiiB

X 1

...1 1

X 1

Totals

2-2

1-1-|_ 4

CRINOIDEA.
Eocvstitca

X 1

X 2

1-1

ANITELIDA.
Aronicolites ... ... .....i.... ......

t 1

1 1

X 2

ScoUthns

1
X 1 1 1

Totals. „

1-1

2-3

(785)

B^ii

i' >

60 CAMBRIAN f^AUNAS OP NORTH AMERICA. tBciuo

Summary hf the Cambrian faunag of North America by genera — Continued.

Lower.

Middle.

Upper.

No. of
genera.

No. of
specieH.

BRACHIOPOOA.
Aorotrota

X 2
X 1

X 1
X 1
X 2

X 1

Aorothele . . ............

Camarella

X 1

X 2

Disoina?

Iphidea

X 1
X 4

I
g

Kutorgiua

X 2

X 2
X 2
X 8
X 8
X

Leptwna

LiDKulu 1

3
a

Liii£ulella

y 8

X 2

LinnarHDonia

X 2

OboIelUi . .

X 5
X 1

X 7

X 4
X 3
X 1
X 1

()

OrthiB

X 2

OriibisiDa

){

Triplesia

Totals

8-12

0-24

12-32

LAMELLIBKANCHIATA.
FordlUa

X 1

GASTEROPODA,
fiellorophon

X 1
X 1
X 1

BiUiiigsia

Kiiomphalns

Harttia

X 1

Holopea

X 1
X 1
X 1
X 1
X 2
X 3
X 1

Maolarea

Metoptoma

OphUeta

Paloiacmea

Platyceras

X 1

Pleurotomaria

Scenella.

X 4
X 2

Stenotheoa

X 6

1 1

X 1

Straparollina

Totals .

3-8

3-7

11-14

• 14

— ._

PTEROPODA.
Diplotheca

X 2

HyolithelluB

X 1
X 6
X 2

Hyolithes

X B

X 3

SaltereUa

Serpnlites

..........

X 1

Totals

2-7

8-9

2-4

CRUSTACEA.
Beyiichona

X 2

Climactichnites

X 1

Hipponicharion -

X 1
X 2

Lepidilla

Leperditia

X 2

•

X 2

Lepldltta -

X 1

Notbozoe

X 1

PrimitUI :, :

X 1

86)

wALcorr.J INTRODUCTORY OBSERVATIONS. 61

Summary of the Cambrian faunaa of North America, hy genera — Cuutinued.

CRUSTACEA— Continued.

Protichnltea

ProtooariB

Totals.

FCEOILOPODA.

Aglaspis

Agraalos

A gnostna

Amphiont

Anopolenns

Anomooare

Arethusina

AHaphisons

Batbynotns ■.

Batbynrnst

Buthyurisons

Chariocephalns

Couoooryphe

Crepicephalna

Ctenocephalna

Dicellocephalns

niwnuma

MeRonacia.

Microdiscns

Ogygia?

Olenellas

Olenoidea

Olenng

Oryctocephalns

Paradoxidea

Pemphigaspia

Ptotypna

Ptychaapis

Ptychoparia (and anbgenera)

Solenopleura

Triarthrella

Totida.

Upper Cambrian. .
Middle Cambrian .
Lower Cambrian. .

Reappearances.
Total fauna —

Lower.

6-7

X 5
X 8

X 1

K 3
K 1

X 2

X 8

X 6

X 1

Middle.

X 1
2-3

Upper.

X 1

4-6

X 3

X 1

X 1
X 1

X 2

X 1
X 4

X 4

X 8

X 1

X U
X 1

X 2
X 10
X 15

X 1

X 12

X 2

No. of
genera.

X 1

X 29
X 1

» 1
X 1

X 1

X 7
X 6U

X 1

»^5

14-45 I 10-146

No of
apucies.

2
3

•29

226

StratigrapMo r^sumS.

Genera.

52
43
32

SpeciuB.

127
35

213

107

306
3

393

(787)

'P: ';

'^-.

!f V ■■ i

CAMBRIAN FAUNAS OF NOBTH AMERICA.
Zodlogic ri»um4.

[BVLU 30.

AlgB

SponRias

n.ydrozoa

Ciinoidea

Annelida

ISrachiopoda

Lamellibranohlata

Gasteropoda

Pteropoda

Crastaoea...

FoBcilopoda

0«Berft.

Specie!.

22(1

39»

§ 131. Oenera limited to the Lower Cambrian. — Eocoryne, Protograj)-
tus, Liunarssouia, Harttia, DiplotUeca, Beyrichona, Hipponicbarion,
Lepidilla, Lepiditta. Priuiitia ?, Paradoxides, Aoopolenus, Conoco-
ryphe, and Ctenocei)lialu8.

§ 132. Genera limited to the Middle Cambrian. — Etbmophyllum, Lepto-
niitus, Iphidea, Fordilla, Scenella, Hyolitliellus, Salterella, ProcOcarivS,
Anomocare, Asaphiscus, Bathynotus, Batliyuriscus, Mesonacis, Ole-
nelliia, Olenoides, Oryctocephalus, and Protypus.

§ 133. Genera of the Upper Cambrian not occurring in the Middle and
Lotcer Cambrian. — Paloeocborda, Scolithus, Discina, Leptaena?, Lingula,
Lingulepis, Triplesia, Bellerophon, Billingsia, Euomphalus, Holopea,
Maclurea, Metoptoma, Opbileta, Palseacinea, Pleurotomaria ?, Serpu-
lites, Climacticbuites, Notbozoe, Proticbnites, Aglaspis, Ampbion ?,
Aretbusina, Batbyurus ?, Cbariocepbalus, Dicellocepbalus, Illaenurus,
Ogygia?, Olenus ?, Peniphigaspis, Ptycbaspis, and Triaribreila.

§ 134. Genera common to the Lower and Middle Cambrian. — Arcbaecy-
atbus, Protospougia, Eocystites, Areuicolites, Acrotreta, Acrotbele,
Kutorgiua, Liugulelhi, Oitliis, Stenotbeca, Hyolitbes, Agnostus, Micro-
discus, Ptyclioparia and subgenera, and Solenopleura.

§ 135. Genera common to the Middle and Upper Cambrian. — Cruziaua,
Palseopbycus, Prolospongia, Arenicolites, Eocystites?, Acrotreta, Cani-
arella, Kutorgina, Liugulella, Obolella, Ortbis, Ortbisina, Pbityceras,
Stenotbeca, Hyolitbes, Leperditia, Agnostus, Crepicepbalus, Micro-
discus ?, and Ptycboparia.

§ 136. Genera common to the Lower and Upper Cambrian. — Den(bo-
graptus, Arenicolites, Eocystites ?, Acrotreta, Kutorgina, Liugulella,
Ortbis, Stenotbeca, Hyolitbes, Agraulos, .A.gnostus, Microdiscus '?, and
Ptycboparia.

§137. Genera common to the Lower, Middle, and Upper Cambrian.—
Protospougia, Arenicolites, Eocystites?, Acrotreta, Kutorgina, Lingu-
leiJa, Ortbis, Stenotbeca, H; olitbes, Agnostus, Microdiscus ?, and Pty-
cboparia.

(788)

WAI.COTT.)

INTKODUCTORY OBSERVATIONS.

§ 138. Of the 52 genera in the Upper Cambrian, 17 may be said to be
typical of the Second fauna, viz, Diaciua, Liugula, Lepttena, Ortliis,
Triplegia, Bellerophon, Euomphalus, Ilolopea, Maclnrea, Metoptonui,
Opliileta, Plenrotomaria, Hyolitliea, Serpulites, Ampliion, Bathyurus,
and Ogygia. Of the above genera, Discina, Plenrotomaria, Ampliion,
Bathyurus, and Ogygia are doubtfnlly identified in the Cambrian. Sev-
eral other genera pass np into the base of the Lower Silurian (Ordo
vician), but are not considered as typical of the Second fauna.

§ 139. When an accurate stratigraphic and paleoutologic study is
made of the passage beds between the Cambrian and Lower Silurian
(Ordovician) systems, or the Potsdam and Calciferous Formations of
the New York and Canadian sections, we shall possess the data upon
which to comi)are the faunas of the two sections. At present thi.s
knowledge is, to a large extent, wanting.

CLASSIFICATION OF NORTH AMERICAN CAMBRIAN BOCKS.

§ 140. The following table expresses my view of the classification of
the various formations that go to make up the Cambrian system of
North America. It is subject to revision in details, but the main di-
visions are based on paleoutologic and stratigraphic data that I think
will render them of service in the permanent classification of American
Paleozoic rocks.

The faunas of the Lower Calciferous unite the characters of those
of the Upper Cambrian and Lower Silurian (Ordovician), and it will
often be difficult to determine to which system the strata containing
them should be referred.

Clas»ification of North American Cambrian rocks.

UPPER
CAMBEIAN.

Lower Calciferous.

Potsdam.
Knox.
Tonto.

Lower portion of the Calciferous Formation of New
York and Canada. Lower Magnesinn of Wis-
consin, Missouri, &o.

Potsdam of New York, Canada, Wisconsin, Texaa,
■Wyoming, Jlont.ana, and Nevada; Tonto of
Arizona 1 Kno.x Shnlos of Tennessee, GeorKia,
and Alabama. The Alabama section may extend
down into the Middle Cambrian.

MIDDLE
CAMBKIAN.

Geor}:ia.

L'Ansc ail Loup.

Prospect

Georgia Formation of Vermont, Canada, and New

York.
Limestone.s uf L'An.<(!au Loup, Labrador.
Lower p.ivt of Cumbrian section of Eureka and

Highland liange, Nevada. LTppor portion of

Wasatch Cambrian section, TJtali.

LOWJSE
CAMBRIAN.

St John.

Bralntree.

Newfonndland.

Wasiitcli.
Tennesson. ?

Paradoxides beds of Braintrec, Mass., St. John, New
Bmnswick. St. John's area of Newfoundland.

Lower portion of Wasatch section, Utah.

Tlje Oeoee conglomerate and slates of East Ten-
nessee are somewhat doubtfully included.

■I

(789)

CAMBRIAN FAUNAS OP NOUTII AMERICA.

|BULU,10.

WAUOTT 1

I '

|t*,:r'.:, <

The Grand Caflon, Lhino, and Keweenaw series are probably of pre-
Cambrian a'^e, and are omitted from the Lower Cambrian, altliough I
have heretofore made }• provision. il reference of them to the Cambrian.

§ 141. The first systematic arrangement of the formations of the Cam-
brian system of North America is that baaed on the pa1eontoIo|;ic work
of Mr. E. Billings by Sir William Logan. The Cambrian as a system
is not recognized, the formations from the "St. John's group" to tlie
Iludson River group, inclusive, being placed under the Lower Silurian.
Owing to its historic interest and value as a contribution to stratigrapliic,
geology, the table is given complete as found on page 46 of the Report
of the Geological Survey of Newfoundland for 1805:

EngUsh
Synonyms.

Caradoo

Caradooi ...

Llandeilo . . .

Tremadoc ... J
Lingula flags, i

Complete SBries.

12. HiulHon Eiver

11. Utloa

10. Trenton groap

9. Chajiy

8. Sillery ]

7. Lanzon y Quebec gronp.

8, Levis J

5. Uppor CnlclferouH

4. Iiower Cslciforons

il. Upper Potsdnu

2. Lower Potadam

1. St. John's gronp

Western Basin.

Hudson Biver .

mica

Trenton gronp.
Cliazy

L. Caloiferous .

U. I'otsdam

L. Potsdam ) .

Eastern Basin.

SiUery. .
Lauzon .
Levis...

L. Potsdam

St. John's group.

Kowfonndlud.

Sillery.
Lanson.
Levis.

V. Calciferoaa.
L. Calciferonn.
V. Potsdiuf .
L. Potsdam.
St. John's gronp.

In commenting on the table the author said:

It thiiB appears tbat tho lower portioa of the series is complete in Newfoundland
nud the upper in Now York and Central Canada. Divisions 3, 4, and 5 have not yet
been recoRnizod in tlio eastern continental region.

The St. John's group, 1, is represented at St. John, New Brunswick, by 3,000 feet
of black slates and sandstones, whoso fauna, described by Mr. Hartt, was correctly
refened by him to Etago C of Barraudc's Prii .ordial zone. It there reposes on older
schistose rocks, as yet unstudied, but by Mcsrs. Hartt and Matthews designated as
Cambrian. Tho slates of St. John's, Newfoundland, and the paradoxides beds of
Braintreo, Massachusetts, also probably bolong to tho same horizon.

. The Lower Potsdam, 2, is represented by several hundred feet of limestones and
sandstones on tho Straits of Belle Isle and on White Bay> in Newfoundland, and by
the slates of St. Albans and Georgia, Vermont.

The Upper Potsdam, 3, is that of Wisconsin and Minnesota, represented in tho
typical Potsdam of New York, which is overlaid by the Lower Calciferous, 4, while
the Upper Calciferous, 5, is only recognized in the northern peninsula of Newfomid-
land.

In addition I wish to add that number 1 is the Lower Cambrian, num-
ber 2 the Middle Cambrian, and number 3 the Upper Cambrian of this
paper. The additions made to our knowledge of number 2 since 1806
have been the discovery of the Georgia fauna about and below Troy,
in the Hudson River valley, by Mr. S. W. Ford; the discovery of tbe
same fauna at Eureka and at various other localities in Nevada and

(790)

Utah by
Lake, B
paper I
own inv<
ontologi
uecessar

§142.
be used
fauna of
rily be d
iiig the

WAUOTT ]

INTnODUCTOUY OUSEnVATIONfl.

Utah by tlie United Stutt'S (Jovcrmneut niirvcyH ; ami at Kicking FTorso
Luke, British America, by the Canadian (ft'ol«>;;;i<!al Survey. In this
jjupcr I have endeavored to HUin np the resultH of pant work and iny
own inveMtigationH, and to eHtHbliHh,on a tinner Htratigraphicand pale-
ontologic basis, the Cambrian Hysteni of the Contnient. The work is
ueceusarily imi)eriect, but it clears the way for future i'lVestigatiou.

ON THE USE OF THE NAME TACONIC.

§ 142. Several American authors claim tliat the name 'laconic should
be used to include the strata characterized by the first or Primordial
fauna of Barraude. If this is done, the term "Cambrian " will necessa-
rily be droi)ped. In reading over the arguments, pro and con, respect-
ing the use of laconic, I have been iniluenced by a desire to do justice
to tlie work >f the author of tlie '*Taconi<! System " and to retain a name
proposed by an Anu?rican geologist. . It is with regret that I find my-
self eomi)elled now to use Cambrian in im'ferenee fo Tai'onic, esi)eeially
!is the Middle Cambrian fauna of this i)ai)er is the fauna of the Upper
TH<!oiiic of EnnnouH, as defined by him in IHrif) ( Amer. Geol., pt, 2, pp.
40-09, l«5ri).

§ 143. There is no doubt that Dr. Emmons was correct in classifying
tlie Upper Taconic as [)rc-Pot8dam. To him bcdongs the credit of rec-
ognizing and lescribing the Middle Cambrian series of North America
as a distiut't formation both on structural and paleontologic grounds;
and it is regietted that we cannot unite with Professors Marcou ami
Winchell in applying the name Taconic to the formation. If we do so,
the great Lower Division, described by Dr. Emmons as the tymcal Ta-
conic, will be dropped entirely, and the Upper Taconic, which is not
now known to occur in the Taconic area, would be taken as the true
Taconic, which it does not appear to be, although Dr. Emmons included
the "Black Slate" in it in 1847.

§ 144. Dr. Emmons deserves great credit for the work that he did.
Struggling under adverse circumstances, at a time when there was
almost nothing known of the pre-Potsdam strata of North America, and
when geologic methods were yet in their beginnings, he accomplished a
work, in one of the most complicated regions of American geology, the
central idea of which, that a great series of Paleozoic strata of pre-
Potsdam age existed east of the Hudson Kiver shales of the valley of
tln! Hudson and Lake Champlain, we now know was correct. In the face
of the almost united opposition of his contemporaries he maintained his
position; and it is one of the misfortunes of his career that he began
his work on the Taconic System in the Taconic area, instead of Western
Vermont or along the Htldson Kiver, as he would then have estab
lished his Upper Division first and given it a name under which the
Cambrian series of the continent might have readily been assembled.

§ 145. It may be that when the entire extent of the typical Taconic
Bull. 30 5 (791)

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area is thoroughly studied the representative of the great limestone
bblt beneath the shales of Georgia, Vermont, maj be determined, and
also the overlying Olenelius shales and the underlying strata. If so, no
one will take greater pleasure in adopting the term Taconic, as equiva-
lent to Cambrian and in place of it, than myself.

§ 146. The following extracts from Dr. Emmons's works, with running
comments, are given to define the position of the two divisions of the
Taconic System.

§147. Dr. Emmons, in proposing the Taconic System, said (Geo).
New York, Surv. Second Geol. Dist., 1842, p. 136) :

The Taconio System, as its nanio is intended to indicate, lies along both sideH of
the Taconio range of mountains, whose direction is nearly north and south, or for a
g- eat distance parallel with the boundary line between the Str.tes of New York,
Connecticut, Massachubotts, and Vermont. The counties through which the Taconic
rocks pass are Westchester, Columbia, Rensselaer, and Washington ; and, after pauH-
ing out of the State, they are found stretching through the whole length of Vermont
and into Canada as far north as Quebec. It is, however, in Massachusetts, in tbo
county of Berkshire, that we find the most satisfactory exhibition of these rocks.
They form a belt whose width is not far from fifteen miles along the whole western
border, end which extends clearly to the western base of the Taconic Range. The
greatest breadth, therefore, as will bo seen by an inspection of any map of this sec-
tion of country, is wider upon the eastern than upon the western side of this range.
In Vermont they range along the upper members of the Champlain Group, and thuB
become connected with the Second district.

§ 148. In speaking of the " Position and relation of the Taconic Sys-
tem," he said further (p. 137) :

In this ouunection, I may state another result as the consequence of the geo-
graphical position of the Ti> conic System : it is the partial blending of the rocks of
the thrftb adjacent systems, the Primary of the Hoosic Ranges upon the east and the
New York Trausiti m System on the west with the Taconic, creating thereby many
doubts and perplexities as it regards the true limits of either system ; and inasmuch
as the whole belt itself of the latter rocks is narrow, doubts are thrown over the
whole as it regards the views we are to take of them. It will bo more clearly seen in
the following pages how it is that differences of opinion prevail in relation to thi'so
rocks. Where they have been cowded together, and especially whore the masses
are lithnlogically similar, it is not at all remarkable that the views and opinions of
geologists should differ ; besides, under the most favorable circumstances, the lines
of demarkation between rocks of diflerent eras are often extreme *y obscured, and
cannot be drawn with that evactitudo wo wish, inconsequence of concealment under
the soil or other circumstances equally effective to render their extent and relations
indistinct and uncertain.

§ 149. On the following page he again speaks of the diflflculty of rec-
ognizing the dift'erences between the Taconic series and the formations
of the Champlain Group :

Much difficulty is encountered, as has been already hinted, when we attempt to
draw the lino of demarkation betwct'u tboshiilcs and slates oast of the Hudson h'ivei'
and Lake Champlain and the slates of the Taconic System. So nearly do the latter
resemble the former in lithologicul characters th;u in specimens of small size the one
niiglit be mist.akon for the other. B.it t lis is a common difUculty, or one common to
all rocks of the same lithologicial idiaracters, and it is not to be considenul as a posi-
tivo objection to the separation which I now i»ropo8 ..

(792)

WaLCOTT.].

INTRODUCTORY OBSERVATIONS.

Tliere are two or three other points it may bf» well to state in this place -• One is
in rejjard to the condition of the country alon/r the line of j>.nction of these and of
iiliiumt all other rocks: thnre is, for example, a concealment of the strata by rooks
and earth for quite a wide space, covering the termination of the masses on either
(tide ; added to this difficulty is the confusion created by the gicat sameness in the
direction of dip, and as both are lithologically slates or shales and both liable to
certain changer, in their planes of straril^cation and of deposition, a wide door is
openod, throngh which we may run into mistakes and crei^to confusion. In fact, it
often happens that where eitlicr of these difficnlties exists a?one ppecial care has to
liii taken to avoid error ; but where they all appear, as in the instance under eon-
sidtiration, we can scarcely expect to escape falling into some grfws mistake, that es-
pecially which concerns the designation of the rock.

§ 150. Dr. Eminons, after raeutiouiug the question of the relations of
the T5U5onic and Cbamplaiu Groups and deciding: that tbey are tuade up
of strata belonging to two distinct geologic systems, proceeds to discuss
the lithologic characters of the series (pages 138, 139, 140), and says in
conclusion (p. 140) :

If the preceding views are admissible, there is sufficient reason for regarding the
roeks which lie between the upper members of the Chaniplaiu Group and the Hoosic
Moiiutaiu as a distinct series at least ; but I would remark that by the expression
"lying between" I have reference to geographical position, for, considered geologic-
iilly. they can be regarded in no other liglit than .as inferior to the Potsdam saiulstouo
or iiH having been deposited at an era eailirr than the lowest member of the New Yf ik
Transition System. We have in no instan je, however, been able to trace a sonneciiou
in these masses, and wo have never found the. Potsdam sandstone resting upon any
(pf the members of the Taconic System. To attempt to explain this remarkable feature
iir fiict would bo premature. The bare fact that the Potsdam sandstone rests on
gneiss or granite, without the in. 3rposition of any other rock, we e.irly pointed cmt,
ami, commencing our series w^ith it, we find it to be unbroken and uninterrupted up
to tiie Ohl Red Sandstone. IJut if we conuuonce an examinatioti at the foot of the
lloDsic Mountain, which is gneiss, we p.ass over a series totnally ditl'eretit from tho.se of
wliich we have just been speaking, and among wliicli the Potsdam sandstone does not
iipiicar, neither a linuistone which can be referred to those of the Chami)lain Group,
or slate or shale whicdi can bo recognized as belonging to the New York System. If
we are correct in this conclusion, if the Taconic rocks differ as much as has been rep-
resented from the Primary and also from the Transition series, then it appears neces-
sary that we should adopt views at least somewhat analogous to those expressed in
file ]>receding pages.

§ 1 ol. On page 142 he again calls attention to the "liability to mistake
the liinestonesof this system for those which lie adjacent" and the "dif-
liiMiIties in distinguishing the slate of the Taconic System."

§ir)2. The first section given, illustrating the Taconic System, is on
piij^e Hi), and extends from Petersburg, Eensf.elaer County, New York,
to Adams, IMassachusetts; and on plate xi Oi the volume five sections
arc given " explanatory of tlic Taconic System." In all of them vrc ihul
on the east the Hudson River Group, represented a# resting unconform-
ably on the "Taconic slote," then the "Sparry limestone" nexteast, and
in st'ctioTis 2, 3, and 4 followed by the " Magnesian slate" of the Taconic
Moiuitains, which is overlaid by the "Slockbridge limestone," &c.

(793)

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CAMBRIAN FAUNAS OF NORTH AMERICA.

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§ 153. After describing the "Rocks of the Taconic System" in a gen.
eral way the author then takes each formation up in detail, beginniufj
with the western mass of slate which is denominated "Taconic Slate"
(p. 150). It is the first member of the Taconic series described, and, I
think, occupies the position assigned to it by its author as being older
than the Potsdanr sandstone of New York, and unconformable to tbe
Hudson River shales.

§ 154. The Sparry limestone is next described, and then follows tlie
"Magnesian Slates," the "Stockbridge Limestone." and the "Graiuilar
Quartz."

§ 155. On page 163 various conclusions of a general character are
given, and in the eighth we find the "Taconic'' correlated with the
Lower Cambrian of Sedgwick :

8. The Taconic rocks apjiear to be equivalent to the Lower Cauibriim of Proi'ossor
Sedgwick, and are alone entitled to tbe coiiHideration of belonging to tins syHtciii,
the upper portion (of the Cambrian) being tbe lower part of the Silurian System.

§ 156. The next extended publication by the author of the "Taconic
System" is in the Agriculture of New York, vol. i, 1847. Dr. Emmoii,s's
view of the presence of a system of rocks older than the Lower Siliuian
of the New York section is evident from the following extracts (i)age 40) :

In the following pages I believe the reader will be satlMtied that in these rocks we
have, for this country at least, the tine j;aJ<?o^oj(; ftosp, and tliat in thetn exist fliose
organic forms which are strictly entitled to the <lesignation protozoic.

This fact is found in the existence of peculiar fossils on both sides of the Atlantic,
Vfhich, so far as discoveries have yet been made, are confined to the slates of the
Cambrian and Taconic System ; and now the grt>at object of the writer is to show
that the above (piestion has not been .settled right or acconling to facts; or, in otliir
words, that the Taconic rocks are not the Hudson Itivor slates and shales in an al-
tered state or that all the Cambrian rocks are not Lower Silurian (p. 40).

I shall take the broad and distinct ground that the Taconic System occupies a iio-
sitiou inferior to the Champlain division of the New York System, or the Lower Divis-
ion of the Silurian System of Mr. Mnrcliison. In order to prove that this po.sitidn is
well chosen it will be necessary to refer the reader to localities where one system of
rocks reposes upon the other, and that I might set this beyond the possibility of ii
doubt I have sought thoso points where the slates of the Taconic Sy.stem come in con-
tact with the lower limestones, or with the Potsdam sandstone of the New York Sys-

tei. r,. r)r>).

§ 157. In the section (page 63, fig. 7) given as showing the position
and t)rder of the Taconic rocks, we find essentially the stune order as in
that of the report of 1842, and beneath it the author begins the de.serip
tion of the rocks composing the Taconic System with the des(!ripti(»ii of
the black slate overlying the "Taconic Slate" and its contained i'os-
sils. The "Black Slate" he considered as indicating a distinct rock
from the Taconic "Slate, and to be the highest member of the Taconic
System. The fossils described are typical of the fauna jireceding the
Potsdam iauna, and occupy the stratigraphic position, in relation to the
Potsdam series of New York, assigned them by Dr. Emmons.

(794)

WAI.COTT.]

VTALCOTT.]

INTRODUCTORY OBSERVATIONS.

§ 158. lu givinj? its distribution he says (J). 71): '

Tilt' Black Slato is not as well exposed an the Tacouic ; there is, therefore, some
iinciTtaiuty iu regard to it. It in the rock adjacent to the Chaniplain and Hudson
Vallt'ys, and more frequently tliat which we observe immediately beneath the calcif-
erous sandroek, or cropping out from beneath it. What we see of it is frequently in
a crnshed condition, and bounding die Taconic Slate on the west in New York and
Vermont. I have not recognized it about Albany or Troy. Greenwich, in WaHhlng-
ton County, is the most southern point at which I have observed it. It extends
north as far as St. Albans, iu Vermont. I speak of those points which I have in-
s[)ected. On St. Albans Bay it is traversed by satin spar. It is also calciferons
liere, as well as at numerous points upon Lake Champlain. It crops out beneath the
calcifiTous sandstone at Sharpshins, near Burlington. I am unable to form an esti-
iDiite of its thickness.

§ 159. Of the Taconic Slate of tlie 1842 report (section 6) he says

(p. 72):

The Taconic Slate, with its subordinate beds, occupies almost the whole of Colum-
bia, Kensselaer, and Washington Counties. It extends to the base of the Tacouic
range of mountains, which divides New York from Massachusetts and Vermont. Ly-
ing in its usual incline<l position, if no repetitions of the same mass occur, it is of
iniinense thickness. For example, from Lanaingburg to the Sparry limestone in the
I'listern part of Hoosic, near the western bounds of Bennington, in Vermont, it is at
least twenty miles in a direct line. Its dip varies from 45° to 70°, But admittiiig
that the same mass reappears, it will still be found immenselj thick. I have often
examined it two miles perpendicular to its strike, and found no indication of repeti
tions. I leave it to a future opportunity to make an approximate determination of
its thickness, or to others who may take up the subject.

Without doubt this immense rock admits of subdivisions; that is, it will probably
lie found proper to uiako those masses which I have treated as subordinate ind<^-
]peiident rocks, of which perhaps others still will be recognized of suflicient impor-
tance to merit the same distinction. In whatever liglit we may regard these minor
IKiints, there is no doubt that the quantify of matter in this slate exceeds that of all
the members of the New York System put together.

The Sparry limestones and other strata to the east are next described.
§ 100. Dr. Emmons again gives a r^suni^ of the Taconic System in
1855 (Amer. Geo!., pt. 2). On pages 5 and 6 he says:

My first business is to sketch a picture of the oldest of the sediments fvs they are
exhibited in a series which collectively constitute the Taconic System, and as it is
(levelojied in the Tacouic ranges of Berkshire and the adjacent country immediately
north and south.

Tlie Taconic System has a clear and well-defined base, which is rarely obscured
liy [liwisages into the primary schists, the pyroplastic rocks, sienites, or granites.

If my views are correct (and I have endeavored to sift fhem of error), wo can go

back no further; we have no older sediments.

• • # » » » •

Thi^ evidence of the existence of a system of rocks beneath and older than the
Silurian System in this country rests on niany well-d(!termiued facts. Tliese fncts
are not all of otjual inijiortance ; but those which are not dir<>ct serve to corroborate
anil sustain those which are. The facts which bear directly upon the evidtiiu-e
ailiidcd to arc superposition, succession, nnconformability, and the iiresence of fo-isils
iliNiinct from those of the Silurian System.

§ 101. On page 12 we have the first proposition to divide the Taconic

(795)

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CAMBRIAN FAUNAS OF NORTH AMERICA.

[nui.i..30.

System into two divisions, Upper and Lower; the Lower to include
all the original Taconic of the 1842 and 184G reports, with the exception
of a portion of the Taconic Shite and the "Black Slate" of the 1847
report.

§ 162. The author describes the Upper Division of the Taconic rocks
as consisting of nun.v.rous beds of slate alternating with shales, thin-
bedded sandstones (some of which are coarse and brecciated), thin-
bedded, bluish limestone more or less cherty and red, and brown and
pnrple roofing slates. Sections are given that cross the Upper Taconic
series at points from Highgate, in Northern Vermont, to Rensselaer
County, New Yoru. Some of the sections have been studied since Dr.
Emmons examined them, and the fact has been ascertained that he did
not, in many instances, recognize the series of north and south faults
that break the" continuity of the sections; but, after dedr 'ting all the
errors, the Upper Taconic remains as a distinct formation uoneath tlio
horizon of the Potsdam sandstone.

§ 103. In 1859 Dr. Emmons again reiterated his views of the Taconic,
System in his little Manual of Geology, tender Taconic System (p. 8i)
we read :

This system desorves tho special attention of yeologists, for two reasons: 1st. It
is probably the base of the sediments. M. It is also probable that it is the Palwozoic
base, and, in both '•espects, it must be regard'"! as the oldest series of the sedimentary
.class.

This system is subdivided into Lower and Upper; the first consists of a conglomerate
at the base, succeeded by silicious talcose beds of considerable thickness, in which
there are frequently pebbles ; next above are three thick beds of sandstone, separali'd
by talcose slates ; these are succi. ded by the Stockbridgo limestone. This is llic
marble of Berkshire County, Massachusetts, and which extends from the State of
Vermont to Georgia. The Stockbridge limestone is succeeded by a mass of s'ate of
great thickness, the upper part of which is suitable for rowflng. The greatest thick-
ness of the Lower Taconic rocks is about r),()00 feet. The upper ipiai'tz beds are often
vitrilied, while a lower one, still many hundred feet nearer the pyro-crystalline rocks,
is a sandstone (p. 85).

The upper series we have just described (§ J 62).

§ 164. Prof. .1. D. Dana considers that most, if not all, of the stnta
included by Emmons in his original Taconic is of Lower Silurian (Or
dovician) age. Dr. T. S. Hunt holds that the term Taconic should bo
restricted to the original or Lower Taconic of Emmons (Trans. Koy. Soo.
Can., Taconic Question in Geology, vol. i. p. 217; vol. ii, p. 125, 1883-'S1),
a view that appeavs to be the correct one ; and whether geologists will
unite with Dr. nunt, and call the series of strata next beneath the Cam-
brian Taconian, is a question that is not yet decided, as it is yet un-
proven whether such a group exists in the original Taconic area. It
appears to exist in other localities where it was described by Dr. Em-
mons, and, if this io verified, the term "Taconic" or "Taconian" may
receive a final resting plaee in American geologic nomenclature.

(796)

If^

WALCOTT.]

INTRODUCTORY OBSERVATIONS.

ACKNOWLEDGMENTS.

§ 165. To Dr. Alfred E. C. Selwyn and Prof. J. F. Whiteaves, of the
Geological Survey of Canada, I am Indebted for the use of a number of
the typical specimens described by Mr. E. Billings, in studjdng the Bic
Ilarbor and L'Anse au Loup faunas, and also for duplicate specimens
of a number of species, without which 1 could not have identified sev-
eral species from Vermont. Mr. Edward Hurlburt, of Utica, N. Y., kindly
sent for study all of his collection of Georgia fossils from Vermont,
iucluding the beautiful relief-specimen of Mesonacie Vermontana. By
au arrangement made with Mr. S. W. Ford, he made drawings of the
type specimens described by him, several ^ '' ^hich are reproduced in this
bulletin. Mr. Ford also kindly pennltteil me to examine his collection
at his home. In the collection and preparation of the material from
Vermont and New York for study, I have been assisted by Mr. Cooper
Curtice, of the Geological Survey. The original drawings are by Mr. J.
L. Ridgeway when not otherwise mentioned.

(797)

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DESCRIPTION OF THE MIDDLE CAMBRIAN FAUNA.

FUCOIDAL REMAINS, TRAILS OF ANNELIDS, ETC.

Mr. Billini^s described two species referred to the Algse from the Georgia
Qtoui), Pala'ophyats incijnensuwlP.congregatus (Geology of Vermont, vol.
ii, pp. 943, 944). Prof. .Jules Marcou mentions the presence of a species
of Oldhanua (Bull. Soc. G60I. de France, 3" ser., t. ix, p. 25, 1881); but
after examining the specimen labeled by Professor Marcou, and now in
the Museum of Comparative Zoology at Cambridge, Mass., and also ex-
amining great quantities of the shales at Parker's quarry, it seems that
the so called Oldhamia is the result of frost and water action, and is
not of organic origin. Tiie Chon<lrites spoken of by Prof. Marcou, and
80 labeled in the Museum of Comparative Zoology, owes its origin to
tine rootlets i)enetrating between the layers of shales and staining
them. Worm trails and borings are not of infrequent occurrence in the
Georgia Group, but with the exception 01 a species of Cruziana, found
east of Highgate Springs, and one in Nevada, and, possibly, the two
species of I'aheophycus described by Mr. Billings, nothing else that can
be referred to the Alga? is known to me.

Dr. E. Emmons described a number of trails and doubtful fucoids
from the "black flags and slates" of Rensselaer and Washington
Counties, New York, and Waterville. Maine, which he considered to bo
from the Taconic System. Owing to their doubtful zoologi<j character
and the insufficient <lata upon which many of the species are referred to
the Upper Taitonic, 1 have omitted them from the present study, and
will not include them in the fauna until collections are made from the
typical localities and their stratigraphic horizon is determined.

When revising the Upper Cambrian faunas, I exi)ect to illustrate the
trails and fucoids ut' the Cambrian System, and will then discuss more
fully those of the Middle Cambrian.

SPONGIiE.

- Genus ARCHiEOCYATHUS Billings.

Archaocjiathiis Billiiij;s, 18C1. Paniplilot; Geology of Vermont, vol. ii, p. S)44 ; Pal.
F08H., vol. i, p. ;J ami ]). ;J54.

Original description. — "Turbinate, simple or aggregate; cup deep.
The internal structure, so far as can be made out, consists of an iinier
wall, constituting the inner surface of the cup, and an external wall or
W (798)

WAI.COTT.)

MIDDLE CAMBRIAN FAUNA.

opitliocii envi'loping tlu' whole. Between the two walls are numerous
riidiatiufj septa, the interseptal spa(;es beinj; tilled with poriferous or
cellular tissue. It is iiighly probable that the inner wall is permeated
by pores communicating- with the interseptal tissue."'

As Mr. IJilliuffs included in. tliis f>enus the species now ])laced under
the <ieuus Ethmoi)hyl]um, it is necessary to emend the above descrip
tiun.

Description ay emended : Bo<ly of sponge simple, elongate, cylindro-
('(inical, concentricall.v corrugated ; cup deep. Both surfaces with
irregularly disposed round or oval i)ores, some of which penetrate a
short distance and others communicate with the canals of the interior.
Interior structure a more or less irregular system of rounded and irreg-
ular passages or canals, many of them terminating as cul de-sacs or
little chambers in the mass of tiie skeleton.

On a longitudinal section the skeleton is seen to be arranged on
arching tranverse lines and vertical, slightly-radiating lines. The
minute structure of the skeleton is unknown. If spicula) existed they
have been destroyed by the crystallization of the calcareous matter now
fdniiing the skeleton in A. Atlanficus ; but in A. BiUhujsi spiculae
occur in the interseptal spaces, the cup, and about the specimens, as
sen ill thin sections, that I think belonged to the species.

AllCH-a^.OOYATHUS AlLxiCNTIOUS.
Plate ii. tigs. 1, la: jtl. iii, ti<^s. 1, la, /», 2, 'ia.

Anhawiiathiix utldiiticKx Billiuf^s, Idlil. Paiuphlut; Geolojjy of Vonnont, vol. ii, p.
•)4r>; Pal. Fo."8., vol. i, \>. f).

Orif/inal dei^cription. — "The only sjiecimen of this s])ecies in the col-
lection is a fragment \h inches in length, 14 lines in diameter at the
larger and t) lines at the smaller extremity. Where the diameter is 11
lines the cavity of the cup is 4rh lines across, and tlie space between the
walls 3 lines. Of the radiating poriferous septa thereare about (!0; they
are so irregular that it is only in certain i)Iaces in tinelyiudished see-
tidus that the radiated structure can be detected. On one side where
tlic specimen is weathered the structure i)resents the api)ear:!nce of a
rather (;cmi)act cellular tissue. The form appears to be elongate con-
ical, gradually tapering, the surface marked by wide shallow encircling
ohiiqiie annulations, from 3 to G lines distant from each other. The
outer wall does not seem to be poriferous, but this appearance may be
due to the crystalline condition of the rock into which it is conveited."

On studying the type sj)ecinientj, 1 observed a small projecting growth
lioni the inner wall (i)l. ii, hg. \a) which had begun to show a cen-
tral cavity and an inner and outer wall. None of the sev.-tions shows
tiic line vesicular structure so i)revalent in E. profundnm, but, in place
ttf the regular septa and dissei)iments, we find an irregular system of
lliicU arched se])ta and vertical partitions, the openings between tlieuj
I'oiining an irregular system of passages or canals, many of which ter-

(799)

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; 'At

CAMBRIAN FAUNAS OF NORTIi AMERICA.

[BULL. 80.

minato jis cul-de-sacs aud others penetrate tlirongli tbc walls, aftbrding
communication between the interior and the cup and also between the
outer suriace and the interior.

In some specimens the interior structure is so irrejjfular that no system
of septa can be determined.

The specimens referred to this species from Silver Peak, Nevada, aro
separated by an interval of 3,000 miles from those at L'Anso an Loup,
but I am unable to detect differences of specific value between them.
Each has the annulated cylindrical form, pitted surface, irregular walls,
the interior skeleton with the irregular system of septa, and verticul
partitions with the round or oval system of i)assages running throuj^li
and between them. Many of tiie sumller specimens are solid to the
center, and may possibly be branches broken off from a central mass;
but, so far as we know, all the specimens are simple and not branched.
There is also a considerable variation in the mode of arrangement of the
canals running through the interior, but I tljiuk all the si)ecimens be-
long to one species.

Formation and locaUties. — Middle Cambrian, L' Anse an Loup ; on the
Straits of Belle Isle, Labrador ; and Silver Peak, Nevada. Longitude
117° 20' E., latitude 380 N.

Ethmopl
Architoi
Archo'oc

I'rotocijc

The
the sp
species
der Et

As
sponge
leal, ci

l/JSj.

ARCHJioocyATnus BiLLiNasi n. sp.
Plate iii, flg.s. 3, 3o-o.

Body of sponge cylindro-conical, annulated; cup deep. Both sur-
faces with irregularly depressed, round or oval pores that penetrate
thiough the w.alls. Outer walls united by arched, transverse septa
that are strengthened by irregular vertical partitions tsubparallel to the
outer walls. Numerous small pores penetrate the septa and afford
communication between the interseptal spaces which, with the outer
pores, gave a free circulation to the water. Skeleton of the walls,
septa, and partitions calcareous, apparently solid. In the cup and iu
the interseptal spaces where spiculge from without ai)parently could
not enter, we find in thin sections numerous small, irregular spicula-
like bodies which I think were the spiculiB of the sponge.

The relations of this species to A. Atlanticus are shown by the form
and by the tendency iu some specimens of the latter to develop trans-
verse septa and vertical partitions subparallel to the walls. Specifically
they differ, but generically they approach each other quite closely, as
may be seen by comparing the figures on plate iii.

The species occurs in a purplish limestone, associated with A. Atlan-
ticus, Ethmojihyllum profundum, &c. The largest example is a fragment
of an elongate cylindro-conical specimen. Its greatest diameter is
15""".

Formation and locality. — Middle Cambrian, L'Anso au Loup, Straits
of Belle Isle, Labrador.

(800)

WAI.COTT.]

MIDDLE CAMBRIAN FAUNA.

Genus ETHMOPHYLLUM Meek.

Elhmophyllum Meok, 1868. Amer. Jonr. Sci. and Arts, 2d ser., vol. xlv, p. 02.
Jrchcmcyathua Meok, 18(38. Amer. Jour. Sci. aud Arts, 2d ser., vol. xlvi, p. 144.
Ai<h(v.oqiatheUu8 Ford, 1873. Amer. Jonr. Sci. and Arts, 3d ser., vol. v, p. 213. Gen-

oric name proposed at eud of description oi ArchvBOcyaihuH f BenHselaericus.
I'rolooyathua Ford, 1878. Amer. Jour. Sci. aud Arts, 3d ser., vol. xv, p. 124.

The original description of the genus by Mr. Meek is descriptive of
the species rather than of the genus, as the latter embraces several
siiecies that vary in details. Mr. Meek's description will be found un-
der Ethmophyllum Whitneyi, the type of the genus.

As now understood, the genus may be defined as follows: Body of
.sponge simple, elongate, cup-shaped, turbinate, clavate or cylindro-con-
i(^al, curved or straight, vertically ribbed or lobed or concentrically cor-
rugated, or both combined. Cup deep, sometimes more or less filled by
a vesicular growth on the inner wall. Both surfaces with more or less
luuiierous round or oval pores in vertical and horizontal rows that cross
t'iich other obliquely or at right angles. The pores usually penetrate
through the walls ; some may terminate in cul-de-sacs. Outer and inner
walls united by transverse vertical septa that originate on the outer wall
and extend inward, ultimately joining the inner wall. Septa usually
poriferous, but sometimes no openings can be detected. Thin dissep-
iments may or may not cross the spaces between the septa. Septa 6 to
112 in number, as now known. Inner wall with or without a vesicular
growth extending into the central cup. The series of septa and walls
may be repeated again and again, or show only one series. Skeleton
made up of fine branching spiculaj in one species {J^. Minganensis), and
undetermined in others, owing, probably, to the replacement of the parts
by calcite.

Mr. Billings, in proposing the genus Archaeocyathus, evidently in-
cluded this type, but at the same time he included another generic form,
A. Atlanticus, and followed the generic description with that species. The
generic description is also more applicable to A. Atlanticus. (Geology
of Vermont, vol. ii, 1861, p. 944.) The second species, A. Minganensis^
is now placed under Ethmophyllum, and A. Atlanticus is taken as the
type of the genus Archieocyathus, although Mr. Billings, in subsequent
publications, evidently considered it a secondary species; inasmuch as
lie did not redefine the genus and as another generic name is needed to
include one of the two genera placed under Archavcyatlius, I prefer to
limit the latter to its type species and use Mr. Meek's genus for the other,
and thus avoid placing Ethmophyllum as a synonym of Archffiocyathus
and creating a new genus to include A. Atlanticus.

Archoeocyathellus Ford, 1873, is gencrically identical with Ethmophyl-
lum. Mr. Ford distinguished the latter genus by its straight form, longi-
tudinally-ribbed exterior, and remarkable poriferous system. I find all
these characters in U. Whitneyi and also the characters of E.jtrofundum.

(801)

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Tri studying tint Htrncture of TJ. WhUnei/i, E. Miiuiancnsis, E. projnndum,
aud E. li'cHiiiielaericKni we tiiul in all an outer poi ilV'tons wall conneetiMJ
to an inner wall by .septa, the double walls forming a tijjure that \h
e.« 'iudro (!oni<ral, clavate, turbiniite, or niodilied forms of all of these;
the central spaee inclosed by the inner wall is usually oi>en, but isonie-
times tilled with a vesicular mass, or it may be a l)ui]din,i»' of wall upon
wall, as in the outer walls. Tliis is shown by tig. \h of jxlatc i and tig. le
of platei V. The outer surfaces of ii-'. MingcmensiH and E. prof nudum show,
in large specimens, a concentric (iorrugation or undidation of the sur-
face, but in the small and slender specimens this becomes less and less
prominent, ai ' in one o""" in diameter it is nearly lost. In E. Whitncjii
l)roa<l undidations begin to show in specimens U)""" in diameter, as seen
in fig. 1, plate iv. The species grows much lai'ger, but jion«' of the larger
specimens show tiie outer surface or form.

The longitudinal ribbingof the surface is prominent in young slender
specimens of E, Wliitneyi, and less so in si)ecimens*l()""" or la""" in di-
ameter. This is owing to the increase iti the nundx'r of septa with the
increase in size. The septa of E. h'ensselnericiun vary iu number, and
the external ribbing vaiies in a corresponding manner.

The poriferous system of E. lieiisselaerieniu appears to be the same as
that of E. Mhufanemh and E. Whitneiji, as iar as known.

The genus J'rotocyathus was projwsed ior a spe<!imen having on the
outer wall a single row of large pores directly on the line of each sei>tum,
the septum oi)posite a row of pores bending around each pore. In tiujt
they correspond, iu position and form, to the jwres of the inner wall.
We have, irom Troy, a specimen with the outer wall removed, that indi-
cates a similar row of larger pores than the w idth of the septum. The
probabilities are that they indicate openings in the outer wall, but of this
there is no positive i)roof. Mr. Ford's type specimen is a cast, nearly
all the outer wall being removed, but on a small bit, still remaining,
a i)oriferous surface is shown.

As far as I know the types of the two genera Archaeocyathellns and
Protocyathus, I refer them to Ethmophyllnm, leaving the question of
their specific relations an open one. The variation in the nun)ber
and in the size of the septa is so great in E. Rensselaer! cam that it
will not be Burjuising to find specimens showing gradational forms be-
tween the two species.

A specimen of E. Whitnei/i, ex.imined since the above was writtc^i,
shows the poriferous outer wall removed in places and the larger open-
ings on the lines of the septa (fig. 1, pi. iv). Comj)aring these with fig. 3,
1)1. ii [E. profundum) and other specimens, we find that this is owing to
the oi)enings in the septa just within the outer wall, as shown in a
restoration (tig. 2, pi. iv). In fig. 2/>, pi. v, the outer wall is removed
and the openings look like pores leading into the interior. Fig. 3 also
shows the same feature.

Mr. Billings, in describing the characters of the genus Archaeocya-

(802)

WAI.CliTI'.l

MIDDLE CAMIMJIAN KAl'NA.

tliiis, as found iu tJ. prof a nil urn, E. MimjanniHiH and A. Atlantkus (Pal.
Koss., vol. i, p. li'il, 180;")), says:

"Tlie followiiij,' arc sonio additioiiiil details of the structure of this re-
markable genus: The general iorin, as exhibited by the three speci«'Siit
present known, is that of an elongated hollow cone, or, rather, a hollow
cylinder with one end narrowed to a point, the smaller extremity being
closed and more or less cur>ed; the l.irgei' end open. They thus re-
semble certain large species ol Zaphrcnth or Cyathophi/llnm, and, in fact,
from their form and septate structure, were at first thought to bo corals.
Some of the individuals a])i»ear to have obtained a length of two or three
feet, with a diameter of three or four inches.

" All of the species are transversely ami more or less deei)ly mark* xl
by irregular annulations. The structure consists of an inner thin wall
or endotheca, lining the great central cavity, an outer wall or ej)ithe('a,
forming the rough external surface, and between theses a system of
radiating septa. The outer wall in two of the speciies, A. profinuhtH
and A. Mhufnneuftis, is p«'rforated with numerous snndl irregular apei-
tares leading «lirectly into the loculi or empty spaces between llie septa.
In the third species, A. Atluntivitu, it (the outer wall) appears to have a

Vu). 7.

Fio. 0.

Fid. 8.

Fl(i. C. Kthinopliylliim Miii^iiiicnsis (iiftcr liiHiiigK).

Fill. 7. Etlimoiihvlliim Jliu^'iincnsis (iiil!ir};cim'iit ol' siirlaci).

Fk!. 8. Etliiii(i|)li,vlliiiii Miii!.'iiii('n.si.s (!<|>i(iilii', cnlar^'ed (o .50 iliniiiftcr.s).

compact, smooth suiface, with only a few perforations. The inner wall
is vei-y thin, with numerous pores leading from the loculi into the great
central cavity. The septa consist of Hiin, Hat plates, arranged longi-
tudinally exactly as in the genus Zaplnrntis. They extend from the
outer to the inner wall and arc i)erforated with numerous small circular
pores, so that the interseptal loculi all couimunicate with each other as
well as with the central cavity and the exterior. The loculi are sub-

(803)

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CAMBUTAN FAUNAS OP NORTH AMKTMCA.

Imii.i,. :io.

«livi(hMl by very tliiii ilisscpinKMitN rcsiMiiUliiiK tlios*- (»f n Cunthnphi/lhim,
but Ibcy are iin'^'iihiily (listrilmtrd, bciiij,' in noimc \n\v\s ciilijfly iibscnt
iiiid ill «»tlii'r pbices sd imiiscioiis that fbcy coiniilett'ly Hll the lociili with
small celKs, (ioiistitutiiiiL,' tlio ' poribMoiis or cellular ti.ssno' nicMiti(»iu'(l
ill tile orifrinal de.scri|»rioii of tlio i^enus. Tlie etMitral eavity extcinls
lu'aily tlie whole length and (constitutes a larf^e jtroportion of flu^ bulk
of the fossil. Helow it. there is a portion of the smaller exireniity or
base, uiiieh is eomjiosed only of the outer wall, the sejita, ami tlic
dissepiments. The section across this part shows that the in'w septa,
which are introduced from time to time, as the diameter increases, do
not at first exteiul to tli<! center, and it would ajipear from this that
they were developed on the inner surface of the outer wiill, and };i;h1-
iiiilly widened as in the jjeiins Zaphnntin. Olose to the extreme jioiiit
of the base the sejita and <lissepimeiit.s liave an irregular arrangeiiieiil,
and the loculi sometimes heni appear to be mere cinnilar perforaticnis.

"The small branching spicnia, above ligiireil, are seen imbedded in
and forming apart of the substaiuM' of the outer wall of .1. Minf/aiicn.iis.
'i'he fusiform and eylindri(;al varieties are also seen, but rarely, eitlicr
adhering to or partially imbedded in the t*auie specimens. As tliev
were obtained in thousands in the sediment left after <lissolving ])icc('s
of the limestone holding fnigments of this species, tliey wck; at tiist
thought to belong to it; but 1 have recently, while treating other
])ie('es of limestone from the sain(^ bed, also holding fragments of .1.
Miiiffarteusis, foniul that another large sjiccmcm, Trichospongia lierieea,
occurs in this rock, portions of which are crowded with, and seem to
be almost altogether composed of, these spicula. It should therefonc
remain an ojien question whether or not these fusiform and cylindriciil
spicula actually form a part of the structure of Archeocyath'^ or aw
those of 7'. sericca. There can scarcely be any doubt about the brandiod
spicula, as they can be seen not only ])rnjecting from the surface of the
silicitied spet'lmens, but also in the thin slices prepared for the micio-
scope. Xo spicula have been detected in A.profundua. In A. Atkotticun
there are several objects visible, in the only siieciinen of that species
that has been colle<!ted, which resemble branched spicula. No silicificd
specimens of these two latter species have been procured, and I thiiiiv
it ])robable that if such could be examined spicula would be found in
them.

" As to the zocHogical rank of this genus there yet remains some
doubt. The general structuie is such that it may possibly be a spoii^^o.
The apertures in the external wall may be the honiologues of the in-
haleut jiores of the ordinary s])onge, while those of the inner wall may
represent the exhaleut orifices. The great internal cavity in that case
would have the same function as the large centr.aj cloaca of the fistulose
genera of sponges. A ra<liate«l and more or less perfectly sej)tatc
structure occurs in many undoubted sponges. In this genus, however,
the substance of the septa is almost as conipact as that of the true

(804)

-T^

WALCon.)

MIDDLE CAMIUMAN I'AirNA.

CDiiils. The iM!rtoriit«'d <'.liiU'iu'tt'r of tli<' oiiti-r wall, ami also of the
8('i)ta, suf^jjest ii comparison with corals of the division /ntnitltarin per-
forntn. The Favoyltrs have also their walls perforated. Dr. .1. VV.
l)aw.son, who hOiS examined a nniidier of the .slieus of A. otIanticuH
and A. pro/xiiidus, wliich have been pre])ared for the mi(!roscope, in of
opinion that the structure of these two Hpecies is similar to that of the
Foraminifera (Can. Nat. and Geol., April, 1H(55). My own opinion is
that all three species belonjj to one generic group <ilosely related to
(Utlathium. This hitter passes into Eospnngia, which, in its turn, grad-
ually merges into other genera that ocftnr in more recent formations,
such as RhyHOspongia, Scyplna, ISipkonia, and others. The resemblance
oetween the whole structure and that of the i)alieozoic corals seems
also to show that in the Lower Silurian seas organic forms existed
combining the characters of the Proto/oa and the CNeU^iterata."

Sir J. \V. Dawson compares the genus with Ko/oiin and gives addi-
tional i)articulars resulting from his study of the genus. He says
(Dawn of Life, pp. 151-150, 1875): "To understand Archa'«)cyathus let
us imagine an inverted cone of carbonate of lime from an inch or two to
a foot in length, and witli its point buried in the mud at the bottom of
the sea, while its open cup extends upward into the water. The lower
part buried in the soil is composed of an irregular acervuline network
of thick calcareous plates, inclosing chambers communicating with one
another. Above this, where the cup expands, its walls are comimsed of
thin outer and inner plates, i)erforated with innumerable holes, and con-
nected with each other by vertical plates, which are also perforated with
round jjores, establishing a commuuicatiou b(!tween the radiating cham-
bers into which they divide the thickness of the wall. In such a struct-
ure the chambers in the wall of the cup and the irregular chambers of
the base would be tilled with gelatinous animal n^^^tter, and the i)seu-
(lopods would project from the numerous pores in ihe inner and outer
wall. In the older parts of the skeleton the structure is further com-
l)licated by the formation of thin transverse plates, irregular in distri-
bution, and where greater strength is required a calcareous thickening is
added, which in some places shows a canal sj-stem like tliat of Kozoon.
(On the whole thtse curious fossils, if regarded as foraminifera, are most
nearly allie<l to the Orbitciites and l)actylopor;e of the early Tertiary
peiiod, as described by Carpenter). As compared with Eozoon the fos-
sils want its line perforated wall, but have a more regular plan of growth.
There are fragments in the Eozoon limestones which may have belonged
to structures like these, and when we know ntore of the deep sea of the
Primordial we may recover true species of Eozoon from it or may find
foiins irtermediate between it and Arch.'eocyathus. In the mean time
I know no nearer bond of connection between Eozoihi and the Primor-
dial iige than that furnished by the ancient cup Zoophytes of Labrador,
though I have searched very carefully in the fossiliferous conglomerates
of Cambrian age on the Lower St. Lawrence, which contain rocks of

(805)

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CAMBRIAN ?AUNAS OF NORTH AMERICJ*.

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«11 the foiiriations from the Laurentiau ui)wards, often with character
istic fossils. I liave also made sections of many of the tossiliferous
pebbles in tliese conglomerates without finding any certain remains of
such organisms, though the fragments of the crusts of some of the
Primordial trilobites, when their tubuli are infiltrated with dark carbon-
iferous matter, are so like the supplemental skeleton of Eozoon that
but for their forms they might readily be mistaken for it, and associated
with then) are broken pieces of other ])orou8 organisms which may be-
long to Protozoa, though this is not certain."

Zittel thinks that the geui'5 may possibly be referred to his family
Euretid.T- (Handbuch der Pal., io80, p. 17;^), and Hiude considers their
relations as doubtful (Cat. Foss. Sponges, 1883, ]). 10).

From the material we have for examination I am inclined to consider
Ethmophyllum a sponge, the spicuhe of which, in several of the species,
have been lost in the crystallization of the calcite now forming the
skeleton. Its mode of growth and the development of the septa ])oinl
to tiie cyathophylloid corals; the interior skeleton recalls some of the
foraminifera, but the i)resen(!e of s])icirhe in E. M i/ii/anensis and the
intimate relationshii) between all the species and J^. Minganensia asso-
ciate it with the Spongiai, close to the family Euretida^ of Zittel. It
may be necessary to establish a new family to receive this and allied
genera.

Dr. Zittel defines the family- Enretida as follows (Handbuch der Pal.,
p. 173, 1880): "Sponge-body cup-shaped, cylindrical, clavate or branch-
ing, fixed. Skeleton reticulate, the crossing nodes of the six-rayed,
cemented spiculra imperforate. External surface naked or protected
by a thickening of the outer layer of lie skeleton ; sometimes covered
with a very delicate network of cemented spicuhii which differ but little
from those of the rest of the skeleton. This mesh-like covering also
extends over the ostia (mouths). Structure of the root like that of the
rest of the sponge. Spiculse of the sarcode wanting or present."

I have recently become acquainted with the work of Dr. J. G. Borne-
mann of Eisenach, on ^jiie Paleontology of the Cambrian District of
Canalgraude in Sardinia. That writer discusses the character of the
fossils referred to the g^nus Archaiocyathus and proposes a new class
of Ccelenterata which he calls Archa?ocyathinai. The genus Arclui'-
ooyathus, as defined by Dr, Bornemann, is the genus Ethmophyllum of
Meek. Nine 8[>ecies are described under it, most of which, it appears
to me, are founded on va/'ietal rather thaii specific characters.

The second genus, Coscinocyathus, is separated from Ethmophyl
lum (=Arch8eocyathu8) by the presence of quite regular cross-se})ta, in
addition to the longitudinal radial septa. This definition would include
our species E. BillingsL Fifteen species are described under Coscino-
cyathus, many of which are based on external form.

The third genus is Anthoinorpha, in which there are irregular cross
septa between the radial septa.

(806)

WALCOtT.]

MIDDLE CAMBRIAN FAUNA.

The descriptions are only outlined, and, as I have not seen either
illustrations or specimens, I wait until Dr. Bornemann publishes his
ilhistrated memoir be .ore comparing or criticising the species.

The principal paptr^ published by Dr. Bornemann, known to me at
present, are:

Sur la Classification des Formations Stratifl«^es Anciennes de I'tle de
Sardaigne. (Compte-Rendn du 2me Congr^s geol. internat., Bologno,
1881, pp. 1-12, pis. i, ii.)

Palaeoutologisches aus deni cambrischen Gebiete von Canalgrande in
Sardiuien. (Zeits. deutsch, geol. Gesellsch., xxxv., 2, 1883, s. 270-274.)

Cambrische Fossilien von der Insel Sardiuien. (Zeits. deut^ch. geol.
Gosellsch., XXX vi., 3, 1884, s. 399-100.)

Untersuchungen cambrischer Archaeocyatbus-Formen uiu! ^erwanu-
ter Organismeu von der Insel Sardinien. (Zeits. deutsch. geol. Ge-
sellsch., xxxvi., 3, 1884, s. 702-706.)

Ethmophylltjm Whitneyi Meek.

Plate iv, figs. 1, la-h.

Ethmophyllum Whitneyi Meek, 18(58. Amer. Jour. Sci, aud Arts, 2d ser., vol. xlv, p. 62.

Ethmophyllum gracile Meek, 1868. Idem.,

ArchaoGiiathus JFIiitneyi Meek, 1868. Amer. Jour. Sci. and Arts, 2d ser., vol. xlvi, p.

144.
Archaocyathts gracilis Meek, 1868. Idem.

Original description. — ''The specimens of this fovssil contained in the
collection are slender, slightly flexuous, arched or nearly straight, and
subcylindrical, excepting near the lower end, where they taper to a
point, by which they were probably attached. They may have gr „ nrn
in tufts or groups, but all the specimens yet seen are single and show
no evidences of growing in contact.

" To the unassisted eye the external siutii ^e of these corallites, with the
•'xception of obscure annular swellinga und constrictions of growth and
faintly marked linear septal cosia , seems to be ntarly or quite smooth.
When examined under a strong lens, however, it is seen to be beauti-
fully punctate, the punctures being minute, of exactly uniform size,
and arranged with mathematical regularity in quincunx, and so closely
crowded that the little divisions between them are scarcely equal in
breadth to the punctures themselves, and form, as it were, an extremely
delicate kind of net work. So remarkable i^ the appearance of this
l)unotured outer wall that the first question that suggests itself, on ex-
amining it under a magnifier, is, whether or not it may be merely an
exceedingly delicate Polyzoon incrusting the whole surface. A clear
oxainination, however, especially in carefully prepared transverse sec-
tions, shows that the punctures actually pass entirely through the wall,
which is very thin, and that they fre not due to the growth of the Poly-
zoon, nor to surface ornamentation.

.if:

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Bull. 30 G

(807)

CAMBRIAN FAUNAS OF NORTH AMERICA.

I BULL. 30.

"On grinding away this very thin punctured wall, the septa are seen
immediately within to be stout, equal, straight, and very equidistant,
but in grinding a little farther in they are observed to become very
regularly waved laterally, exactly like the septa in theforaminiferous genun
Fusulina. So striking is this resemblance that it was not until after
ascertaining from cross-sections that the fossil has not an involuted
structure that I could get rid of the suspicion that it might be a type of
Foraminifera allied to Fusulina, instead of an extraordinary coyal.

" By grinding still farther in (to a depth of about 0.06 inch, in a speci-
men 0.34 inch in diameter), the lateral waving of the septa already men-
tioned is seen to be there suddenly and so strongly marked that they
connect b'terally in such a manner as to form a kind of complex inuer
wall between the great central cavity and the outer septate zone. This
wall, however, does not completely isolate the septate outer zone from
the central cavity, but is perforated by a series of round equal canals,
very regularly placed, one within each of the lateral curves of the septa,
so that those on the opposite sides of each septum alternate with exact
regularity, as do those of each of the two rows within each interseptal
space. These canals have no similarity to the minute punctures of the
outer wall, being greatly larger and very differently arranged. They
do not pass directly through the inner wall, but :ire directed obliquely
upward and inward, so that as seen in transverse sections of the coral-
lites they present the appearance of a double row of vesicles cut across.

"Both longitudinal and transverse sections show the large central
cavity to be without any trace of septa or columella. From these sec-
tions I was likewise at first led to believe this central portion to be also
an entirely open cavity or calice the whole length of each cora'.Ute, but
on sending specimens to Professor Verrill he called my attention to
some obscure appearances of transverse plates in one of the specimens
cut longitudinally and requested me to cut others with the view of as-
certaining whether or not these ai-e plates. A longitudinal section of
another specimen, however, when carefully polished, reveals no traces
of proper transvere plates ; but when examined by the aid of a strong
magnifier it shows the whole interior to bo occupied by a dense vesicu-
lar tissue, the walls of the vesicles being of ';X>eme tenuity. This
structure is seen in the interseptal spaces of the outer zone, as vt^ell as
in the central cavity within.

"In regard to the afdnities of so remarkable a type, it seems scarcely
safe to express an opinion without a better series of specimens fo»'
study. Some of ' s internal characters, as suggested by Professor Ver-
rill, would seem to indicate remote affinities to the CyathophylUda; ;
but its peculiar perforated outer wall would, on the other hand, appear
to remove it from the primary division of corals including that family.
" 1 am therefore led to believe it a new genus, and most probably
typical of a new family, in which opinion Professor Verrill concurs
with me. For this genus 1 would propose the name Ethmophyllum.
' (808)

wALCorr.

MIDDLE CAMBRIAN FAUNA.

"Among the specimens in the collection under examination there are
apparently two species of this fossil. That considered the type of the
genus is larger and more robust than the other, and more conical in
form, especially near its smaller end. None of the specimens seen are
quite perfect at the larger extremity. One measures 0.37 inch at
its imperfect larger end and seems to have been 2.J to 3 inches in
length. In this there are sixty septa, while its outer septate zone is
0.07 inches wide. Another fragment, however, measures 1.20 inch in
diameter at the larger end, and was probably 5 to inches or more in
length, with 112 septa at the larger end. This large fragment shows
that the septate outer zone does not increase in thickness or breadth in
1 retortion with tii3 size of the corallites, since it is only 0.15 inch broad
in this specimen, the increase in thickness of this corallite being made
up by the increased size of the non-septate interior. For this larger
species I would propose the name Ethmophyllum Whitneyi, in honor of
Prof. J. D. Whitney, to vhom I am indebted for the use of the speci-
mens.

" Of the other species I have seen but a single specimen, which is im-
perfect at l)oth extremities, about 2.15 inches in length, and only about
0.20 inch iv diameter at the larger end and 0.15 at the smaller, with
some 24 to -■ t pta. In addition to its much more slender form, it dif-
fers from th«i ulaer species in having its sei)ta so strongly waved later-
ally as almost to divide the interseptal spaces into cells, nearly to the
outer wall. For this, if it should prove to be a distinct species, I would
j)ropose the name Ethmophyllum gracile.''^

A few months later Mr. F. B. Meek wrote Prof. Dana respecting the
genera Ethmophyllum and Archieocyathus, and his remarks were
printed as follows (Amer. Jour. Sci. and Arts, 2d ser., vol. xlvi, p. 144):

*' Since preparing my remarks, published i-, the Journal of Science
(Jan. number, p. 62, 1868), on the curious fossil from Nevada, for which
I proposed the name Eilimophyllum, I have been led, by further com-
parisons, to think it probably not generically distinct from Archccocya-
thus of Billings. At any rate, it seems to agree very closely in internal
structure with his A. Minganensis and A. profundus. The Nevada spe-
cies differs so widely in form and general appearance as scarcely to
suggest a comparison with Mr. Billings's species, and, besides, I had
derived my impressions of his genus entirely from his typi(;al species, A.
Atlanticus, which also differs so materially in internal structure that
Mr. Billings suspected it might be generically distinct from ins A. Min-
ganensis. If these types are generically identical, however, I can
scarcely entertain a doubt but that the Nevada fossil will fall into Mr.
Billings's genus, which has priority of date. In this case, the namee of
the Nevada species would beoo">': Archococyathus Whitneyi and A. grac-
His.'"

The original specimens described by Mr. Meek are in the collection

^809)

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CAMBRIAN FAUNAS OF NORTH AMERICA.

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of the United States National Museum, and a number of thin Koi'tions
have lately been made from some of them that show the details of struct-
urti. An examination proves that the typo species is generically thw
same as Archceocyathellus EensselaericuH of Ford, and that it is generically
identical with Archceoci/athMsprofundus of Billings. The septa join the
inner wall regularly when there is no vesicular structure within it, but
when the latter is present the septa ternrinate irregularly and the inner
wall is imperfectly developed. In the lower and smaller end both walls
and septa are regular, the vesicular structure and irregular growth com-
ing in with the growth of the individual. The structure is shown by the
figures of plate iv.

Sometimes the outer wall and septa are broken away, leaving the
vesicular interior. I find that the form desci-ibed as E. graeile by Mr.
Meek is the result of such an accident, as it corresponds in structure
to the vesicular interior of other specimens of E. Whitneyi,

We also observe that the thin arched dissepiments between the septa
increase in number with the growth, and that where two dissepiments
partition otf a cavity between the septa a pore opens into it through
one of the adjoining septa. The number of septa in seetions of the
same diameter varies considerably, eight to fourteen in sections ll'""'
in diameter. The thickness and direction of the septa are also variable
in different specimens and in different parts of the same specimen.
Frequently the differences might be taken to be of specific value, but I
regard them as variations of growth caused by local influences on the
individual sponge, such as being crowded by its fellows, fragments of
other organisms getting into it, variation in supply of food, &c.

In a thin section, tubes two-fifths of a millimeter in diameter appear
as simple rings crossed by light bands, which are the interseptal spaees.
In other small sections the entire section is solid.

As the genus ArchiEOcyathus is restricted to the type species A. At-
lanUcus, E. Whitneyi falls back into the genus proposed for it.

Formation and locality. — Middle Cambrian. Silver Peak, Western
Nevada. The s-^ecies occurs in a limestone and calcareous shale, asso-
ciated with Archceocyathus AtlanticuH, fiyclithes jjrinceps, Olertellus Gil-
bertij &c.

Ethmophyllttm profundum Billings.

Plat« 1, i\g<i. la-c; pi. ii, figs. '.i,3a,b; pi. iv, fig, 3.

Jrvhteocyathus profundus Billiugs, 1865. Pal.Fo88.,T(>l. i,p. 4.
Original description. — "Elongate, turbinate, more or less curved, the
basal one or two inches sleudei, then rapidly expanding to a diameter
of from one to four inches, then beroming cylindrical. The form is that
of a large Ctiathophyllnvt or Zapkrentis. The cavity of the cup extends
In de[)th nearly to tln' base. Tiio radiating septa are tlun and closely
crowded together, there being eight or ten in the width of three lines.
The surface is auuulated by strong roagh ridges from three to six lines

(8It^)

■v^'

WALCorr.l

MIDDLE CAMBRIAN FAUNA.

distant from each other, the interveninf? larrowa bciug two or three
lines deep,. The inner wall of the cup is exceedingly thin, apparentlj-
loss than half a line.

"In none of the specimens is the outer wall preserved except in «|H>trt,
and th^re only partially. The large individuals appear to ha ve attained
a length of more than one foot with a dianieter of fronk two tx) four
inches,"

Having received from the Geological Survey of Canada some frag-
ments of limestone containing specimens of this species, several thin
sections were prepared, from which illustrations have been taken that
show most beautifully tht' manner of growth and the minute structure
of the organism so far as preserved. The vesiculose character of por-
tions of the structure give it the ai)j»earance of a Oystiphylloid coral.
Beside the cnp-shaped mode of growth, there are small stems 5'"™ to 10™"'
in diameter that are solid to the ceuter, and one pisce 20""" in diameter
has no central oi>ening. In sucli examples the septa and dissepiments
iire thicker than in the examples with a central opening.

In the enlarged section of a sponge, shown by tig, 1, pi. i, and fig. 3,
l»L iv, the growth has been a combination of the regular double walls
with vertical septa and the vesiculose structure shown by fig. Id, pi. i.
The septa exist between several different, more or less entire, inner
walls, and the thin arched dissepiments crow<i all the open places be-
tween the septa and the irregular breaks in the walls. The siiecimens
represented by figs. 16, Ic, pl„ i, show the irregular vesiculose struct-
ure carried to the extreme, the central cup being filled up for some
distance. The outer wall, with its attached venicai septa, appears to
liave been broken or worn off of tlie specimens represented by figs. 1,
1ft, of pi. i. This is not an uncommon feature of the specimens from
L'Anse an Loup, and is very nusleading in studyi/ig cross sections, as
the irregular vesiculose interior often resists <le,^truction better tliau
the exterior., and an entirely different species app* ars to exist. Mr.
Meek was misled by this in proposing E. ffrarile for the center of E,
Whitneyi.

Formation and lovalitt/. — Middle Oambriau. L'Anse au Loup, Straits
of Belle Isle. Labratlor.

Ethmuphyllum ?( nsspt.aericitm Ford,

Plato V. fi^8. T, 1*^.

Arclmo«yaiheUmf Iiennsdaericus Fiwd, 187.3. Amer. Jour. 8ci. and Arts, ;id itev., v»l.
V, p. 211, iig. 1. Gontis ArchiBocyit thellos proposed at end of desor'ptioii.

Original dencription. — "The only 8pecim*»n clearly belonging to this
species tlutt has come under Ttiy iiotice is ex<(;eeding[y small, Ineing only
o,.{0 of an inch in length and having a diameter of aot more than 0.1 <)
of an inch at the largi r extremity, when jierfect. Thi^ njiecimen iH. in
appearance, a slender, delicately fiiitfi cone, about one-chird of viriuch,

(811,-

CAMBKIAN FAUNAS OF NORTH AMERICA.

[BULU 30.

WAtXIOTT..

If ■•
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iucluding the apex, is imbedded id the rock. Of the remainder a con-
siderable portion is in a badly-damaged condition, the outer wall, with
the greater part of its underlying septa, having been partially torn
away. Such portion as remains uninjured, howevei', is in an excellent
state of preservation and shows the leading features of structure in a
very perfect manner. There remains, notwithstanding, much yet to ht'
desired in order to completely characterize the species ; and I have de
ferred any special notice of it hitherto in the hope of being able to
obtain other, and possibly more perfect, specimens; but, failing in this,
1 have thought it advisable to carry the description as far at this time
as the material at hand will permit. The species may be described for
the present as follows:

"Elongate, conical, straight, gradually expanding from the base up-
ward. Cup moderately large, depth unknown. Outer wall thick and
strong, inner wall api)arently much thinner. Radiating septa thin, nu-
merous, not far from forty, judging from the number seen, sometimes
a little irregular in their spacing. Dissepiments slender, occasionally
absent, at other times dividing the interseptal spaces or loculi for a short
distance into several compartments. Surface faintly annulated and lon-
gitudinally marked by numerous low, rounded ridges, with shallow in-
tervening furrows, the ridges and furrows of about equal width. The
ridges mark the position of the loculi, while the middle of each furrow
indicates the place of one of the septa. Along each furrow and run-
ning its entire length are two straight rows of minute, closely-arranged
circular pores, opening into the loculi. The rows of pores of any given
furrow are separated from each other by a thin strip or plate of the
outer wall, corresponding in position and thickness to the septa ; and
iC is a singular fiict that the pores of either row are arranged alternately
not only with respect to the other, but also with respect to those of
the succeeding row in the next nearest furrow. The pores all commu-
nicate with the interior close to the septa where these latter join the
outer wall ; and, as the rows of pores along any given furrow lead into
distinct though adjacent loculi, it follows that all of the loculi were con-
nected with the general surface by means of a double set of apertures.
Whether the inner wall and radiating septa are perforate has not yet
been made out. Color of the fossil, in gray limestone, when a little
weathered, light brown.

" The above are the characters, so far as known, of this interesting
and beautiful species, embracing only such as are displayed by the speci-
men mentioned at the beginning. These characters taken together are
quite sufficient to distinguish it readily from any described species
while in respect to several of them, such as its straight form, longitud
inally-riblied exterior, and remarkable poriferous system, the species
appears to me at present sufficiently distinct from Archwocyathtts to
constitute a nevy though closely allied genus. Should a further study

(812)

TTITT

■K

WALCOTT.]

MIDDLE CAMBRIAN FAUNA.

of it conflnn this opiuion, I propose to call it Archceocyathelhis. Until,
however, more can be said about it, I prefer to class it as above."

Having obti*<iued more perfect si)ecimous I a«Ul to the above descrip-
tiou. '

There are froui three to six rows of iniimte pores on each of the
slightly raised longitudinal lobes formed by the sslight depression along
the line of each septum. The entire surfswie is poriferous, and some of
the rows of pores open directly on the line of the septum. This must
influence in a measure the attachment of the septum to the outer wall.

The inner wall has a row of large pores, some of which are opposite
the line of attachment of the septa and others open directly into the
interseptal spaces.

The number of septa varies from nine to eighteen in the specimens
we have; the type specimens, figured by Mr. Ford, show twenty or
twenty-one. In most examples the septa are thin, but in one they are
considerably thickened, as well as the outer and inner walls, the inter-
septal spaces being much reduced in size. That the septa are perfo-
rate where they join the outer wall is seen in the several examples ;
a diagrammatic sketch of this is shown by fig. 2, pi. iv.

The cup is very deep and extends nearly to the smaller end, which is
closed or rounded off, terminating rather abruptly.

Mr. Ford states that several dissepiments divide the interseptal
spaces, but none has been observed in the half dozen sections 1 have
studied.

Formation and locality. — Middle Cambiian. (Conglomerate limestone
on the ridge east of the city of Troy, If. Y.

Ethmophtllum RARTJMFord.

Pliito V, figs. 22a-b.

Prntccyathus rarus Foid, 187S. Amer. .Jour. Sci. and Arts, Sd ser., vol. xv, figs, la, ft,
p. 124.

Original description. — "The fossil form for which the above generic
and 8i)eciflc names are proposed belongs to the Archwocyatlms group
and finds its nearest analogue in ArchavcyatheUus of the writer, from the
same locality and geological horizon (this Journal, Marcli, 187.'')). The
only specimen at present known to me is but 0.22 of an inch in length
and has a width of only O.j'* of an inch at the larger extremity. The
general form is that of a minute cone with the apex broken oil'. Tiie
width at the smaller extremity is 0.12 of an inch, and of this fully one-
third is occupied bj' the cup. The cu(> itself is filled witli light colored
liujcstone, rendering it easily distinguishable from the interseptal areas,
which are filled with a darker colored material. These latter appear to
have been twenty-eight in number. The radiating septa may be ob-

(813)

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CAMBRIAN FAUNAS OF NORTH AMERICA.

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served in two or three places, and are seen to be thin and delicate.
The outer wall has been almost wholly removed and the portions of it
that remain are much weathered. The material ])resented for study
consists, therefore, of the solid molds of the iuterseptal spaces, the
cup filled with limestone, a small number of the septa, a transverse
section of the inner wall, and the impression of a considerable portion
of the outer wall. The latter shows that the external surface when
perfect was longitudinally furrowed as in ArclKcocyathelhts. In that
genus, however, so far as known, there are two rows of pores along
each of the furrows, one on either side of the septa, wliereas in the
present genus there appears to have been but one, and that placed di-
rectly on the line of the septa. The evidence of this consists of rulely
circular holes placed at regular intervals along the middle of each ur-
row in the cast. These appear to me to argue the existence of funnel-
like projections inward of the outer wall at the place of the openings.
That they mark the position of orifices leading into the interior appears
to me in the highest degree probable. Their position is, however, so
remarkable, that I was for a long time unable to understand the mean-
ing of them.

" On one side of the specimen there are a small number of the iuter-
septal molds that project beyond the others, and one of these shows
one of its lateral faces for a considerable distance lengthwise, and also
nearly down to the outer surface of the inner wall. An examination of
this face shows that the cavities observed along the furrows extend but
a short distance inward, and that the septa arched around the funnel-
like projections which they represent from below, striking the outer
wall only at the intervening spaces. * * * * * It is further
shown that these cavities are directed slightly upward, or toward the
aperture of the cup. These characters serve to distinguish the form at
once from ArchcBocyathellus, in which the septa meet the outer wall un-
interruptedly.

"If I am right in viewing the cavities along the furrows in the cast
as indicating the presence of external orifices at these points, then it
follows that these orifices were doubtless functionally equivalent to the
double row of orifices along the furrows of the outer wall of Archavcy
athellus. In proof of this it may be remarked that the size of the cavi-
ties indicates that the orifices were, proportionally, considerably larger
than those of the only known species of Archceocyathellm {A, Rennse-
laericus), while their position is such as to present no obstacle in the
way of regarding them as having communicated simultaneously with
two of the iuterseptal spaces."

As stated under the generic description, the proposed genus Proto-
cyathus does not appear to be well established. The difference given,
the occurrence of a single row of large pores over the septum which is

(814^

WAI.0OTT.1

MIDDLE CAMBRIAN FAUNA.

based on the inner cast of the outer wall, is not, so it appears to nie,
of generic value. The same structure is shown in fig. 2 of pi. v, a
sj)eciineu that 1 doubtfully refer to this species in preference to JU. h'em-
selaericum; the reason for this is shown by fig. 2, i»l. iv, the holes being
tlie openings through the septa connecting the intcrseptal spaces; the
outer wall having been removed in figs. 2, 2ft, of pi. v. We shall await
further evidence before accepting the genus Protocyathus.

Formation and locality. — Middle Cambrian. Conglomerate limestone,
ou the ridge east of the city of Troy, New York.

Genus LEPTOMITUS n. gen.

, LeptoH (fine), niitoH (thread).

Elongate bodies, formed of line thread-like longitudinal lines (?) ap-
parently imbedded in a delicate membrane (?), slowly expanding from
a narrow base.

The appearance of these bodies is such as might be formed by the
tuft of long silicious spicules of the glass-rope sponge, Ilyalonema, if
the latter were pressed out between the layers of the shale and the ani-
mal matter formed a film about the fine, delicate, thread-like spiculae.
In the type specimen a confused mass of spiculfc (1), crossing each other
at right angles, occurs at the larger end. Type Leptomitus Zitteli.

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Several fragments of this form were found in the fine-grained argil-
lites at Parker's quarry in association with Olenellvs Thompsoni, Prot»-
caris Marshi, &(i. The resemblance to a bundle of the elongsite spicule
of Hyalonema is very striking, and the occurrence of the confused and
broken spicules at the larger end of the best preserved specimen, and
the crossing of the lines or striae and their breaking up into several
parts at the opi)08ite end, give added force to the coini)arison.

Although we have no proof that the sharp raised lines were slender
silicious spicules, there is little doubt in my mind that in this form we
have a representative of Hyalonema in the Middle Cambrian.

My first impression was that the species was related to Serpulitcs dis-
solutns Billings, of the Trenton limestone, but an examination with a
uiagnifying glass at once dispelled the idea and caused a reference to
tlie SpongisB.

Formation and locality. — Middle Cambrian, Georgia Formation.
Parker's quarry, Georgia, Franklin County, Vermont.

(816)

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90 CAMBKIAN FAUNAH OF NORTH AMERICA. iBUtuaa

Genus PKOTOSPONGIA Salter.
Protospongia Salter, 1864. Quart. Jour. Geo). Soc, vol. xx, p. 238, pi. xiii.

Peotospongia fenestbata Salter.

Plate vi. fig8. 2, 2a-b.

Protospongia fenestra ta SahcT, 1HG4. Quart. Jour. Geol. Soc, vol. xx,p. 2;{8, pi. xiii,fig.

12o-6. iWd, Cat. Cumbrian and Silurian Fossils, p. :<, 1H7H.
Hicks, 1H74. Quart. Jour. Gool. Soc, vol. xxvii, p. 401, pi. xvi, fig. 80.
Zittel, 1877. Abli. derk. Imyer. Akadeniie der Wiss., "2. L'l., xiii. Bd. "Studiin

ii. Fossile Spongicn " (p. 4.'), s«p. copy).
Carter. 1877. Ann. and Mag. Nat. Hist., ser. 4, vol. xxv, p. 177.
Brogger, 1878. On» paradoxidesskifrene ved Krekling. Separataftryk af Nyt

Magazin for Naturvidensk., vol. xxiv, i,p. 20, t. 6, f. 14..
Sollas, 1880. Quart. Jour. Geol. Soc, vol. xxxvi.p. :162, figs. 1,2.
Roomer, 18H0. l^ethea Geogu., 1. Th., p. 316, f. 59.
Hiude, 1883. Cat. Fossil Spongps, p. 129, pi. xxviii, fig. 2.
Walcott, 1884. Monographs U. S. Geol. Survey, vol. viii, p. 11, pi. ix, figs. 5,

rya, b.

Mr. Salter originally described tlii.s interesting sponge as having a
loosely reticulate skeleton formed of very large cruciform spiculai, the
branches of which cross each other at an angle of 80°, and only iu one
plane, no ascending or descending branches rising from the point of
conjunction. The angles occasionally vary, but not much.

More perfect specimens obtained by Dr. Hicks show the spiculae to
be quadriradiate, slightly raised at the center, and formed of four nearly
cylindrical rays.

The skeleton, as described by Mr. Sollas, is composed of large primary
ppiculae, with the interspaces filled in by three series of spiculae, each
formed of spiculae smaller than those preceding it, their rays all lying
regularly disposed iu two directions at right angles to each other, and so
building up a net-work with square meshes.

The skeleton is not preserved in any of the Nevada specimens, the
dift'erent sized spicnilae lying scattered on the surface of the limestone
shale or crowded together w ithout any regularity in the direction of
the rays or the size of the spiculae. The spiculae, however, appear to
be identical in all respects with those described by Messrs. Salter,
Hicks, and Sollas, and if they had not been scattered or crow<le(l
together by accident would form a skeleton siniilar to that described by
Mr. Sollas. The under side of the spiculae shows no trace of a fifth ray
or its jiointof attachment, appearing in this respect like the upper side,
except that the surface is a little concave instead of convex on the upper
side. They are silicious and difler in mineral character from the
spiculae of the Cambrian rocks of Wales which have been replaced
by pyrite.

Dr. Hicks states that P. fenesti ata occurs in the Longmynd Gronj), in
the Menevian Group, and also in the Upper Lingula flags to the base

(816)

WALCOTT.]

MIDDLE CAMBRIAN FAUNA.

of the Tremadoc rocks, j^iving u verticuil range of from 8,000 to 10,000
feet (Quart. Jour. Geol. Soc. London, vol. xvii, 1872, p. l^<l). It also
occurs in black shales of Cambrian age in Norway and Sweden.

Mr. G. F. Matthew also notes the presence of the genus in the St.
John Group of New Brunswick.

Formation and locaiiticH. — Middle Cambrian, Prospect Mountain lime-
stone. In the mountain shale near the Eldorado mine and in the
Secret Cation shale on the east side of Secret Canon, Eureka District,
Nevada.

Genus STREPHOCHETUS Seely.

Strephochetus Seoly, 1885. Ainer. Jour. Sci., 'M ser., vol. xxx, p, 357.

Original dsscription. — " A free calcareous sponge, showing in structure
concentric layers composed of minute twining canals." Under the de-
8crii)tion of the type species, S. oeellatus, the author says: "A compact
calcareous sponge, spherical or slightly flattened, distinctly concentric
in (character, usually less than half an inch in diameter, forming, when in
masses, a tough limestone. When weathered the concentric cliaraiifer
is very evident, the fossil then looking like little eyes peering from the
stone.

"These forms are often gathered in crowded masses, the interme<liate
spaces being filled with fragments of the fossil mingle<l with oolitic
grains. More rarely they appear here and there in a mass of oolite."

With the exception of the minute twining canals, the above description
applies closely to the sponge or Stromatopora-like bodies from the Mid-
dle Cambrian of Nevada. The minute structure has been destroyed by
crystallization, and the reference to Strephochetus is simply to call at-
tention to the presence of organisms resembling the type species 0. ocel-
latus from the Chazy limestone of the Lower Silurian (Ordoviciau).

Strephochetus? sp.f

Spherical or oval bodies with a concentric structure, averaging 1.5"""
in diameter and occurring scattered through a compact limestone and
an arenaceocalcareous rock. Minute structure unknown.

Formation and localities. — Middle Cambrian. Calcareous layers in
the sandy shales above thequartzite of Prospect Mountain, Eureka Dis-
trict, and at Silver Peak, longitude 117° 20' west, latitude 38° north,
Nevada.

HYDROZOA.

Dr. Emmons described a number of Graptolites from "Tacouic"
rocks (Amer. Geol., vol. i, pt. 2, pp. IO'4-IIO), but, when we come to
study them and also the author's remarks on their stratigraphic posi-
tion, we are compelled to reject all but two species from the Georgia
Formation or Middle Cambrian ; tiiese we found in the argillaceous
shales at Parker's quarry, Georgia?, T ermont.

(817)

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CAMBRIAN FAUNAS OF NOBTH AMERICA.

[BVLUM.

In a letter written to Prof. Jules Marcou, December 28, 1860, Mr.
Emmons states "that most if not all those beautiful graptolites referml
fo the Hudson Biver Group by Prof. T. Hall belong to the Taconiv.
There are probably two species in the Trenton and the slates above.
No more." (Proc. Amer. Acad. Arts and 8ci., new ser., vol. xii, 1885,
p. 188.) This proves that Mr. Emmons had not a clear idea of the por-
tion uf the shales of the Hudson Biver Valley that contain the grapto
lites described by Prof Hall, nor of the shales at Point Levis carrying
the graptolitic fauna. Elsewhere in Vermont, Virginia, and Tennessee
he did not distinguish between the older rocks and those of the Hudson
Biver Formation. Of this we will speak at another place and time.

Prof. Hall described Chraptolithtis Milesi (Geology of Vermont, vol. i,
1861, p. 372) as from a bowlder of Georgia slate picked up in the town
of Monkton, Vermont. The species is of the type of those from Point
Levis, and as nothing of the kind has yet been found in situ in the
Georgia shales, and the bowlder was found on the line of the glacial drift
from Canada, I do not think it best under the circumstances to admit
the species to the Georgia fauna. Prof. Hall thinks that " it is proba-
bly of the Quebec Group." (Can. Org. Bemains, Dec. II, p. 63.)

On plate i of his American Geology, Prof. Emmons figures two species
of graptolites, fig. 11 as Diplograptus s&Mlinm and fig. 2 as an unde-
termined species.

At Swanton Falls, Vermont, a species of graptolite occurs in the
shales that is identical with Climacograptua bioornis of the Hudson Bivei-
Formation. I rof. Marcou refers the strata containing the graptolites
to the Taoonic, and places it below the I otsdam sandstone, but I think
without either stratigraphic or paleontologic evidence.

Genus DIPLOGBAPTUS McCoy.
Diplograptus ? simplex Emmons.

Plato xi, figs. 4, 4a.

Diplograptu9 simplex Eionions, 1855. Auier. 6eoI.,voI. i.pt. 2, p. 104, pi. i, tig. Vi.

Original description. — *' Straight ; serrations pointed, cells, rather dis
tant oblique to the axis; the serration equal in length to one-sixth
or one-seventh of the width of the stem. The u,>per or young part of
the stem is three-eighths of an inch wide and the number of serrations
is 24 to an inch. It narrows towards the base, where the serrations iiro
rather obtuse and more distant than those above, and is 10 inches long
as exposed upon the slate. It is confined to the Hoosic rooting slate."

Dr. Emmons originally applied the name Fucoiden simplex (Tnconic
System, 1844, pi. v, fig. 1 ; Agric. Kept. N. Y., pt. 6, 1846, pi. xvii, fiji- 1)
to a species previously named by Prof. Amos Eaton (see Twentieth Kept.
N. Y. State Mas. Nat. Hist, 1868, p. 268) as Fucoides secalinm. Sal)-

(818)

WAtoorr.]

MIDOLG CAMBRIAN FAUNA.

seqiiently be referred the species named by him to Eaton's F. seealinuSf
calling it JMplogmptus aecalinuSy gave a description as above, and at the
same time figured another species which we have tbund in the fine ar-
gillaceous shales of Parker's ledge. For this I have decided to use
Emmons's name aimplexj the name D. secalinus being restricted to the
species from the Hudson Biver Group, as described by Prof. Hall (Pal.
N. Y., vol. i, 1847, p. 267).

The specimens from Vermont are completely flattened in the shale,
and are small as compared with the stipes described by Dr. Emmons,
as the largest one is scarcely 2 inches in length and the small ones have
much the same appearance as the compressed frond of a Phyllograptns,
but the similarity between the figure given in his American Geology and
tlie central portion of the longer fronds from Vermont is so marked that
I think they are identical. Dr. Emmons states that the known locality
was in the Hoosic slate, but I suspect, from his having worked to the
north in Washington County, New York, he may have procured the spec-
imen figured from some other place, referring the slate to the same geo-
logic age as that at Hoosic ; this is the more probable, as a similar con-
fusion of localities is to be detected in other parts of his work. The
details of the description are drawn apparently from the small speci-
men figured, rather than from the distorted specimens usually observed
ill the Hoosic slate. In several of the Vermont specimens there is a
Htrong, round, central axis, as shown in fig. 4 of plate xi, that appears
08 though a hollow axis had been filled with sediment in a more or less
complete manner, thus preserving the form of the axis, while in other
specimens it was compressed and all traces of it lost.

Formation and locality. — Middle Cambrian, Georgia Formation. Par-
ker's quarry, Georgia, Franklin County, Vermont.

Genus CLIMACOGRAPTUS Hall.
Climaoograptus f ? Emmonsi n. sp.

Plate xi, fig. 5.

The only specimen we have of this species is the upper portion of a
single stipe found by Mr. E. Hurlburt in the same band of shale with
Diplograptua f simplex, Meaonacis Vermontana, Olenellua Thompaoni, and
Protocaria Marahi.

The stipe is elongate, narrow, and with narrow, deep indentations on
each side, at right angles to the axis of the stipe, that reach well in
towards the center, leaving short, strong pinnulalike projections be-
tween them that alternate, with relation to each other, on the opposite
sides of the stipe. Where the stipe is 4"'" broad, ten indentations
occur in a distance of 11""". The position and character of the cellules
are unknown ; whether they are in the deep indentations, and the speci-
men shows the lateral view of a compressed stipe, as in Climaoograp-

(819)

■ i;

' iC

CAMBHiAN FAUNAS OF NORTH AMERICA

tBULL.90.

tns when similarly compressed, or whether they form the rather large
projecting points between the indentations, somewhat as in Rastrites,
is not determined. The reference to Glimacograptns is entirely provis
ional, and not intended to indicate the presence of that genus in the
Georgia Formation, but that v form too imperfect for a close generic
reference, resembling compressed specimens of Climacograptns, occurs
at that horizon.

Sooner or later more extensive collections will be made in the Georgia
shales, and it may be that the gi'aptolitio fauna will be more fully de-
veloped.

The specimen figured by Dr. Emmons as ^intermediate species"
(Amer. Geol., pi. i, fig. 2) appears to be the same as the specimen under
consideration. No description or reference to locality is given by Dr.
Emmons.

The specific name is given in memory of Dr. E. Emmons, who strag-
gled so long to maintain the pre-Potsdam age of the formation in which
this graptolite occnrs.

For the use of the specimen I am indebted to Mr. E. Burlbnrt, of
Utica, New York.

Formation and locality. — Middle Cambrian, Georgia formation. Park-
er's quarry, Franklin County, Vermont.

BCHINOZmRMATA.

Genus EOCYSTITES BilUngs.
Eoe^Hlet BillingB, 1668. Acadian Geology, p. 643, fig. 220.

EOOYSTITES f t LONGIDAOTYLUS n. Sp.
Plate y, fig. 3 ; pi. vi, figs. 1, lo-o.

€leneral form elongate-oval or ovate, as far as can be determined from
the crushed specimens. Plates numerous, disposed without apparent
order and varying in form, size, and surface characters on the same
body. The margin of many of the plates appears to be indented so as
to leave an opening, or pore, that passed into the central cavity; these
plates are grouped together on one side, so far as we now know. The
surface of the plates varies: (1) smooth and nearly flat; (2) smooth
and slightly elevated at the center ; (3) smooth and depressed at the
center, with more or less distinct ridges radiating out to the margin;
(4) more or less prominent ridges radiating out from the center to the
margin. The plates of type 4 have crenulations on the margin that give
rise to an appearance of the presence of pores. None of the opeuiDgs
of the body has yet been observed.

A row of long slender arms appears to have surrounded the summit.
Unfortunately our specimens do not show the summit distinctly, nor the

(820)

WALOOTT.]

MIDDLE CAMBRIAN FAUNA.

arrangement of the arms about it, although, in the speciraens repre-
seoted by figure 16, the bases of several arms are present on what ap-
liears to be the inner side of the summit of the body. The arms are
formed of two series of plates that slightly alternate in relation to each
other, as shown in fig. lb. Oasts of short piuuulsB are seen along the
side of several of the arms — a pinnule to each plate on the side at
which it occurs. None of the arms show an ambulacral groove. St«m
or pedicle unknown.

The specimens collected are from a pinkish argillaceous shale and
have been injured by distortion and compression. Plates of the same
general type were found 1,000 feet lower in the strata in the Ely Mount*
aius associated with Olenellua Gilberti ; also, it Parker's quarry, Georgia,
Yt., associated with Olenelltu Thompsoni^ Olenoides Mareouij Protypui
Henectus, &c.

The reference of this species to the genus Eocystites is entirely pro-
visional, as the genus was founded on loose plates of a cystid found
in the St. John Formation of the Lower Cambrian System. The St.
John Formation plates are more strongly ridged than those of E.f t
longidactyltUy but I know no way of generically distinguishing them,
or either of these, from the plates described as Protocystites Menevensi»
Hicks (Quart Jour. Geol. Soc., vol. xxviii, p. 180, pi. v, fig. 19). Under
the circumstances I prefer to wait until more is known of the described
genera before definitely expressing an opinion on the generic relations
of P. t f longidaotylus.

Troohocystitea Bohemicua Barrande (Bull. Soc. G^ol. de France, 2* s^r.,
t. xvii, p. 537, pi. viii, fig. 1) appears to be distinct &om both Eocystites
and Protocystites.

Formation and locaUties. — Middle Cambrian. Chisholm mine, south-
west slope of the Ely Mountains near Pioche ; also, in the Highland
range, eleven miles north of Bennet's Spring, Nevada, associated with
Olenoides typicaliSj Bathyuriacm produetUj Ptychoparia PtooAenm, &o.

BRACHIOPODA.

Genus LINGULELLA Salter.

UnguUlla Salter, 1861. Memoirs Geol. Surv. 6t. Brit., p. 333.

LiNOULELLA G^LATA Hall (sp.).

Plate vii, figs. 1, la-i.

Orbioula oalata Hall, 1847. Pal. N. Y., vol. i, p. 290, pi. Ixxix, figs. 9a-c.
UlioUUa (0.) oalata Ford, 1871. Ainer. Joar. Sci., 3d ser., vol. ii, p. 33.
LinguMla calala Ford, 1878. Amer. Jour. Soi., 3d ser., vol. xv, p. 127.

Original deeoripiion. — *< Orbicular, small; apex excentrio, depressed
along the center, and subplicated near the margins ; surface marked by

(821)

CAMBRIAN FAUNAS OF NOBTR AMERICA.

[nULi.. 30.

fine coiioentric lines and miiinte elevated points, giving it the appear,
anoe of being covered by a poriferous coral/'

Mr. Ford subsequently studied the species and described it as fol-
lows : '< The ventral valve is somewhat elongate-ovate, with the beak
pointed, slightly elevated, and conspicuously channeled for the passage
of the iiedicle. The convexity is moderate and nearly uniform. On
the inside there are two prominent, elongate, curved scars, one on either
side of the median line, with their concavities directed outward. These
recall by their form and position the large lateral scars of the ventral
■valve of certain species of Obolella (e. g., 0. ohromatica). The otiier
impressions of this valve have not been made out.

*' The dorsal valve is more rotund than the ventral and has the heak
much depressed. The convexity increases with increasing age, and in
adult specimens is such as to sometimes give the valve a semi-globoae
appearance. A shallow depression extends in all the specimens from
the beak to the front margin, but in fully grown forms it is often incon-
spicuous. On the inside there are four prominent ridges. Of these the
more central two commence close to the median line a short distance in
front of the beak and extend into the forward third of the shell slightly
diverging throughout, while the lateral pair take tlieir rise close to the
beak and reach to points a little in advance of the raid-length. There
is also a short, slender ridge directly beneath the beak, on the median
line. The central portion of the valve in the upper half is slightly ex-
cavated. The description of the interior of titis valve has been mainly
drawn up from an excellent natural internal mold.

"The surface of both valves is ornamented with moderately conspicn-
ous radiating and concentric lines, the latter irregularly grouped, and
covering the whole a fine papillose network, the points of which are ar-
ranged in concentric series, those of one series alternating with those of the
next, and so on, as first pointed out by Professor Hall in his description of
the dorsal valve. (Pal. N. Y., vol. i, p. 290, pi. V9, fig. 9.) The effect
of this style of ornamentation is very beautiful, and when, as is usually
the case, the shells have a dark, polished aspect, with a setting of liglit-
colored limestone, few handsomer fossil objects can be named. The
shell is thick and of a finely lamellar structure. The usual length of
the ventral valve is about three and one-half lines."

To Mr. Ford's description we may add that the interior of the shell
shows rather large punctie or small pits, as in the type of the genus
Lingulella Davisii. There is also considerable variation in the strength
and character of the papillose surface. In some small shells it is very diffi-
cult to detect it at all, and in others the arrangement of the papillte is so
broken by the fine, wavy concentric lines and stronger, radiating, undu-
lating lines that the surface appears more like that of some species of
the genus Kutorgina than that of the typical species of Lingulella.

(822)

mvccfiT.]

MIDDLE CAMBRIAN FAUNA.

Formation and locality. — Middle Cambrian, Georgia Formation. Con-
glomerate limestoue on the ridge east of tlie city of Troy, N. Y.; also,
cue mile Bouth of Scliodack Lauding, in Columbia County, New York.

LlNGULELLA EllA H. & W.
Plate vii, fig. S; pi. viii, fig. 4, 4a-«.

LinguUpia Ella Hall & Whitiiflld, 1877. Oeol. Ezpl. Fortieth Par., vol. iv, p. 233, pi.
i, flg. 8.

Original description. — *< Shell below tlie medium size. Dorsal valve
subcircalar or oblate, the width slightly exceeding the length ; the beak
perceptibly projecting beyond the general contour of the shell, but very
obtuse and slightly truncate ; sides and base rounded, the latter more
broadly curved. Surface of the valve depressed-convex, a little the
most prominent on the umbone ; marked by line, irregular, concentric
lines of growth on the upper part, becoming more strongly marked and
finally quite lamellose toward the margin of the valve. A few very
indistinct, radiating lines may be seen near the beak by the aid of
a strong magnifier. Ventral valve unknown. Shell-substance phos-
phatic.

"There may be some doubt as to the true relations of this shell. The
broadly oblate form would be an objection to considering it as a true
Lingula, while the truncation of the beak of the dorsal valve would
accord more nearly with what is known of some forms of Lingulepis.
It is possible it may prove to be Lingulella, but in the absence of the
ventral valve it cannot be satisfactorily determined. It diifers from
most known species very perceptibly in the oblate form of the valve.

^^ Formation and locality. — In greenish argillaceous shales of the age of
the Quebec group, in the canon above Call's Fort, north of Box Elder
Cafioh, Wasatch Range, Utah. Collected by S. F. Emmons, esq."

The reference of the species to the Quebec Formation is incorrect, as
it occurs with a characteristic Middle Cambrian fauna, 2,000 feet below
the Potsdam horizon of the Upper Cambrian.

More perfect specimens of the dorsal valve show the surface charac-
ters, and also show that the beak is slightly more projecting.

The ventral valve is longer than wide ; angle formed by the cardinal
slopes about 65° in uncompressed specimens and 90° to 120° in flat-
toued, compressed specimens; sides arching to the broadly rounded
frontal margin ; area flattened, rather broad, and with a narrow median
groove. The cast of an interior of a dorsal ? valve from the Oquirrh
Range shows two long lateral scars gradually diverging from near the
beak, also a central median depression with two posterior adductor
sc^ -'s, and the anterior adductor scars near the terminus. The system
of scars, so far as preserved, is much like the dorsal valve of Obolella
erawa. (See pi. x, flg. le. Compare also with Lingula, Monographs
United States Geological Survey, vol. viii, plate xxi, figs. 18-20.)
Bull. 30 7 (823)

iii

m - 1

CAMBRIAN FAUNAS Oy NORTH AMERICA.

iBULu sa

Surface marked by fine concontric lineH of growth, and on Home n)mAh
fine radiating lines are seen near the beak ; when the surface is entire
a secondary system of ornamentation is seen as very fine concentric
strite, broken by very short undulations that give almost a reticulated
surface.

The Wasatch specimens show valves 2""" to 9'"'" in length. Those
firom near Pioche are more compressed and appear more quadrangular
and broader than the Waibatch forms, except in the small shells, which
are very much alike. When the dorsal valves are compressed longitud-
inally, the cardinal line is straightened and the concent lic stria; are
depressed, so that the shell might readily be taken for a species of Ku-
torgina.

Figures 4& and 4c, pi. viii, are drawn from casts of the interior of the
two valves as they occur in the shales of the Highland Bange and at
the Ghisholm mine, near Pioche. Figure 4(2 shows the relative propor
tions of the valves to each other when flattened in the shale.

Formation and localities. — Middle Cambrian. Box Elder Gaiion, above
Call's Fort; Big Cottonwood Canon, one mile below Argenta, Wasatch
Mountains; East Cafion, above Ophir City, Oquirrh Mountains, Utah,
in dark silicious argillites ; also, in the pinkish argillaceous shale at the
Ghisholm mine, southwest face of the Ely Mountains, near Pioche,
Nevada.

Genus ACROTEETA Kutorga.

Aorotreta Kutorga, 1848. Yerhandl. der rnHsisch. kais. niin. Qesellsch., St. Petera-
bnrg, 1847, p. 275. Type A. mhconica, same report, p. 275, pi. vii, flgs. 7a-c.

AoBOiRBTA GEMMA Billings.

Plate viii, flgs. 1, la, h.

Aorotreta gemma Billings, 1865. Paleozoic fossils, vol. i, p. 218, figs. 201a-/.
Aorotreta tuhconica and A, Aitenuata Meek, 1873. Sixth Ann. Rep, U. S. Geol. Surv.

TeiT., p. 463.
Aorotreta pyxidicula White, 1874. Geog. and Geol. Expl. and Siirv. West 100th Merid.,

Rep. Invert. Poss., p. 9; vol. iv, pt. 1, p. 53, pi. iii, tigs. 3o-d, 1875.

Aorotreta gemma Walcott, 1884. Moiigraphs U. S. Geol. Survey, vol. viii, Pal. Eureka
diatrict, p. 17, pi. i, figs, la, 16, \d, \f; pl.ix, figs. 9,9a.

Original description. — "Shell very small, about 1 line in diameter;
one valve nearly flat and the other acutely conical. Dorsal valve very
gently convex, nearly circular; sides and front margin uniformly
rounded; posterior margin very obtusely angnlated at the beak, on
each side of which a portion of the cardinal edge, equal to onc-lourth of
the whole width of the shell, is nearly straight; umbo very small ; beak
apparently depressed to the hinge line and not projecting beyond it;
cardinal angles compressed, broadly rounded ; a wide, shallow, mesial

(824)

WALOorr.]

MIDDLE CAMBRIAN FAUNA.

sinuH extends from the front niargiu about balf wuy to the beak;eUe-
where the valve is gently convex or nearly tlat.

"Ventral valve acutely conical, with a flat triangular area which iti
IM^rpeudicular to the plane of the lateral margin, its base half the widtli
of the whole shell. In the apex of this valve there is a minute circular
aperture, and in one specimen a dark line extends from it down the
middle of the area, which appears to represent the forumiual groove
of this genus; but in two other specimens of the ventral valve, with
the area well preserved, there is no indication of a groove. Surface
with very fine concentric striae.

"Width of dorsal valve, about one lino: length, about I'ight-itintlis
of a line. The height ot the ventral valve is about one line.

"The form of this species is very like that of A. nuhconica (Kutorga),
but that species is twice the size of this and has the area distinctly
grooved."

The groove on the aree, of which Mr. Billings speaks, is variable; in
some specimens it can be scarcely determined and in others it is quite
distinct. As far as the size is concerned, we have specimens from 2'"°>
in diameter up to 5°"". The variation in the height of the ventral valve
is also considerable.

The relations of the species to Acrotreta suhconica Kutorga (Cber die
Bracbiopoden-Familie der Siphonotretsese. Yerhandl. der russisch.
kais. min. Gesellschaft, 1848, p. 275, pi. vii, flgs. 7a-c) are strong, and,
except the greater elevation of the ventral valve, there are no marked
differences. Without a direct comparison of specimens, I do not think
it best to identify the American form with the Russian, although, from
its having such a great geologic range, it was probably widely distrib-
uted in the Cambrian seas.

In the Paleontology of the Eureka District, pages 17 and 18, I Imve
giren the range of this species as then known. We now have to add
that it occurs at a horizon 4,000 feet below the lowest horizon there
and is associated with species of Olenellus just above the great series
of Cambrian quartzites. The shell is more robust and larger than the
average specimens of the Upper Cambrian, but specimens fi'om the
Upper Cambrian beds on the Gallatin Biver are nearly as large, and the
form of the exterior of the valves and their interior muscular markings
are essentially the same ; the differences are so slight that I do not hesi-
tate to place them under one species. More favorable conditions of
habitat and food would produce the variation in size; also, the change
liable to occur in a species living through so long a period of time as
the .accumulation of 3,000 feet of limestone would require.

The associated species are Kutorgina pannula, Acrothele aubaiduaj Or-
thisina sp. f , and trilobitic remains.

Formation and locality. — Middle Cambrian. East side of anticlinal, in
limestone just above quartzite, Pioche, Nevada.

(825)

100

CAMBBIAN FAUNAS OF NOUTH AMEBICA.

limx.M,

Genus IPHIDEA Billings.
IphUm BilUngs, 1874. Cau. Nat., new Mr., vol. vi, p. 477.

IPHIDEA BELLA BilUngS.
Plate vii, fig. 4.

li>kMra kfllla Billings, 1872. Can. Nat., new ser., vol. vl, p. 477. Idem, 1B74. Pal.Foaa.
vol. ii, pt. 1, p. 76.

The descriptions of the genns Iphidea and the type species I. bella
were united in the following:

Original description. — *< Of this genuH we have no H])eciuien8 showing
the internal structure, but the external characters seem sufficient to Hep-
arate it from any described generic group. The ventral f valve of /.
hella is conical, strongly elevated at the beak, hinge line nearly straight,
posterior angles narrowly rounded, sides and front nearly uuiforatly
rounded, forming rather more than a semicircle. PoHterior side with a
large false area and a convex pseudo-deltidiuni, the width of which at
the hinge-line is nearly one-third the whole width of the shell. The
dorsal valve is semicircular, moderately convex, most elevate<l at the
beak. The hinge-line appears to be straight. The form and structure
of the posterior side (such as the area, foramen, deltidium, &c.) cannot
be made out from the specimen, owing to its imperfection. The surface
is covered with fine concentric striaei, which in the ventral 1 valve are
continued around on the area. Of these strisB there appear to be from
fifteen to twenty in the width of one line, their size varying somewhat
in different parts of the specimen. There are also a few obscure radi-
ating strisB. Width of ventral valve, seven lines; length, five lines;
height, two lines.

<* In the specimen above figured there is an aperture in the beak, but
in another there is no appearance whatever of a perforation. This
geuu.a resembles Aerotreta, but differs therefrom in having a large con-
vex deltidiam. It seems to be also closely allied to Kutorgina. The
shell which I have described under the name of Obolus Labradoricw
belongs to this genus.

''J. bella was found by T. G. Weston, in a bowlder of limestone asso-
ciated with numerous fragmentary trilobites, of primordial age, near
Trois Pistoles, below Quebec. A closely-allied species of the same
genus occnrs in the primordial limestone at Topsail Head, Conception
Bay, Newfonndland."

As will be seen by my refeience of Obolus Labradoricus to Kutorgina,
I do not agree with Mr. Billings in his reference of that species to
Iphidea. There does not appear to be much resemblance between the
two. when a series of the specimens are compared.

When studying the brachiopoda of the Upper Cambrian (Potsdam)
horizon the genus will be more fully described, as we have very perfect

(826)

WAUxnr.)

MIDDLE CAMBRIAN FAUNA.

101

H{)eciuieD8 df a species from the Touto formation of Arizona that ap
pear to be identical with Iphidea omatella, described by Dr. O. Linnais-
Hon, from the Cambrian of Sweden.

Formaiion and localities. — Middle Cambrian. Besides the localities
mentioned above, Iphidea bella occurs in the limestone of L'Anse au
Loup, on the straits of Belle Isle, bnt its presence in Vermont, New
York, or Nevada has not yet been recorded to my knowledge.

Oenns KUTOKGINA BUlings.

Kutorgina Billings, 1^1.
nnt4). Idem, 1865.
Kutorgina DHvidaon, 1871.

Pamphlet; and Geology of Vennont, vol. ii, p. 948, foot-
Pal. FoM., vol. i, p. 9. .
Mon. Brit. Fosa. Bracb., vol. iii, p. M2.

\ Upper Oaipbrian.

Mr. Billings proposed the genus Kutorgina in a foot-note accompany-
ing the description of the type species K. oingulata. He says: "Since
the above was written I have examined many casts of the interior of
this species, and am inclined to the opinion that it is generically dis-
tinct from Obolella chromatica. From the very considerable elevation
of ')e beak the dorsal valve must have au area and probably a foramen.
In one specimen there are two large oval impressions fafntly impressed,
but still distinctly visible. There is no trace of the lateral scars; and
the form, notwithstanding the characters of the surface, conveys the
idea of an Orthviina. Should, upon further examination, my suspicions
turn out to be well founded, I shall call the genus KuTOsaiNA, after the
celebrated European naturalist, Eutorga."

The species now referred to the genus are:

Kutorgina sculptilis Meek,

Whitfleldi Walcott,

cingnlata Billings,

X'Sl.'mu "'"""'' ^ Middle OambriM.
Prospectensis Walcott,

From the character presented by these the following generic diagnosis
is drawn:

Shell inequivalvo, transverse, or elongated ; hinge-line extended nearly
to the width of the shell.

Larger or ventral valve convex, elevated at the beak, which is straight
or incurved, with or without a mesial sinus ; area narrow, or without a
true area ; when present it is divided by a wide, open fissure. Smaller
or dorsal valve flat or slightly convex, beak marginal.

The areas of both the ventral and the dorsal valves of the species
which we have showing them are very narrow and the fissure between
tbcni broad and relatively large. A number of thin longitudinal sec-
tions, cut so as to cross the beak and also out on the cardinal edges, fail
to show any covering to the fissure, and the area appears to be little
more than the reflexed shell, as the lines of growth of the valve extend
over and upon it.

(827)

: 'Ik

102

CAMBRIAN FAUNAS OF NORTH AMERICA.

fiiui.L.a«.

Exterior of valves marked by concentric strite or lines of growth
tbat terminate on the cardinal edges of the valves, as in K. cingulata;
nearly smooth and shiny, as in K. Labradorica; like that of TrematU,
K. pannula, or Lingulella, K. aoulptilia.

The intei iors of the valves of the only species that we have showing
the interiors, K. oingulata, have numerous, radiating strite extcn<lin}r
from the beuk outward toward the margins of the shell.

In the interior of the ventral valve four pairs of scars extend Iroui
the beak forward, as shown in flg. Id, pi. ix.

The interior of the dorsal valve is divided midway by a narrow mesial
ridge that separates two pairs of scars (adductors?) ; the anterior pair
small.

Shell structure calcareous {K. oingulataf K. Wkitfieldi)^ or horny [K.
Labradorica, K. novlpHl'u).

EUTOBOINA omauLATA BillhigS.
PUte ix, flgB. 1, la-Ti.

Oholella oingulata Billings, 1861. Faciiphlet ; Geology of Yermont, vol. ii, p. 948, figs.

347 and 349. Idtm, 1863. Geol. Canada, p. 264, figs. 387a, ft.
ObolfUa (Kutorgina) oingulata Billings, 1865. Pal. Foss., vol. i, p. 8, figs. 8, 10.
Oholella (f ) Phillipii Davidson, 1866 Men. Brit. Fobs. Braoh., vol. iii, p. 62, pi. iv.

figs. 17-19.
Kutorgina cingulata Davidson, 1868. Quart. Jour. Geol. Soo., vol. v, p. 312. Idmo

1871. Mon. Brit. Foss. Brach., vol. iii, \i. 342, pi. 4, flg. 2^.
Kutorgina cingulata var. purilla, Linnarsson, 1873. Braoh. Par. Beds of Swedpii.

Bihang till k. Svensk.Vet.- Akad. Hand!. 7)and 3,N:o 12, p. 25, pi. iv, figs. M, M

Original description. — <^ Hinge-line straight, a little less than the
greatest width of the shell ; sides straight or slightly convex for about
one-half the length ; anterior angles obtusely rounded, front margin
either uniformly convex or with a small portion in the middle somewhat
straight. Greatest width a little in front of the middle. Ventral
valve strongly and uniformly convex, most tumid about the middle ;
beak depressed below the greatest convexity of the shell ; cardinal
edges straight or gently concave, diverging from the beak at an obtuso
angle ; area unknown. Dorsal valve somewhat flat, most elevated at
the beak, in front of which, along the middle of the shell, there is »
wide, shallow concavity extending to the front margin ; on each side of
the beak, descending with a somewhat flat slope to the cardinal angles;
area unknown, apparently half the height of the ventral area and
nearly at right angles to the plane of the margin. Beak erect, obtusely
pointed, forming the most elevated part of the shell. Surface witli
strong concentric sublamellose ridges, which do not converge to the
beak, but terminate on the cardinal edges, their course conforming to
the margin of the shell. Four or Ave ridges in the width of one line.

tt Length of largest dorsal valve seen, six and one-half lines; greatest

(828)

WALCOTT.]

MIDDLE CAMDBIAN FAUNA.

103

width, eight lines. Length of largest ventral valve in » strui^lit line
from beak to itont, seven lines; width, ten lines. The proportional
length and width appear to vary. The apical angle of the ventral valve
also varies, being in some specimens inncli more pointed at the beak
than in the one above figured. Specimens of all sizes occur from three
lines in width upward."

Having obtained a large series of specimens ft'oni east of Hwanton,
Vermont, the following observations are added to the above descriittion:

Shell transversely to longitudinally oval; more or less plano-convex;
(iardinal angles about 100°; hinge-line a trifle less than the greatest
width of the shell. Ventral valve convex; arching gently from the
frontal margin to the deepest part of the valve, it curves more abruptly
over to the slightly incurved, pointed beak; a mesial sinns of varying
strength occurs on many shells and in others it is e;.iu»Iy absent; a
false area without a trace of an opening extends some dib^^uice beneath
the beak and out to the extremity of the hinge-line, wher< ii narrows to a
little more than an inflected cardinal margin. Dor^i . valv^ tranpvcise,
depressed, rising to the highest point at the beak, whicli is <ilovated,
but not inci . 1, over the hinge line; in somo examplj»; ^he valve is
unusnnlly flat, with a low, round, pointed beak risiug at the center
of the cardinal line; in others the beak is more elevated, the body of
the valve sloping up towards it. Shell structuie calcareous. Surface
marked by concentric striae and undulations of growth that give the
older shells a rough appearance.

The muscular impressions of the ventral valve are preserved as dark,
narrow, elongate scars, two each side of the median line and two near
the lateral margins; the central pair (fig. 1, pi. ix) appear to diverge
from a single scar extending forward from near the beak; the next pair
are broader and longer and much like the two lateral pairs. Numerous
striffi, about .6°"" apart, radiate from the vicinity of the beak forward
and laterally to the margins of the shell.

The scars of the interior of the dorsal valve are better preserved than
those of the ventral ; a short, central, elevated line extends about half-
way from the beak to the front margin, separating two large posterior
and two small anterior (adductor?) scars; the posterior scars have a
low ridge bounding them, outside of which numerous strong lateral
sinuses radiate out a short distance; the radiating lines observed on the
cast of the ventral valve also occur on casts of the dorsal valve. I am
not sure but that Mr. Billings's fig. 348 (Geol. Vermont, vol. ii, p. 948) is
similar to the compressed specimens of tht ventral valve from l^arker's
quarry. Figures Ig, lA, plate ix, are taken from two compressed ven-
tral valves from the arenaceo-argillaceous shales at ti.e Parker quarry.
But for the fact that we have specimens showing forms between figures
la, lb, and Ig, lA, the tendency would be to separate the latter as a dis-
tinct species, as the outline of the valve is lost and the surface cbaraC"
ters are largely obliterated.

(829)

:< ■ !'l

104

CAMBRIAN FAUNAS OP NORTH AMERICA.

[BULU 80.

The scars of the ventral valve appear much like those of the ventral
valve of Lingula Feistmavieli Barrande (Syst. Sil. de BohSme, vol. v, pi.
106, III, lA), and what is seen of the muscular impressions of the dorsal
valve recalls the adductor scar of the Lingulidee more than those of the
ObolidfiB. Until more is known of the interior of the valves it is hazardous
to make comparisons, for, in the case of the Lingula figured by Barrande,
he found later, and figured on plate 110, quite a change in the scars as
compared with those shown on plate 106.

In Sweden, K. cingulata is associated with ParadoxideH Forchammeri
and Agnoatm Icevigatus. The English specimens are found in the Middle
and Upper Lingula flags and Lower Tremadoc. In America, as far as
known, it is confined to the Middle Cambrian or Oleuellus zone.

Kutorgina Prospectensis differs from K. cingulata in having regularly-
rounded surface stria), and also in the more narrow form of the valves.

Formation and localities. — Middle Cambrian, Georgia Formation. Mr.
Billings described the species from L'Anso an Loup, Labrador. It is
abundant in the lenticular mass of limestone intercalated in argillaceous
shales carrying Olenellus Thompsoni, on the Bullard farm, about two
miles east of Swantou, Vermont. In the form of compressed casts it
occurs at Parker's quarry, town of Georgia, Vermont. It is also identi-
fied from the Malvern Hills of England, the island of Bornholm, and
from Sweden.

This, or n closely allied species, occurs at the same geologic horizon,
on Silver Peak, Western Nevada, longitude 117° 20' W., latitude 38° N.

Kutorgina Labeadoeioa Billings (sp.).

Plbte ix, figs. 2, 2a, h.

Oholtu Labradoricua Billings, 1861. Pamphlet; Geology of Vermont, vol. ii, p.
946, fig. 345. Idem, 1863. Geol. Canada, p. 248, fig. 291. Idem, 1865. Pal.
Fo88., vol. 1, p. 6, fig. 6.

Original description. — " Porsal valve subcircular, the hinge-line
straight and equal to about three-fourths the width of the shell ; rather
strongly and uniformly convex, most prominent at one-fourth the
length from the beak, the latter small, neatly pointed, scarcely distinct
from the cardinal edge. Surface with flue concentric striae, which con-
verge slightly on approaching the cardinal edge, 15 to 20 in one line,
and also with a few coarser concentric undulations of growth, the whole
crossed by minute radiating striae just visible to the naked eye. The
shell is black and friable like that of a Lingula. Length, 5^ lines;
width, about 6 lines.

"Ventral valve unknown."

This species occurs in great abundance, associated with K. oingulata,
in a hard gray limestone east of Swan ton, Vermont.

I add to the original description the following :

The ventral valve elevated, with the apex rising slightly above thQ

(830)

WAUXMT.l

MIDDLE CAMBRIAN FAUNA.

105

plane of the large triangular area ; the surface of the area is unknown,
except a narrow reflected margin.

The dorsal valve is slightly elevated at the beak, more transverse
than the ventral, and with a narrower area.

Surface similar to that described by Mr. Billings.

Unfortunately none of the specimens shows the two valves united and
the areaa of the valves are not preserved. From their pon-preserva-
tion in this species and also in all the known species of the genus the
presumption is that the greater portion of the area was open or else
covered by a thin film of shell that is not preserved. There is consid-
erable variation in the relative length and breadth of different shells
aud in the height of the ventral valve.

An examination of the type specimen of Obolus Labradoricus, in the
collection of the Geological Survey of Canada, led to the identification
of the Vermont specimens as the same species and the generic reference
was changed to Kutorgina.

Formation and localities. — Middle Cambiian, Georgia Formation. In
a lenticular mass of limestone intercalated in argillaceous shales carry-
ing Olenellus Tliompsoni, on the Bullard farm, about two miles east of
Swanton; also, about two miles east of Highgate Springs, Franklin
County, Vermont, and Mr. Billings describes it from limestone at L'Anse
au Loup, Labrador.

KUTOEGINA PANNULA White, (sp.)
Plate vii, figH. 3, '3a, pi. viii, figs. 2, 2a-<!.

Trematiat pannulus White, 1.574. Geog. and Geol. Expl. and Surv. West 100th Merid.;
Prelim. Rep. Invert. Foss., p. 6. Idem, 1875. Same report, vol. iv, pt. 1, 36,
pi. i, figs. 4a, b.

Original description. — "Associated with Olenellus Gilberti Meek, a
single imperfect specimen of Trematis has been discovered, which, al-
though consisting only of a single valve, possesses such characteristic
surface -markings as to indicate its specific separation from all other
known forms of the genus.

"The diameter of the specimen is about three millimeters; outline
apparently subcircular or a little broader than long; apex moderately
prominent and situated noar the posterior margin. Surface marked by
a very fine net- work of cMique raised lines, dividing it up into minute,
four-sided, pore like pits, which cause it to resemble, under the lens,
the texture of finely- wovcsii cloth.

"In the character of its surface-markings this species is nearly re-
lated to T. punctata Sowevby, sp., as figured by Davidson in his Mono-
graph of British Fossil Brachiopoda, part vii, No. 1. That species,
however, reaches a much larger size than onr shell, and the small pits
that similarly m*irk its surface are six sided, instead of four-sided as in
ours. The surface of T. siluriana Davidson, another allied species, has
the pits arranged in radiating instead of oblique lines."

(831)

m I

■1 'S

I;!

'.■.*t»t

106

CAMBRIAN FAUNAS OF NORTH AMERICA.

(BUM. DO.

The type specimeD is a fragment apparently of the ventral valve.
The author's generic relereuce depended entirely npon the surface char-
acters and was necessarily provisional. I know of another species with
a nearly similar surface, from the Tonto Gronp (= Potsdam) of Ari-
zona. The type is not otherwise known from the Cambrian System, to
my knowledge.

The writQT in 1885 visited the locality from which the type specimen
was collected and found a number of well-))re8erved ventral and dorsal
valves. The ventral valve is elevated at the beak and projects back
over the a;-ea, which is divided by a broad tissure; the area is a little
more than the reflexed margin of the shell. Dorsal valve depressed;
beak marginal on a nearly straight hinge line.

As stated by its author, the surface of this shell is similar to that of
several species of Trematis. It cannot now be referred to that genua,
as the form of the valves is that of Kutorgina. We now have species
of Kutorgina with surface characters like those of Lingula, K. Labra-
dorica; of Lingulella, K. sculptilis; of Trematis, K. pannula; of Obo-
lella, K. cingulata.

Formation and locality. — Middle Cambrian. Pioche, Nevada, one mile
below Argenta, in Big Cottonwood Canon, Wasatch Mountains, Utah.

Kutorgina Prospectensis Walcott.

, Plato ix, tigs. 3, 3a.

Kutorgina Proapectcnsk Walcott, lf*84. Monographs U. S. Geol. Survey, vol. viii,
Pill. Enroka District, p. 19, pi. ix, figs. 1, la, 6.

Original description. — ''Shell rather small for a species of the genus.
It is thick and black, like a linguloid shell.

" Ventral valve elevated, with the apex projecting over the triangular
area and extending considerably beyond the posterior margin. Owing
to the exfoliation of the shell the extremity of the apex is unknown;
the surface of the area is also unknown. Ventral valve depressed,
slightly convex, without a mesial sinus; marginal outline subcircular,
with the posterior margin obtusely angular at the beak; the beak is
slightly depressed below the highest point of the shell, and apparently
projects a trifle beyond the cardinal edge. Surface marked by stronglj-
defined, fine concentric striae, ten in a distance of one millimeter, where
they terminate on the posterior margin.

"The dorsal valve of this species is much like that of Iphidea Labra-
doricns J3illings, but does not appear to come within the limits of that
genus as defined by the type species."

A few more specimens have been collected since the original descrip
tion was written, but none of them shows the interior of either valve or
other characters not shown in the types. The strong, concentric stria;
and thick shell separate the species from all others of the genus known
to me except K. cingulata, from which it difiers in having a regularly

(832)

WAuarr.]

MIDDLE CAMBKIAN FAUNA.

107

convex dorsal valve, and tbe surface covered with more nniform, equi-
distant, concentric striae.

Formation and locality. — Middle Cambrian. In an arenaceous shale
resting on the Prospect Mountain jjuaitzite, summit of Prospect Mount-
ain, Eureka District, Nevada.

Tbe associated fossils are Olemllus lloicelli, 0. Gilberti, 0. JrfdiMjr«t,and
Anomocare f parvum.

Genus AGBOTHELE Linnarsson.

genus.

Labra-
of that

iescrip-

alve or

c stri*

known

gulariy

Acrothele Linnarsson, I87(i,
Vet. Akad. Handl.

Brnch. Par. Bods of Swt'don, Biluing tiilte k. SviMiHk.
Bd. 3, N:o 12, p. 1»0.

Original description. — "Shell corneous, composed of several lamiuee,
the inner smooth and polished, the outermost one rough and opaque.
Ventral valve slightly conical, with excentric umbone, pierced by a
minute foramen, in front of which there are, at least in one species, two
Hmall wart-like protuberances; the field between the umbone and the
posterior margin is usually a little flattened, thus forming a slight indi-
cation of a false area. Dorsal valve with marginal umbone, consisting
of two wart like protuberances. In the interior of the dorsal valve
there are two oblong, diverging muscular scars close to the posterior
margin, and two small, rounded scars near the middle. The muscular
scars are separated by a longitudinal ridge."

Mr. Linnarsson considered ( )bolella and Acrotreta as probably the
most nearly related genera to Acrothele.

From our present knowledge of the genus Obolella I think it best not
to group Acrothele with it. The genera Acrothele, ESchizambon (Mon-
ographs United States Geological Survey, vol. viii, p. 69), Acrotreta
have a perforated ventral valve that is more elevated than the dorsal.
The muscular impressions vary materially, but not sufficiently to pre-
vent the genera mentioned from being grouped together. The genus
Linnarssonia has a perforate ventral valve, but it differs in the struct-
ure of the shell and the character of the muscular impressions.

The species now referred to the genus are:
Acrothele coriacea Linnarsson.
granulata Linnarsson.
8ubsidua White.
Bohemica Barrande.
= Obolm ? Bohemicus Barrande (Syst. Sil. Boh£me, vol. v, p. 102, pi.

vii, figs, la, 2a, 3a).
Acrothele Matthewi, Hartt (sp.) (U. S. Geol. Survey, Bull. No. 10, p. 15,

1)1. i, flgs. 4, 4a).

Acrothele f dichotoma Walcott (Monographs United States Geological
Survey, vol. viii, p. 14, plate ix, fig. 11) is quite as properly referred
to the genus Acrotreta. Omitting this, all the known species are froiu
the Cambrian or first fauna.

(833)

I !

;'*; US

108

CAMBRUN FAUNAS OF NORTH AMERICA.

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There is a utriking similarity in all the speciea yet described, and a
comparison of specimens appears necessary to distinguish between A.
Bohemica, A. coriacea, and A. Matthewij and A. granulata and A. sub-
sidtta.

AOEOTHELE SUB8IDUA White.

Plate ix, figH. 4, 4a-o.

Aorotreta t subsidua White, 1874. 6eog. and Greol. Expl, and Surv. West 100th Merirt. ;

Prolim. Rep. Invert. Foss., p. 6. Idem, 1«75. Same report, vol. iv, pt. 1, p. 34,

pi. i, figs. 3a-d.
Acrothele aubsidua White, 1880. Proc. U. S. Nat. MuHeum, vol. iii, p. 47.

Original description. — "Shell thin, corneous, discoid, subcircular or
somewhat snboval in outline, the transverse diameter being a trifle
greater than the longitudinal ; sides regularly and front broadly rounded ;
posterior margin slightly straightened, forming a comparatively short,
slightly convex, or nearly straight hinge-line.

"Dorsal valve flattened; beak marginal or nearly so, not prominent;
interior surface having a slightly elevated median ridge, beginning be-
neath the beak and extending to about the middle of the valve, where
it disappears.

"The condition of all the specimens of this species which the collec-
tions contain is such that the muscular impressions are not distinctly
shown, but those of the posterior adductors appear to be small and
placed nearly beneath the beak, one on each side of the median ridge
just mentioned ; between these muscular impressions and the posterior
margin there is at each side an obscure diverging ridge or fold, whicb
seems to blend with the posterolateral margin.

"Ventral valve moderately convex in the umbonal region, but more
flattened anteriorly and laterally ; beak eccentric, somewhat prominent,
and minutely perforate. Some of the specimens show what appear to
be small adductor impressions placed in the ai)ex, close to the foramen,
one at each side of it. One specimen shows a slight flattening of the
space upon the outer surface, between the apex and the hinge, produc
ing the appearance there of an indistinctly defined cardinal area.

"The inner surface of both valves of all the specimens of this species
contained in the collections has been more or less exfoliated by weather
ing, whereby some of the principal characters have been obscured. Con
sequently, the foregoing description is not only incomplete, but it is
probable that the discovery of more perfect specimens may show the
necessity for modifying it. The cast of a single valve found associated
with those used ih this description, showing large and distinct muscular
impressions, already suggests such a moditication; but its characters
are not embodied in the description, because that specimen is not cer-
tainly known to belong to the species. The specimen referred to is
illustrated by fijg;ure 3d, plate i. The other specimei)^ ^11 show &m

(834) . .

WAMXWT.]

MIDDLE CAMBRIAN FAUNA.

109

radiating lines in the stractare of the shell, and also concentric latuino;
of growth. They are all compressed in dark shale, and show only the
interior surfaces of the valves, none showing the external 3urfa«e. The
latter is supposed to be lamellose or otherwise so roughened as to have
caused it to adhere to the shale, while the smooth interior surface has
readily separated in the plane of fission."

The outer surface of this species is minutely papillose, the papillae
being arranged in a rough, quincunxial order or irregularly crowded
together along the spaces between the concentric lines of growth. This
surface was found on specimens from the typical locality at Antelope
Springs, and also on others from Pioche, Nevada.

Acrothele granulata Linnarsson is a very closely related species, and
it is difficult to give specific differences between them on a comparison
of the ventral valves, which is all that has been found of the Swedish
species.

Acrothele Matthewi Hartt (see United States Geological Survey, Bul-
letin No. 10, p. 15) is very much like A. subaidita. Like A. subaidua,
the outer granulated surface is rarely seen, as it clings to the matrix,
taking a thin coating of shell with it.

Formation and localities. — Middle Cambrian. Calcareous shale at
Antelope Springs, Utah, in association with Ptychoparia Kingi, Amphis-
CU8 WheeUri, &c. At Pioche, Nevada, it is in an argillaceous shale with
Olenellm GiWerti.

Genus OBOLELLA Billings.

Obolella Billings, 1861. Geology of Vormont, vol. ii, p. 946. Idem, 1865, Pal. Foss.

vol. 1, p. 7. idem, 1872. Can. Nat., new ser., vol. vi, p. 217. /dcm, 1872. Amer.

Jour. Sci.,3d ser.jvol. iii.,p. 35.5. /dem, 1876. Samejou vol. xi, pp. 176-178.

Idem, Hall, 1863. Sixteenth Ann. Rep. N. Y. State Cab. Nat. Hist., p. 131. Idem,

Ford, 1881. Amer. Jour. Sci., .3d ser., vol. xxi, p. 131.
DicelUmua Hall, 1873. Twenty-third Rep.:' Y. State Cab. Nat. Hist., p. 246. Type

0. crassa.

Original description. "Oenerio characters. — Shell ovate-circular or
subquadrate, convex or plano-convex. Ventral valve with a falserarea,
which is " laetimes minute and usually grooved for the passage of the
peduncle. Dorsal valve either with or without an area. Muscular im-
pressions in the ventral valve, four, one pair in front of the beak near
the middle, or in the upper half of the shell, and the others situated one
on each side near the cardinal edge. Shell calcareous ; surface concen-
trically striated, sometimes with thin extended lamellose ridges.

" In general form these shells somewhat resemble Obolus, but the ar-
rangement of the muscular impressions is difPerent: In Obolus the two
central scars have their smaller extremities directed downwards, and
couverging towards each other, but in this genus the arrangement is
exactly the reverse."

Type, Obolella chromatica.

Later, 1872, Mr. Billings redefined the genus; in 1876 he more fully

(835)

I
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W
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■'■.Mi
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. • ■ f

i:,

110

CAMBRIAN FAUNAS OP NORTH AMERICA.

[Bl'LL. 30.

described the type species, accompanylDg it with figures, two of which
we reproduce, together with the description.

Pig. 9.

Fig. 10.

Fia. 9.— Diagram abowing the ponitioD of the Rcan of the vnntral valve of O. ehromatiea.
Via. 10. — Diagram showiDg the poHition of the scare of the dorHal valves (aft«r BilUnga).

'* Oeneric characters.— Shell nnarticulated, ovtite or sub- orbicular, len-
ticular, smooth, coucentrically or lailiately striated, sometimes retic-
ulated by both radiate and concentric strite. Ventral valve with a solid
beak and a small more or less distinctly grooved area. In the interior
of the ventral valve there are two elongated sublinear or petaloid mus-
cular impressions, which extend from ueartbe hinge line forward, some-
times to points in front of the mid-length of the shell. These are either
straight or curved, parallel witli each othi'r or diverging towards the
front. Between these, about the middle of the shell, is a pair of small
impressions, and close to the hinge line a third pair, likewise small,
and often indistinct. There is also, at least in some species, a small pit
near the hinge line, into which the groove of the area seems to termi-
nate. In the dorsal valve there are six impressions corresponding to
those of the ventral valve, and sometimes an obscure rounded ridge
along the median line.

" If we compare the interior of the ventral valve of an Obolella with
that of Obolua ApolUniSy we see that there are six muscular impressions
in each, but not arranged in the same manner. The two small scars aa
at the hinge line are most probably the same iu both genera. The two
lateral scars bb of Obolus have no homologue in Obolella, unless they be
represented by the two large ones, dd. Should this be the case, how-
ever, the great difference in their position would no doubt bo of generic
value. I think it more probable that the large scars dd of Obolella rep
resent the central pair cc of Obolus. Again, Eichwald says that iu the
interior of the ventral valve of 0. ApolUnis there is a longitudinal sep
turn (shown in the above flg. at s), which separates the two adductors,
cc, and extends to the cardinal groove (I suppose he means the groove
g on the area). No such septum occurs in any species of Obollela. I
have not seen- any description of the dorsal valve of the 0. Apollink
sufficiently perfect to afford a means of comparison with that of Obolella,
but the differences in the ventral valve alone are so great that the two
genera can scarcely be identical. They are, however, closely related,
and occur in nearly the same geological horizon."

In the rocks below Quebec and at the Straits of Belle Isle, we find

the following species of Obolella :

1. "O. desqiiamata K&tt = Avioulaf desquamata, Pal. N, Y., vol. i, p. 292, pi. 80, fig. 2.
Goonrs at Troy, New York.

(836)

•"i.
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"5.
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!»':

wALoon.]

MIDDLE CAMBRIAN FAUNA.

Ill

Occurs at Tr«)y.
Oconra at Troy.

"2. O. cragaa Hall = OrMoufa t craata, op. oit., p. 299, pi. 79, fig. S.

'•:i. 0. calata Ha.ll= Orbioula ctelata, op. oit., p. *290, pi. 79, fig. 9.

"4. O, gemma, n. Hp.

"5. 0. Circe, n. sp.

"6. O. chromatica BilliugH has been found us yet only at tbe Straits of Belle Isle."

Of the species enumerated above, 0. desquamata has beeu uuited with
0. craasa and 0. cctlata is referred to the genus Lingulella by Mr. Ford.

Obolella dettiderata Billings (Pal. Foss., vol. i, p. 69) is not a true
Obolella, but a, form that with Obolella f amhigua Walcott (Monographs
U. S. Geol. Survey, vol. viii, Pal. Eureka Dist., p. 67, pi. i, flgs. 2a-c)
will form a new genus or subgenus of the Obolidte. Both species occur
at the same relative geologic horizon at the base of the Lower Silurian
(Urdovician) or Oalciferous Group of the New York State section.

Obolella pretiosa Billings (Pal. Fo8s.,vol. i,]). 68) is more closely related
to the genus Acrothele than to Obolella, and, with the type specimens
before me, I cannot make a generic reference that is at all satisfactory.
We must await the discovery of specimens showing the interior of the
shell.

Obolella Ida Billings (Pal. Foss., vol. i, p. 71) is very doubtfully re-
ferred to Obolella. Like 0. pretiosa it will require better material for
study before a satisfactory generic reference can be made of it.

Obolella polita Hall (sp.) (Sixteenth Ann. Rep. N. Y. State Cab. Nat.
liist., p. 133, pi. vi, flgs. 17-21). This species departs further from the
tyi)e 0. chromatica in the size of the muscular scars than any of the
Middle Cambrian species, but their system of arrangement is essentially
the same as far as I have yet been able to determine.

Obolella Nana M. L,nd H. (Pal. Upper Missouri, p. 4, pi. 1, flgs. 3a-d).
The collections of the National Museum contain the types of this species
used by Meek and Hayden, and also a large series of Obolella polita from
various localities in Wisconsin. A comparison between the Black
Uills specimens on which 0. Nana was founded with the latter prove
them to be the same. Figures 3c, Zd of Meek and Hayden show the
interior of the ventral valve, and flgures 3a, 36, the exterior of the dorsal
valve. All the characters shown in the types of 0. Nana are well
sliowu in specimens of O. polita from the Potsdam sandstone oi' Eau
Claire, Wisconsin.

Obolella discoidea H. and W. (Geol. Expl. Fortieth Par., vol. iv, p. 205,
pi. i, flgs. 1, 2). This species must remain doubtfully referred to the
geims until interiors of the valves are discovered. It recalls 0. f Ida^
when imbedded in a hard limestone matrix.

Obolella transversa Hartt ^ lAnnarssonia transversa ( Amer. Jour. Sci.,
3d ser., vol. xxix, p. 116).

Obolella miser Billings (Pal. Foss., vol. ii, p. 6D). This species is re-
ferred to the genus Linr ?d*88onia by Mr. G. F. Matthew, in a letter to
the writer.

When the detailed study of the Upper Cambrian fauna is taken np,

(837)

-(K'fif

V'? .-f'l

■!■■■

112

CAMBRIAN FAUNAS OF NORTH AMERICA.

(bull. 30.

the vurious species from that horizou will be studied and illustratHd,
uud theu we shall have data for a more extended and accurate compari-
sou of all the species belonging to the genus.

Obolella chbomatioa Billings.

Plate xi, figs. I, la, b.

Obolella chromatica Billings, 1861. PampLlet; Geology of Vermont, vol. ii, p. 947,

ligH. 346o-d. Idem, 1863. Geology of Cauuda, p. 284, ligs. 288a-d. Idem, im*.

Pal. Fo88., vol. i, p, 7, figs. 7a-d. Idem, 1876. Anier. Jour. Sci., 'Ml ser.. vol. xi,

p. 176, figs. 1, 2, 3; p. 177, flgH. 4a-d. Idem, Ford, 1H81. Amor. Jour. Sci., *1

ser., vol. xxi, ]). 13:{, tigs. 3, 4.

Original description. — ''Broad oval, the rostral extremity obtusely
pointed, front broadly rounded, greatest width a little below the mid-
dle; both valves rather strongly and uniformly convex, most tumid at
about one-third the length from the beak. Ventral va've more acute
above than the dorsal, beak depressed below the greatest elevation of
the shell, slightly elevated above the margin, with a small area beneath
it which is inclined backward at an angle which varies from 45° to 60°.
Dorsal valve with an obtusely rounded umbo, the beak scarcely dis-
tinct from the cardiutal edge and not elevated above the margin. Snr
face, with fine concentric striae or small minutely rugose ridges of
growth, of a \ ariable size, from four to eight in one line, often smooth
from exfoliation or wearing. Color of the shell in the reddish limestone
a honey-yellow, in gray limestone grayish; when exposed to the weather
becomes white and minutely fibrous.

"Length and breadth about three lines.

"In some specimens the ventral valve is depressed convex, the beak
being on a level with the greatest elevation of the shell. The shell is
thick and stronf , and when well preserved breaks with a granular
fracture. When tveathered a tendency to fibrous exfoliation is mani-
fested.

"This species is closely allied to the form that is found so abundantly
in the Troy limestone, but the muscular impressions in that one are
rather closer together and nearer the beak. (At least they are so in
the specimens in my possession.)

"Many of the specimens are a little more obtuse in the upper half
than those figured. The individuals are exceedingly numerous and
differ little in size."

In 1870 Mr. Billings added the following details of the interior of tlie
valves:

" In the ventral valve there is a groove in the binge line for the
passage of the pedicle. On each side of the grove there is a small,
somewhat deeply excavated, cardinal scar. In the cavity of the valve
there are two elongated scars, which extend from near the cardinal scars

(838)

WAIX;OTT.]

MIDDLE CAMnuIAN FAUNA.

}i;5

1 Ll. !! i

forward tibout tworliinls of (ho Icntjtli of tin': shell. Tlicsc divrr^^c froiti
each other, more or loss, in their extension forwiud, iuxl are usually
curved, but sometimes neatly strai}>ht. They may be called laterals.
They are, in general, separated from each other about one-third of the
width of the shell. A little above the mid length, and l)etween the two
laterals, there is a pair of small scars arranged transversely, with their
inner extremities directed somewhat forward, Tlu? space above these
two scars, between the upper portion of the laterals, is generally tumid
from the thickening of the shell. In one of the specimens there is a
small i)it in the center of this space.

" The dorsal valve has a small area, or nearly ihit Iniige facet. The
minute beak is slightly incurved over rhe edge of the area. Beneath the
beak there is a small subangular ridge, on each side of which there is a
cardinal ? scar. The elongated scars, which seen) to conespond to the
laterals of the ventral valve, are here altogether in the upper half of
tlie shell. They diverge widely in their extension forward. They are
in general very slightly im|)ressed, and would, most probably, esj^ape
the observation of any one who did not expe<'t to tind scars where they
are situated. In thet cavity of the valve there is a low rounde<l median
ridge, which extends from a point near the, hinge line forward a little
below the mid-length of the valve. About the mi<ldle of the shell there are
two small scars. These are usually striated longitudinally. The me-
dian ridge passes between them. The area is coarsely striated.

" The above are the principal characters of this species, and they are
subject to some variation, one of which is particularly worthy of notice.
The two small cardinal scars of the dorsal valve are sometimes elon-
gated laterally. This is carried to such an extent in another species
(0. gemma) that they not only extend the whole length of the hinge-line,
but are curved forward at their outer extremities aiul continued <lown
into the cavity of the valve. In such cases they present an appearance
similar to that of the groove beneath the hinge line of the genus Oho-
kUina. In other species of this genus the lateral scars of the dorsal
valve are sotuetimes conuected together by their upper extremities.
But this is not a constant character. In ditlerent indivduals of the
same si)ecies these scars are either conne<!ted or uol. The laterals are
also sometimes connected with the cardinals.''

In an interior of the dorsal valve from L'Anse au Loup, now before
me, I And that the cardinal ? scars extend down into the cavity of the
valve, and also that the central scars on the opposite sides of the median
ridge are elongated and have much the same form as those of the same
valve in 0. craHsa and O. gemma.

Formation and localiUi. — Middle Cambrian, associated with Olenellus
ThompHoni and other fossils characteristic of the j\Iid<lle Cambrian or
Georgia horizon. L'Anse au Loup, on the north side of the Straits of
Belle Isle, Caiuxda.

Bull. 30 8 (a;39)

, .If

: H

i u
' 'ii

• ' us I

!«.' \f\

< k

If-f,"

114 CAMBRIAN FAUNAS OF NORTH AMERICA. Ibbll-IO.

Obolklla crassa HhU (sp.)

Plate X, ftgH. 1, la-/.

Orbieula f vraHna Hull, 1H17. Pal. N. Y., vol. i, p. 'JOO, pi. Ixxix, fig. 8a.
Avivuhi t (ItHiiiutmahi Hall, 1HJ7. Pal. .N. Y., vol. i, p. 2\>2, pi. Ixxx, figs. 3a, h.
OholeUa (Orhiculii f) vrnnHU Fold, IH7I. Aim^r. Jour. Sci., IM «er., vol. ii, p. WW,
Obolvlla uruvna, O. dvHiiuamala Hilling.s, 18T1. (Jan. Nat., now 8cr., vol. vi, p. 218. Idem,

1870. AiiHT. .lour. Sci., :!d wsr., vol. iii, p. :!."»().
DUellomuH crmnn Hall, 1873. Twonty-tbird Kt^p. N. Y. StatoCali. Nat. Hi8t.,p. a4(i, pi.

xiii.HgH. (5-0.
Obolella vraiwa Ford, 1881. Amur. .Joiir. Sci., 3d Hur., vol. xxi, p. 131, figs. 1,2.

Tbe ori$;iiial (le.s(5ription of tlie species appears to be that of the ex-
terior of the veutial valve, aud i.s as follow.s: 'M^vat-eorbicular, with
the apex near the narrow extremity; apex obtu.se; surface marked by
strong concentric wrinkles and fine rtuliatiug strise.

"These characters are preserved in the cast, a small portion only of
the shell remaining upon the specimen.

^^ Position and locality. — This species was found in the intercalated
calcareous strata, among the shales of the Hudson Eiver group, two
miles northeast of Troy."

Mr. Billings, in J8U1 (Geol. Vermont, vol. ii, p. 947), thought that
Aviculaf desquainata Uall might be referre<l to the genns, and in 1S71
Mr. Ford referred Orbieula.* crasna Hall to Obolella. Later, in 1877
(Amer. Jour. Sci., M ser., vol. xv, j). 128), the latter observer placed
Avieulaf desquamata as a synonym of O. crasna, saying: ''The species
known as Obolella cransa of the Troy beds may also be briefly noticed
in this connection, [t iucludes the species already widely known under
the name of 0. desquamata, from the same locality, this latter, as may be
shown, having been founded upon tbe dorsal valve of the former. The
ventral valve is always more acutely pointed at the beak than the dor-
sal, but beyond this feature there is nothing, so far as I have been aide
to discover, by which they may be distinguished from eacji other ex-
ternally. The surface of each, when perfect, is both radiately and con-
centrically striated. As a rule, however, the imbricating edges of the
successive layers of growth are the only markings visible.

"Of the interior of the ventral valve an excellent figure was given
by Mr. Billings (Amer. Jour. Sci., 3d ser., vol. iii. May, 1872, p. li'iB);
but the interior markings of th(i dorsal valve have nowhere, to my
knowledge, yet been accurately shown. The scars are nearly the same
with those of the dorsal valve of 0. ihromatica, but the smaller pair
close to the beak are here, in the majority of cases, distinctly connected
with the larger pair directly benciith them; while the central i)air,
instead of running parallel with each other throughout, diverge at tbe
mid-length of the valve, and extend onward in .slender falcate forms
into the anterior fourth of the .shell. Their parallel portions are, bow-

(840)

'," I

WALOOTT.)

MIDDLE CAMBRIAN FAUNA.

115

ever, the only parts usiuilly seen, tuid it was only after collecting the
.species for u number of years that I obtained evidence that what had
come to be looked upon as wholes were, in reality, only parts of much
more extensive impressions."

The species was more fully described by Mr. Ford, in 1881, under
remarks on the genus Obolella (Auier. Jour. Sci., 3d ser., vol. xxi, pp.
1;H, 132).

"The shell of Obolella crasna is suborl»icular, with the beak of either
valve extending slightly beyond the ])eriplieral contour. As a rule,
the beak of the dorsal valve is curved downward so as to almost touch
the short, indistinct hiuge-liue, while that of the ventral valve is less
depressed and slightly more projecting; and these are tlie only features
by which the two vfilves may be externally distinguished. The majority
of the specimens of the ventral valve have an extremely shaUow de-
pression running from the beak to the anterior margin along the median
line; but I have found that even this is uot distinctive, inasmuch as
some of the dorsal valves exhibit it. The sjH'cimens in my possession
vary in length and breadth from li to lines, the two diameters being
generally nearly equal. The surface of both valves, when perfect, is
both radiatel}' and concentrically striated. The shell is thick and solid,
showing no tendency to break up into successive laminie on weathering.
I have had portions of it ground and i)olished for microscopic exam-
ination, but am unable to make out any detinite structure.

"In the interior of the ventral valve there are two small, ovate mus-
cular scars, situated close to the beak, one on either side of the pedicle
groove; and immediately in advance of these a pair of large, elongate,
curved scars, which sometimes extend forward into the anterior fourth
of shell. Between these latter, and somewhat above the mid-length of
the valve, there are two small subcircular imjiressions. All of these
vscars are, in well prewerved specimens, <leeply impressed, and, taken to-
gether, constitute a conspicuous and beautiful system. There it' uwually
a distinct ridge running along the niiddle of the large lateral impres-
sions, dividing tliem at bottom into two i)ortions; and in some cases its
wider upper portion is minutely pustulosis The rostral ])ortion of the
valve is often much thickenetl, the several scnrs bounding the elevation.
The interior surface of the forward ]>ortioii of the valve is niarke<l by
tine radiating striie.

"The dorsal valve possesses a small though distin(;t area, wlii<rh is
divided into two equal portions by a feeble longitudinal ridge. The
slender cardinal line is delicately notched in the muhlle, and has imme-
diately in advance of it a deep transverse groove.^ On either side of the
longitudinal ridge referred to, there is a snuUl, ovate, cardinal nmscular
scar. These scars have their a))ices directed ilow award and outward,
their upper portions cutting across the extremities of the cardinal line

' Fig. 'Zh iu origiual.
(841)

i M

116

CAMBRIAN FAUNAS OK NORTIf AMRRICA.

[BI!1.LS0.

and limiting it. DirtMitly in front of the canlinalH thcro arc two lartrt' iiii
prcHsionH of Miinilar NliaiHi and direction, tlio laterals, wliicli cxtond lor.
ward to the niid-loni;tli of tlio hIu*11. Them; two pairs of iinprcNsioiiH nu^
frequently connected with each other by the passa;;(' of the canliiialM
down into the latorals ; but, as will be nimmi, tlu'y are not so connected in
the specimen floured, wiiitth has been selected in order to illustrate iiuiic
(d«arlyth«'ir essential independen<!e. In tin; (u-ntral |>ortionof the valvo
there is a pair of still larjfer impressions,' bavin*; their upper portions
parallel and their lower, falcate i)arts widely diver;;iu},'. r»etween their
parallel portions there is a low mesial rid^e, which dies()ut before reacli-
iUK the liin;;e line. The falciform i>orlions of these H<'ars are, in {general,
very faintly impressed, an<l mi}xht readily »'s(*ape observation. The in-
terior surface is usiially smooth."

In specimens from a li};ht-}iray, granular linuistone, tlu": tendency <»r
the shell to break on the surface and show successive lamina' is quite
])ronounced, but usually it is, as Mi-. Fcu'd says, not so.

The differences lM«ween the muscular scars of O. erassn and the type
of the y;enus (). ehromatica are not as marked as I had suj»posed froiii
the Hjiures fjiven by Mr. Billiuffsaiul iMr. I'^ord. A study of the iiiterinr
of the valves of O. vhromatica shows that the central s(!iirs ol" II dorsul
valve are not uidike those in (). cnissn and that those of tin cntral
valve are essentially the same. It is dirti<!ult to lind two iiitcriois of
the same valve in either species exactly alike, a fact owin;;' to the ori;;-
inal condition of the scars on the shell and much more to the changes
passed throufjh since the tleath of the animai that inhabited it.

Formation and localities. — Miildle Candirian. In the even-bedded and
confflomerate limestone on the ridjje east of tluHsity of Troy, New York:
at the same jjfeologic horizon one mile below Schodack Landing, in Co-
lumbia County, New York ; also, at Ht. Simon and at Bic llarbor, on the
St. Lawrence Itiver below Quebec, Canada.

Oboi.ella gemma Billings.

Plato X, fig8. "^ ->■

rt-C.

Obolella f/emma Billiiifj.s, 187'^. Can. N.at., new sor., vol. vi,p. 218, fi(f. ."), of p. 217.

Original ileHcription. — •' Shell very small, about two or three lines in
length, ovate, both valves moderately convex and nearly smooth. Vent-
ral valve ovate, the anterior margin broadly rounded, with sometimes a
portion in the middle nearly straight ; greatest width at about one-third
the length from the front, thence tapering with gently (!onvex or nearly
straight sides to the beak, which is acutely rounded. The area is about
one-fifth or one-sixth the whole length of the shell, with a comparatively
deep groove, which extends to the apex of the beak. The dorsal valve

' ccin.Drif^inal.

(842)

WAirOTT.l

MIDDLE rAMHRIAN FAUNA.

117

JH ri(>iirly (HnMilar, ohscurcly iin;;iiliii- at tlu; lunik, iiiid riitiuM- iiiorv
Itioiully roiiiulcd iit tlic IVoiit iiiiii';;iti tliiui nt Mic .sido.s.

"Ill (lie iiitcrioi' of tlif vcntnil valve t here are two siiiiill intiseiiiar
iiiipn'MHJoiiK of a Innate form, close to the eanlitial inat'<;iii, one on each
Hide of the median line. A second pair consists of two elongate snb-
linear scars, \vhi(!li extend from the posterior third of the length <»f thei
sliell to ]>oints situated at ahont oiie-fonrth the len^fth from the front
inat'^'in. Tlies*^ sears are nearly straight, parallel or slightly diver;riii^
forwards, un<l divide the shell loiifjitndinally into three nearly eqnal
poll ions. Between them, abont the middle of the shell, are two other
small obscnrely-deflned impressions. There is also a small pit close to
the liiti^e line and in tint median line of the shell. In the interior of
the dorsal valve there is an obscnre ronnded riilp^, which rnns from
the beak alon^ the median line almost to the front margin. Close to
the hiii^e line there is a pair of small sears, one on ea(;h side of the
ridffe. The other impressions in this valve have not been niide out.

'•The snrfacii of both valves is in jjeneral nearly' smooth, but when
well preserved shows some obscnre »!oiieentrie strii«."

When breakiii}; up some bits of limestone from Hie I larboi-, obtained
I'roiM the Geological Survey of Cana«la, 1 found a comparatively perfe<!t
interior of the dorsal -alve of this species that shows two rather larj'c
clon^^ate iw'vs near the cardinal mar^Mn, a median groove ehannelin^ the
beak, a de|.iessed area just in front of the latter that is bounded on either
side by a strong ridjje that unites in front of it, a. faint muscular scar
or scars showin;; Just in front of the jmint of union; laterally a ridge
passes oft' from each side and gradually diminishes as it advances into
the cavity of the valve. In another example the elevated ridges are
neiirly lost, probably by the compression of the shell.

A beautifully ])reserved interior of the ventral valve fiom Troy, New
York, shows the muscular scars in a better state of preservation than any
I have seen from IJlc Harbor; nearly all the specimens from the latter
l)la(!e appear to have been partially macerated and then more or less eom-
l)rossed before the consolidation of the sediment. The principal defect
in the Troy si>ecinieii is the obscure character of the elongate lateral
scars. The shell also shows radiating lines that appear to have been
color lines in the original shell. Specimens from I>ic Harbor show the
various features seen in the Troy specimens, but not in as perfect a con-
dition in any one specimen.

1 do not think there is much doubt of the identity of the shells found
at Troy with those from Bic Harbor.

Formation and localities. — Middle Cambrian. In the conglomerate
limostonea of St. Simon and Bic Harbor, on the St. Lawrence River,
below Quebec, Canada. Mr. Ford discovered the species on the ri<lgo
east of Troy, New York, in association with other well-known fossils of
the Middle Cambrian fauna.

(843)

l^m

118 CAMBRIAN FAUNAS OF NORTH AMERICA. [ntJix. 3o.

Obolella Ciuok Billings.

ri:llc X, li^H. :!, lid
Obolella Cine BiWmgs, IS'i-J. Can. Nat., in'w ser., vol. vi.p. 219.

Original (lescription, — "Ovtite, front and sides uniformly rounded; pos
terior extremity more narrowly rounded than the front, length and
width about e»|ual, greatest width at the mid-length, rather strongly
and uniformly conve.\:, surface nearly smooth, but with fine concentric
strisB. Length, seven lines; width, a little less. The rostral portion of
the shell is much thickened for about one-fifth the length, and \n this
part there is a deep and wide groove. In front of the thickened por-
tion the muscular impressions are indistinctly seen, but appear to be
formed on the same j)lan as those of the ventral valve of the genus.

"The above description is drawn up on one exterior and several in-
teriors of the same valve, apparently the ventral valve. The exterior
is very like that of O. (h'squamata, and is of the same siae, but the in-
terior shows it to be an entirely distinct species.

" Length of the largest s[»ecimens seen, seven lines ; width, about the
same or slightly less."

Through the kindness of Professor Whiteaves T was permitted to study
all the sj)ecimens of this species in the collection of the Geological Sur-
vey of Canada. Specimens of the valve described by Mr. Billings as
the ventral show the deep rosf ral cavity, from the anterior side of which
a ridge extends forward on each side into the cavity of the valve, nuicli
as in O. gemma ; inside of these there are two narrow elongate scars and
two oblong central sci;"s; n luimber of elevated radiating striae cross
the central portions of the interior and extend more faintly nearly to
the frontal margin.

But one interior of the dorsal valve was observed. This shows the
same character of area as 0. evassa ; the lateral scars are of the same
character, but the central scars are confined more to the rostral half of
the valve.

Formation and hcaUty. — ^liddlc Cambrian. Limestone couglomerato
sit Trois Pistoles, on the St. Lawrence Kiver, below Quebec, Canada.

Obolella nitida Ford.

Plate xi, t\'/. 2.
Oholella nitida Ford, 1873. Amer. Joiir. Sci., 'M 8(^r., vol. v, ]>. 213.

Original dcfieription. — "Shell transversely suboval, small. Dorsal
valve gently but irregularly convex, the greatest elevation occurring at
a point about one fifth the length of the valve froni the apex. From
this ]>oint the licak curves sharply down to the hinge line, which it
almost touches. The hinge line itself is slightly curved and apparently
equal to about one-third the width of the shell. At the most elevated
l)oiut of the valve commences a well-defiueu mediuu depression, which

(844)

WAI.C(

exte
gra(
l)ort
alia
oftl

we t

WAIXOTT.)

MIDDLE CAMBRIAN FAUNA.

119

extends forward for a distance of about one-half the length of the valve,
gradually widening and becoming more shallow till it disappears. A
])ortion of the don il valve close to the margin is sometimes nearly flat
all around. The internal markings are not well enough shown in any
of the specimens that I have seen to admit of description. The surface
is '^T'uamented with very fine concentric striae and na'uerous close-set
rauiating striae, the whole just visible to the unassisted eye.

"The ventral valve is not certainly known. The width of the largest
dorsal valve that I havs seen is 0.14 of an inch and the letigth O.IO of
an inch."

The above description and the figure of a type specimen are all that
we have of the species.

Formation and locality. — Middle Cambrian. Even-bedded and con-
glomerate limestones on the ridge east of the city '^f Troy, New York.

Genus ORTHIS Dalmsa.

OHlm Dalumu, 1827. See Brit. Fo88. Bracli., vol. i ; Geul. Introductioa, p. 101.

OETHIS ? HiGHLANDENSIS U. Sp.
Plato viii, ligs. :?, 3a, 6.

Shell about the average size of the Cambrian species, but below the
size of those from the Silurian. Transversely oval or subrotund, front
broadly rounded and nearly straight in the dorsal valve ; hinge line
shorter than the greatest v idth of the shell. Ventral valve moderately
convex, most elevated toward the beak, which is slightly arched over to
meet the nearly perpendic ular area : mesial sinus broad and shallow or
nearly obsolete; areailat; foramen unknown. Dorsal valve associated
in the same hard specimens of limestone, more convex than the ventral
valve ; hinge line ver^, short, median fold but slightly raised above the
general surface ; area unknown. Surface marked by concentric lines of
growth and finer striae. No traces of radiating costae are seen except
on the interior of the shell towards the margin.

Casts of the interior of the ventral valve show the dental plates,
median ridge and bifurcating ridges extending nearly to the margin;
also, two lateral grooves. Tlu> specimens of the interior of the dorsal
valve show only faint Impressions of a large oval soar each side of the
median line.

The form of the dental plates, the prolonged ridges, and the short
median ridge of the ventral valve associate this species with Orthis
rather than Orthisina. The interior of the ventral valve alHes it closer
to 0. Pepina Hall (Sixteenth Ann. Rep. K. Y. State (Jab. Nat. Hist., p.
l'{4,i)l. vi, figs. 23-27) of the Wisconsin and Texas Upper Cambrian (Pots-
dam) horizon than to the species of the Middle Cambrian, unless it be
Ortlmiua f Orientalis. It is to be regretted that we have not better
material for the study of this and the species placed under Orthisina.

(845)

■fflw

120

CAMBRIAN FAUNAS OF NORTH AMERICA.

|BUU,. 80.

Formation and localities. — Middle Cambriau. In the limestono with
OlenelluH Gilbert!, Olcnoides let-is, &c., at Pioche, and also on the west
8ido of the Highland Range, 11 miles north of Bonnet's Springs, and
at the south end of the Tinipalmte Range, Grooiue District, Nevada.

'"O't

Genus ORTHI8INA D'Orbigny.

Orthisinn D'Orbiguy, 1841). See Brit. Fosb. Brjich., vol. i, Genl. latroduction, p. 104.

Orthisina Orientalis Whitfield.

Plate vii, fig. 6.

Orthisina Oricnialis Whitfield, 1884. Bull. Amer. Mus. Nat. Hist., vol. i, p. 144, pi. xiv,
fig. 0.

Original description.—''' Shell quadrangular in outline, somewhat
higlier than wide, with vertical and sub-parallel lateral margins, and
broadly rounded base. Cardinal line rai)idly sloping from the apex to
the extremities, which are slightly rounded. Hinge line straight, as
long as the greatest width of the shell. O.irdinal area broad and high,
divided in the middle by a triangular foramen, which is about as high
as wide. Surface of tlie ventral v.alve moderately convex, marked by
very fine radiating striiB and also by several concentric lines of growth.
Filliug of the rostral cavity and foramen large and prominent. Speci-
men, a cast in shale, of the ventral valve only."

The specimen described above is flattened in the shale and also ap-
parently compiessed laterally. IJnoompressed specimens referred to this
species, from intercalated limestone beds ("lentile") in the slialeseast of
Swanton, show it to ha\e been moderately convex, and also specifically
distinct from O. Pepina of the Potsdam group in W'sconsin and in Texas.

Formation and localities. — Middle Cambrian, (ieorgiah'ormation. Sil-
ico-argillaceous shales ; Parker's quarry, town v'f Georgia, and in a gray
limestone "lentile" two miles east of Swanton, Vermont, at about the
same relative geologic horizon.

Orthisina festinata Billings,

Plato vii, HgH. 7, 7a, h.

Orthisina J'rulinula BilliugH, IHtil. Paiiiphlet ; Geology of Vcriiioiit, vol. ii, !». IM'.I,
ligs. ;jr)0-:{5>. nirm, 18(5:?. G<H)1. Cuuada, p. 281, figs. 28!»«-f. Idem, ISflri. Pal.
FosM.,v(»l.i,p. lO.flg. 11.

Original description. — " Sub(iuadrate or seuji-oval, hinge line eciual to
tiie greatest width of the shell. Ventral valve subpyraniidjil, beak ele-
vated, suiface witli a straight or slightly convex slope in all directions
to the margin, area triangular, a little inclined backwards, ibramcn
about as wide as liigh, closed by aiionvex deltidiunj wliich is i)erforated
at the beak. Dorsal valve nearly flat. Surface with angular bifurcat-

(846)

WALCOTT.J

MIDDLE CAMBRIAN FAUNA.

121

iiij,' rib.s, five or six iu the width of two lines at the margin, crossed by
tine coneentric strijp, of which there are from seven to ten in one line.

"Width on hinge line from ten to fifteen lines; length about one-third
less than the width. Height of central valve from two to three lines.

"Both valves show longitudinal undulations radiating from the beak
to the margin.

"This species closely resembles some of the ordinary forms of the
fjenus, but difters internally from any known to me in the Second Fauna
in the absence of the dental plates, no traces of which can be i)erceived
ill the casts.'"

Specimens were collected from a limestone iu the typical locality, but
no casts of the interior were found. The radiating costne are finer and
more numerous than those ou the cast figured by Mr. Billings, imt in other
ciiaracters they appear to belong to the same species. East of High-
gate Springs the species is quite abn.idant in a hard, arenaceous, mag-
iiesian limestone, and shows the costte to have been roughened by
spinous projections and also by rather strong concentric lines of growth.
These characteristics are also preserved in a cast from the argillaceous
shale of Parker's quarry. Several illustrations are given of specimens
tVoiii <litiereut localities.

Formation and localities. — Middle Cambrian, Georgia Formation, in
liinestono "lentile" about two miles east of Swauton; in silico-argil
laceous shales, with Olenellm Tliompsoni, Parker's quarry, town of
(leorgia; and in arenaceous magnesian limestone about two miles east
of Highgato Springs, Franklin County, Vermont.

* !)■

ilv

IW.

Orthisina? tkansversa n. sp.

Plate vii, figs, r>, 5o.

Shell small, transversely subquadrangular in outline, front broadly
rounded, angle formed by the union of the cardinal slopes of the ven-
tral valv(3 155° to 165^, hinge line straight and as long as the width of
tlie shell. Area of the ventral valve of moderate height, bent back
lioiii the hinge line, divided by a triangular foramen that is higher than
\viil(! and covered by a convex deltidium ; the area of the dorsal valve
is bent back at more than right angles to the hinge line ; foramen higher
rliaii wide, covered by a <leltidiuin.

Surtiure marked by numerous radiating, fine, even costu', eight in a
distance of .')""", on the frontal margin of the ventral valve; a few con-
centric lines of growth cross the radiating costje, but not so as to give
tlioiii a nodose character.

Interior characters unknown. The fine radiating striae and transverse
Ibni) distinguish this from other described spe(Mes known to me.

Formation ami locality. — Middle Cambrian, Georgia Formation. Sil
ico argillaceous shales of Parker's quarry, town of Georgia, Franklin
County, Vermont.

(847)

>h "^^t

122

CAMBRIAN FAUNAS OF NORTH AMERICA.
Obthisina? (sp. undt.)

(BULL. 30.

There are two upecies represented by fragmentary material that np
pear to be distinct from any described. One occurs east of Highgate
Springs, the other at Parker's quarry.

Two undescribed species of Orthis or Orthisina, from L'Anse au Loup,
on the Straits of Belle Isle, Labrador, that have not yet been described,
occur in the collection of the Geological Survey of Canada.

Genus CAMARELLA Billings.

Ccmarella Billings, 1859. Can. Nat., vol. iv, p. 301.

Original deaeription. — "Family RhynchonellidaB; ventral valve, with a
small triangular chamber beneath the beak, supported by a short mesial
septum as in PentameruH. Dorsal valve, with a single mesial septum
and two short lam< llae for the support of the oral appendages, as in
Ehynch4)neUa."

The type of the genus is C. Volborthi, the description of which follows
that of the genus, and, on page 1 43 of The Geology of Canada, 1863, illus
trations are given, figs. 77a, b, c. The species referred to the genus from
the Middle Cambrian may belong to it, but we have only the general ex
ternal resemblance on which to accept the generic reference. The second
species mentioned in the list of species is more like Triplesiaprimordialis
(Geol. Wis., vol. iv, p. 172, pi. x, tigs. 1 and 2, 1882) than any other
species with which I am acquainted. The only specimens now knowu
to me of the second species are in the collections of the museum of the
Geological Survey of Canada, and have not yet been described.

CAMARELLA ANTIQUATA Billings.

Plate vii, tig. 8.

Camarella aniiquata Billings, 18(31. Pamphlet; Geology of Vermont, vol. ii, p. 949,
fig. .?.',n. Idem.imx Geol. Canada, p. 284, fig. a90. Idem, l&X,. Pal. Foss.,
vol. i, p. 10, tig. 13.

Original description. — "Ovate or subcircular, beaks obtusely pointed
(as seen ou the cast), both valves moderately or rather strongly con
vex. Surface with from eight to ten small rounded ribs which do not
reach quite to the beaks.

"Some of the specimens .are proportionally more elongated than
others. The front margin appears to be always broadly rounded, and
the greatest width at about one-fourth the length from the front margin.

"Length, from 4 to lines; width, either equal to or a little less thtm
the length.

" This species resembles G. varians of the Chazy, but is more uumei-
ously ribbed."

(848)

WAICOTT.]

MIDDLE CAMBRIAN FAUNA,

123

We have seen but two syeciiiiens of the cast of a single valve of this
species aud cannot add to the description given by Mr. Billings.

Forinationand locality. — Middle Cambrian, Georgia Formation. About
2 miles east of Swantou, Vermont.

LAMELLIBRANCHIATA.

Genus FORDILLA Barraude.

Fordilla BaTT!im\n,lSiil. Ac6phal6.s. Etudes Loc. et Comp. 8°. Description of pi. 361.

The first notice we have of this interesting genus is by Mr. S. W.
Ford (Amer. Jour. Sci., 3d ser., vol. vi, p. 130, 1873), who called atten-
tion to it under the title of "Bivalve of uncertain class; gen. nov. ?"
lie described it as follows :

" Shell transversely oblong or suboval in outline, convex, widest pos-
teriorly, narrowed at either extremity, with an oblique posterior ridge,
and small depressed unibones situated anteriorly, sometimes present-
ing an obscurely bi-lobed appearance in front. Dorsal margin nearly
straight, ventral margin uniformlj' rounded. In the interior of the left
valve, as shown bj' a gutta-percha cast of an impression in stone of this
valve, there is a wide and deep furrow with a slightly raised line along
tiie middle of it, corresponding to the oblique ridge on the outside ; and
a distinctly impressed line ])assing from the lower anterior into the
upper posterior i)ortion of the valve, following the curved ventral edge,
iroiu which it is sei)arated by a broad flattened border. This line is
deeply suidion anteriorly, becomes almost obsolete or discontinuous in
passing the oblique internal furrow, beyond which, in the posterior por-
tion of the shell, it is less distinct, though clearly shown. Just in front
of and above the anterior limit of this line there is a slight conical pro-
tuberance. Further than this nothing can be made out, owing f(» the
iin])erfection of the material. The shell is thick, with the surface finely
striated concentrically.

" I have never observed a specimen of this singular little shell vnth
the two valves together, but they are frequently found side by side in
the same hand specimen of stone.

"Length, rarely more than 0.10 of an inch; usual width, about 0.10."

Subsequently Mr. Ford sent specimens to M. Barrande, who pro-
posed the above generic name and gave several excellent figures, but
retrained from publishing a generic and specific description.

iMr. Ford remarks before his descri])tion : "Externally they [the sin-
fjle valvesj jn-esent something of the ap[»earanceof a small ModivlopsiH.
As no uiuloubted lamellibranchiates have, however, been hitherto d<v
teeted in strata certainly more ancient than the Calciferous Sandrock,
it is quite possible th.at, when they come to be better understood, they
will be found to belong to some as yet imperfectly known group of crus-

(849)

\ ''\ m^

.124

CAMBRIAN FAUNAS OF NORTH AMERICA.

iBULL. 30.

taceaus." Mr. Ford, however, was strongly iucliued to the belief that
they were lamellibrauchs. aud iu this I agree with him.

M. Barrande says ( Acc^phales. Etudes Loc. et Comp., S°, pp. 391-393) :

" L'itnpression qui est result^e de cjs Etudes dans uotre esprit se
resume eu quelques mots :

" D'apr^s leurs apparences ext^rieures, ces petites valves pourraieut
£tre consid6r6es comrae appartenant ^ un lamellibranche.

" Au contrairo, les apparences des monies internes offrent des carac-
t6res que lious ii'avons jamais observes sur les monies correspondants
des Acephal^s.

" La description de M. Ford, dont la majeure partie est consacr(^e tt la
surface du raoule interne de I'une des valves, constate I'importance de
CCS apparences insolites et confirme bien nos impressions.

"Nous sommes done disposes tt considdrer ces petites coquilles comme
appartenant H un Crustac^ primordial et nous rappelons qu'un autre
Crustace coexistant est 6num6r6 par M. Ford, sous le nom de Leperditia
Troyensis, dans le tableau que nous venous de reproduire.

"Ainsi, on remarquera qu'il u'existe sur le contour de ia charni^re
des valves de Troy aucune trace de series de dents, comme dans les
Nncula et aatres genres anciens.

*' On constatera de mfime, sur ces petites valves, I'absence de toute
impression muscnlaire, comparable ti celles qui sont habituellement tr^s
bien conservees dans le meme genre Niicula et dans beaucoup de types
des fauues les plus anciennes.

« • * • * * *

" D'apres ces considerations, nous ne pouvons pas admettre que la
preuve de I'existence des lamellibranches dans la faune du Gres de
Potsdam soit etablie par les petits fossiles de Troy. Nous devons
laisser i\ I'aveuir le soin de nous fournir des informations finales et
indiscutables au sujet de leur nature, aujourd'hui problem atique."

Fordilla Troyensis may be the shell of a crustacean, but I think it is
extremely improbable.

The exterior appearance and thickness of the shell united to the
probability that a muscle scar exists nearly in the same position as in
the genus Modiolopsis, leads me to consider the shell as belonging to
the lamellibranchiata. Just in front of the little rounded boss described
by Mr. Ford, there is a minute flat depression in two examples that
strongly suggests a muscle scar. In casts of the interior of the same
shells, hardly a trace of the strong interior ridges and lines shown in
other casts of the interior one is to be seen. When we consider the
minute size of the shell and that it is separated by a great duration
of time from the Calciferous formation, in which the first undoubted
lamellibranchiate shell has been found, it is evident that we will not
find the same structure as in the lamellibranchdate shells of the Lower
Silurian ( .rdovician).

(850)

WAtcorr] MIDDLE CAMbRIAN FAUNA. 1^5

FoEDiLLA TpoYENSis Barrande.

Plate ::i, figs. 3, 3a-c.

The references and description are the same as that of the genus
Fordilla.

Formation and localities. — Middle Cambrian. On the ridge east of
the city of Troy, New York, and also one mile south of Schodack Land-
ing, in Columbia County, New York.

GASTEROPODA.

Genus SCENELLA Billings.

Scenella Billings, 1872. Can. Nat., new ser., vol. vi,p. 479; Pal. Fossils, vol. ii, p. 77.

The generic description and the specific description of the type species
were given together. Wo now have Scenella retusa Ford and 8. conula
and 8. varians Walcott to add to the type 8. reticulata, and the generic
description may be separated from that of the type species, as follows:

Small subconical, patelliform shells; aperture elongate oval to nearly
circular ; apex usually eccentric. Surface smooth or marked with fine
concentric striai or both concentric and radiating striae.

I now have before m§ two specimens of 8. reticulata that are supposed
to be the types, as no others are known in the collection of the Geo-
logical Survey of Canada and they are from the typical locality. The
shell is calcareous, and, in appearance, a smooth species of the genus
Stenotheca. The carina spoken of by Mr. Billings is exceedingly ob-
scure, and is not discernible at all in one of the specimens. 8cenella
retusa Ford has a carina on the side opposite the direction of the curv-
ature of the apex, and also two faint lines running down the opposite
side from the carina. 8. conula Walcott (Monographs IT. S. Geol. Sur-
vey, vol. viii, p. 15, pi. ix, fig. 0) shows a faint line on one of the more
elongate sides, while 8. varians has, so far as known, a smooth surface.
The above species form a group of small, patella-like shells that differ
from the species referred to Stenotheca in their surface characters, and
I think Mr. Billings acted wisely in proposing a generic name to include
them.

Stenotheca elongata and Scenella conula (Monographs U. S. Geol. Sur-
vey, vol. viii) were referred to the Pteropoda, but I now place them
under the Gjisteropoda.

Scenella reticulata Billings.

Plato xii, ligs. 0, (ia.

Scenella yeticulata Billings, 1872. Can. Nat., 2jl ser., vol. vi, p. 479.

Original description. — " Shell small, almost uniformly depressed,
conical ; apex central or nearly so ; an obscure carina extending from

(851)

126

CAMBRIAN FAUNAS OP NORTH AMEfilCA.

(aui,u30.

the apex down one side to the margiu. Aperture nearly circular, apex
very slightly incurved towards the side opposite the carina. Surface
reticulated with fine radiating and engirdling str'nxa, just visible to the
naked eye. Diameter of the aperture of the largest specimen col-
lected, 3 lines; height of apex, 2 lines."

A larger specimen, now in the collection of the Canadian Geological
Survey, has at the aperture a length of 14""'" and a breadth of 11""";
height, 6™'". The apex is eccentric and curved over beyond the highest
point of shell. A smaller specimen has a pointed and more nearly con-
centric apex.

Formation and locality. — Middle Cambrian. Limestone at Topsail
Head, Conception Bay, Newfoundland, associated with Stenotheca . su,
Iphidea bella, and Protyphus scnectua var. parvulus.

SOENELLA EETUSA Ford.

Plate xii, figs. 3, 3a.

Svenella retuga Ford, 1873. Amer. Jour. Sci., 3(1 ser., vol. v, p. 213, figH. 2a, b, on p. 214.

Original description. — "Shell small, rather strongly convex, aperture
ovate, sides curved. Apex obtuse, nearly central, curving down a little
toward one side. On the side toward which tlje apex is directed there
are two faint grooves commencing near the tip of the apex ynd diverg-
ing to the margin. On the side opposite there is a well-marked carina
running from the apex to the margiu along the line of the longer axis
of the shell. The slope of the shell is unequal, being most rapid toward
the margiii to which the apex inclines. The surface is marked by a few
fine concentric and radiating lines, the latter only visible under a mag-
nitier, and with obscure imbricating lines of growth.

"Length of the largest specimen obtained, 0.16 of an inch; height,
about 0.08 of an inch. Occurs in both even-bedded and conglomerate
limestone of the Potsdam group at Troy, associated with the preceding
species collected by the writer.

" This species is closely related to Scenella retviulata, the only hitherto
published species of the genus described by Mr. Billings from the Mene-
vian group of ^Newfoundland. That species is, however, considerably
larger than ours, and is, further, destitute of the diverging grooves
which exist in 8. retma, and by which this latter species may be easily
recognized,"

The only specimen known to me of this little shell is in Mr. Ford's
collection, and the figures were drawn by him from the type of the
species.

Formation and locality. — Middle Cambrian, Georgia Formation. Even-
bedded and conglomerate limestone on the ridge east of the city of
Troy, New York. A specimen apparently identical with this species,

(852)

WAtCOTT.I

MIDDLK CAMBRIAN FAUNA.

127

^•m,

tbat in labeled from Bic liarbur, i8 in tbu coUeutiun of the Geological
Survey of Canada.

SOENELLA? VABIANS U. 8p.

Plato xii, llgs. 2, 2a.

Shell small, depressed, coiiicnl; apex central or subcentral; aperture
ovate or broad ovate. Surface of cast smooth.

This little shell is quite abundant in the decohiposed arenaceous,
magnesian limestone east of Highgate Springs. In form it is Metop-
toma-like, and the reference to Scenella is provisional, as nothing is
known of the outer surface except that it has a few concentric strife of
growth on an apparently smooth surface. I know of no cloi?ely related
species from the Middle Cambrian. An undescribed species from the
Potsdam sandstone of Wisconsin and 8. f comtln (Monographs, U. S.
Geol. Survey, vol. viii. Pal. Eureka Dist., p. 15, pi. ix, fig. 0) are closely
allied, but diflfer in being more elevated, and S. rctusa is more depressed
and probably of a different shell substance.

Formation and locality. — Middle Cambrian, Georgia Formation.
About two miles east of Highgate Springs, Vermont; also, at St. Anne,
Province of Quebec, Canada; collection of the Canadian Geological
Survey.

Scenella? conula Walcott.

Scenella f conula Walcott, 1884.
tig. 6.

Plate viii, figs. 2,2a.
Monoprraphs U. S. Geol. Survey, vol. viii, p. 15, pi. ix,

Shell small, conical ; apex subcentral, apparently with a tendency to
bend a little to one of the sides on which there is a very faintly-indicated
line running from the apex to the margin. Apertnre ovate. Surface
smooth to the unaided eye ; it shows tine concentric striae and a few ob-
scure lines of growth, when examined by the aid of a strong magnify-
ing glass.

Dimemions. — Greater diameter, 3™'" ; lesser diameter, 2.25""" ; eleva-
tion, about 1.75'""'.

This is a small Metoptoma like shell, the generic reference of which
is provisional, as it differs from the type of the genus Scenella reticulata
ill not having a carina running from the apex to the margin ; the curva-
ture of the apex is not positively known, as its summit is broken off in
all the specimens in the collection.

Formation and locality. — Middle Cambrian. In a shaly band of lime-
stone 3,000 feet below the Secret Canon shale with Olenellus Gilberti;
also, 500 feet above the great quartzite, on the east slope of Prospect
Mountain, Eureka District, Nevada.

(853)

12^

CAMBRIAN PAtlNAS OF NORTH AMERICA.

|bULL.3U.

GeiiUH STENOTBECA Salter.

Stenotheca Saltor. Name propoHed 1866; ptiblislied by Mr. Henry Hicks, 1872. Quart.
Jour. Geol. Soc, vol. xxviii, p. 180.

Mr. Hicks does not give a description of the genus, but from the fig-
ures of the type species 6'. cornucopia there is little difficulty in identi-
fying S. rugosa with it geuerically.

The genus may be provisionally described as follows :

Shell depressed conical ; aperture oval, elliptical or narrow elongate
oval ; apex eccentric and curved over towards one end of the shell ; sur
face marked by more or less strong undulations and lines of growth.

The rougher surface and the strongly-arched curvature from the beak
to the side opposite to which it curves seem to distinguish Stenotheca
from the closely related genus Scenella.

When reviewing the fauna of the St. John Formation, contained in
the Hurtt collections, I referred Discinia Aca<lica of Hartt to the genus
Palieacmea, as the material for study was too fragmentary to change tlie
gen(!.ri(! reference made by Mr. Whitfield (United States Geological Sur-
vey, Bull. 10, p. 19). Subsequently I saw specimens of titenotheca rngoHU
that showed that, in exterior appearance, 1>. Acadica was a true Ste-
notheca? (Amer. Joiir. Sci., 3d ser., vol. xxix, p. 117, 18^5). More re-
cently Mr. G. F. Matthew has published a note on S. Acadica, describing
the interior, and proposes that it be placed in a subgenus of Stenotheca,
"characterized by its subcircular aperture and patelloid form." No
name is given for the proposed subgenus (Canadian Eec. Sci., vol. ii,
p. 10, 1886.)

Stenotheca rugosa Hall (sp.).

Plate xii, figs. 1, la-e.

Metaptomat rugosa HaM, 1847. Pal. N. Y., vol. i,p. 306, pi. Ixxxiii,fig8. 6a-o.
Stenotheca rugosa B'lllinga, 1872. Cau. Nat.,uew ser., vol. vi,p. 479.
Stenotheca pauper Billings, 1872. Can. Nat., new ser., vol. vi, p. 479.

Original description. — "Elliptical, with the sides straight; apex ele-
vated and slightly bent forwards; posterior extremity broader than the
^anterior; surface marked by strong concentric undulations, which in-
crease in number on the posterior side.

^^ Position and locality. — In the subcrystalline calcareous beds, asso-
ciated with the Hudson Eiver shales, near Troy."

The usual outline of the aperture is that of an elongate oval, varying
somewhat in proportion and the curvature of the sides, so as to be sub-
circular in some examples. The apex varies in position from a point
nearly over the anterior margin to one-third the distance between tlie
anterior and posterior margins. On a young shell, 3""" in length, the
apex overhangs the anterior margin. There is considerable variation
in the surface markings; the strong annulations of growth seen on some

(854)

WALCOTT.I

klDDLfi CAMBftfAN PAtFNA.

129

sIu'IIh are reduced in size and incrensrd in numbers in others, iuid in
the yonng shellH only the fine striie seen on ;uMi between th(? annuhi-
tions on the older shells are seen. The nnnuliitions also vary from
evenly-rounded to sharp, almost inibriciitin^' liilf'es. Tin; entire surface
is eoveied by very line, somewhat irrcyuUir stria'..

JMmeiisiom. — An average sized speeiinen has a heij^ht of 7""", with a
diameter at the ajierture of 10""" and 13""", respinttively.

Steriotheea contuvop'm Salter (Quart. .Tour. Geol. Soe., vol. xxiii, pi. vii)
is a more erect, conical shell, but presents nlatively the sanie stroiiff
concentric undulations and lines that occur on *S'. rvgosa^ although a
much smaller shell. The shell figured from the Spanish Cambrian is
so closely related to IS. riu/osa that, from the tigures, it is difficult to And
si)eciflc distinctions between them. It is rjot specilically named, but
placed under the name of (ja]»ulus, luidt. In (lie text the suygestion
is made that perhaps it may belong to the gtMius Metoptoma (Bull. Soc.
Geol. de France, t. xvli, ]). 531, ])1. viii, tigs, 3, 3rt, h).

Sfenotheca acadica Hartt appears to l)e a coiiipresseil shell that, when
compared to flattened, comjn'essed specimens of S. nufofia, is generically
related to it.

On examining the type of Sfenotheca pauper., in tlie collection of the
Geological Survey of Canjida, 1 fonnd it to be a lioarselyribbed variety
of S. rvgosa, such as occurs both at Troy, New York, and liic JTarbor,
Canada. A variety occurs at L'Anse an Loup that has ranch sharper
ridges of growth and strong radiating lines, and it is much more ele-
vated and conical than the typicral forms of the species found elsewhere,
with the exception of a single Iragment from Troy, New York.

Formafion and hcalilies. — Cambrian, Georgia group. Conglomerate
limestone on the ridge east of the (lity of Troy, New York; Bic liarbor,
below Quebec; L'Anse an Loup, on the north side of the Straits of
Belle Isle ; and at Topsail Head, Conception Bay, Newfoundland.

• .1

StENOTHECA ? ELONOATA Walcott.

Plate xii, fig. 4, -la, b.

Sicnoiheca cloiigataWtdcott, lt^!?4. Monographs U. S. (ieol. Siirve.v, vol. viii, p. 23,

pi. ix, fi}?8. 2, 2a. k

Original description. — '' Shell small, elongate, with the ai)ex incurved
and depressed nearly to the nnirgin ; laterally compressed so as to form
ii, ridge nearly the entire length. Aperture elongate, ovate, somewhat
acutely pointed at the end towards which the apex curves, and rounded
at the opposite extiemity, the greatest width occurring about two thirds
tlie distance from the narrow end. Surface marked by numerous line
concentric striio and lines of growth.

"The imrrow elongate aperture, depressed apex, and fine lines of
growth serve to distinguish this from described species of the genua.
Bull. 30 9 (865)

' Mm

130

CAMBRIAN FAUNAS OF NORTIT AMERICA.

|nui.L. 30.

Ah far as yet known the genuH Steuothecu is conflneil to the Oambiiuu
fauna."

The Nevada specimens correspond so closely with those from L'Anse
an Loup that I fail to find good specific characters to distinguish be-
twt'tju them. There is a certain irregularity in the form of the aperture
that, united with the rounded carina or angular dorsal ridge, suggests
a bivalve shell not unlike the young of the common Mytilus edulin, but,
Judging from the material at hand, I think it is only a superficial re
semblance.

Formation and looalitieH. — Cambrian. In the passage beds between
the typical Middle Cambrian (Georgia) and Upper Cambrian (Potsdam)
faunas, Secret Cafion, Eureka Mining. District, Nevada. At L'Anse*
an Loup, on the north side of the Straits of Belle Isle, it is associated
with a typical Middle Cambrian fauna that occurs in a hard reddish-
colored limestone.

Genus PLATYCERAS Conrad.

Platjfceraa Conrad, 1840. Ann. Rop. Geol. Surv. New York, p. 205.

The genus Capulus Montfort, 1810 (Conch. Sypt., p. 55), appears to
include the species under Platyceras, but, until more is known of the
American species, we shall follow the example of Hall and Billings, and
refer them to Platyceras.

Platyceras ""Eimjevum Billings.

Plate xii,

v 5a.

Ptatyceraa primaivutn BiWinga, 1871. Can. Nat., ne. 't., vol.vi, p. 220.

Original description. — " Shell minute, consisting of about two whorls,
which, as seen from above, are ventricose, but most narrowly rounded
at tiie suture ; the inner whorl scarcely elevated above the outer. The
under side is not seen in the apecime,;. Diameter, measured from the
outer lip across to the opposite side, one line; width of last whorl at
the aperture about one-third of a line.''

Tlie Troj' specimens correspond closely to the above description, and,
as they are associated with the same species as P. primwvum at Bic, I
have little doubt of their specific identity. From the description, tlie
Bic specimen showj the right side. A specimen from Troy is nearly free
from the matrix, and proves that the dorsum is nearest the right side
and that the left side is more ventricose. The surface is also pre-
served, and shows fine striiB Jind lines of growth that arch backward
over the dorsum, indicating a deep dorsal sinuosity in the peristome;
a second series of fine striae cross the striai of growth and form a fine
reticulated surface.

Dimensions. — Diameter of cross-section of tlve outer volution, 3"""j
diameter of aperture, l.Tfl"""' and 2.5"'"'.

(85G)

WALcorr.]

MIDDLE CAMUUIAN FAUNA.

181

riaiyceroH minutimmum Wuhiott (Pum. in advance 32(1 Re]). N. Y.
State MiiH. Nat. Hint, 1880), from the Upper Cambrian (PotHdam)
liorizon, is a Hmull Hbell related to P. primnvum. It ditferH in liavinp;
Htrou^er surface Htrite, a more prominent dorHal ridge, and the whorl
lar^fcr and more prouiiueut.

Formation and locality, — Middle Cambrian, Georpia grouj). In the
conglomerate limestrno on the ridge east of the city of Troy, New York,
and at fiic Harbor, below Quebec, on the St. Lawrence liiver, Canada.

PTEROPODA.

It is with considerable reservation that I place the genera Ilyolithes
• and Matthevia under the Pteropoda. The genera Oonnlaria, Ilyoli-
tiiellns,Coleoprion, ColeoluH, Hemiceras, Salterella, Pterotheca, Phrag-
inotheca, Matthevia, and i)erhaps Palu^nigma form a group that, although
representative, in a measure, of the recent Pteropoda, differ in other re-
spects so much that it appears as though a division of the Gasteropoda
efjuivalent to the Pteropoda might be consistently made to receive
them. . ,

The following families of this group occur in the Paleozoic:

Hyolithes.

Hyolithollus.

flumiceras.
Hyolithellidu). i Coleopriou.
I Coloolus.
I Camurotheca.
VDipIotheca.

Tentaoalidffi.

ConularidsB.
SalterollidiB.

Matthevidtn.
Pterothecidto.

5 Tontaculites.
\ tjtyliola.

Conularia.
Salterella.

J Matthevia.
I PaliBuigma f f .

SPterotheca.
Phrajnnotbeca.

Genus HYOLITHES Eichwald.

Unolithea Eiohwald, 1840. Sil. scbicht. Syst. in Elmtl., ]). 97.

Thfca Soworby, 1845; Pugiunculua Barraudo, 1847 ; Vaywella d'Orbi^ny, 1850.

Mr. Hall gives a history of this genus and a list of American species
placed in it (Pal. N. Y., vol. v, pt. 2, pp. 191-195, 1879). Groupe*! oppo
site Potsdam sandstone we find H. excellens, a Lower? Cambrian si)eci '•■
from Newfoundland, and the following from the Middle Canibiian,
Georgia Formation: H.- Americanus, H. communis, H. Emmonsi, H.
iwpar, and H. princeps; and from the Potsdam sandstone, or Upper
Oaiiibrian, H.ffibbosus, H. gregarim, and IF. primordiaUs, a total of nine
«l)i'cie8 from the Cambrian System.

Since that pubhcation a number of species have been described, and

(857)

132

CAMBRIAN KAl^NA.S OF NORTH AMERICA.

fBtLL. 30.

If '.

the American species of the geuns Hyolitlies are distributed us follows,
those from above the Potsdam sandstone according to their respective
authors and those of the Cambrian in part by the writer :

ilyolithes (Tbeca) aculcatus Hall,
carbonaria Walcott.

aclis Hall,
triliratus Hall,
singulus Hall.
Btriatus Hall.

ligea Hall,
principalis Hall.

^ Lower Carbonifw-

( 0U8.

Hamilton Formation.

\ Upper IIeld(rl)erg
S Formation.

centennialiH Barrett Lower Heldcrbcrf;

Formation,
p^rviasculus Hall Hudson River For-
mation.

Vannxemi Walcott Lower Silurian ^Or-

dovician).

gibbosus H. & W.
primordialis Hall,
(=gregarin8.)

Americanus Billings
Billiugsi Walcott.
communis Billings.

var. Emmousi Ford,
impar Ford,
princeps Billings.

Shaleri Walcott.

Upper Cambrian.
'Potsdam Sandstone,

Middle Cambrian.
Georgia Formation.

Lower Cambrian.
Braintree Argilliti's.

Lower Cjvtabrian.
Newfoundland.

Lower Cambrian.
St. Jolin Series.

excellens Billings.

(Camarotheca) Daniana Matthew,
gracilis Matthew.
Micmac Matthew.
(Diplotheca) Acadica Hartt.

rar. obtus.a Matthew.
var. crassa Matthew.
var. sericoa Matthew.
Hyattiana Matthew.

rar. caudata Matthew.

In the description of tlie speiiies the flattened side, with the ])rq I'ot
ing margin, is considered the dorsal side and the rounded side the ven-
tral. This is the reverse of that u.sed by Mr. Billings, Profe.ssor Ilnll,
and heretofore by the writer; but a comparison with the shells of the
recent genus Cleodora shows the projecting side to be thedor.sal. This
view was held by Morris and Sowerby in the de.scrii)tiou of the genus
Theca,and by Salter in the description of species (Mem. Geol. Surv. (Jieat
I>rit., vol. iii).

Hyolithes Americanus Hillings.

Plate xiii, tigs. 0, Cm-f.

Thvva f triattijularis Hall, 1817. Pal. N. Y., vol. i, ]>. 'M'^, pi. Ixxxvii, figs'. Irt-rf
Tluva Iriangvlaris Ford, 1H71. Anicr. .lour. Sci., ;id ser., vol. ii, ]>. ',1',].
Uiiolilhen AmcrivatuiK Billings, 1872. Can. Nat., '2(\ ser., vol. vi, j). 211'), tigs. *Ja,/>, p.
2i;t: Amor. .Four. Sei., M ,s(>r., vol. iii, p. '.io'.), ligs. 2a, b.

Original ilescription (Hall). — "lUulies of ji slender i)yra'iiidal form,
flat behind and rounded at the larger extremity, angular iti front ; small

(858)

WALCOTT.l

MIDDLE CAMBRIAN FAUNA.

133

extremity pointed ; section (aperture?) triangular. The surface shows
HO dclined markings, though the outer covering is not preserved in the
specimens which I have seen." .

^^r. BilUngii'H description. — "i7. AmericanuH. — Length from twelve to
eighteen lines, tapering at the rate of about four lines to the inch.
Section triangular, the three sides flat, slightly convex or slightly con-
cave, the dorsal [ventral] and lateral e«lges either quite sharp or acutely
rounded. Lower [upjjcrj lip rornded, projecting about two lines in full-
grown individuals. Surlace flu'^ly striated, the striie curving forwards
on the ventral [dorsal] side, and passing ui)wards on the sid«s at nearly
a right angle, curve slightly backwards on the dorsum [ventrum]. In a
specimen eighteen lines in length the width of the aperture is about six
lines and the depth about four, the proportion being slightly variable.

••The operculum has a very well-defined conical ventral [dorsal] limb,
the apex of which is situated above the center, or nearer the dorsal
iventral] than the ventral [dorsal] side. The dorsal [ventral] limb forms
ii Hat margin, and is so situated that when the operculum is in place
tlie plane of this flat border must be nearly at right angles to the lon-
{fitiulinal axis of the shell. In an operculum six lines wide the heigiit
of t lie lower limb to the a;pex of the cone is two and a half lines, and the
width of the flat border, wh'ch constitutes the dorsal [ventral] limb,
about one line.

'•Tliis species occurs at Bic and St. Simon; al^o, at Troy, New York,
wlierc it has been found abundantly by Mr. S. W. Ford, of that city.
It is Thcva trian(fulariH of Hall (Pal. N. Y., vol. i, p. 313, 1847). As that
name was i)reoccupied by a species previously described by Colonel
I'oitlock (Geol. Kep. on Londonderry, p. 375, pi. 28 A, figs. 3rt, 3ft, 3c,
1843), it must be changed. It is a very abuiulaut species and varies
a good deal.''

The small shell figured on plate xiii, fig. b/, is broader at the aperture
tliau the typical form, but flg. is intermediate, and other specimens
still more closely unite the two < xtremes. Thic same range of variation
is observed in the common, species of the Potsdam sandstone of Wis-
consin, //. primordialin. The operculjB of the two si)eciei.* are also of
the same type, and when we coajpare the shells oi H. Americnnm, witii
a rounded ventral angle, with the specimens ot H. primor alalia. ^ having
a hi<;h ventral angle, the two species approach each other quite closely,
the latter species being the representative in the tipper Cambrian of
V..e forr.i ^pecjes in the Middle Cambrian.

There is a considerable range of variation in the anglb .tf divergence
of the sides, and also the angles formed by the union of the three sides.
TMd species is quite abundant at Troy, aIthou;jh finely-preserved speci-
iiieiu- are rare.

Formation and localities. — Middle Cambrian. Conglomerate limestoiui

oil the ridge east of Troy, New York, and iu a similar formation at Uic

and St. Simon, Canada.

(859)

■ ^ ■■ .lis

134 CAMBRIAN FAUNAS OF NORTH AMERICA. [bull. 30.

Hyolitiies Billingsi n. sp.

Plate xiii, flgs. 1, la-d.

SaUcrcUa ohtuaa BillingB, IHtil. Geology of Vermont, vol. ii, p. 955. Idem, 1865. Pal.

FoHS., vol. i, p. 18.
HyolUheH pr'mordialh 1 Wliito, 1874. Gcog. and Geol. Expl. & Surv. West lOOtb Merid.

Pvelim. Rop, Invert. Foss., p. 6, and vol. iv, pt. 1, ]>. 37, pi. i, tigs. .'ia-e.
Not 77i(;rrt ohtusa Salter, 186G. Mem. Geol. Surv. Great Britain, vol. iii, p.:i52.

Original description. — " From 8i.\ to eight lines in length; diameter at
aperture about three lines. The transverse section is always subtrian
gular, and in some of the specimens one side appears to be flat like a
Theca, and I would refer it to that genus, only that the tube is composed
of successive layers. None of the specimens are perfect, but the form
is sufficiently different from that of the other two to indicate a distinct
species."

When breaking up a piece of rock holding Salterella pulchcUa from
L'Anse au Loup, I found several specimens of this species corresponding
to the above description, and, not being able to separate them iVom
typical forms of the genus Hyolithes and as several species have two
or three layers of shell, 1 refer the species to that genus. The shell is
very thick aud strong in the specimens identified with H. ohtusa from
Nevada.

The Nevada shell agrees in every respect with those from L'Anse au
Loup. The operculum associated with it appears to be identical with
that of H. Antericanus, except in the more rounded ventral angle. //.
Billingsi appears, in many examples, to be very closely related to tlie
smootlier shells of R. Americanus, and I am strongly inclined to con-
sider it little more than a variety of that species. It is, in fact, a form
intermediate between the latter and R. primordinlis, and, if the throe
forms had been found in the same layer of rock, I shouhl be incline d
to unite them in one species; but, as they are from widely separated
localities and R. primordialis associated with a different and later fauna,
it appears best, until the three are found associated, to consider them
as distinct.

As the specific name was preoccupied by Salter's R. ohtusa, I propose
R. Billingsi, in honor of the original discoverer of the species.

Formation and localities. — Middle Cambrian. L'Anse au Loup, Lab-
rador, on the north side of the Straits of Belle Isle, in a hard reddisli
limestone; at Pioche, Nevada, it is associated with Olenellus Gilhert!,
&c., in a gray granular limestone. In the llighhuid Ifa'ige it occurs in
the shales above the Olenellus shale ; and one mile below Argenta, Big
Cottonwood Cafion, Utah, it is abundant in a silicoargillaceous shale.
The specimens in the shale are compressed, but they appear to be idcu,
tical with those from Pioche, Nevat'a.

^860;

WAUXOT.] MIDDLE CAMBRIAN FAUNA. 135

Hyolithes princeps Billings. <

Plate xiii, figs. 5, Twi, ft.

ffyolithea princeps Billings, 1872. Can. Nat , new ser., vol. vi, p. 216, figs. 4a, b, of p.
2i:i.

Original (lexcription. — "Shell large, sometimes attainiug a length of
three or four inches, tapering at the rate of about three lines to the inch.
In perfectly symmetrical specimens, the transverse section is nearly a
semicircle, the ventral [clorsalj side being almost flat, usually witli a
slight convexity, and the sides and the dorsum [ventrura] uniformly
rounded. In, many of the individuals, however, one side is more ab-
ruptly rounded than the other, in consequence of which the median
line of the dorsum [ventrum] is not directly over that of the ventral
[dorsal] side, and the specimen seems distorted. This is not the result
of pressure, but is the original form of the shell. Sometimes, also,
there is a rounded groove ahmg the u)edian line of the dorsum fven-
ifumj. The latter is somewhat more narrowly roun<led than the sides.
Lower [upper] lip uniformly convex and projecting about three lines in
a large specimen. Surface with fine stria? and small subimbricating
ridges of growth. These curve forward on the ventral [dorsal] side. In
passing upwards on the sides, they at first slope backwards from the
ventral [dorsal] edge, and then turn upwards and i)a8s over the dorsum
[ventrum] at a right angle to the length".

" When the width of the aperture is seven lines, the depth is about
five. The operculum has not been identified."

With the exception of referring to the convex side as the dorsal and
the fiottened side as the ventral, I will not attempt to add to the above
(iescrii ^iou.

Hyr ill,! ft excellens Billings (Can. Nat., new ser., vol. vi, p. 471) is a
ver> < !o:j.' ' related species; the differences are in the greater apical;
«; fl' ." /'. excellens, 22°, and the rounded lateral angles, those of ff.
pn.tc(\ • 'iin^ quite sharp and the apical angle 15°.

The SI. 11 •• sjjells o{ JI. princepfi are much like those ofiT. Americanus,
the i)riii(jipal difference being in the sharper ventral angle of H. Ameri-

This is the largest species of Hyolithes known, H. elegans Barrande
(Syst. Sil. Boheme, vol. iii, pis. xi and xv) and a few other species
alomi equaling it in size.

Till; spe<!imens of this species from Silver Peak are identical in form
V. :'« those from Canada and occur in a limestone containing Olenellus
U 'hf.yf'^ Kutorgina like K. cingidaia, and several species of sponges —
E»J' : oi^liyilum, &c.

Formation and locu'ities. — Middle Cambrian. In the conglomerate
limestones of St. Siii;on and Bic Harbor, below Quebec, on the St.
Lawrence Eiver;.al8o, on Silver Tciik, Nevada, long. 117° 20' W., lat.
380 N.

(8(il)

I 'M

f}'

(

i
(i

'iJl

.A ^^k^UfUL.M

136

h'n

CAMBRIAN FAUNAS OF NORTH AMERICA.
Hyolithes communis BilliugB.

[BULL. 30.

Plate xiv, fifjH. [i, 3a-e.

Hyolithes commurtw BillingN, 1872.

p. 213.
Couipare H. impar Ford.

Can. Nat., new ser., vol. vi, p. 214, tigs, la, ft, of

OrUjinal description. — "'This si)ecies attains a length of about eight
een lines, aithoujjh the insOority of the specimens are from ten to fifteen
lines in h>nglh. The ventral [dor.siiij .side is flat (or only slightly con
vex) for about twothinis the \vi<ltli, and then rounded \\\) to the sides
j The latter are uniformly convex. The dorsum [ventruni], although de
pressed convex, is never distinctly lidttened, as is the ventral [dorsal
side. The lower lip proi<'ct»! forward for a distance equal to about one
fourth or one-third th' S pMi of the .shell. In a specimen whose width
is three lines tlie dci)th ;• 'ines and a half.

"The operculum is uea.n.\ .rcular, gently but irregul::rly convex ex
ternally and concave within. Tlie ventral [dorsal] limb is seen on the
outside as an obscurely triangular, slightly-elevated space, the apex o;
the triangle being situated nearly in the center of the operculum. The
base of the triangle forms the ventral [dorsal] margin. This limb occu
pies about one-third of the wliole superficies of the external surface
The remainder, constituting the dorsal [ventral] limb, is nearly flat,
slightly elevated from the mr/gifi towards the center. On each side o!
the apex of the ventral [dorsal | limb there is a slight depression run
ning from the nucleus out to the edge. On the inside there is an ob
scure ridge corresjionding to each one of the external depressions. It
is most prominent where it reaches the edge. These two ridges meet
at the centor and divide the whole of the inner surface of the operculum
into two nearly equal proportions.

" The surface of the operculum is concentrically striated. The shell
itself in some of the specimens is covered with fine longitudinal striae,
from five to ten in the width of a line. The shell varies in thickness in
different individuals. In some it is thin and composed of a single
.ayer, but in others it is much thickened by concentric laminte, and
thus approaches the structure of a Salterella. There are also fine en
girdling striae, and sometimes obscure subimbricatiug rings of growth."

With the exception of reversing the use of the terms ventral and
dorsal, little can be added to the above very complete description of the
Canadian specimens, but those from Troy, New York, show that the
shell was partitioned off by imperforate septa near the apex, in the
same manner as H. impar and H. communift var. Emmonn.

H. Emmonsi Ford is very closely related to this species, and, I think,
not more than a variety of it, as the characteristic depression on the
flattened face of H. Emmonsi is .slightly shown on a specimen of il.
communis, and other speciu'ens still further unite them.

(862)

sto
Ki
on

WAL'JOTT.]

MIDDLE CAMBRIAN FAUNA.

137

Formation and localities. — Middle Cambrian. In conglomerate lime-
stones of St. Simon and Bic Harbor below Quebec, on the St. Lawrence
Eiver, Canada; also, in the even-bedded and conglomerate limeHtones
ou the ridge east of Troj', New York.

Hyolithes communis var. Emmonsi Ford.

Plato xiv, ii^H. 4, 4a, b.

SaUerella Forrt, 1871. Auiw. Jotir. Sci., Ikl ser., vol. ii, j). [U.

HjioUfheH Emmonsi Ford, 187:1. Ainer. Jour. Sci., ;{d tw^r., vol. v, p. 214, tigs. ^a-v.

Original description. — ''Shell elongate, slender; apex neatly pointed,
transverse section subtriangnlar ; sides gently rounded and meeting
to form a tolerably prominent thougii often scarcely perceptible dorsal
[ventral] ridge in the forward part of the sliell, which quickly dies down,
so that a transverse section taken near the ajiex would be almost a
semicircle. Ventral [dorsal] side flattened, with a wide, shallow de-
pression along the middle, which ruus the whole lengtii of the shell ;
lateral edges rounded up to the si<les. The most projecting point of
the lateral walls occurs c'ose to the ventral [dorsal] side. When the
width is 0.24 of an inch the depth is 0.18 of an inch. The walls of the
shell are thick and appear to be made up in some instances of succes-
sive layers of laujinai. The surface is ornamented with very flue con-
centric striae, which run directly around the shell or at right angles to
its longitudinal axis. The tubes sometimes attain a length of 2 inches,
even when imperfect, but the majority of the specimens in my posses-
sion are less than an inch in length.

"The operculum has the same contour as a transverse section of the
shell +'vken at about tbe mid-length, and is, accordingly, distinctly
otfiarginate at the middle of the border of the ventral [dorsal] limb.
Tbe ventral [dorsal] limb itself is in the main flat, or nearly so, and em
braces not far from two-thirds of the whole superficies of the operculum.
Through the middle of it, beginning at the emargination, runs a low,
rounded, conical elevation having the apex directed toward the dorsal
[ventral] limb and slightly encroaching upon it. The dorsal [ventral]
limb, unlike the ventral [dorsal], is highly convex, except a narrow si)ace
near the margin, which is flat. A narrow groove, extending from the
iipex of the cone jusr mentioned, or nucleus of the operculum, to the mar-
gin, occupies the central portion of this limb and divides it into two equal
parts. (A similar division is frequently well shown in the opercula of
adult specimens of HyoUthts Americanus.) A portion of the operculum
about the nucleus, of a triangular shape, is sometimes more elevated than
the rest of the surface, and ai)pears like a little plate added for strength.
The surface is covered with tine, thread-like, concentric strire.

" In the slender form of the shell, the direction of the surface lines of
the same, and the internal thickening already noticed, this species ap-
proaches closely the structure of a ISaltereUa, Especially is this truo

(863)

«" 'i

iff]

! I

138

CAMBRIAN FAUXAS OF KORTH AMERICA.

fni'i 1.. ao.

#^1

nift

»l!

::is

when the specitneus are quite small, as is usually the case ; and in an
earlier communication (this Journal lor July, 1871), published prior to
the discovery of specimens of its operculum, the species was referred
by me to that genus. It may be readily distiuRuished from either of
the species of Hyolithen found with it by the direction of the surface
lines of the shell and its distinctly hollowed dorsal side.''

To Mr. Ford's excellent description of this species it may be added
that when we tind a specimen of H. impar with an unusually flattened
dorsal side it approaches very closely iu form to the more rounded .'•hells
of ^. JUmmomi, in which the dorsal depression is very slight.

Another character observed is one that occurs in H. commnnlH and
H. impar. It is the presence of a transverse diaphragnt in the tuby
towards the apex. This appears to have caused the shell to become
deciduous in many instances, and we now tind numerous examples show-
ing the blunt terminal portion. Some shells show the rounded smootii
end without any constriction ; others have a narrow concentric constric-
tion just within the termination. The cast of the surface of the septum
shows a slight central cicatrix or scar, but no evidence of a perforatic^
in the septum could be observed. The average size of the tube at the
point of decollation is 1""". The largest seen is 1.5""" and the smallest
.75""". When studying the septum, the close similarity between it and
the tirst septum of the species of Orthoceras and Cytoceras, as figured
by Barrande (Cephalopodes, Iiltudes generales, 1877, pis. 487, 488), was
at once brought to mind, and also the interesting question of the rela
tious of these shells to the Cephalopoda.

A paper has been lately received from Mr. G. F. Matthew, in which
he states that several of toe Hyolitbes from the base of the St. John
group have distinct septa at the base of the tube. The genus and
species are not mentioned (Nat. Hist. Soc. N. B., Bull. 10, j>. lOL', 188.5;
In the American Journal of Science, vol. xxx, [). 29'i, 1885, Mr. Matthew
describes the genus Diplotheca.

Mr. Matthew quotes, in the former paper, from a letter written by IMr.
Alpheus Hyatt, where the latter says: " These fossils, with their dis
tinct septa, are startlingly similar to certain forms of Nautiloidea, but
there is no siphon. They, however, confirm Von Jhernig's and my
opinion that the Orthoceratites and Pteropods have had a common, but
as yet undiscovered, ancestor in ancient times."

Mr. Ford speaks of the thick shell, and that it is apparently made up
of successive layers of laminai. Several specimens in the Survey coUec
tions show this feature. The shell is formed of three or more layers:
first, a thin outer layer, with rather strong even striae that cross the
flattened ventral face nearly direct and arch forward on the dorsal face,
the flattened side in this species being the ventral face and not the
dorsal, as in most species; the second layer appears to be of a smooth,
even character, much like a filling between the outer and inner shell;
the inner shell is thin and concentrically striated in a slightly ditt'ereut

(864)

WAI

mi
am

slK
slij
B.
spt

bei

WAICOTT.]

MIDDLE CAMBRIAN FAUNA.

139

manner from the outer shell; a fourth layer appears to exist in one ex-
ample, but it is too obscure for study.

1 find associated with the typical forms of Mr. Ford's H. Emmomi
shells that form a gradation between them and H. communis. The
slightly convex dorsal side becomes flat and then slightly raised, as in
H. communift. With a series of specimens, it is difficult to determine
spec'llic diflorciices between them. Following the series towards the
more rounded forms, we find that H. im])ar is readily reached. H. com-
viuniH appears to be the central portion of a series uniting H. impar
and H. Emmonai. The most decided point of difference between H.
communis and H. Emmonsi is the apical angle, that of H. communis
being about 13° and that of H. Emmonsi about 8°. The two specimens
1 ave before me of H, communis from Bic show only coh centric stiise,
as in M. Emmonsi.

H. communis var. Emmonsi is associated with E. Americanus, H. com-
munia, H. impar, Hyolithellus micans, Stenotheca rugoaa, &c.

The cross section of the tube is much like that of H. teres Barrande
(Syst.* Sil. Boheme, vol. iii, pi. x, fig. 4), except in the slightly convex
ventral face.

Formation and locality. — Middle Cambrian. Even-bedded and con-
glomerate limestone on the ridge east of the city of Troy, New York.

Hyolithes impae Ford.

Plate xiv, figs. 1, la^e.

Hyolithes impar Ford, 1872. Amer. Jour. Sci. , 3d ser., vol. iii, p. 419, figs, la, h, 2a, 6.

Original description. — " The shells of this species are plump, elongate
bodies, tapering to an acute point. The largest specimen obtained
would, if perfect, be 1^ inches in length. The usual length, however, is
about 1^ inches. The section is generally broadly and regularly oval,
but in some specimens is rather more flattened on the ventral [dorsal]
side than in the diagram of the one below given. Some specimens show
a tendency to become keeled along the dorsum [centrum], but this feat-
ure is rare and not well defined in any case. In an imperfect specimen
1.14 inches in length the rate of tapering on the ventral [dorsalj side is .10
of an inch m a distance of .60 of an inch. The width of the tube at the
aperture is .32 and the depth .20 of an inch. In this specimen the lower
[upper] lip projects beyond the limit of the dorsum [ventrum] .14 of an
inch. The surface is ornamented with fine engirdling lines, which upon
the ventral [dorsalj side curve gently forward, thence more sharply back-
ward upon the sides until they reach a point at about the middle of the
<lepth, where they are again deflected, and flow across the dorsum
[ventrum] in uninterrupted, slightly forward-bending curves. There
are also prominent subinibricating lines of growth, which give to some
of the specimens an exceedingly rugose aspect.

'*The operculum is of an oval ibrni, irregularly convex externally, and

(865)

\ f'

140

CAMBRIAN FAUNAS OF NORTH AMERICA.

[B(n.L. 30.

for the most part coucave within. The uucleus is (situated at the center,
and in perfect 8})eeinieus is vertical and acute. On either side of the
nucleus, in the line of the longer diameter, there exists a conspicuous
groove, which gradually widens in passing from the center out to the
edge. With the exception of the nucleus, which barely 8e])arates them,
these grooves divide the operculum externally into two equal i)arts.
These are, respectively, the dorsal and ventral limbs. The ventral
[dorsal] limb is smooth on the outside or broken only by concentric lines.
Its convexity is greatest at the nucleus. The dorsal [ventral] limb
has nearly, sometimes quite, the same degree of convexity, but may be
readily distinguished from the ventral [dorsal] by the presence of two
obscure ridges radiating from the nucleus to the margin and inclosing
a triangular sjjace along the central portion of the limb. The two
limbs are so situated relatively to each other as to give to the base of
the operculum a curvature equal to that indicated by the form of the ap-
erture of the shell. In the interior of the operculum there is a little pit
directly beneath the nucleus. From this point radiate two strong
wpdge-shaped ridges correapouding to the exterior grooves. There are
also two ridges of similar form running from the same point to the mar-
gin of the dorsal limb, lying beneath an, included within the limits of
of the triangular space seen on the outside of that limb. All of these
ridges are widest at their junction with the margin. They severally
terminate in the central pit and divide the interior into four unequal
parts.

"The surface of the operculum is covered with tine concentric
striae, trom 8 to 10 in the space of .06 of an inch. Along with these
there somet , nes occur coarser lines of growth. The interior is both radi-
ately and concentrically striated. The concentric lines are mostly
coarser, fewer in number, and far less regularly disposed than those on
the outside. The radiating lines are very numerous, and with the con-
centric lines give to the interior a singularly reticulated appearance un-
der the magnifier. They are barely visible to the naked eye.

"This is a well marked species and oft'ers but little variation of Ibrni.
It is closely related to Hyolithes communis Billings (Can. Nat., vol. vi, p.
Iil4, December, 1S71 ),l)ut is nevertheless quite distinct therefrom. In H.
communis, according to Mr. Billings, the shell is sometimes longitudi-
nally striated, which is not the case, so far as observed, in the shells of
this species. The operculje are also dift'erent. In the operculum of H.
communis there are but two ridges in the interior. These corresi)oi.d to
the longitudinal ridges of our species as shown in ligure 26. There is
also a slight variation in the rate of tapering of the two species. Theyare,
therefore, entirely ditterent. A species of about the Same size and form
occurs in the Potsdam sandstone of Wisconsin (16th Reg. Eep., p. 135*,
pi. vi, tigs. 30 and 31)."

The species last refern'd to by Mr. Ford has a similar apical angle,
but the cross section and the operculum are quite different. I also

(866)

Wiacotr.J

MIDDLE CAMBRIAN FAUNA.

141

io*.

suspect that a comparison of specimens with H. comimmin Billings will
show mnch closer relations than noted above. ,

One peculiarity of this species is the stroniof, thick shell. In a tube
5'""' in diameter the shell is 1""" thick. In a shell of if. Amerieanm
of the same size, it is not more than .5""" in thickness. T'h® shell ap-
pears to be made up of an inner and outer layer, with a space between
of irregular width, which is filled in with a layer of mineral matter not
unlike the thin inner and outer layers of shells ; the effect is that of an
inner and an outer shell that did not fit exactly, with the interspace filled
with foreign matter.

The sh'jll of if. Emmonsi appears to be of the same character, and
H. impar has imperforate septa towards the apex of the shell similar
{o those of H. Emmonsi. -

Three of the figures illustrating this species were drawn by Mr. Ford
from the type specimens in his collection.

The section of H. cinctus Barrande (Syst. Sil. Boheme, vol. iii, pi. ix,
fig. 11) is much like that of H. impar. Usually specimens of this genus
are so crushed and flattened that it is difficult to institute com])ari8on8
between the species preserved in slates and shales and those imbedded
in limestone.

Formation and locality. — Cambrian, Georgia Group. Conglomerate
and even-bedded limestone on the ridge east of the city of Troy, New
York. '

HYOLITHES sp. undet.

In the " Red sandrock " of Vermont, a species of Hyolithes occurs
that, in its apical angle, 15°, and the outline of its cross-section, resem-
bles H. primordialis of the Potsdam sandstone. The material is so
poorly preserved and the species of the genus so often are closely re-
lated in certain characters, while differing in others, that I hesitite in
identifying it with any described form, and, for the present, prefei to in-
dicate only the presence of the genus at that horizon.

Formation and localities, — Middle Cambrian, Georgia Formation.
About one mile east of Highgate Springs, in a reddish-colored, decom-
posed, arenaceous, magnesian limestone ; also, in a purplish sandstone
above the Olenellus bed east of Swanton, Vermont.

At the Highgate locality, Olenellus Thompsoni and Ptychoparia Adamsi
occur in the same layer of rock.

Genus HYOLITHELLUS Billings.

IIjIoHthcllus Billiugs, 1872. Can. Nat., new, ser., vol. vi, p. 240,

Discinena Hall, 187.3. Twenty-third Rep, N, Y. State Mas. Nat. Hist,, p. 246.

Original description. — " Since the sheet containing the description of
Hyolithes micans was printed ofi", I have arrived at the conclusion that
a new genus for its reception should be instituted. I propose to call it

(867)

Ti^fi

I
i

;iJwH

''^'tfl^^H HK^

Ipl

142

CAMBRIAN FAUNAS OF NOllTH AMERICA.

[HULL. 30.

';!.

HyoUthellus. It diifera from HyoUthcs in its lonj^f, sleiulor form and in the
peculiar striKjturo of its operculutn."

Hyolithellus, in tbo slender, elongate form of its sliell, ni)i)ear8 to rej).
resent the forms referred to OoleoUis and Coleoprion from tlid Upper
Silurian and, Devonian, but the peculiar operculum associated with it is
so distinctive that it is readily distinguished from them and also from
the more cylindrical species of llyolithes.

The description of Mr. Hall's jienus Discinella is that of the opercu-
lum of this species, and as the type material is from the Troy beds there
can be little doubt of the identification.

The following is the original description of Discinella:

" In the limestone beds accompanying the shales of the Quebec Gronj)
near Troy there is a minute discinoid phosphatic shell which I have long
known in its exterior character as having the concentrically-striated
and obscurely-radiate surface, with an eccentric apex, like ifiany of the
Discinae. The interior of the shell (dorsal valve) is distinctly marked
by nine radiating depressions, the central one of which extends toward
the margin uear'ist the apex, with four others upon each side. At the
extremities of some of these depressions there are distinct muscular
markings ; but were all these to be considered due to the muscular or-
ganization we would scarcely recognize the fossil as a Brachiopod,
but rather as a Gasteropod. The general character of shell, however,
is such as to ally it with the Discinidae, and, since we do not yet know
any Gasteropod of similar form and character in the older rocks, I pro-
pose for this fossil the name of Discinella?^

As there is but one species referred to Hyolithellus, the generic and
specific characters are given in the description of that species.

Hyolithellus micans Billings.

Plate xiv, figs. 2, 2a-e.

Hyolithea micana Billings, 1872. Can. Nat., 2d sor., vol. vi, p. 21f), figs. 3rt, h, of p.
213.

Original description. — "This is a long, slender, cylindrical species,
with a nearly circular section. The rate of tapering is so smiill that
it amounts to scarcely half a line in [a] length of eighteen linos, where
the width of the tube is from 1 to 2 lines. The largest specimen col-
lected is 2J lines wide at the larger extremity, and if perfect would be
4 or 5 inches in length.

"The operculum does not show distinctly a division into a dorsal and
ventral limb. It is of an ovate form, depth somewhat greater than the
width, the nucleus about one-third the depth from .the dorsal margin.
Externally it is gently concave in the ventral two-thirds of the surface ;
a space around the nucleus is convex and finely striated concentrically.
On the inner surface there is a small pit at the dorsal third of the depth,
indicating the position of the nucleus. From this point radiate ten

(868)

WALCOTT.]

MIDDLE OAMBUIAN FAUNA.

elongate ovate ars, iiiTiuij{<'(l in tlic form of ii star, the rays towiiids
the ventral side being the longest. None of these scars quite ivm-Ai
the margin.

''The shell and o|>erculum are thiu and of a Anely lamellar structure,
smooth and shining.

"Occurs at Bic and St. Simon ; also, at Troy, New York.

" Collectors, T. C. Weston and S. W. Ford.

"Sometimes numerous small specimens from ^ a line to 3 lines iu
length are found with the operculum on the same slab.

"This shell appeal's tomeat])resent to constitute a new genus, differ-
ing from the majority of the sijecies of HyoIitheH in its circular section,
the operculum not divided into dorsal and ventral lines, and in the
remarkable system of muscidar impressions on the interior. Barrande
has tigured an operculum of the same type, differing from this in having
only three instead of five pairs of impressions. They are, however,
arranged on the same plan in both the Canadian and Bohemian species.
It is possible that our species may be a Salterella."

From material in the collections of the United States Geological Sur-
vey, I find that the outer surface of the shell, although apparently
smooth in many specimens, is also marked by concentric strife of growth
that in some examples are quite strong and regular in arrangement.
The scars on the operculum also show lines of growth. The shell, for
tiie first 10""" or 15""", is often curved and almost twisted in some
examples. All the larger portions seen are straight.

Tiie cross section is circular or broad-ovate, as is seen by comparing
the outline of different examples of the opercula.

Why Mr. Billings suggested the possibility that this species might
be a Salterella I cannot tell, as it appears to have nothing iu common
with it except a circular or ovate cross section.

Formation and localitien. — Middle Cambrian, GeorgiaFormatiou. Con-
glomerate limestone at Bic and St. Simon, Canada, and Troy, New York.

A species of Hyolithellus, apparently a large H. micans, occurs with
the Middle Cambrian fauna, in the silico-argillaceous shales, one mile
billow Argentii, Big Cottonwood Canon, Utah.

Genus SALTERELLA Billings.

SaUv.rella Billiiigs, 18fil. Geology of Vermout, vol. ii, y. 1)54. Jdim, 18(50, Pal. Foss.,
vol. i, p. 17. ■

Onginal descnption. — " Small, slender, elongate, conical tubes, consist-
ing of si^veral hollow cones placed one within another, the last one form-
ing the chamber of habitation of the animal. The cross section of these
tubes is cir(!ular or subtriangular, and they are either straight or gently
curved ; the surface is concentrically or longitudinally striated.

" I think these fo.ssils, although no doubt allied to Serpulites, suffi-
ciently different therefrom to constitute a distinct genus. Their struct-

(869)

■7 .'ilvv's'.'nji -'fl

■■■■■'■■ '^^1

■ '-'PI

.', IS]

-:■ . h

•5 ::iPi

144

CAMBRIAN FATTKAS 07 NORTH AMERICA.

titnix.M.

ur« \H MO compnct timt tli«\v am Heldoin fonii<l comproHHod, while ;ill
»l}i}v.\cA of iSerimliteH arc iilriioist invariably in that condition, showin^r
t)iat thuy couHist in general of .sonietliin^' more like a nuMnbraneous him;!;
than a hard-Mhelled tube."

The shell of the species of this genus is strong and conii)aiatively
thick, much more like those of Tentaculites than Serpulitos, and i am
inclined to agree with M. Barrande that the relations of the getuis nw
with Tentaculites and Hyolithes (Sys. Sil. liohenie, vol. iii, j). l.W, 1,S«»7).

The three species described by Mr. Billings, iS'. rnyom, S. pulcltella,
aiul S. obtusa, are from the Middle Cambrian, Georgia Gronp, on tia^
north side of the Straits of Bel'e Isle, the two latter species occurring
in the same hard specimens of rock'.

Salterella obtusa proves to be a species of Hyolithes and is removed
to that genus.

ISalterella BilUngsi Saflford (Geology of Tennessee, p. 289, 1809) i.s
from the Trf utou Group. Until more is known of the genus 1 would
place this species under it with a query.

Saltebella pulchella Billings.

Plate xiii, figs. 3, Ha, pi. viii, 7, "ia-c.

Salterella pulfihella, Billings, 1861. Geology of Vermont, vol. ii, p. 9^>f). Idem, iti''
Pal. Fobs., v"l. i, p. 18.

Original description. — " Elongate, conical, gently curved, from six to
eight lines in length and from one line to one and a half in wi 1th at the
aperture. Surface ornamented with small encircling stria) just visibh-
to the naked eye.

"This species is larger thaa 8. rugona, always a little curved, not so
abundant, and when weathered does not present the sharp imbricatinji
annui'ations of that species."

The species in the Winooski marble is observed only on the polished
sections, and it is very difficult to determine its specific characters. It
appears to have a smooth outer surface, as no annulations arc shown in
the longitudinal sections. In form it varies from the tlo8(!ri])tion of /S.
pulchella, in being shorter and larger at the aperture; but, as we find
numerous examples of a form that corresponds to 8. pulchella 300 feet
higher in the section, associated with the casts of shorter, stouter shells,
and also forms that appear intermediate between the slender and stouter
examples, it is probable that all belong to one species. In all the
specimens yet obtained but a single shell or sheath is shown. This may
be owing to the fact that in those from the "Winooski marble the sep
arate shells may have disappeared in the semi-crystallization to which
the calcite replacing them has been subjected, and all the specimens
from the gray and reddish magnesian limestones are in the form of casts
of the interior and exterior surface or else showing only the outer sur-
face.

' ' . (870) .

WkUXTt.]

MIDDLE CAMBRIAN FAUNA.

145

SaUcreUa pulchella was first annouuced as occurring in the Georgia
Group of Vermout by Mr. BillingM (Can. Nat., 2(1 ser., vol. vi, p. 351,
1871), who identified it in frajrnients of the Winooski niurbh' from
Swunton, Vermout, sent to him by Mr. Solon M. Allis, of Burlington,
Vermont.

Dr. A. R. C. Selwyn, Director of the Geological Survey of Citnada,
found a weathered specimen in the conglomerate limestone of Point
Levis that shows a cluster of the tubes of this si)ecies in a beautiful
Htate of preservation. Dr. Selwyn kindly gave me permission to use
the specimen for study and illustration. Several of the shells show, in
cross sectiousj three tubes or coues, one within the other, the walls of
the inner cones blending at the larger end with the general wall of the
shell.. The occurrence of this species at Point Levis does not indicate
that it belongs to the Upper Cambrian (Potsdam) fauna or to the Cal-
ciferous fauna of the shales in which the pebbles holding it are imbedded,
as the pebbles are rolled and worn and are a jiart of the detrital inatter
making up the Point Levis strata and were derived from pre-existing
rocks, as are also the pebbles and bowlders carrying the Potsdam and
Calciferous faunas.

Formation and localities. — Middle Cambrian, Georgia Formation.
L'Anse au Loup, Labrador, on the north si<le of the Straits of Belle
Isle, and in conglomerate limestone of Point Levis, opposite Quebec,
Canada.

In Vermout, the form referred provisionally to this species ranges
through about 500 feet of the mangnesiau limestones of the upper ])or-
tiou of the limestone belt, and is host observed in the so-called "Red
saudrock" beneath the argillaceous shales, in association with Ptycho-
paria Adamsi, Olenellus Thompsoni, &c., east of Highgate Springs, and
Swantou, Franklin County, Vermont.

Salteeella rugosa Billings.

Platfl xiii, fig. 2.

Salterella rugoaa Billings, ISOl. Geology of Vermout, vol. ii, p. 954, fig. 362. Idem,
1865. Pal. FcB8., vol, i, p. 17, fig. 23.

Original description. — "This little species is straight, conical, taper-
ing uniformly to an acute point. Length from two to four lines, the
greater number of the specimens being under three lines ; diameter at
the larger extremity, one line in a specimen four lines in length; the
smaller ones are often a little more obtuse. Aperture circular, equal to
about three-fourths the whole diameter. It is not certain that in any
of the specimens observed the surface is preserved; they all appear to
bo divested of the outer covering and exhibit from four to six imbri-
cating sharp annulations in the length of one line, the edges towards the
larger end. These are doubtless the exposed edges of the several
sheaths of which the tube is composed. They are usually straight, but
some are slightly curved."

Bull. 30— 10 (871)

■%■!

'MM

:t>f

^i V

146

CAMBRIAN FAUNAS OF NORTH AMERICA.

[BULL. 30.

•^ it'

i'^i't.

* i- ^

sir

This is the most marked species of the genus yet desc :ibt^cl. As far as
known to me it has not been discovered except at the typical locality.

Formation and locality. — Middle Cambrian, Georgia Formation.
L'Anse au Loup, Labrador, on the north side of the Straits of Belle
Isle. ^

CRUSTACEA.

Genus LEPEEDITIA Eoualt.

Leperditia Roualt, ia")l. Bull. Sue. G<Sol. do France, 2« s^r,, t. 8, p. 377. Type L. Bri-
tanniea. Same bulletin, p. 378, figs. 1-3.

LEPEEDITIA Troyensis Ford.

Plate xvi, fig. 5.

Leperditia Troyensia Ford, 1873. Amer. Jour. Sci., 3d ser., vol. vi, p. 138.

Original description. — "3 he following description is based upoa a
single right valve, the only specnnen of this species that I have seen.

^^Description : Minute, obscurely pentagonal in outline, greatly nar-
rowed in front, broad behind, narrowed at either extremity, posterior
one somewhat obtusely angular. Dorsal margin straight, ventral mar-
gin gently rounded. Surface depressed convex, convexity greatest at
little behind the mid-length. Eye-tubercle prominent. Marginal rim
well defined all around except at the hinge. A distinct marginal
groove «an be traced entirely around the carapace, but it is very faint
in the upper pordoa. It is most distinct along the forward half of the
ventral outline. Surface smooth and polished.

" Length, 0,18 of an inch ; breadth, 0.12 of an inch. Occurs in even-
bedded limestone of the Lower Potsdam at Troy. Collected by the
writer.

"The characters of this species agree very closely with those of
Leperditia Solvensis Jones (Annals and Magazine of Natural History,
2d ser., vol. rvii, Feb., 185G, p. 95), from the Menevian gi'^^up of Wales;
but our species is larger, a little different in shape, and provided witlx
a distinct eye-tubercle. They appear, however, to be very nearly
related."

The only specimen known to me of, this species is in the collection
of Mr. Ford, a'ui I am indebted to him for the illustration.

Formation and locality, — Middle Camlrian. Conglomerate limestone
on the ridge east of the city of Troy, New York.

Leperditia f Argenta n. sp.

Plate viii, fig. 5.

Carapace large; dorsal margin nearly straight; dorsal angles pro-
duced into acute elongate points; anterior and posterior ends oblique

(872)

WALCOTT.]

MIDDLE CA.AIBRIAN FAUNA.

147

to the dorsal margiu above aud rouiidiug iuto the Lvoadly-rouuded
veutriil margiu below; auterior eud slightly narrower thau the pos-
terior.

Length, 56™'"; height, 31"'^. The length and heiglit are probably
slightly increased by the liattening of the shell by <;ouipressiou.

Surface markings, if any, nnknowu. This large speciiiien was found
associated with characteristic Middle Cambrian fossils, in the silico-
argillaceous, shaly beds resting on the great quartzitic series of the
Big Cottonwood Cambrian section. The carapace is ti>utened between
the laminiB of the shale, and only a slight rim arouDu the ventral, an-
terior, and posterior margins indicates any original irregularities of
the surface. The unusual feature is the presence of the spinous dorsal
angles. A tendency to an almost spinous angle is seen in some of the
Silurian species of Leperditia. This is the largest species now known
to me from the Cambrian System. Several species occur at the Pots-
dam or Upper Cambrian horizon tiiat will be described with that fauna.

It may be that the reference to Leperditia is incorrect, but, with the
evidence at hand, it appears to be re«iuired. The form suggests at first
a reference to the carapace of a phyllopod crustacep allied to Hymeno-
caris or Prctocaris, but the straight dorsal margin and acute dorso-
lateral ausrles are very much against this view.

Formation and locality. — Middle Cambrian. One mile below Argenta,
in Big Cottonwood Canon, Wasatch Mountains, Utah.

Genus PROTOOARIS Walcott.

Protocaria Walcott, 1884. Bull. U. S. Geol. Survey, No. 10, p. :,0. (Dated 1884, but
not generally dlHtributed until 18H.").)

Carapace without evidence of a dorsal suture, rounded on the dorsal
line, aud bent downward on the sides ; without any rostrum. Body
many-;iointed, 31 segments extending out from beneath the carapace,
the last segment broader than the preceding and terminating iii two
spines. Type, Protocaris MarHhi.

In comparing Protocaris (P. Marshi) with Ilymenocaris [H. vermi-
Cauda Salter, 1852, Brit. Assoc, liep., i)t. 2, Xotice.^ . d Abstracts, p.
58; Mem. Geol. Surv. Great Brit., vol. iii, p. 293. »!ate ii, figs. 1-4;
plate V, lig. 25, 18GG), we find that in the simple b* il or folded eyeless
shield or carapace tuey are closely related, but in the structure of the
body tliey differ uiaterially. Ilymenocaris has, in O'le instance, 9 strong
segments shown in its more elongate body, the terminal one ending in
threa pairs of spines; usually 6 or 7 segments are seen; 8 or 9 are less
frequent (Brit. Assoc. Rep. 1883, p. 219). Protociiris has 30 narrow seg-
mtTits, a huge terminal segment or telson, with two rather strong caudal
or terminal spines.

(873)

K'H.

',( ''':■

I' h

'I'^i

148 CAMBRIAN FAUNAS OF NOETH AMERICA. iBnix-W.

Peotocabis Makshi Walcott.

Plate XV, fig. 1.

Frotoearia MaraM Walcott, 1884. Bull. U. S, Geol. Survey, No 10, p. 50. (Dated
1884, but not generally distribnted until 1885.)

The specimen on which the genus and species are founded is com-
pressed between the laminee of the slate so that the entire outline of
the carapace is shown and the body is widened out. As flattened the
carapace is rounded quadrangular in outline, with a more or less dis
tinctly defined marginal rim all around. The general surface appears
io have been smooth. No evidence of eyes.

The body projecting beyond the carapace is about two thirds as long
as the carapace, narrowed posteriorly and made up of numerous nar-
row segments, each about one-third of a millimeter in breadth ; the last
segment or telson, which is 2.5°"" long, supports two caudal spines 7 or
8°"" in length ; 30 segments appear between the posterior edge of the
carapace and the telson ; the segments appear to have been smooth and
without a spinose or crenulated posterior margin ; the telson and cau-
dal spines also appear to have been smooth and without ornamentation.

Dimensions. — Total length, 42°"" ; lengih of carapace, 21""°; width,
26™°' ; length of body, IS™"*, exclusive of caudal spines ; width of body
where it passes beneath the carapace, 10™"* ; at telson, 4"™.

The specific name xs given in lionor of Prof. O. C. Marsh.

Formation and locality. — Middle Cambrian, Georgia Formation. Par-
ker's farm, town of Georgia, "Vermont.

This is probably the oldest Phyllopod crustacean known at the present
time. We know nothing of the animal that inhabited the shell (the
shell itself is flattened by compression), but by flattening out the cara-
pace and segmented body of Apus glacialis, or any allied form, we see
at once the striking resemblance between the recent Apus and ancient
Protocaris, the most marked difierence being the absence of eyes in
the Cambrian Protocaris.

Mr. J. L. Kiugsley requested me to study Protocaris with a view of
ascertaining its relations to Apus, but the material is too imperfect to
arrive at a satisfactory conclusion. The animal is Apus-like, and it also
appears to be connected with the ISTebalidse through Bymenocaris, Pel-
tocaris, Ceratiocaris, »&('. Ip this connection T wish to quote an observa-
tion by Prof. E. Ray Ldpoaster. He says : " Apus cancriformis is, iu
many respects, one of the mo.st important of the Crustacea. * * *
It possesses peculiarities of organization which mark it out (together
with its immediate congeners, the Phyllopoda) as an Archaic foru),
probably standing nearer to the extinct ancestors of the Crustacea than
any other living members c^ the group." ("Observations and reflec-
tions on Appendages and on the Nervous System of Apus cancriformis,"
Quart. Jour. Micro. Sci., vol. xxi, n. ser., p. 343, 1881.)

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MIDDLE CAMBRIAN FAUWA.

149

PCECILOPODA.

Genus AGNOSTUS Brongniart.

Agnottita Brongniart, 1822. Crust. Foss., p. 38, pi. iv, figs. 4a, h,

AGNOSTUS INTERSTRICTUS White.

Plate xvi, figs. 6, 6a.

Agnoatus interatrictua White, 1874. Geog. and Geol. Expl. and Surv. West 100th Merid.,
Prelim. Rep. Invert. Foss., p. 8. Idem, 1875. Vol. iv, pt. 1, p. 38, pi. ii, figs. 5o, b.

Original description. — "Head and pygidium of almost exactly equal
size and general shape and otherwise closely resembling each other.

" Head a trifle broader than long, regularly rounded in front ; sides
at the posterolateral regions subparallel ; postero-lateral angles trun-
cated ; the whole exterior margin, including the truncated portions just
named, provided with a narrow, raised rim, the elevation of which
forms a linear depression, or groove, between it and those portions of
the bead which it incloses ; space between this marginal depression
aiiv^ the glabella a little wider posteriorly than it is in front, convex
throughout, and its surface apparently smooth. Glabella conical,
widesi posteriorly, moderately convex, sides nearly straight, well de-
fined by the dorsal furrows, abruptly rounded in front ; a minute tuber-
cle situated on the median line near the posterior end, and a shallow
groove or furrow extending across near the front end, defining a frontal
lobe of moderate size.

" Thorax narrower than the head and pyf;idinm, giving the body the
appearance of being constricted at the middh >xial lobe broad, con-
sisting of two segments, both of which are tuning at the ciuIn adjoining
the dorsal furrows; lateral lobes very narrow; 'jjleurje almost as wide
as long; each pleura tumid and rounded at its exterior end.

" Pygidium having an outline like that of the head, and is also pro-
vided with a similar elevated marginal rim and linear depression within
It ; axial lobe a little longer than the glabella, and consequently that
lobe reaches a little nearer the posterior margin of the pygidium than
the glabella does to the anterior margr.i of the head, moderately convex
in elevation and also in each lateral outline ; a minute tubercle is situ-
ated on the median line near the anterior end, corresponding in size
and relative position with the one on the glabella before mentioned ;
space between the dorsal furrows and the margin convex, its surface
ai)parently smooth ; upon the outer edge of the border of the pygidium,
at each side and a little nearer to the axial extremity than to the antero-
lateral angles, there is a minute protuberance, suggestive of an incipient
spine. Besides the slight differences between the head and pygidium,
already referred to, the pygidium differs also in having a faint appear-
ance of segmentation of its :< xis and in a slight folding backward of the
marginal rim at the antero-laieral angles.

(875)

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C AMEBIAN FAUNAS OF NORTH AMERICA.

[BULL. 30.

1
_ 1

" Length of body, 8™" ; width of head and also of the pygidium,
5mm . width of thorax, i"'™.

"This beautiful Agnostus is quite unlike any described American
species, and is more nearly related to A. integer Beyrich, from the
Primordial strata of Europe, than any other known to me. Compared
with that species, it is found to reach a larger size; its glabella is nar
rowed in front instead of having its sides near ;? parallel ; the axial lobe
of the pygidium is narrower behind than jn front, instead of being of
nearly the same width at each end, and has tlie sides of that lobe con-
vex instead of nearly straight, as they are in A. integer.''''

Direct comparison with specimens of Agnostus pisiformis shows a
striking similarity between it and A. interstrictus ; the diilerences con-
sist in the form, and this is owing largely to the compression to wiich
A. interstrictus has been subjected. Agnostus bidens Meek (see Mono-
graphs U. S. Geol. Survey, vol. viii, p. 26) and Agnostus tumidosus H. &
W. (Geol. Expl. Fortieth Par., vol. iv, p. 231), of the Upper Cambrian,
are also closely connected with varieties of A. pisiformis.

Our knowledge of the American species of the genus Agnostus is
now very imperfect, and much work is needed to obtain a thorough
understanding of them.

A species of Agnostus occurs in the Prospect Mountain Cambrian •
limestone of the Eureka District, Nevada, that appears to be, in the
head shields, identical with A. interstrictus. It also may be identilied
with A. communis H. & W. (Geol. Expl. Fortieth Par., vol. ir, p. 228,
pi. 1, figs. 28, 29). Not \vishing to' introduce a doubtful occurrence of
another species into the fauna, I identify the head shield with A. inter-
strictus, which we know to occur at about this horizo) at another locality.

Formation and localities. — Middle Cambrian. Bluish-gray calcareous
shale, Hou.se Range, Antelope Spring, Western Utah; Shaly limestone,
600 feet above quartzite, eaat slope Prospect Mountain, Eureka Dis-
trict. Nevada.

, AGNOf^.TUS NOBiLis Ford.

Plate xvi, fig. 7. . .

Agnoxlua nohilia Ford, 1872. Amor. Joiir. Sci., 3d ser., vol. iii, p. 421, figs. 1, 2.

Original description. — "Head and pygidium of nearly the same size
and form, both exceedingly convex. The head is broadly .semi-elliptical,
wider than long, the length to the breadth about a.s 5 to G. Convexity
greatest along the median line, reaching its maximum on a straight hue
joining the posterior angles. From thence the sloi)e is nearly equal to
the front and sides. The sides, anterior margin, and part of the jxks-
terior margin, abrujjtly concave, rounded, and slightly incurved. Po.s-
terior angles rounded. The posterior outline is slightly concave lor a
short distance on either side of the middle, leaving a .strong, tapering,
median i)rqiection. The extremity of this jnojection is truncate and
appears to form a nearly flat articulating face. The head is surrounded

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161

by a narrow convex border directed a little downward, of uniform
width, or but slightly attenuated on the posterior outline. On either
side of the head this border is set o(f with a row of prominent tubercles,
from seven to eight in each row. No tubercles have been observed on
the extreme front and posforior portions of the border. The surface of
the head, including Ihc border, is transversely crossed by numerous
faintly impressed lines, curving backward, for the most part invisible
to the naked eye.

''The pygidium is of equal length and width with the head. The con-
vexity, however, is a trifle greater along the middle, and the anterior
angles rather less rounded than the corresponding angles of the head.
The greaiCoL convexity occurs at the anterior thiid of the pygidium.
The anterior outline is slightly concave at the middle and is then feebly
rounded in passing outward and backward to the angles. The contour
of the sides and posterior margin the same as that of the sides and an-
terior margin of the head. A narrow margiual border similar to that
of the head, though not tuberculated, surrounds the pygidium, termi-
nating on either side of the concave portion of the anterior outline. The
surface is covered with delicate lines similar in character and direction
to those of the head.

" The two extremities are connected by a single thick thoracic ring.
This ring is partly shown in the figure. From the appearance of the
figure, however, there would seem to be room for a second ring, but
this appearance is due to the damaged condition of the head.

"Two specimens only of this species have been obtained, one a head
with a small portion of the pygidium; the other a nearly perfect indi-
vidual. The dimensions of the latter are as follows : Length of entire
animal, .64 of an inch; length of head along the median line .30, width
at posterior angles .30 of an inch; median length of pygidium .30,
width at anterior angles .36 of an inch ; width of head aiul pygidium at
one-third the length of each from their smaller extremities, each .28
of an inch; width of thoracic ring, .10 of an inch. This is likewise the
width of the ci-cave portion of the pygidium with which it lies in con-
tact. Greatest depth of pj'gidium .14 of an inch ; greatest depth of
head .12 of an inch.

"The proportions of tlie other '-.ead slightly difterciit, the length
being .34, the width .39, and the greatest depth .14 r,t" an inch. The
specimens were found lying close to each other in the same hand frag-
ment of limestone. Occurs in even-bedded limestone east of Troy, New
York, in the same layer with Olenelhis asaphoUJes, Agnostiis lobatus, Oho-
lella cwlafa, and O. desqimmata.^^

Mr. Ford states that he is not sure which is the cephalic shield; also,
that the species is of the same type as A. parilis Hall, of the Potsdam
saiulstone of Wisconsin, but it differs in size characters too much to be
specifically related. Mr. Ford informs me that the type 8i)ecimen is

(877

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CAMBRIAN FAUNAS OF NORTH AMERICA.

[BULL. 80.

lost, so we can only reproduce the rough wood cut given with the orig-
inal description.

Formation and locality. — Middle Cambrian. Even-bedded limestone
on the ridge east of the city of Troy, New York.

Genus MIORODISOUS Emmons.

Miorodiaous Emmons, 18.55. Amer. Geol,, vol. i, pt. 2, p. 116.
' Type, M. quadricostatus.

Original description.-^^* M'mnt^, oval, middle lobe of the cephalic
shield strongly developed; ribs of the body or abdomeu, four; of the
tail, four or five. The form of the cephalic shield is only obscurely in-
dicated ; the size of this trilobite is shown in the small figure. It is
found in the white fragile shales of Augusta County, Virginia, associ-
ated with minute molluscas and graptolites."

1 have long had a suspicion that the original specimen on which the
species M. quadricoatatus was founded was a youug specimen of Trinu-
cleus concentricu8, or a species of that genus, although It might be the
young of some species of the genus Ampyx; the former is more proba-
ble, as specimens of the latter genus are of rare occurrence in American
strata and Trinucleus concentricus is quite abundant at the same hori-
zon in which Dr. Emmons found the specimen described by him. It is
the type of the young Trinucleus, as may be seen by comparing it with
Barrande's figure of T. ornavm, showing four segments in the thorax.
The glabella is clavate and of the type of that of Trinucleus; the
pygidium is essentially that of Trinucleus, as are also the thoracic seg-
ments. When collecting from the Hudson River shales, in Central New
York, I found the heads of T. concentricus distorted and with the punc-
tate margin and genal spines so broken away that they appeared similar
to the head of M. quadricostatus. We now know that the light-colored,
fragile shales of Augusta County, Virginia, belong to the Hudson River
group, and that they carry graptolites and minute shells such as Dr.
Emmons mentions. In view of these facts and since all the species
subsequently referred to the genus Microdiscus have the head and
pygidium subequal in size and form and a cylindro-couical glabella, I
am inclined to consider Emmons's type as belonging to the genus Tri-
nucleus and take as the type of Microdiscus the next species referred
to it, M. punctatus.

The above was written before I had read M. Barrande's observations
on the same trilobite. He was of the opinion that Dr. Emraons was
probably in error in referring the species to the lowest geologic hori-
zon of his Taconic system and that M. quadricostatus recalled the young
of Trinucleus : " D'apr^s cette circonstance, que la forme de la t6te est
obscur^ment indiqu6e, il est impossible de juger avec 86curit6 1 nature
de ce Trilobite. Sa taille et ses appareuces nous porteraient k croire
que le specimen flgnr6 repr6sente le jeune Age de quelque esp^ce dont

(878)

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MIDDLE CAMBRIAN FAUNA.

153

les iDclividus adaltes n'ont pas encore 6t6 observes. En ontre, la grande
saillie de la glabelle, le nombre des segments libres au tborax et des seg-
ments encore sondes au pygidium, rappelient les appareuces des jeunes
Trinncleus. Oes observations ne doivent pas 6tre consid^r^es comme
une determination g^n^riqaetqai seraittrop hasard^e, d'apr^s des docu-
ments si incomplets." (Bull. Soc. G60I. de France, 2» s^r., t. xviii, p.
280.)

^[r. Salter, in describing Microdiscuspuncfattis, remarks that Barrande
thinks that the minute form described by Emmons may be the young
state of Trinucleus or some such Lower Silurian genus, but that Em-
mons's figure is singularly like the fossil he. had under observation and
that he did not feel inclined to institute a new genus for it while there
was a possibility that it might be the fry of some larger trilobite.

The discovery of several well-characterized species and the reference
of Agno8tu8 lohatvs to the same group have fairly established a generic
form, and the old name proposed by Emmons, although no longer ap-
plicable to the type species of the genus, is retained and the genus de-
fined as follows :

Trilobites of a small size; elongate-oval in outline; head and py-
gidinm subequal, without eyes or facial sutures; glabella elongate, con-
ical or cylindro-conical, with or without glabellar furrows and occipital
furrow ; pygidium with or without grooved pleural lobes ; thorax with
three or four segments; pleural lobe of segments grooved, much as in
the Paradoxidae.

Tyitea, M. punetaius, M. speciosUs.

In classification, Microdiscus occupies a position intermediate between
Agnostus and Conophrys (Callaway Quart. Jour. Geol. Soc, vol. xxxiii,
p. 667) or Shumardia (Billings, Pal. Foss., vol. i, p. 92), if the latter is
found to have a thorax similar to that of Conophrys.

As in the genus Agnostus, there is considerable range of variation
between the species referred to the genus.

The glabella of both M. punctatus and M. pulchellua carries a strong
nuohal spine; otherwise the head is of the same type as iliat of M.
sculptus, M. speciosus, M. Bawsoni, M. lohatus, M. I'arleri^ and M. Meeki.
The pygidia of M. punctatus, M. pukhellus, and M. speciosus are simi-
lar in form, while those of M. sculptus, M. htbatus, M. Parlcri, and M.
Daicsoni resemble each other in having the pleural lobes strongly
ribbed, a more transverse outline, and a ir ^re strongly defined mar-
ginal border.

Pemphigaspis hullata Hal! (Sixteenth Jtep. F. Y. State Cab. Nat. Hist.,
p. 221) appears to be closely relate! to this group, but until more is
known of it I do not think we can indicate its? relations to the Agnos-
tidse, the family under which Microdiscus is placed. Conophrys and
Sliumardia are ilso placed under the same family as trilobites with few
segments and without eyes or facial sutures.

The genus Microdiscus, so far as we now ktow it, appears > be con-

(879)

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CAMBRIAN FAUNAS OF NORTH AMERICA.

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fined to the Cambrian system ; M. punctatus, M. sculptus, and M. pulchel
lu8 appearing in the Lower Cambrian ; M. speciosus, M. Meekly M. Parleri,
and M. lobatus, in the Middle Cambrian; iind, if Pemphigaapis buJJata
proves to belong to the same group, we have one species from the Upper
Cambrian, and all the species now referred to Microdiscus would then
be referred to Peniphigaspis, as Emmons's original name of MicroflLscus
could not be retained, as it appears to have been founded on a specimen
of the genus Trinucleus.

In my review of the fauna of the St. John group of the Hartt collec-
tion I referred the St. John species to M. Dawsoni and M. punctatus.
A reconsideration of the last species causes me to refer it to the species
pulchellus, a name proposed by Mr. Hartt in cataloguing the species of
the St. John Formation (Bull. U. S. Geol. Survey, No. 10, p. 24).

Microdiscus speciosus Ford. ,,

Plate xvi, figs. 3, 3a-c.

MicrodUcuB apecioaus Ford, 1873. Amt>r. Jour. Sci., 3d Ber.,vol. vi, p. 137, figs. Va, 6.
Idem, 1877. Same journal, vol. xui, p. 141.

Original description. — "Head destitute of eyes and sutures, semi-ellip-
tical, with a conspicuous border all around, thickened at the edge, which
in the majority of cases carries from Ave to six minute tubercles on each
side; border expanded in front. Glabella long, conical, prominent,
smooth, without neck furrow, extending in an obscurely triangular ])ro-
jection slightly beyond the po.steriort)utline, separated from the cheeks
by rather wide and deep dorsal furrows, sometimes, though only in very
rare instances, obscurely loi 1 by from three to four faint furrows on
each side. Cheeks convex, prominent, well defined by the dorsal and
marginal furrows. Posterior angles narrowly rounded.

"Thorax with four equal segments. Pleurfe pointed, straight except
at their extremities, which are bent down and slightly recurved, deeply
grooved for nearly their whole length. The rings of the axis have a
slight groove across them in the posterior half of each. The fourth or
hindmost ring appears to be anchylosed to the pygidium; at least, it
invariably accompanies it when the latter is found isolated.

" Pygidium as long as the head and of nearly the same shape, but
slightly narrower, taking the extreme measurements and more rapidly
tapering, gracefully curved in outline. Marginal rim distinct all around,
widest anteriorly, distinctly raised or thickened at the edge. Axis
•conical, sometimes acutely so, long and slender, extending very nearly
to the margin, divided by faint cross furrows, directed slightly back-
ward into eleven rings or segments. Side-lobes highly convex and with-
out furrows. The axis and side lobes appear to overhang the marginal
rim at the posterior extremity, giving the border the appearance of being
only about half as wide behind as it is in front.

" The entire surface is finely punctate. In one specimen of the pygid-

(880)

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MIDDLE CAMBRIAN FAUNA.

156

iuin, out of a large number of perfect specimens examined, there ap-
])ear8 to be a twelfth ring in the axis.

" Length of a specimen of the usual size with all the parts in place,
but too imperfectly preserved to bo fipurod, half an inch. Length of
thorax, 0.13 of an inch. 1 have seen but a single specimen showing con-
cUisively the true number of thoracic .segments. Tliis si)ecies had the
habit of rolling itself up into a ball, and is quite often found in this
state. In the specimen just noticed, the pygidiuin is bent slightly
under the body. Nearly all of the specimeas that I have seen that
were in a perfect condition before extraction, exhibit this tendency to
coil themselves up, which appears to account for the thorax breaking
away in most cases.

" This pretty little trilobite occurs in both even-bedded and conglom-
erate limestones of the Lower Potsdam at Troy; also, at Bic Harbor,
Canada, where it has been collected by Mr. T. C. Weston, of the Geo-
logical Survey of Canada. The Troy specimens were collected by the
writer. It is a rather common fossil at Troy, the head and pygidium
usually occurring detached from the thorax. The head sometimes
attains a length of 0.38 of an inch, but this is quite unusual.

"This species closely resembles Microdisciis pttnctattis (Salter), from
the Menevian group of Wales (Quart. Jour. Geol. Soc, Aug., 1804, p.
237) ; but it difters from that species in not possessing a neck spine, in
the greater number of its caudal rings, and in having the marginal rim
of the head tuberculated. The head, compared with that of Micro-
discus JDmvsoni, from the St. John group of New Brunswick (Acadian
Geology, Dawson, 1808, p. 054), is proportionally longer, and is want-
ing in the grooves of the border of that species."

Mr. Ford subsequently discovered more perfect speciUifjns than those
from which the above description was drawn, that pr )ved that the
thorax was comijosed of three segments, also that the postenor segment
was not anchylosed to the pygidium.

The pygidium of Microdisvus imlchellus Hartt is of the same type as
+liat of M. speciosus, and it has eleven rings on the axial lobe. The head,
however, varies materially in the possession of a strong nuchal spine,
crenulated border, and in the proportions of the glabella and cheeks.

M. speciosus is not a rare form at Troy, although not occurring in as
great abundance as M. lobattis.

Formation and localities. — Middle Cambrian. Conglomerate aiid even-
bedded limestones, on the ridge east of Troy, New York; also, at Bic
Harbor, Canada.

IIiCKODiscus Meeki Ford.

Plato xvi, fig. 4.

Microdiscua Meeki Ford, 1876. Amer. Jour. Sci., Sd ser., vol. xi, p. 371.

Original description. — *' Head broadly rounded in front, nearly semi-
oval in outline, greatest width at about the mid-length, slightly narrowed

(881)

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CAMBRIAN FAUNAS OF NOBTH AMERICA.

(BULU30.

in passing backward from tbis point to the angles. Glabella conical,
about two-thirds the length of the bend, with two straight, moderately
deep furrows extending all across, dividing the glabella in advance of
the neck furrow into three parts of nearly equal length. Neck furrow
extending all across and deeper than the other glabellar furrows. The
form of the neck segment cannot be clearly made out, owing to the
damaged condition of the specimen at this point. Dorsal furrowH
narrow, not deep, dying out toward the front of the glabella. Cheeks
prominent, much swollen in the posterior third, without eyes or sutures.
Marginal rim well defined all around, widest in front, with a conspicu-
onsly raised edge, inside of which there is a nearly flat or feebly con-
cave space, and so bent upward in front as to give to the head, on a
side view, a kind of slipper-like appearance. On either side of the
head, just inside of the raised marginal edge, there are three small
tubercles situated within the limits formed by a line drawn across
the head through the middle of the cheeks and another drawn parallel
with it just in advance of the front of the glabella.

"Greatest width of the head, one and one-half lines; length along
the median line, including the neck segment, the same. Differs from
Microdiacus {Agnostus) lobatns Hall (Pal. N. "X., vol. i, p. 258, pi. Ixvii,
figs. 5a-f), fron) the same locality, in its shorter and transversely fur-
rowed glabella, its tuberculated margin, and in its general proportions."

The figure illustrating this species was drawn by Mr. Ford from the
type specimen, which is the only one yet known of the species.

Formation and locality. — Middle Cambrian. Conglomerate limestone,
on the ridge east of Troy, New York.

MiCRODISCUS LOBATUS Hall (sp.). I

Plate xvi, figs. 1, la, I.

Agnostus lobatua Hall, 1847. Pal. N. Y., vol. i, p. 258, pi. Ixvii, figs. 5a,/.
Microdiacus lobatua Ford, 1873. Amer. Jour. Sci., 3cl ser., vol. vi, p. 135, foot-note.

Original description. — " Minute, trilobate, with a narrow border around
the base and sides; middle lobe often with a small tubercle near its
larger extremity.

"This species bears considerable analogy to the Swedish specimens
from a similar geological position, but they are not identical. Our spe-
cies is always smaller, and I have never seen the small node or tubercle
at the base of the central lobe ; but it presents a similar character on
the other extremity. All our specimens have the appearance of the
caudal shield of a small trilobite, and two or three iu<lividual8 are ap-
IJarently articulated."

The head is convex, bordered all around by a strong marginal ritn,
and without eyes or facial sutures. Glabellaprominent,cylindro conical;
in the great' r number of examples there are no traces of glabellar fur-
rows, but in others the furrows are indicated by slight indentations

(882)

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MIDDLE CAMBRIAN FAUNA,

157

close dowu by the lateral margins; iu fiome specimens there is one fur-
row that cuts entirely across above the well defined occipital furrow,
aud in some a second furrow, so that the glabella is divided into three
ueurly equal lobes by the two well-marked transverse furrows; the form
of the glabella also varies from cylindro conical to semi-cylindricai, and
the outline of the head varies in its relative length and breadth. The
clieeks are strongly convex and arch over to the rounded groove within
the marginal rim. Occipital segment strong and rising at the centers
almost to a point or node.

Thorax unknown.

Pygidium strongly convex, bordered by a rounded rim; axial lobe
proitiiuent, divided into three equal segments and one more elongate
terminal portion by three well defined transverse furrows; lateral lobes
marked by three principal furrows and three slight furrows correspond-
ing to the pleural grooves of the thoracic segments.

A peculiarity of the head, in some of the specimens, is interesting, as
it points to a feature more fully developed in the genus Shumardia
(Billings, 1862, Pal. Foss., vol. i, p. 92) and the closely allied genus
Couophrys (Callaway, 1877, Quart. Jour. Geol. Soc, vol. xxxiii, p. 667):
it is the presence of two minute depressions running outward from the
dorsal suture opposite the anterior end of the glabella, the 8i)ace be
tweeu them being conne(ited with the glabella by a low ridge crossing the
dorsal suture. This character i« spoken of under the genus Microdiscus.

The small heads of Microdiscus speciosus appear much like those of
M. lobotus, but they differ in form and the pygidia are entirely difl'er-
eut. The most nearly related 8i)ecies to M. lohatus known to me is M.
sculptits Hicks (Quart. Jour. Geol. Soc, vol. xxvii, p. 400, pi. xvi, figs.
9, 9«, 10, l6a). The figures of M. sculptus are not very clear, and no
description is given, but, with the means of comparison we have, the
two appear to have many points in common.

Formation and locality. — Middle Cambrian. Conglomerate limestone,
on the ridge east of the city of Troy, New York.

MlCEODISCtJS Pakkebi n. sp.

Plate xvi, figs. 'i,;Ja.

H'^ad and pygidinm subequnl in size and form, strongly convex, and
witli a narrow, prominent, median lobe.

Tiie marginal border of tlie head is narrow ; glabella narrow, elongate-
coiiiciil, and reaching to the anterior border, without transverse furrows
except an indication of a shallow occipital groove ; cheeks convex but
not tumid ; posterior margin with a narrow groove inside the margin.

Without eyes or facial sutures.

Thorax unknown.

Pygidium with a narrow marginal rim ; medium lobe narrow, elongate-
conical, and extending to the posterior groove just within the margin j

(883)

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CAMBRIAN FAUNAS OP NORTH AMERICA.

[DULL. 30.

divided by traiiHverae furrows into eight or nino riugn ; lateral lobes
marked by six or seven ribs tiiat extend out to the margin. Surface
characters unknown.

This species is very closely allied to M. sculptus Flicks (Quart. Jour.
Oeol. Sec., vol. xxvii, p. 400, })1. xvi, tigs. 9 and 10), from the Long-
myud Group. It differs somewhat in the proportions of the glabella and
pygidium, as far as may be judged from the figures given of M. soulptus.

The specific name is given from the name of the quarry where the
greater jiortion of the Georgia fauna of Vermont has been found. The
present Noah Parker's father discovered the trilobites that were sent to
the Kev. Z. Thompson, who forwarded them to Prof. Hall. They were
then described, and one, OlenelluH Thompsoni, was named after ]\Ir.
Thompson. I wish to connect the name of the original discoverer of the
locality with the fauna and the locality. The quarrj' is now known as
Parker's trilobite quarry and is located about one mile north of Georgia
Plains post office.

Formation and locality.— M\CL6\e Cambrian, Georgia Formation. Par.
ker's quarry, township of Georgia, Franklin County, Vermont.

Genus MESONACIS Walcott. .

(/j^ffof, inUldlo, uikI iiKic, point, spear. )
MeBonaoia Walcott, 1885. Aiiier. Jour. Sci., 3d Her., vol. xxix, p. 328, figs. 1,2.

Type of the genus OlcneUus Vermontana Hall, the generic characters
are given under the description of the species. The genus is referred
to the family Paradoxidai and is regarded as occupying, in classificatiou,
a position between the genera Paradoxides and Oleuellus.

Mesonacis Vermontana Hall (sp.). 1

Plate xxiv, tigs. 1, la, b.

Oletius rerniontana Hall, la^iO Twelfth Ann. Rep. N. Y. State Cab. Nat. Hist., p. 60, fig.

2; Pal.N.Y.,vol. iP,p.527.
Barrandia Vermontana Hal), 1860. Thirteenth Ann. Rep. N. Y. State Cab. Nat. Hist., p.

117. Idem, 1861. Geology of Vermont, vol. 1, p. 370, vol. ii, pi. xiii, fig. 2.
Paradoxides Vermonii Eniinons, 1860. Manual of Geology, p. 280, note A.
Paradoxides Vermontana Barrando, 1861. Bull. Soc, G<5ol. de France, 2» 8€r.,t. xviii,

p.«?77,pl.v,tig.8.
Paradoxides F«?rmo«<oHa Billings, 1861. Geology of Vermont, vol. ii, p. 950, 1863. Geol-
ogy of Canada, p. 953.
OUnellus Vermontana Hall, 1862. Fifteenth Ann. Rep. N. Y. State Cab. Nat. Hist., p.

114. (Generic name Olenellus proposed.)
OlenelluB Vermontana Billings, 1663. Pal. Foss., vol. i, p. 11.
Olmellus Vermontana Whitfield, 1884. Bnll. Amer. Mus. Nat. Hist., vol. i, p. 152.

(Referred to Olenellus .Thompsoni.)
Mekonacis Vermontana Walcott, 1885. Amer. Jonr. Sci.,3d ser., vol. xxix,p. 328, figs.

1,2.

The original description of the species is as follows :
" General form elongate ; the posterior extremity obtuse. Head semi-
oval, twice as wide as long, the posterior angles produced in short acute

(884)

WAl.COTT.)

MIDDLE CAMBRIAN FAUNA.

159

.,t. xviii,
i;{. Geol-
,Hi8t.,P-

spiiu's. Eyes na»row, elongate; the space from the center of the head
to tlie outer margin of the eye much greater than the cheek, and the
(listaiice from the anterior angle of the eye to the frontal margin less
than the length of the eye. Glabella lobed ; hypostoma broad oval.

'•Thorax imperfect, preservin^f mx articulations and part of the sev-
entli ; the middle lobe wider than the lateral ones. The third articula-
tion Ih much broader towards and at its lateral margin and is prolonged
obliquelj' downwards in a sharp spint. vhich reaches below the seventh
art"«ulation ; the lateral extremitit's of the other articulations produced
in short, acute spines.

"Another fragment, which is apparently of the same species, preserves
eleven articulations of the thorax and the pygidium. The upper artic-
ulations are imperfect at their extremities ; the last one is bent abruptly
downwards, and terminates in a long spine on each side reaching below
the pygidium. Pygidium semioval; the axis marked by four annnla<
tions, the two upper of which are faintly indicated in the lateral lobes.

" This species differs from the preceding in its proportionally narrower
form, the relative proportions of the parts of the head, and the short,
acute posterior spines. The comparative width of the middle and lateral
lobes of the thorax is a very distinguishing feature.

'' Oeological poaition. — In the shales of the upper part of the Hudson
River group."

The fragment of the thorax aid pygidium described above proved, on
subsequent examination, to be a portion of Bathynotns holopyga (Thir-
teenth Ann. Rep. N. Y. State Cab. Nat. Hist., p. 389), which left the
posterior portions of O. Vermontana undescribed.

No further information of the species has been published to date.
Mr. Whitfield (Bull. Amer. Mus. Nat. Hist., vol. i, p. 152) says: "On
a critical examination of these forms and comparison with the different
sizes of 0. Thompsoni in the collection, 1 find that the distinctive feat-
ures of 0. Vermontana become less and less marked and become merged
into those of 0. Thompsoni a& the specimens increase in size, and I am in-
clined to think the two species represent only different stages of growth
or development of one form." He also figures on plate xv three speci-
mens of 0. Thompsoni as 0. Vermontana.

The species is of rather rare occurrence. During the summer of 1883,
the writer obtained one specimen, and two more the following year.
Tiiey were associated with Olenelhis Thompsoni. Mr. Edward Hurlburt,
of Utica, New York, collected at the same locality, and fortunately found
51 very perfect specimen with its matrix ; the latter was secured for the
National Museum collections, and a cast taken from it which is the orig-
inal of the figure on plate xxiv. Mr. Hurlburt kindly loaned the relief
specimen for study, and from it and three other specimens the following
description is drawn :

Description. —General tbrm narrow, elongate, tapering gradually from
the base of the head to the pygidium.

(885) ■

' IT

f I 1

K 11

I' V

160

CAMBRIAN FAUNAS OP NORTH AMERICA.

[BULL. 30.

Head three-tenths the leugth of the entire animal; length and breadth
as 3 to 4J. Margin bordered by a narrow, rounded rim that is continued
at the genal angles as comparatively sliort aciculate spines ; posterior
side transverse to the pleural angle/ where it bends obliquely forward
to the genal angle, a small short spine marking the pleural angle. Gla-
bella elongate, of nearly the same width throughout, and marked by
four lobes, the anterior of which is large, subcircular, and more or less
convex ; the three posterior transverse lobes are of nearly equal size,
the first and siecond being confli ent at their extremities and uniting with
the anterior end of the palpebral lobes ; occipital segment rather broad
and not well defined from the glabellar lobes preceding it. Eyes elon-
gate, narrow, and arching from opposite the anterior glabellar furrows
back to a point opposite the second posterior lobe of the glabella and at
a little distance from the dorsal furrow. Fixed and free cheeks not
definitely separated anteriorly ; back of the eye the facial suture extends
obliquely outward, cutting the posterior ritn of the head at the pleural
angle. Free cheeks large, roughly subtriangular.

Thorax elongate, tapering gradually to the pygidium ; segments, 26;
the two anterior segments arch slightly forward and terminate abruptly,
the posterolateral angle of the pleura being jiroduced into a short back-
ward-pointing spine ; the third segment has its pleural lobes greatly de-
veloped in width, and terminating in a strong spine on the same plane
as those on the two anterior segments ; the 14 segments back of the large
third segment are uniform in character, decreasing in breadih, but hav-
ing the geniculated portion of the i)leural lobe increasing in leugth and
.size; the fifteenth segment is deeper than the fourteenth on the axial
lobe, but the pleural lobes are much shorter, and a long acicular dorsal
spine arises at the center of the axial lobe and extends back over the
succeet3ing 11 segments to the pygidium or beyond ; the 11 posterior
segments are smaller and a))i>ear to have been of a more delicate texture
than the anterior 15 segments. The pleural groove of the lateral lobes
is broad, flat, and continued outward beyond the genal ungles to the
union of tli.> two niargins of the segment to form the terminal spine or
point.

Pygidium small, ovate, terminating in three points posteriorly ; the
axial lobe occupies all the central portion, leaving a narrow pleural lobe
on each side; posterior margin concave between the outer terminal
points, and with a slight point at the center.

Surface of the entire body, except the free cheeks, very finely gran-
ulose under a strong magnifier ; from the base of the eyes, irregular,
venulose lines radiate towards the outer margin.

Observations. — Tlie genus appears to be one intermediate between the
genera Paradoxides and Olenellus, or a form in which the character-

'The plouial auglo is tbo auglo o tlio posterior margin of the head, opposite the
geuiculatiou of the pleural lobo of the thorax.

1VAI.C0TT.1

MIDDLE CAMBRIAN FAUNA.

161

istios of Paradoxides aro changing into those of Ok^nellns, the hea;l
and the tirst 14 sej^uients u-inj; in all ]Kirti(!nlars the type of Oleiiellus,
and the pygidiura and 10 posterior segments more the type of Para-
doxides ; the fifteenth segment represents the telson'of Olenellus Tliomp-
soni.

Under remarks ou the genus Olenellus, the relarioiiships to that ge-
nus are mentioned, and we will next consider the body of Mesonacis
hack of the fourteenth segment.

The fifceenth segment fits snugly up against the fourteenth ; the axial
lobe is strong and su])ports the base of a long, slender spine that^, as
now preserved, extends back to the i)yj.vidium j the base of the spine
originates on the dorsal surface of the segment and also extends back
so as to include the posterior margin, and causes the latter to curve
back towards the center; the lateral i)lourfB of the segnK-nt are short,
and in their structure are diminntive representatives of the large pleurae
of the . egments anterior to tha tifteenth.

The succeeding eleven posterior segments apjjear as though formed
of a more deli<;ate test than the anterior portions of the body, as they
are much more tlattened and compressed than the latter and the pleu-
ral grooves are almost obsolete. The pygidium is also small and deli-
cate.

The body back of the spine-bearing segment appeal's as though be-
longing to a different animal, and looks more like that of a Kemopleu-
rides than either Olenellus or Paradoxides, but, on a close examination,
the pygidium is found to be much like that of 7'«r</(/ai'<(/e,s ruguUmiH,
and the free ]»leurie bend back as in that species. (Compare fig. 16 of
l)late xxiv with fig. 2 of same plate.)

Comparison with other (jcnera and species. — The form of the head is
similar to that of, Olenellus Thoinpsoni, except that in the less com-
pressed examples it is not i)roportiorally as broad; this may be also
said of the entire body. The genal spines are n^ore slender and the
frontal glabellar lobe is closer to the anterior margin.

Among the described species of the genus Olenellus some si)ecimens
of the head of O. Gilberil api>roacli very closely U» that of Mesonacis
Vcnnontana, and I was surprised when i i'ound that the f(»rmer <lid not
prove to be generically or speciiii ally lelated to the latter.

We do not find among the Atiii-ricau s[ie('iesof Paraik'xidcs foiins to
coMi])are with either Olenellus or Mi'somu-is, <'xce])t in the outline of the
postei'ior margin, as mentio led under the genus Olenellus. Europe
gives one from Sweden, P. EJ'irntJi,^ the head oi' which s'low.s o'her feat-
ures comnion to Olenellus and Mesonacis, as n!<'iiii"!'.'.",l under the de-
scription ol' the former genus.

la the contour of the ailult form of the head, P. sjiinosii.:, J', i'fadt'ri,^

'OfvtTsigt k. SveuHk. Vet.-Akad. Fuibuud. N:p G, y. 71)0, Tull. xvi, ligii. 1, '.i,
Stockliulm, l-iTl.
^>Syst. ISil. H(]li('iu<', vol. i, Irro'i.

Bull. ;30-

-11

(887)

162

CAMI5RIAN FAUNAS OF NORTH AMERICA.

[BULL. 30.

&c., may be (joiuparcd with the species under consideratiou. The gla.
belhi and the eye lobes \'ary from all excei»t P. Kjerulfi.

The thorax has already been spoken of in the remarks following the
description.

The denticulated form of pygidium in the genus Paradoxides with two
terminal i)oints is shown in the pygidia figured by Mr. Matthew' from
the St. John group; and on the pygidia of P. rugidosus Corda, P. Ly-
elli Barrande, P. expectans Barraude, and P. Oelandiem Linnarson, four
terminal i»oints occur, as far as can be determined. The one specimen
showing the i^ygidium of M. Yermontana has three terminal points, cue
central and one on each side.

Under the general remarks on the genera Ulenellus, Mesonacis, and
Paradoxides, the generic relations of Mesonacis Vcrmontana are still
further discussed.

Formation and /ocwV^Vt/.— Middle Cambrian, Georgia Formation. Park-
er's quarry, township of Georgia, Franklin County, Vermont. Speci-
mens corresponding to the head of this si)ecie8 occur Jit Bonne Bay,
Newfoundland, and L'Anse an Loup, on the north side of the straits
of Belle Isle.

Genus OLENELLUS Hall.

Elliptocephala Einiiioiis, IS IG. Af;riciiltiii(.' of Ni'w York, pt. 5, p. 65, figs. 1-3.

ElUptocepJialus Eirimoiis, IB.'jo. Aiuer. Geo!., \)t. ii, p, 114.

EUiptocephaliis ^lUirctm, I860. I'loc. BoHton Soe. Nat. Hi.st.,p. 371.

Oleniis Hail, 18.")!). Twcimi Aim. R.'p. N. Y. State C.ib. Nat. Hist., p. 59.

Olenus Marcon, 18K). IJiill. Soc. Gt^ol. ile Fr/uice, ;{'■ n6v., t. ix, p. 25.

Barrandui Hall, IriCiO. TliirteentU Ann. Kcip. N. Y. 8tate Cab. Nat. Hist., p. 115. Idem,

• 1801. Gt!oloj>y of Vorniotit, vol. i,p. :i6"J. ,

Paradoxkles EniuionH, l8G0. Manual Geol., p. ii80.

Paradcxidca IJarrandc, 1801. Bull. Soc. G(?ol. do France, 2"= sdr., t. xviii, p. 277.
Paradoxides Maroon, 1805. Proc. Boston Soc. Nat. Hist., p. 245.
ParatZorirfM Billings, 1801. Gfol. Vcrniont, vol, ii, p. 9.">0. Idem, ISChi. Gool. Canada,

p. 953.
Olenellus Hall, l.-^O's!. Fiflecnth Ann. R.^p. N. Y. State Cab, Nat. lli.st., p. 114.
OleneUm Marpon, 1802. Paniplilct, p. 5. Cainbiidj;t', Mass.
OleneUus Bi'.liugH, 1805. Pal. Foh.s., vol. i, pp. 11, 305.
OleneUm Ford, 1877. Amor. .Jonr. So!,, vol. xiii. j). 205.
OloieUns W^iitfiold, 1884. Bull. Amor. Mn.s. Nat. Hisl ., vol. i, p. 151.
Olenellus Walcott, 1«84. Monogni))bs U. S. (.Jcol. Sur\ oy, vol. viii, ]). 28.

Dr. Emmons originally [daced a s])ecies of this genus under the ge-
neri(r name of JCllijiloceidiala (I^^'-IO), ''onsidcring it a new g(Mieri<5 iorni ;
subsequently (IsrM, Amer. Geol., p. 114) he called atfisntion to tlic
simihirity of the name to Ellipsoceplialus (Zenker, IS.'J.'J), but concluded
"to retain it for the i)resent." ]\loie recently Die name Elli])to(;epliala
has been j'ecognized {OlancUu.s {EUipiocvphalus) asaphoiiles, Vovd, Amer,
Jour. Sci., 3d ser., vol. xiii, p. iHib, 1877), but 1 think without good rea-

' Trans. Roy, 8oo. Canada, vol. 1, pi. x.
(888)

WAI.COTT. 1

MIDDLE CAMBRIAN FAUNA.

163

son, as it diflfers only by an error of spelling from Zenker's genas EUip-
s(K!(*pbalu8,tlie elliptical form of tlie head being the basis of each name.

The following is the original description of the genus Barrandia Hall,
af't(^rwards changed to Oleuellus Hall :

"General form broadly ovate or elong.ate-ovate, distinctly trilobate.
Cephalic shield broad, somewhat semicircular; the width more or less
than twice the length, with the posterior angles projecting in long spini-
forin points ; the posterior margin is nearly straight or slightly concave,
with a slight sinuosity at the outer angle just within the cephalic limb;
the anterior and lateral margins have a tliickened or elevated border,
wii'...n wliich is a well marked groove or depression of the crust. The
fiiabellais well pronounced, of nearly equal width throughout, or slightlj'
iiiinowing and rounded in front ; marked by three paifs of furrows (per-
haiKs from two to four), the posterior one of which is nearly or quite con-
tinuous across from the posterior angles of the eyes. The facial suture
has not been fully determined, but appears to extend in a curving line
from the front margin to the anterior angle of the eye, and from the
posterior angle of the eye it turns abruptly outwards towards the pos
tero lateral angle of the cephalic shield.

"Byes large and well developed, <.iongatesemilunate, extending from
near the base of the shield more than half way to the anterior margin.
Ilypostoma broadly ovate, little longer than wide.

"Tiiorax composed of 13 or 14 articulations, the axis being moder-
ately convex and usually much narrower than the lateral lobes (and
sometimes ai)parently marked by a row of nodes or short spines along
tlie summit). Lateral lobes nearly flat; the ribs, to about the eighth or
ninth, extemling almost rectangularly, or slightly inclined from the axis
for one-third to one-half their length, where they are bent abruptly
bat;k wards. The third segment is stronger and much more prolonged
than the others. The last segments of the lateral lobes are produced
directly backwards, or sometimes a little convergent below. The seg-
ments of the lateral lobes are marked by a broad longitudinal furrow
nearly parallel to the anterior margin ; leaving an abruptly elevated
rid'je oi border upon that side as far as the geniculation of the segment,
where the groove runs along the center, dying out on the recurved ex
treniities.

"Pygidium distinct, narrow, elongated, the axis narrow and acutely
pointed; without rings? Lateral Jobes narrow or obsolete, and free
IroMi transverse ridges or furrows."

Tlie direction of the facial suture is left in dimbt. For the type
speiiies 0. Tlionipsoni, Prof. Whitfield has shown it as though passing
from the posterior end of the eye obli<iuely and almost directly back to
the ])osterior margin (Bull. Airier. INI us. Nat. His., vol. i, pi. xv, fig. 1).
iToiii the examination of a large number of well preserved speciuiens,
i am led to think that the sutuies reiire.sented are accidental breaks

(889)

i '!

l'.'.

if?

^/ii

164

CAMBRIAN FAUNAS -OF NORTH AMERICA.

|I1ULL.3(I.

and not the true sutures, as we invariably find the line of the sutnrc
running obliquely outward and tenninatiuft- at or very near the pleural
angle. It occurs in this way in all other .species of the geiuis in which
we have ob.served the suture.

Tht. ' itures are shown for 0. HowelH and 0. Oilberli in the same man-
ner (Expl. and Surv. West 100th Merid,, vol. iv, pt. 1, pi. ii, figs. .'{, f),
but with the type specimens before ine I fail to find a trace of the suture
indicated on the specimens of 0. HowellL and the one specimen oi" 0.
Oilberti showing the sutures has them running out to the pleural aunle.
Xt..iier Mr. Meek nor Dr. White spt-aks of the facial sutures in his
descriptions, so we conclude that the artist in charge of the drawin;ns
traced fhem in to meet his conception of their position.

When studying the variations in the head of O. GilbcrtK— (). Hon-
elli, Monographs U. S. Geol. Survey, vol. ,i l, p. 32), the writer di'tcr
mined the direction of the facial sutures, and found that they varied
in direction with the configuration of the head, but that they always
terminated at the pleural angle.

Mr. Ford, in .speaking of the suture of 0. asaphovles, says: "The
shield appears to have fractured as easily in one dire(;ti)n as another.
This would seem to indicate that the cheeks were very firmly united at
the sutures in fn nt" (Amer. Jour. Sci., 3d ser., vol. xiii, jk 271, 1S77).
Jle regarded this as the result of the metamorphoses accompany in;;-
the development of the young, when constant changes were occuiriD.n'
along the line of the sutures back of the eyes. After once obtaining an
adult size, the test on the line of the sutures appears to have bccoinc
strongly united back of the eyes, as in nearly every case the line of
fracture is back from the eye to the margin, as the point of least resist-
ance; and this is probably why the suture of 0. Thompnoni and (). Gil-
herti have been represented at that point. In uninjured casts of the
interior of the test of the head, the direction of the suture is indicated
by a slightly rai.sed line from the eye back to the pleural angle.

Fi/gidUim. — 'to the original description add the word rcry before
elongate.

BELATIONS OF THE GENUS TO OTHER UENERA.

Professor Hall notes the <liftV reuces as comiiared with Olenus and Para-
doxides (Thirteenth Ann. Kep. N. Y. State Cab. Kat. Ilisi., p. ill) as
follows:

'*Wheu wo compare with Paradoxides, we find the cephalic shield
proportionjiUv oroader and shorter, wiiile there is no expansion of the
glabella towards the front, nor do the transverse funows extend en-
tirely j'.'TOSS this part, except at its base. This leatuie and tlie faci.d
suture, though indistinct, ccurespond mort^ nearly with Olenus.

"The smaller number of thoracic segnuuits is a distinguishing fent-
ure, and the direction of the segnn'iit-furrow differs essentially. In
one feature, that of the greater developnu'ut of the tliird segnu'nt, it

(890)

WAt.COTT,]

MIDDLE CAMBRIAN FAUNA.

165

Tlio

('oiii'spoiKls with Paradox ides, whore the second segment has a greater
(U'\ c'lopineiit than the others. Ta the extreme development of the pos-
terior .si'jjments, in one species, there is likewise a similarity with Para-
(loxidcs In the slijjht development of the pygidinm, oar fossil corre-
si»'»nfls in some degree with Paradoxides."

To these ditferences may be added that the pleural groove on the
Mi;iii('iit of Olenellus is shallower, broader, and less oblique than that
of I'aradoxides.

'Uw late Mr. G. Linuiirsson considered Olenellus Thompsoni as having
110 iiiHtiity to Olenns, but as a true Paradoxides or Anopolenus (Brach.
Piiiiidoxides l>eds of Sweden, p. 28. Bihang till k. Svensk. Vet.-Akad.
llaiidl. Bd. 3, N:o 12, 1 ' .i).

With the first I am ii: accord, but, on comparing with Anopolenus
Salteri, as illustrated by Mr. HickR ((Juart. Jour. Geo!. Soe., vol. xxi, p.
isi. ti^'. 1, ItSli.")), I fail to recognize the characters uniting the two
foriiis. Tiie remarkable develo})ment of the posterior portions of Anop-
olenus and the peculiar glabella and eyes serve to distinguish it as a
distinct genus from Paradoxides and Olenellus; and with Paradoxides
tliere are the ditl'erences given by Proi'essor Hall and the writer (ante) ;
but, as stated by Mr. Ford, the adult form of O. asaphoides as known
to biiii dilfers only in one feature from the structural peculiarities
pouped under the genus Paradoxides, and that is the segment furrow
or ])lciiial groove. To this I think we may now add "and in the elon-
uato, simple lelsoii or i)ygidium."

One marked peculiarity is that the extended pleura of Olenellus
occurs on the tliird, while tliat of Paradoxides is on the second, segment
of tlie thorax. ■

before

id L'ara-

U4) as

c sliiehl

m of lilt'

tend eii-

le facial

iiig feat-
illy. Ill
anient, it

UELATIONS OF J'lIE GENERA PAIIADOXIDES, MESONACIS, AND OLE-
NELLUS.

As inentioiM'd under the description of the genus Mesonacis, that
jii'iiHs is regarded as intermediate between Paradoxides 'and Olenellus,
or II ltd ill preserving t^ pical features of each genus.

.\l('S()na(;is is distinguished from Paji^adoxides by the character of the
pleural grooVe of tlie segment, the ])resence of a dorsal spine on a mod-
ilied form of segment on the fifteentii segment of the thorax, and the
(liawiiii; in <»f tlie eye, esju'cially of tlie posterior end towards the gla-
bella, 'fiio points of reseniblaiKU' aie the ('ontignratiou of the head, the
t,vi)e()f the segments (except in the pleural groove), and the form of tb6
li.Vii'idiniii.

The features of the head and tlun-axof Mesonacis, back to the fifteenth
se;;iiieiil, ar(! in all (l(>1ails essentially tlios*^ ol' Olenellus, but the py-
j;i<liiuii belongs to a dill'ereiit Ibnii and the eleven posterior segments
:il»iK'iir to go with the jiygidium rather than with the anterior portion
of tlie tliorax.

The heads of young specimejis of OkncUuH Oilhcrti and those adults

%i^

166

CAMBRIAN FAUNAS OF NORTH AMERICA.

[BUtl.. 30.

preserving embryonic characteris, sliow, in the position of the ej'e and
the run of the facial suture to tlie posterior margin, features common to
the genus Paradoxides. Tlie eyes of P. rugitlostis Corda and the group
of Paradoxides from the St. John Group of New Brunswick approacii
the glabella at their anterior end, as also P. Kjcrnlji Linnarsson, but
the posterior end Is distant from the glabella, as seen in the typical
forms of the genus. In the normal adult of all species of Olenelluaaud
Mesonacis known to me the eye is drawn in close towards the glabella
at both ends and the suture curves out to cut the i^osterior margin at
the pleural angle, as in Paradoxides, whether that angle be preserved
or absorbed in the straightening of the margin.

Although Mesonacis is found at the same horizon as Olenellus, I re-
gard it as showing the transition from Paradoxides to Olenellus. A
Paradoxides-like form first takes the characters of Olenellus in a degree
by having » spine originate on the fifteenth segment; then the body
was shortened by the absorption of the pygidium and eleven posterior
segments, until the elongate telsou of 0. Thompsoni is the only repre-
sentative of the parts lost in the transition.

Prof. Whitfield in mentioning the telson says : " There is not the slight-
est evidence of any lateral lobe or expansion, or anything analogous to
this part as seen on other genera, and the median ridge shown upon the
specimen figured, as abo' "> referred to, does not always exist. On one
specimen the fourteenth axial rin^f looks almost as if it might have
formed an anterior lobe or ring of the telson ; but iu others it is seen to
be distinctly separate and articulated, as are the forward axial rings to
each other. This feature of the pygidium is so distinctive among all
other trilobites that it alone would serve as a generic distinction, and
if the condensation of parts indicates development of organization this
form would appear to be below even the Paradoxides, and should pre
cede it in age."

From our present knowledge of these forms we reverse the applica
tion made above and regard the telson as representing the condensed
parts, and the form as higher in organization an*^. succeeding Paradox-
ides in time.

Mr. Fonl considers the relationship between Olenellus and Paradox-
ides one of genetic character (Amer. Jour. Sci., 3d ser., vol. xxii, p. 257,
1881), and that Olenellus is a later and higher form than Paradoxides.

We assent to this, and add that Olenellus is the representative of tlie
group of Paradoxides of the I ower Cambrian iu the Middle Cambrian,
and expi'esses, in one of its species at least, the decadence of that branch
of the type. The examiJe is 0. Qilberti, where, in the retention and
great development of the embryonic stages of growth by adult individ-
uals, we have an example of the loss of power in the larger number of
the individuals of a species to develop to the adult form. In other
words, it is au instance of retrogression towards the earlier forms of the

family to which it belongs.

(893)

wALCorr] MIDDLE CAMBRIAN FAUNA. 167

Olenellus Thompsoni Hall.

Plate xvii, tigs. 1, 2, 4, 9 ; pis. xxii, xxiii, tig. 1.

Olenus Tltompsoni Hall, 187)0. Twelfth Ann. Ecp. N. Y. State Cab. Nat. Hist., p. 59,

fig. 1 on p. tiO; Pal. N. Y., vol. iii, p. 52o.
Barrandia Thompsoni Hall, 1800. Thirteenth Ann. Hop. N. Y. State Cab. Nat. Hist.,

p. IIG.
Paradoxidea Thompsoni Emmons, i860. Manual of Geology, p. 280, note A.
^'•radoxides Thompwni Banande, 1861. Bull. Soc. G<Sol. do France, 2" s^r., t. xviii,

J). 276, pi. V, lifT. 6.
Paiddoxides Thompsoni Billings, 1861. Geology of Vermont, vol. ii, p. 1)50. Idem, 1863.

Geol. Canada, p. 953.
Paradoxides maorocephalus Enmions, 1860. Manuiil of Geology, p. hB, i'lg. 70. On the

preceding pag(!, fig. 70 is rcAMred to as Paradoxides asaphoides; but from the

flgnro th(*re is li( tie donht that it was taken from a speeinien of O. Thompsoni.
OkncUm Thompsoni Hall, 1862. Fifteenth Ann. Rep. N. Y. State Cab. Nat. Hist., p.

114. (l»Mieri<! name Olenelliis proponed,
Olenellns Thompsoni J{illing,s, 18()5. Pal. Foss., vol. i, p. 11.
Olenelliis Thompsoni Whitlield, 18>i. Bull. Am<'r. Miis. Nat. Hist., vol. I, p. 151, pi.

XV, figs. 1-4.

The original description ol" the species i.s a.s follows:

"General form ovate, the length and breadth being nearly as six to
five. Head broad lunate, with the ijostero-lateral angles much ex-
tended; the width from the center to the outer margin of the eye almost
equal to the width of the (jheek. Eyes (whicli are imicli crushed in the
specimen) elongate semi-oval, equal in length to the space between the
anterior angles and the frontal margin ; glabella distinctly lobed, nar-
rower in front.

"Thorax with the lateral lobes about once and a half as wide as the
luitldle lobe, consisting of fourteen articulations, the third one of which
is much longer than the others, and curving downwards with an exten-
sion reaching as far as the line of ;irticulation of the seventh rib. The
posterior articulations are bent abruptly backwards, so that the free
extremities are pai^allel with the axis. Pygidiuin small, pointed, with-
out visible rings and having a narrow ridge running down the centre."

Prof. Hall revised this description in jiroposing the generic name Bar-
randia. (See description under OJeneJlufi, ante, ]). 101.)

In 1884: Prof. Whitfield gave a description of the direction of the fecial
sutures and figured examples of the species that ])roved the pygidium
to be as given in Prof. Hail's second figure (Thirteenth Ann. Eep. ^.
Y. State Cab. Nat. Hist., p. 110, 1800) and ahso rruich more prolonged.
Prof. Whitfield's referenc to the spe(nmcn "figured in lOth Kep. State
Cab." ])robably refers to the figure in the fifteenth report.

Our studies of this species prove that there is a narrow and broad
form, as shown by plates xxii and xxiii ; also, quite a range of individual
variation. This is shown by Prof. Whitfield's group of figures (Bull.
Amer. Mus., pi. xv), where he refei's specimens varying in form to
Olenellus (= Menoiiacis) Vennontana.

(893)

'1 .wM

168

CAMBRIAN FAUNAS OF NORTH AMERICA.

I HUM,. 30.

it-^i

Quite ii lUiirkt'l vsiriation occurs in two heads from near Swantoii,
Vermont. It iiS in tiic j^realer breadth ol" the mar;;iiial rim, as sliowii in
flfi'. 1 of phite xvii. Other cliaructer.s of tlie species are jiiven under re
iiiarks on tiie {T;enus of wiiicli O. ThowpHitni is the type.

FormntUm and lovaliti/. — Middk? (Jambiiaii, (Georgia formation, in
the argillaceous shales of Parker's quarry, townshij) of Georgia ; east of
Swantoii, oil tlie Dullard farm ; west of St. Albans, in the outskirts of
the city J in the massive magnesiaii liaiestones west of l*.irker's(]inirr,v,
and also about one and one half miles east of the hotel at Ilighgate
Si)ring8, Vermont. Mr. Billings cites the species from Bonne Bay, New-
ibundland; L'Anse au Loup, on the north shore of the Sti its nf Belle
Isle; and the conglonu'rate limestones of Bic Harbor, on the St. Law-
rence Itiver, below (Quebec.

(Jlenkllus ASAPnoiDES Emmons, sp.

]'I;ito xvii, li>>.s. 4-S, 10; |)1. xx, lij;.s. 'A, '.Ut,b; )>l. xxv, i\'^. 8.

l^lliiitoccphala uHoiiUoidin Eiuiiioim, 1844. Ta^onic System, p. ','1, figs. 1, 2, :{, 184tj.

Agriciiltiin- of New York, vol. 1, p. (i'l, ligs. 1, 2, i.
Oleiiii'' a8a2)hoi(hN Hull, 1847. I'ii.. N. V.. vol. i, p. '27)i\, pi. Ixvii, iig-i. '>a-c. Idem,

Fitch, l(-4t». Trans. N. V. State A;;. Soc, vol. ix, j). e(i,'».
JiUqitocejihaltm ui^apiioiilitu Eiumon.s, L'^4y I'roc-. Aiiht. Ahsoc. Advt. Sci., vol. i, p.

18; hlaiiif lsri.">. Aiucr. fii'oL. vol. i, \)t. '2, p. 114, tigs. 1, 'i, ;{; pi. i, tig. 18.
ParadojridcH uixiphoidix l^iiiiiioiis, l.-^ii). Manual of Geology, p. ^7, iiaiiio of tig. 70.

IJudor till' ligiiic on tlio following page tlio naiiie. is ParadnxldrH mavrovephuliiv,

and till' ligmt' is taken tVoiii an Dlciirllui ThoiiijiNoiii (Ijanande, IHiil. Bull.

Soe. (ii'ol. d(i Fiance, 2'- isc'i-., t. xviii, p. x!7:?, jil. v, tigM. 4, .5).
Oleiidlun anaiilioideti Toi'd, 1,~7I. Auier. .Jour. S.i., lUl sur., vol. ii, p. ;'..!. Idem, 1877.

Saiiit! .jouiiial, vol. xiii, p. ~'(ir>. Jdum, 1878. Same J(uirnal. \t)l. xv, p. I'i!).

Idem, l88l. Same Journal, vol. xxii, ]>. i.'.O,

The history of our knowledge of this trilobite may be divided into
two epochs: First, that of the original discovery and (h'S(uiption of the
adult form and its connection witii the Taconic controversy; secondly,
that of the des(!ription of the embryonic jdiases of its growth ; the first
extending over a i)eriod from 1S44 to I8!i() and the second from 1871 to
the present time, the period intervening between lS(»()aiid bSTl being
one in which little additional information was gained.

The material upon whicli this species was founded shows .some of the
chara(!ters of the head and thorax. The author gives Hgures of the
head and six segments of the thorax of a Itirge individual, a smaller
crushed head, atid a fragment of a thoracic segment. The same spe',;i-
mens were subse(puMitly tigured in tlie Paheontology of New York, vol.
i, pi, Ivii, ligs. 2(i-c, an<l accomjjanied l>y a description,

Dr. Emmons subseciuently obtained a more complete specimen of the
thorax, which is tigured on plate i, tig. 18, of his American Geoh)gy.
Fourteen segments occur in the thorax and decrease in size and length
regularly from the head backward, a feature not observed in the other
species of the genus and one that seems to distinguish the species from
the closely related 0. Thompsoni.

- (894)

WA1.C0TT.1

MIDDLE CAMBRIAN FAtTNA.

)01ll<i'

»r fiio

1G9

The pygUlium is not shown in any of Dr. Ki. lOiiis's specimens or in
tliosc obtained by Mr. Ford at Troy, New York. AVe have not observed
it in i)laceon the trilobitc but from finding an elongate telson bke that of
0. Tliompsoni in the limestone at Troy associated vith fr.ifiments of O,
asdjihokles, it is qnite pi'obable tliat tlie pygidinm is of tlie same char-
acter. The objection to tliis is tl»(^ broad si)iice at the base of the four-
teenth segment in the specimen lignred by Di-. Emmons (Amer. Geol.),
and also at the elcventli segment in .Mr. Ford's figure (Amer. Jour. Sci.,
vol. xiii, p. 265, tig. '), 1S77). Tlie plenra>. of the segments resemble those
of Mesonacis Vermoninna in tlieir curvature rather than the strongly
recurved jileura' of O. Thomimnii, of the eleventh to th(^ fourteenth
segments. The discovery of more i)erfect specimens can alone deter-
mine the number of segments and the character of the pygidinm.

The second epo<;h in the history of the species we owe to the investi-
gations of Mr. S. W. Fonl, who discovei'ed in the limestones at Troy,
Mew York, a number of minute specimens showing some of the meta-
inorpiioses of the species.

Two of i\Ir. Ford's figures I have reproduced, one showing a young
stage, where the body is i)artia]ly developed, and the other the mature
form; iilustratiotis are also given of two very small heads, figs. 5 and 0,
plate xvii. Fig. 5 has a length of four-fifths of a millimtiter, and fig. (i,
of 1.75'"'". Mr. Ford calls the spines a; a? the interocular spines ; these
are absorbed during tlie development oi' the animal and also to a great
extent their continuation up on the head; the surface of the latter. is
(Tos.sed by elevated lines corresponding in jxisition to the glabellar fur-
rows; they appear to indicate the original segmentation of the head»
most of which is lost by absorption during the subsequent development,
except on the glabella; the connection between the frontal lobe of the
glabella and the ocular somite or segment is beautifully shown. As far
as can betletermined, the thorax is not yet developed in either specimen
represented by figs. 5 and 6. Fig. 8 shows the great development of
the third thoracic segment, and also the interocular spines and genal
spines, which are placed so close to each other in figs. 5 and 0. A speci-
men figured by Mr. Ford shoMs them separated by a slight crevice. Fig.
8 also shows the tenden<\v of the genal angles to extend forward, a feat-
ure so extravagantly develoi)ed in 0. Gilberti.

Mr. Ford has discussed the metamori)hoses of the young of O. am-
phoiflcs in a minute and able manner, and the reader is referred to his
])iipers (Amer. Jour. Sci., 3d ser., vols, xiii, xv, and xxii) for further in-
formation.

The geographic range of 0. amphoUles is not yet well determined,
owing to the fact that when in a fragmentary condition it is impossible
to detect tiie dittei-ence between it and 0. ThompHoni and 0. Gilberti
when the latter is also without the thoracic segments.

Formation and localities. — Middle Cambrian. In argilhuieous shales
at Keynohls's Inn, northeast of ]>ald ^lountain, Washington County,

(895)

'^'m

■'.y.m

170

CAMBRIAN t'AUNAS OF NOUTIl AMERICA.

[uuLi..;',).

New York. Mr. Ford lius also found it iu the liiuestones on the ridf^c
east of Troy, New York, and also one mile below Schodack Landing,
New York.

Olenellijs iDDiNGsr Walcott.

Plate xix, fig. 1.

Ohnellua IddingH Walcott, IHHS. Monographs U. S. Geol. Survoy, vol. viii, j). LM,
1>1. ix, fig. 12.

Original description. — "General outline of the head roughly subtri
angular, with the length one-half the breadth of the posterior border;
strongly convex; the rather narrow rounded riin bordering the anterior
margin suddenly becomes thickened and rounded o[)j)osite the eyes,
and is extended back in the short, strong, slightly curved, genal spinet;,
the narrow posterior marginal border uniting with it at the genal
angles. Glabella elongate, narrow, divide«l by lour transverse fui--
rows into Ave lobes; the anterior is round, tumid, and expanded later.
ally, while the four ])osterior are narrow, transverse, of equal size, and
with their sides parallel ; occipital ring and furrow not recognized ; eyes
luuate, situated opposite the central lobes of the glabella. Facial
suture in front of the eye unknown ; back of the eye it extends obliquely
outward and backward, (mtting the posterior margin about two-tliirds
the distance from the glabella to the posterolateral si)ine.

•'Thorax andpygidium unknown."

A second visit to the type locality of the species resulted in tinding
a number of larger heads, but no traces of the thorax or the i)ygidiuni.
The most prominent peculiarity of the head is the development of the
genal spines, as seen on slabs of limestone from the Groonie District,
Nevada, on which they appear, when broken from the Jiead, like uiiiUil
valves of a species of Leperditia. From the new specimens we also dis-
cover that the occipital ring had a low, blunt point at the center of its
posterior margin.

Formation and localities. — Middle Cambrian. From a fine-grained.
arenaceous shale near the summit of Prospect Peak, Eureka Disiriri,
Nevada, and also iu limestone at the south end of the Timpahute ltan;^f.
Eastern Nevada, brought in by Mr. G. K. Gilbert (Geog. and (Irol.
Expl. and Surv. West 100th Merid., vol. iii, p. 109, section xviii, 2c).

Olenellus Gilberti Meek.

Plate xviii, iigs. l,la-c; pi. xix, figs. 2,2a-h; pi. xx, figs. 1,1a-?, and 4.
Olenellus Gilbei'ti Meek, 1874. (Maiiusci'ii)t. )
Olenvllua Bowelli ^Idtik, lS7i. (Manuscript.)
Ohnellua Gilbcrli. White, 1874. Geog. and Geol. Expl. and Surv. West lOOtli Merid.,

Prelim. Rep. Invert. Foss., p. 7.
Olenellus nowcUi. White, 1874. Geog. and Geo!. Expl. and Snrv. West 100th Merid..

Prelim. Rep. Invert. Foss., p. 8.
Oknus (Olenellus) Gilherll Gilbert, 187.5. Geog. and Geo]. Expl. and Snrv. West U"'lh

Merid., vol. iii. Geology, p. 182.

(896)

WALCOIT.]

MIDDLE CAMBRIAN FAUNA.

171

Ulcnuii {OlcneUim) HowcUl Gilbert, 187r.. Geog. aud Geol. Expl. and Siirv. \V«'st lOOth

Merid., vol. iii, Geology, p. 18H.
Olrnellus Gilhirti White, 1875. Geog. and Onol. Expl. aud Surv. W«'st 100th Merid.,

vol. iv, p. 44, pi. ii, figs, '^a-e.
Ulciiellus liowelli White, 1875. Geog. and Geol, Expl. and Surv. West lOOIli Merid.,

vol. iv, p. 47, pi. ii, figs. 4a, ft.
OUnMua Gilherti Walcot ' , 18^4. Monographs U. S. Geol. Survey, vol. viii, p. 29, pi. ix,

figs. 1(5, 16a; pi. xxi, fig. I'.l.
Oltiiiilm Hon Hi Walcott, 1H84. Monograi)hs IJ. S. Geol. Survey, vol. viii, p. *J!), |il. ix,

ligs. 15, 15a, b, nnil pi. xxi, ligs. !-',».

Ill the original notice of this Hpecics by Mr. Meek, he comi)ai't's it
with M€so7iaci8 (0.) Vermontana to show the <littbn?nre8 between the t\v(»
forms.

Mr. White gives an elaborate description of tlie head and fragments
of the thorax ; aud tlu^ writer has described the Eureka (Nevada) foruis,
lomarking that the ditt'ereuces between tlicin and the type specimens
are almost entirely in tlie frontal limb, the )riner having a much broader
space between the front of the glabella and the marginal rim.

.Mr. Meek, in describing 0. Iloirelli, compared it with 0. ThompHoni
without giving a description of the parts knowu. Dr. White gave a de-
tailed description t)f the type specimens (Geog. and Geol. Surv. West
lOOth Merid., vol. iv, p. 47), and the writer described them as they occur
in the Eureka District.

0. Hoicelli was considered by Mr. Meek as distinct from (). (iilbcrii,,
and Dr. White and the writer followed his authority. The same speci-
mens were studied by each observer, and it was not until alter the writer
had visited the type locality and secured a large collection of spcci-Mens
that it was shown that the large convex head preserved in the granular
limestone matrix, and named 0. Tloivelli, was the same as the flattened
heads in the argillaceous shales referred to O. Gilberti. We now have
a series of heads uniting the characters shown iu the typical 0. Hoicelli
with the typical forms of O. Gilberti, and, as the latter .spoides (tomes
first in the order of description, the si)ecilic name is retained.

The following is a description of the adult form : Outline of body
ovate to elongate-ovate. The general outline of the head is semi-elli])-
tical or semicircular, and more or less strongly convex. The margin is
bordered by a narrow, rounded rim, which becomes thickened near
the genal angles and is continued posteriorly in rather short, sharp
spines. The glabella is elongate and more or less expanded in front and
behind, contracting a little mi<iway ; four ])airs of glabellar furrows ]h'u-
etrate from each side ; they are somewhat strongly impressed on each
lateral third of the width of the glabella, becoming more shallow as
they pass into the less marked furrow that unites them across the? cen-
ter of the glabella; in the younger specimens this furrow is undistin-
guishable from the lateral furrows, and they all unite as one distinct
furrow, crossing the glabella from side to side, siiid, even in the adults,
this feature is strongly marked in some individuals; the anterior lobe of

(897)

■,.;^t.

■' -I I I

■ ■ . -^ I

;in

ii!

172

CAMBRIAN KAUNAS OF NORTH AMERICA.

riii'i.t,. ;i(i.

•■I
Mi'- ;■

1 IH!

lH;

;

(,:|

, m ^'~$

tliP yliilu'llii is more »ir less timiitl, subliemisplierical or ii litth^ transverse
and wider than the greatei!it width of the glabelhi iiiiin'ediately iH^hiiid it;
the next jKKSterior lobe is rather narrow and transverse, dillerinjf tVoin
tiie next two posterior lobes, which are wider and curved a little forward
at the ends, by the din^ction of the furrows; the posterior lol)e cone
spondin{j to the occipital rinjfor se^fjnent is l>r(Jad and essentially of tiie
same chara(!ter as that ])recedin}X it; the finrow separating tliein is
very shallow at the center and inclined obliquely backward at tiie sides;
a small node occurs on one examphi at the center of the occipital rinj,'.

Eyes elonjfate, narrow, an«l arching- from ojjposite the anter'or ^da-
bellar lobe to opposite the occipital furrow. The dorsal furr<.'.vs are
narrow, distinctly but not deeply impressed. Fixed cheeks a little ex-
l)and('d anteriorly and s(;arcely more than a line in width between tla^
elonfjate palpebral lobes and the doisal furrows, while posteri()rly the.>
me]'<;e into the small trian(;ular lateral limbs; frontal lind) variable; it
varies in width on different spettimens from scarcely a line to a broad,
fattened area between the {flahella ami the anterior marj^ln. Free
cheeks rou<,'hly subtriangular iu outline, variable in yidth and in the
outljnc of the curve between the jjenal anjjle and the inner margin.

The facial suture cuts the anterior niarjjin some distance outside the
line of the outer mar<,dn of the glabella and passes oblicjuely inward to
the anterior anjult? of the eye lobe; curving around the outei- nuirgin of
tliis, it passes obliquely outward to the posterior margin, cutting it
midway between the glabellar lobe and the outer margin of the geual
angle.

Thorax with fourteen segments; axial lobe moderately convex and
narrowing gradually to the posterior segment; lateral lobes flattened
out to the geniculation of the segments; segn..!nts nearly transverse
out to the geniculation of the pleural lobe, where they c«irve backward,
terminating iti long slender points; pleural groove broad, well defined,
and <!ontinuing nearly to the point of the segment. The axial lobe of
the third segment is dcuveloped equally with its associates, but the pleu
ral lobes are greatly expanded and their spinose extensions are much
longer and stronger than on the other segments. The form of this seg-
ment varies in different specimens.

Pygidium an elongate, slender telson, without segments or lateral
lobes.

The surface of the glabella is beautifully ornamented with transverse,
fine, irregulai,'ly-waving, snbimbricating lines that give the appearance
of imbricating lamello! resting one under the other from before back-
ward; this feature is only seen on the most perfectly preserved speci-
mens ; the surface of the cheeks is slightly granulose under a strong
magnifying glass, and has slightly irregular lines which radiate from
the base of the eyes and glabella out to the marginal rim; the surface
of the segments of the thorax shows a fine tracery of inosculating, un-
dulating stria) subparallel to the segmcMit, crossing the axial lobe and

(898)

WAI.COTT.J

MIDDLK CAMBRIAN FAUNA.

173

i'xtpndiiig out to the uxtreinitics of tho ulcural IoIm'h. Tlio MurfiUM^ of
tlif tiilson is not preserved no :is to show its cJiiitiU'ti'is. Tlir test itself
is very tliiii iiiul fragile, iiu«l is usuaily broken iiwny.

The above description is that of what is (ionsidcred as tlie normal
ailult typf^ and omits altogether the phases of this remarkable species
that are shown in its various stages of growth and development. Tln^
relation of thisspeeies to Olencllvs Thompsoni are very intimate in what
I called the normal adult type, but when we study it in all its details
it appears best to consider the western form as representing a distinct
species.

The form of the pleural lobes of the third segnu'ut is frequi^ntly like
that of the corresponding segment in i]feiionacis VcnudiildiKi ; it is there
broad and nearly straight from the outerangle to the sjjinose tenninatiou
of the pleura; in other individuals it is more narrow, rounded on the
genal angle, and curves gracefully outward and backward to tlie loug,
slender points, as in sonui examples of M. Vermoutaua.

The largest head yet observed has a length of (}«'" and a width of 12""'.
Comparing this witlia smaller entire indivi<lual, we find that the animal
to which the large head belonged had a length of over 14"", exclusive
of the elongate telson, which was from 0""" to 8"'" long if projwrtionato
to that of the smaller individual.

The original specimens upon which the two species <). Gilhcrti and
0, lloirelli were based were collected at Pioche, Nevada, by I\Ir. ICdwiu
llowell, of the Wheeler Survey.

Formation ami /«6Yf//^jV,s. — IMiddle Cand>rian. The species occurs in
limestone and argillaceous and sandy shales, and ranges through from
50 to 300 feet of strata overlying a massive belt of reddishbrowu
quartzitetl)at is 3,000 feet thick in the Wasatch Mountains. In Nevada.
0. Oilbcrti has been found a^ 'ioche on both sides of the anticlinal arch
of (luartzite; on the western side of the Highland Itange. S miles
north of Bennet's Spring; in the Groome District, near the south end
of Timpahute Range, on Silver Peak, longitude 117° 20' west, latitude
.'58° north; and on the summit of Prospect Mountain, Eureka District.
In Utah two localities are known: one in thcM-auou Just above Ophir
City, in the Oquirrh Range, and the other in T.ig Cottonwood Cafion,
Wasat<;h Mountains, one mile below vVrgenta. Tiie sp(>cimeiis brought
in from Kicking Horse Lake, British (Columbia, by Mr. (leorgti M.Daw-
son, appear to be identical with those from Nevada and Utah.

OBSERVATIONS ON OLENELLUS GILBET?TI.

'" """SI

'id

f lit m

"lip

Under the title of "Observations on OleneUns HoiceUi" (Monographs
U. S. Geol. Survey, vol. viii, p. 32), 1 have attempted to describe the
remarkable series of variations observ(Ml in the head of this species
(biiing several stages of growth. Additional material has since been
obtained, and the principal facts are here brought together.

(899) *

pr^

!>''lt

174

CAMBRIAN FAUNAS OF NOETH AMERICA.

[BULL. 30,

Unless otkerwLse ineiitioned, all the specimeiKs are from the same
striiliim of rock.

('o:itour of the head. — The smallest specimen of the head observed, fig.
]<•, pi. XX, is L'.o'""' in length, and resembles in its outline the larger head,
tig. le, which has a length of 7.o""", which is seen more clearly by comjjar-
ing tiie latter with the enlargement of fig. lc=fig. 1. Between tigs. Ic mul
U', in size, is the form represented by flg. 3^, which is transversely quad-
rilateral in outline, with the genal angles and spines carried forward to
form antero lateral angles on a line with the frontal margin of the head;
ai.d the geiiici'lrttion of the posterior margin, which is so strongly
niitrked in flg. 1, is still further increased to form an angle of nearly
".>()"', which, from its position, might bo incorrectlj* viewed as the true
genal angle if the anterior si)ines were broken away or obscured and
the course of development of the si)ecies unknown. In fig. Ig the geual
sjrines are still more anterior thari in the smaller forms (figs, le and le),
and present a transition stage — not considering the size of the head, but
the general form — between figs. Ic and Id, or Id and le; the angles of
the posterior margin .vx are also more obtuse, and the frontal margin
broadly rounded Through the forms represented by figs, le, Ig, 1/j,
the modification of these features is very uniform to the normal adult
tyjM' of the contour of the head, as shown by fig. It. In figs. Im and
T7^, however, which ar«' considerably larger specimens, the angularity
of the liosterior margin is a prominent feature, the genal angles being
advanced as in the forms before fig. 1?. In fig. 11 the outline is still
further diversified by having the angularity of the posterior margin and
the position of the genal spine on one side different from the other
side. Fig. li is considered as nearly typical of the adult outline of the
head as the largest si«ecimen found, and a number of medium size have
the same form, and it is characteristic of other species of the genus.

The geniculation of the posterior margin is an embryonic character
that is singularly ])ersistent in many examples that have otnerwise
adult characters. In fig. 36 the adult form of the head of another species
of the genu- is shown.

The speciiiien represented by fig. 1/is from the south end of the Tini-
I)ahute Kaiig'% 1*00 miles south of the Eureka district. It is associated
with such form.', as Ic, le, and li, and also with O. IddingHi on the same
slab of limestone. It has the genal spines even more anterior than in
fig. \d. Wit'i it occurs the form on ])hite xix, fig. 2d, which, in the posi-
tion of the glabella, is much like the tyj)ical O. GUbcrti of Meek. One
other .specimen of the head that is 3""" in length has the outline of tig.
\g, and three others, having a length of 2""", 1.8""", and 1.5°>"', respect
ively, have a contoui' as siiown in lig. LV, pi. xvii.

(Jlabella. — In the smallest head tli«' glabella is depressed between
the large crescent shaped eyes, and the anterior lobe iijjpears to be a
link uniting the anterior ])ortions of the two eyes to form a semicircle
around the depressed glaUella back of its anterior lobe; in succce<liiig

(900)

WALf-orr.]

MIDDLE CAMBRIAN FAUNA

175

stafftK of growth the glabella rises and expands in front, as shown in
f,^. 1 of ]>hite XX. Comparing with tlie glabella of the adult, it is to b(^
observed that in the younger individuals the glabellar furrows exteu<I
entirely across the glabella, while in the older ones they iire more or
less interrupted or united only by very sjjallow transvers*- I'mrows at
tlie center, and that the frontal lobe of the glabella i.s more expanded
proimrlically in the young forms.

h'l/es. — The usual form of the eye of the adult of this genus is shown
by the e^ye of O. Thonipsoni. fig. 0, i»late xvii.

In the youngest stages known to us of the head of 0. Oilhcrii, 1..')"""
in length, the eyes are very large and elevated above the glabella and
are the most ijrominent feature of the he id 5 on a larger head. 2""" in
leatrth, they still predominate, but in a he.id 3™"' long they are situated
a little distance from tlie glabella toward the center of the clu'ck and
united to the anterior lobe of the glabella by a strong, elevated, ocular
ridge that crosses and interrupts the continuity of the dorsal furrow
(see figs. 1, Ifi and 1/, pi. xx). There is considerable variation in the
relative })Osition of the eye and the length and strength of the ocul;ir
ridge in difl'eieut examples of the head. 1 n fig. Id the ocular ridge of the
left side is elevated, and, with the high margin of the eye lobe, partially
incloses the depressed area within, while on the right side of the same
individual both the ridge and eye are less elevated, and, tlu^ ocular ridge
being shorter, the eye is brought in neaier to tlie glabella. In fig. l_r/
tlie ocular ridges is narrower ;it ^'le point of union with thi' glab-dla and
a'tached farther bade, near the posterior margin of the Iroiita^ lobe,
Frecjuently the longitnt'inal axis of the eye is sligbtly oblicpu' fr( m its
anterior end backward and outward. With tbe uiciease in size, tbese
features usually disappear, altliongh in fig. 1/ there is an excei)tion, as
they are retained in .1 modified degree after other accompanying em
bryonic features of the i.ead have disapi)eared. Between the eye and
the glabella, wl.on the former is situated well out on the clirek, a smaJl
round or oval bo is occurs, as shown in (igs. Ir/, If, l^/, and 1/.

Facial suture. — The cotirse of the facial suture in front of the adult
head is shown by the free clieek, fig. \c of plate xv. Of its v.M'ianon
from this course during tlu' dev(>Iopnient of the individual nothing is
known from actual observation, but, i'iom the iact thai the relative po
sition of the eye changes, it is probalde, indeed almost certain, '.hat its
direction is somewhat varied, and we know that such is the o-ase in its
direction back of the eye when tlie latter is situated on the cheek o:
near the glabella. Back of the eye, in all the instances iu which il iias
been observed, its direction is slightlj' outward, with a siguioidal eiirv
ature to the angle of tin; posterioi' margin, or, in its absenee, to tin;
broad (airve denoting the position of the angle about midway liftweeii
the dorsal furrov. and the genal angle, figs. Ic, Iq, l/i, and 1/, pi. xx. In
the large adult s])ec'iiien its c 'irse was ])i'obably as indicated ity t!ie
traced lire in tig. 1/, Mhere it is minh the same as in the genus Ogygia

(901)

liiiil

\% .-■'■■ .;•..• I

t, •;' .'ill

•^JC

I ' ' '5.S M

'■i't''

tn;:'.

176

CAMBRIAN FAUNAS OF NORTH AMERICA.

fn"r I,. 30.

or Dicc.llocephalus, and even more so in the cheek, fig'. \c of pi. xviii, if it
cut the posterior margin at the angle x, as it does in all known cases in
the smaller specimens, ti<>s. 1/t and 1?'. Coiuparin^^ this with tlie direc-
tion of the stages of growth shown on figs. \e and \g, wiiere anotlter
generic gronp is suggested l)y its Paradoxides-like course, the contrast
is very striking.

It is stated on p. 34, Monographs United States Geological Survey,
vol. viii, that in adult specimens of O. Gilherti and 0. Vernionfana the
course of the facial suture is almost directly backward from the eye to
the margin. This statement was based on the published figures of the
two species. I now have before me the type specimens of (). Gilherti,
and I fail to find a trace of the facial suture sliowing on any one of ihem,
and their course is not mentioned by either ^Ir. Meek or Di. Wlii't', tlic
artist evidently having indicatetl in the drawings his personal views of
where they should be placed.

In well-preserved speciuiens of O. Thouipsoni the suture back of tlie
eye extends outward to the pleural angle, as in O. Gilharti.

?[ode of (lerelopmtiif. — The iiorniid development of a trilobite from tlic
earliest embryonic condition with which wc are acquainted to the adult
form is marked by the disai>])earance of the embryonic characters, one
by one, as the individual increases in size and assunu\s unnv and juore the
features of the fully develoi»ed animal, all of which usually takes place,
except in size and surface ornamentations, when it is quite small. Tlie
retaining of au embryonic feature after the imlividual has passed in
size, or in any other character, the stage at which it usually disappears
in the regular course of the development of the sjiecies is an excee;!-
ingly rare occurvencte, and is unknown to our knowledge, except in the
increase in size of the body m certain species, so that in tlieir course of
development certain individuals are in fact larger than those of the same
species having a greater number of segments in the thorax and being
consequently more advanced in development. INF. T.arrande has shown
this to be the ease in the (Unehqiment oi' A rcllni.siHa Kdniimhi, Frocfiis
(IccoruN, and F. vemisttiH (Syst. Sil. Boheme, i, p. LMkS, 1852), and we have
observed it in Triarthrns Bed!, where the relative size, proportional to
the development, is very marked; .. g., an individual with thirteen seg-
ments in the thorax is 21""" in length, and (uie with sixtecm segments
but Hi.")' " long, while the fully grown exaniple of sixteen s*»gm( iit>
reaches a length of 53'"'", and some with thiiteen segments are but 7""
in length (Trans. Albany Inst., x; Fossils of the Utica Slate, p. 211,
l;sri>).

This jteculiarity of growth is shown, in the species mentione<l, only
by the lliorax, for, if we take the head nlone, there is little or nothing
to prove that its size is not pioportional to the stnge of develoi)ment;
but in OJenelluH (lilherti the heii<l jnoves this to be otherwise, and tlicn^
may be added to the stntenient that, in certain sjiecies, the size is
uot proportional to the number of liberated segments in the thorax,

(902)

fll'TI.. 30.

WALCOTT. I

MIDDLE CAMBRIAN FAUNA.

177

tliat ill this species the size of the head is not always projtortioiial to its
stii}>e of deveh)pinent.

The smallest specimen we now have (it is doubtfully referred to this
si)ecie8) is 1.5'"'" in lon«;th; but, owing to its having been exposed to
;itinospheri(! action, tlie details of its surface are not well j)reserved;
tlie general form and the j)ronunent eyes, narrow glabelhi, and de-
pressed margins an' all that can be satisfactorily determined} these
are shown in tig. 2c, pi. xix.

The course of d(iveloi)ment would appear to have been from some such
form as this througli forms similar to those represented by tigs. Ic, I5,
l/(, and li, i)late xx, but we find forms like tigs. Id, 1/', and J// associated
with the former forms, in the same pieces of rock, at localities 125 miles
distant from each other, and then^ is in each lociility a gradation of
tbnn uniting such extremes as tigs. ]/ and 1/. Separating the two ex-
trci'ies, as two species, will solve the diflQculty of giving a common
origin to such forms ii.s iigs. Ic, 1^/, Ic, 1/, l(j, lli, and 1/ represent, but
we capuot obtain evidence to warrant such a separation. JJotli at Eureka
and in the Tim])ahute llange, the evidence is strongly in favor of refer-
1 ing all the variable foiiiis of the head to one s|)t'(^Mes.

It is observed that tigs. Im, 1/.', and 1/ precede 1/ in the stage of de-
elopmeut of the contour of the head, at the same time showing a more
accelerated development in the form of the eye. The eye of tig. 1/t is
more advanced than that of tig. 1/, while the posterior outline of the
liciid is more embryonic in its character. With these examples it is
readily conceived that Iigs. !</, 1/, and 1// are large forms that preceded
tig. Ic* in development, and tlie eye of fig. Id su])poi'ts this Aiew, as it
is, in its strongly <leveloi)ed ocular ridge which is more marked than
in tig. I and more anterior in r-iation to the frontal lobe of the ghibella,
essentially more embryonic; ■ nd the position of the genal angles and
spines is either a decidedly euduyonic feature or such a sport as, with
tig. la to connect it with tigs. Ic or 1^, would not be considered i)robable.

From the material now at oar command 1 thiidv that the earlier form
»)f the youTig was similar to that of tig. 2r, pi. xix, and that the char-
acters of the head at the stage of developmeiit represented by tig. Aa,
pi. XX, of 0. amphoide.s w(?re pernninently retained l)y many individuals
u.itil reaching adult size, (»r that such forms as tigs, i.f, h\ h/, !/.•, 1/,
and Im repi'esent the stage ol develo])nient ])ass»'d through in the usual
growth of the young of 0. asaphoidcs and <). (Hlhtrti before reaching
tlie size of tig. Ic. and that what is a transition stage in (). dsaplioidcs
(lig. 3fl) is often extravagantly developed and becomes a tixed stage in
a large proportion of the individuals of 0. ilUhcrii.

h'rintion.s to otlur .sjicciis and (jcnuHi. — The ditliculty met with in <;om-
paring the <leveioj)ment of this species with that of other s)»ecies in
which the thorax and pygidinni are known, is also felt in studying its
relations to various species ami genera in which the structure of the

(!)03)
Bull. oO 12

h': .'l

■'■\

178

CAMBRIAN FAUNAS OF NORTH AMERICA

tnuix. 30.

n il^

1 1

;i.

entire body is known, as we have bnt few entire iiidividiials and but
one shows embryonic chaructors.

The heads of the species associated with Olenellus Gllbcrfi and 0. Td
dingsi are small, but they do not present any lecognized embryonic
features.

As already stated, the suture lines shown lor O. GiiherH are jinroiy
imaginary in the type tipjnres (Geoj;. and Geol. Surv. West 100th Meri<i.,
vol. iii, pt. 1, pi. ii, fij^s. :^a-c), and tlii'ir course is, in all probability, as
in other species of the genns.

Mention has been made of OlenoUnfi asoplioldes iind of certain rescin
blances in the contour of its head at the s+age of <kn clopnjent repre-
sented by fig. 3rt, pi XX. and that of the head of 0. Oilherti as seen
in tigs. Ic, Ic, 1/i, &c. The curious inicrociilar spines of the former
have not been seen in 0. (rilhcrti, Mr. Vonl lias c<il!ed attention to tiie
Para.(loxi<les like run of the posterior margin of the head, g x. x g, fig.
3a, and states that it disappears altogether during th(i embryonic life
of that specips. We have sliown that it is extravagantly develoi)ed in
0. Gilberll. even to the extent of changing the entire contour of tij-'
head, figs. Id, If, and !</, and that it ])ersisTs in the adnit stage of many
individuals of this species, and is also present in Menonaci.^ Vermoutano.

In all the observed specimens of 0. Oilherti showing tlie fa(;ial suture
back of the eye, the posterior Tnargin is cut at the angle within the pes
tero lateral angle, as Mr. Ford has ixjiuted oat for the form, fig. 3ff, of
ofiaphoiden, and also for the genus Para(h)xides.

Attention is again called to the direction of the facial suture back of
the eyes in tigs. 1e and 'ig and the position and obli<piity of the eyes in
relation to the median !'ne of the glabella, characicrs o!' Paradoxide>,
iis seen in P. ■splno-sit.i. Of all liie species of lii*^ lai tc- genus, /', Kjefulii
(Ofversigt k. Svens!;. V.-s.-Akad. Vorhandl. N:o 0, p. 790, faii. xvi,
figs. 1. 2 Stockholm, 1871) alone shows the presence of an ocular ridge
unit/ing the eye Jiiid tiie :roiit;il livbe of llie glabella (fi,u. -, pi. xx), a
feature so inominent in .lie young «»t' (). (illbern, as well hh the small
rounded proluberance bi'tween the eyes and the glabella, sliowu in
Liuuarsson's fig. ~ of P. Kjerulji. Tin' iailcr character Mr. Ford dis-
cov<>r(Hl in the young of (>. n sap ho ides, ^nd noted its rcsoniblanee to tlie
same In P. Kjirnlji. The ocular r'dgf, a. teature in .he latter thai is
perniamMit, is also present iu the young and adult of (), GUbcrti and in
O. ThompKoni.

Resume. — The study of I he head of 0. GUberti, prov«ifi ,

First. That iu certain in(li\iduais of this species tlie existence of eai
bryonic features contimi^'s 'ong after thr indiv idnal has reached tin-
size at which mu-Ii features are u^ualIy lost in the proccMs of develop
ment of the other species of the genus.

Secondly. Ttiat, \n individuals otherwi.se develo|)etl equally iu all re
spects. some one of tiu'u\ m.iy have a characteristic feature, such as the
eye or the geual ar^le <ievelope(l to a grea'er or less degree than in the

WALCorrJ

MIDDLE CiVMBRIAN FAUNA.

179

otbers, ami that (hi.s feature may pernist even after the individuiil hav
]',}';; it liii.s passed in size or other clnnaeters the ^tage at w'uieh it is
usniiUy lost.

Tliirdly. That the develojunent of certain <'!»aracter8 is present in
Hii inieqiuil dep:ree iii the e(Mn's()<)ti(lin*f p;ir!x of the same individual.

I'iiially, that cert;tin t"'?<)tures pre.senr, in the younger individual and
(lisitjipearing during suhse(|uent 'jrowlli are peimaneut features in sorne
species of the f»en us Paradoxides.

To tl»e biologfist this spec^ies lias a peciiliiir interest, as we ai>i)ear to
liavc the remains of ;tn animal that was a]ipr(iiiching extinetion and
gradually losinjj it« vital force to .sueh an extent that tlie younj; were
unable to de\<'lop to the adult form except in u more or less imi»erfect
(lejjree, and, jks a result, retained embryonic features althou;;h having
the power to grow to tlu' adult size in only h ('<>iTi]>arative degree enn
wo say that it is a cas'' of rever.sioii to the original forms of the genus
Of family to which it belongs, as we know so little of the progenitors of
the Paradoxi<les. That certain characters of P;iradoxides are present
ill the young of OlsneVns GUbcrti that are not present in the adult type
of tlie genus, and that these chiiraeters are present in many but not in
a!l adult spfciniens of 0. GHherfi., we do kuov/, and to that extent a re
versioti to the (diaracters of its ancestry is shown in the period ap
])roa(!hing the extinction of the species.

During the summer oi 1885. the writer visited Pioche and the High
land Range, Xevada, and obtained <i l.irge collectioo of Cambrian fos
siis, among them severa' entire e.v.unples of 0. Gilboii. Oue with a
length of li5"'">, exclusive of tlic telson, which is quite as long as the
body, shows most decided embryonic chariict«*rs in the head, and the
third segment of tiie th.orax has a peculiar toiui iothe pleural lobes and
is prolonged to a^i extr.ivagant leng;!'. The form of the third segment
is not entirely normal, as it liny been 'vowded forward and the pleural
(iTO(>v«' depressed. The pieune figured on pi. xix. hgis. 2h and 2i, prob
ably belonged to an indivitiual like fig. _ of pi. xxi.

-Vnofher sp(»cim«'n, ;'0""' in length, t'xclusive of the telson, pi. xxi,
lis I, is e>;>ea' lal'.y a y«>ung soecimen of (Henelht^Thoynpsoni, diHeriu^i
■IS, specieN tii.4n from liie specimen mentioned above The

only ivason 1 have f»r !ea\ tng O. Gilherti undei a differtut specific name
IS the fact of its haviu'.;: sucU a peculiar and abnormal variation ivi difier
ent individuals.

If the two specimens vepresenred by tigs. 1 :*iid L* of plate xxi were
submitted to a paleonr,oiogi>^t he wtmld be v«-!y apt r.» consider tbetn
not only as specitically di,stiJK;t, but perliaps reiev tig. '2 to * subgenus
<>( i\ii. 1 ; and i acki'owledge That, in asking th<* student ■&* consider
'IitMu as different ptiases of one t^peci^^s. 1 am requiring htn to accept
'■videuce which is e.idy paftially given in ti«»» illustrations of the species;
"'If. if lie iins fol!ow<^d •111- 10 the pre- iliiiju pag<^•^ o* Ocsc-'-iption of ().
HiUicrtl he may uuderts' .iid why the n^-ad represeW'ed mv lig. 1/of pi.

;1N

m}" 1a:-'<

;[

180

CAMBRIAN FAUNAS OF NORTH AMERICA.

[BUI,1.30.

XX is regarded as specifically coiiuected with that of tig. 1, pi. xviii, or
fig. 1ft of pi. XX, and that figs. 1 iMid 2 of pi. xxi are considered to be
si)ecifically the same.

There are no dittercnces of the bodies of figs. 1 and 2 of i)l. xxi that iirc,
essential, except in tlie third segment of the tiiorax, as the broad and
narrow forms of the figures are owing largely to the sj)eciiiiens luiviii;,'
been compressed in opposite directions. The dilference in the form of
thb, third segment is of the same type as that in the genal spines of tlie
head.

Fig. la, pi. xxi, shows the hesid of iig. 1 natural size. Fig. 2 of pi.
xix is evidently the same; also figs. 2a and 2ft of the same plate. Witli
tig. 2a of pi. xix the transition to figs. 1ft and 1? of pi. xx is natural,
and then from fig. It of pi. xx to ti};s. 1ft, Ic, h/. Id, and If. That tlii.s
change is not a direct embryonic developnieyt is shown by the size of
the heads and by the fact that it occurs in lieads of nearly the same
size, as in the head of fig. 2a, i)l. xxi, figs li, 1/, Iwj, pi. xx, and tig. 2b,
pi. xix.

H' we do not accept the view that only one sj>pcies is represented, and
begin to break up the series, the complications tluit arise are iiiu(;li
greater than the acceptance of one variable species, abnormal in its
growth, as already described.

The spines of tlie head of fig. 2 of ])1. xxi are of the same type a.s
those of fig. 2d of pi. xix and l/'of \)L xx. If there is a sjjecific ditfcr
eiice between figs. 1 and 2, pi. xxi, it is in the length of the gvnal spines,
as we have specimens with the long spines showing the variation in tiic
outline of the head from fig. 1/, pi. xx, to a head of the same outline a.s
the head of fig. .1, pi. xxi. Ii, fact, tig. I of ])1. xx is more nearly le-
lated to fig. 2 of the same jilate, in respect to the strength of tiie .spines,
than to the average head of the species. With all the data that 1 can
obtain, I think that we have but one species now placed under (>. (ill-
berti.

Genus OLENOIDES IMeek.

O'f'Hoidcs Meek, 1H77. Gcot. Expl. I'orticlli l';ir., \i>l. iv, pt. 1, p. 2.1.

Type Paradoxiden f NevadenniH ^lucK, ifiH). Viw. A(;;nl. >i:il. .Sci. I'liila.,v(>l. xxii, p. O'i.

The generic des(?rii)tioii is drawn from the type species and thesecuiid
speci«^s, (). fi/picaJifi.

General outline ovale. Head large, semicircular. Glabella straiglit
or slightly expanded in front; marked by three pairs of fuirows in 0.
tjipicalis. Eyes elongate. The facial sutures extend obli(|nely ontwaid
IVom the anterior base of tiie eyes and cut the frontal margin : pos-
teriorly they cut the margin at the |)leuial angle and nin subparaliei to
the margin, to the posterior end of the eye.

Thorax with eight or more segments ; axis strong and pleural l<iljes
well defined ; pleural groove broad.

(f)O(i)

•f 1

[BUM. 30.

)1. xviii, or
ere«l to bo

xi tliat lu'c,
broad aii(|
MJ.S liiiviii','
he loriii of
ities of tlie

is- ^ of pl-
Ue. Willi
is iiiitiiral,
That tills
the size, of
,' the saiiK'
Aud ti^-. 21),

;0Tited, and

are iiiu<;li

uial ill itis

ne type as

eifi<! ditVcr-

iiai 8])iiie.s,

tioi) ill tlic

oiitliue a.s

iieiirly le-

tiie spiiK's,

that 1 can

Mer 0. <iil-

.\Nii, \l. <W.

the .second

a stmi^ilit
rows in (f.
y outwiiifl
r.iiiii : |«'s-
[)arallrl to

nraJ

il)e.s

WAUOIT.]

MIDDLE CAMBRIAN FAUNA.

181

Pysidiuin marked by transverse furrows on the axis, and the lateral
.sediments are directed backwards.

The jjenus is referred to the family Paradoxidse. It is a tyt>e niilike
I'aradoxides, Olenellus, or Dicelloctephaliis. and yet includes in its tlio-
liicicses'iiuMits features eoiiimoii to tht' two former genera and. in the eyes
1111(1 lacial sutures back of the eyes, characdcrs found in Dieellocei'iialus.

The stratigraphic jiosition of tlie species referred to it, 0. Xevevlensix,
0, ii/pioalis, 0. .^pinonv.s, and O. flanrictiudus, is between the Middle
Cambrian (Olenellus) horizon and U])per Cambrian (Dicellocephalus)
horizon.

The ty]»e sjiecimen of 0. Nevadensis preserves the occijiital segfuient
of the head, the eight thoriicic segments, and about two-thirds of the
livv.idiiim. The secon<l species is known by its entire form and is vh-
ft'iicd to (iie genus from linviiiga simiiar tyjie of thoracic segment an<i
ii itygidium, so far as is now known, of the same type. I had described
and proposed a gemnic name for 0, tifpicalis, but, on discovering that
Mr. IMeek had proposed the name Olenoides for a species that, so far
as Iviiowii, could be generically associated with 0. typlvaiiH, I adojjted.
tlie name, being ])Iaced in tlie dilemma of having a s])ecies with a
generic name jiroiio.sed " in ease it ni'ujht be fonnd to be a distinct
generic type," to which to refer the species, or of giving a new generic
iiiiine tliat. on finding more perfect material of Parado.videsf N'eradentiis,
iiiigiit |)Vove to b(! congeneric witli the hitter. To avoid introducing a
new name that might l»ccome a synonym, all the species originally
anaiiged with the s[)ecies 0. tiUJicaUs are now placed with it under the

genus Olenoides.

OLE^'OIDES Xevadensis Meek.

I'late .Kxv, (ij;. 7.

I'nru(ti>xi<1fiif Xeradcii^in Alcok, 1870. Pioc. Acad. Nat. Sci. Pliilad., vol, xxii, p. 62,
Idem, 1877. Gcol. Ivvj)!, F(•r^i(^^ll Piir.. vol, iv, y». 'ili, ])1. i, fiy;. f).

The original desciiption appeared in IS70 and was reprinted in 1877,
the only change being in the proposal of the generic name Olenoides
in event of the species proving to belong to an undescribed genus. The
later description is as ibllows : " Of the thorax, eight of the posterior
seuiiients are jireserved. These siiow the axial lobe to be much de-
pressed, and ibont as widt; as the lateral ones, exclusive of the free re-
eurve<l points of the pleurae The segments of the axial lobe are defined
I»y ;i broad, rounded furrow, or dei)ression, acro.ss the anterior side of
'■acli, and have much the genei al ai)])earanee of those of some species of
Panula.ridcs, being a little thickened, squarely truncated, and .slightly
ciirved forwai'd at the ends. IJut they diller in showing distinct r<Mnaius
of a mesial s))ine, or tubercle, on each, and in having an obscure, oblique
lurrow, or depression, on each side, passing outward and backward

(907)

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182

CAMBRIAN FAUNAS OV NORTH AMKRTCA.

ftil.'M.. 30

from the broad, auterior, transverse furrow to tin; posterior lateral angles,
so as partly to isolate the slightly-thiekened and truncated extremities
of each. The lateral lobes are nearly flat and compose<l of i)leura) that
extend straight outward at right angles to the axis to their free ex-
tremities, which are abruptly contracted (almost entirely on the ])osteri()r
side) into slender, rounded, very sharp spines, which curve backwtird
and outward. Each of the pleural is also provided with a broad, rather
deep, flattened furrow, which commences near the inner end and ex
tends straight outward for some distance, with i)arallel sides, but grad-
ually tapers, mainly on the anterior side, to a lanrreolate point, before
reaching the free extremities. These furrows have not the obliquity
usually seen in those of Faradoxides, but run parallel to the direction
of the pleura?, so as to leave a slender straight ridge of equal size along
the anterior and ])osterior margin of each rib.

"The pygidium, exclusive of the ])ortions of the free border broken
away, has a nearly semicircular outline, being about twice as wide as
long, while it is as much flattened as the thorax. The part remaining
equals in length the five thoracic segments next in advance of it. Tts
mesial lobe is much depressed and about three-fourths as wide ante-
riorly as the breadth of that of the thorax at its widest part seen. Pos-
teriorly it tapers moderately, and extends nearly the entire length of
the pygidium, as seen with the free border broken away. It is evident,
however, that the flattened border projected more or less behind its ter-
mination. It shows distinctly five segments, with indications of about
two others at the posterior end. The lateral lobes have each three seg-
ments, the anterior one being extended out nearly parallel to those of
the thorax, while the others are directed more obliipiely backward, and
rapidly widen outward. Like the pUnuiB, they have each a broad, flat-
tened furrow, that of the anterior one being nearly parallel to tiiose of
the pleurae, while those of the other two are diiected more obliquely
backward, particularly tlie ))()sterior one, which is almost i)arallel to the
longitudinal axis of tiie body. These furrows are so deep and broad as
to give the three segments of each lateral lobe the appearance of six
irregular ridges, the irregularity being produced by the posterior two
furrows, instead of i)assing along tlie middle of each segment, being
curved backward so as to divide it very unequally, k'a\ ing the anterior
part much the broader. No fine surface-markings are preserved on the
si»ecimen.

"Entire length of the imperfect specimen, nearly ."{ inches, of which
the remaining eight tliorax'ic segments form 1.70 inches; breadth of the
thorax, exclusive of the free spiniferous ends of the pleurie, 2.05 inches,
and, including the projecting <'nds of tiie ideune, LMO inches; length of
what remains of the pygidium, l.O.'i inches; breadth of the same, about

1.80 inches.

• • • * * « #

(90S)

WALCOTr.]

MIDDLi: CAMBRIAN FAUNA.

183

"It is i)Osalble I should call this spt'cies OlenuH or P<troholina Neva-
densis; but its large size seems to be an objection to placinp; it in any
8e(;tion of either of these groups. In the possession of a node or spine
on each of the thoracic segments, as well as in the direction of the pos-
terior segments of the lateral lobes of the pygidiuin, it agrees with the
type of raraholina; but, unfortunately, the specimen is not in a con-
dition to show whether or not these segments of tlie pygidium termi-
nated in pro<luced marginal spines, while the furrows of its pleurae
have not the obliquity of those seen in that type, but agree more
nearly with those of some species of (Jonocoryphe. The comparatively
large size of its pygidium, and the nodes, or spines, on its thoracic
segments, as well as the nature of the furrows of the jdeurae, are rather
against its reference to Faradoxiihs, and h ad me to thinli that it may
belong to an undescribed genus; if so, it might be called Olenoidet:."

Fnrmution and locality. — Middle Cambrian. Bluish-gray calcari'.ous
shale, House Kange, Antelope Spring, Western Utah.

Olenoides 'j ypicALis n. sp.

Plato XXV, ligs. 2, *2a.

Form ovate. ' Head large, semicircular in otitline. Glabella elongate,
not quite twice so long as wide; sides subparallcl ; front broadly rounded ;
general surface moderately convex and maike.l by four i)airs ol' glabellar
S'lnrows that extend about one-third the distance across, the anterior
being scarcely disceruable in most specimens; occipital furrow well
defined; occipital ring strong, not very cionvex, and with a rather
strong central spine ])rqjecting l)a(;kwards over the thorax.

Fixed cheeks broad inside the rim of the eye, contracted at the front
of the eye and expanding to unite with the frontal limb, wdiich is of
medium width, concave, and bordered by a narrow, rim-like n)iirgin;
postero-lateral limbs nariow, elongate, with a central longitudinal ridge
and a rather h)ug spine extending l)ackwar<l just within the extremity
of the limb. Free cheeks large, bordered exteriorly by a ratluir thick
rim that is produced into a strong genal spine. Eyes narrow, elongate,
reaching from opposite the thir<l i)air of glabellar furrows back neaily
to the posterior margin, conforming in direction to the eye of Para-
doxides ricgulosus.

Hypostoma elongate, strongly convex, broadest anteriorly, narrowing
towards the front; a sulcus, that rises on the lateral margin, separates
a narrow posterior lobe; two small lateral depressions, or muscular im-
I)ressions, occur a little in advance of the sulcus; anterior wings small;
frontal margin broadly rounded. The hypostoma is more like that of
I'tychopana than that of Paradoxides, Olenellus, or Dicellocephalus.

Thorax with nine segments; axial lobe convex, broad, and tapering
very gradually towards the pygidium ; a furrow crosses obliquely from
each posterior side of the segment aud almost unites before the base

(909)

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184

CAMHUIAX FAUNAS OF NORTH AMKIMCA.

|llfI,l,.Hfl.

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of a sljort spinci that ori,i(iiiat('s nt tlio cciitor of o-.wh sof>'inoiit mid cv
tends ui»ward and baiikward. Tlic spine on the eij-lith .sc^Mncnt is jno-
longed and extends back (piite a distance beyond tlie extremity of tlic

terminal spines of the i)yf,Mdinni. An individnal lo lonj; sliows tlic

s])ine with a lcn;?th of 10""". Tiie spine is ernsiicd down on the IkmIv .
but appears to have been slender and cnr\('<I nj) and- I)a<!k in a manner
similar to that on the! sixteenth segment of the thorax of Cyphnnji'is
BurmciHicri Barrande. (Syst. Sil. de IJoheme, vr»l. i, pi. xviii, flji'. (L'.)
The body of the pleural lobes is narrow, and each pleura is extended in
a long' si)ine; pleural grooxe short and nearly as broad as iu the genus
Olenellus.

Pygidium subquadrangular ; m»'dian lobe obconical, convex, divided
into three segments and a terminal portion ; lateral lobes formed ol
three segments directed backward, terndtniting in sharp points and
gradually decreasing in sij^e backward.

Surface finely granulose: radiating venulose lines ornament the pal-
pebral lobes and free cheeks, and longitudinal striio the genal spines
and spinous extension of the pleurtc.

The si)eeimen figured has all l)nt the free cheeks in position; these
were drawn from a smaller si)ecimen.

The general form of the i)ygidiuin is similar to that of one figured by
Mr. Billings (Pal. Foss., vol. i, p.3;54, fig. 3.'52/>), from Point Levis, Can
ada, where it was associated with Upi)er Cambrian fossils, and it may lu^
that Avhen entire specimens are found some of the species referred to
Dicellocephalus, from the same bed and locality, will prove to belong
to this genus.

Formation and lovaUiy. — Middle Cambrian. Tn a light pinkish-colored
shale above a belt of limestone resting on the shales carrying OleneUun
Oilberti, Pioche, Nevada.

Olenoides spinosus Walcott.

I ij

I Mi

Plate XXV, figs. 6,6 a.

Ogygiaf sj^inosa Walcott, 1885. Monograplis U. S. Gool. Survey, vol. viii, p. 63, pi.
ix, lig. 2'2.

The orighial specimen preserves only the central portions of the head
within the free cheeks. The glabella resembles that of Ogygia, so a
I)rovisional reforetice was nuide to that genus.

The discovery of 0. iyplcaUs gives the generic reference and a sec-
ond specimen of the sanui parts of the head from the arenaceous shales
at the same relative geologic horizon at Pioche aflords details not shown
in the Eureka specimen. The glabella is expanded more in front and
the posterolateral limb is presi'ived ; no tracje of the occipital spine is
shown, but this was probably carrie<l away with the test. Four pairs
of glabellar furrows occur, instead of three, as mentioned in the origi-
nal descriptio 1. ,

(910)

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WAIIOTT.]

MinnM", rAMHRTAX lAirXA.

185

Formation and loralitien. — Middle ('nmbiiiiii. At tlio biiRo oC tlio
Sccii't ('iinoii shiilo, it) Si'crrtOaiioii, I'^iirckii Dictrict, Nt'Viidii ; also, at
rioche, Xt'vadii, in arciiaceons sbulc iiiterbedUcd iu iirgilluceoiiH mIisiIijj
Niitional Musoiun collect ion.

OLENOIDKS? FLAaBIOAUDUS Wliitti.

I'liito XXV, li|n. 4.

DircllocephahiH ? Jlanr'uaiithin Wliilc, IH7I. (ivAx^. and ficol. F.\\)]. luut Surv. WcHt
lOOtli Mcrid., I'rcliiii. Uip, liivrit. t'oss., |i. 1'^. Jihiii, 1875. Siiiiio reiuirt,
vol. iv, pt. 1, |i. t'pi», |p1. iii, lii^. t*ii,l),

Oriffinal description. — " Pyj'idiiiincontractodjfsin-Hliiipod; lateral lobes
viu'}\ coiisistiiifjf of three segments directed bacikward; tlie inner one of
oacli sid(^ l.vinjj- (dose to the dorsal furrow, iieiirly parallel with the axis
of the body or converj^inji^ a little posteriorly, and be('oinin<>' obsolete
upon each side of a small, but comparatively wide, sloping' border that
extends around the posterior end of the axial lobe.

"The middle pair of segments commences at the dorsal furrow of each
side res])ectively, near the anterior end of the pygidinm, bend abrn])tly,
and extend backward parallel with the lirst, and prcjject beyond the
liorder as converging j»osterior spines. The third and outer i)air of
segments conimenc anteriorly at the dorsal furrows, where they are
very narrow, extcMid outward a little, then (Mirving abruptly backward
tliey lie parallel with the others and form raised lateral margins of
considerable but unecpuil width to the pygidiimi, and thenc(! they
extend posteriorly as an outer pair of converging spines. Axis promi-
nent, especially at its ai)e\, where it terminates in a moderately distinct
angle, about one-quarter wider anteriorly than ]>osteriorly, well defined
by the nearly straight dorsal furrows, and marked by five or six dis
tinctly defined segments, which cross it almost transversely, but with a
slightly sinuous course.

"Length of the pygidium along the median line, 7"""; greatest trans-
verse diameter, 9'""'.

"The collections contain only the ])ygidium of this species, and I
have therefore referred it doubtingly to I)iveUoceph((ius, although it
niight perhaps, with e(iiial projiriety, be referred to Aiitphion. It has a
general resemblance to the i)ygidium (»f J>. mdnniJioiN Billings, and a
still closer resemblance to J).? Corux Billings, from the Quebec group
of Canada.

'■'■ Position and locality. — Strata of the age of the Quebec group of
Canada. Schellbourne, Scliell Creek range, ]S^evada."

The species is referred to the Quebec group ; but without a better
knowledge of the stratigraphy than we have, and also of the associated
fossils, it is difficult to locate the exact horizon, and 1 suspect that
further investigation will place it in the Cambrian.

The generic reference is made entirely on the form of the pygidium.

(911)

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186

CAMBRIAN FAUNAS OF NORTH AMERICA.
Olenoides ? Maecgui Wbitfield.

[nui.uSO.

Plate xxvi, figfl. 5, 5a, 5.
r
Dikellooephalm t Marcoui Whitfield, 1884. Bull. Ainer. Mu8. Nat. Hist, vol. I, p. 150,
pi. xiv, fig. 7.

Original description. — "This species is only kuown, as yet, from frag-
iiieuts of the pygidiuiU; but the form is so remarkable for a primordial
trilobite and so distiuctive iu its characters that it will be readily rec-
ognized in other specimens when found; consequently there can be no
good reason why it should not be described even from the imperfect
material.

"The pygidium has been broadly fan-shaped, with a strong central
axis, and broad convex lateral lobes; form nearly semicircular, with a
moderately convex anterior margin. Axial lobe about two-thirds as
wide j\s each lateral lobe, strongly convex, marked by about nine or pos-
sibly ten annulations (seven appearing iu the fragment), the anterior
three each bearing an elevated node or subspine in the middle, the
fourth one having only a low node, the remainder plain. Lateral lobes
divided into five or more annulations, exclusive of the narrow anterior
one, by deep narrt)vv grooves or furrows, which terminate a little within
the border; each annulatiou being marked on its surface by a faint,
depressed longitudinal line. Outer margin of plate bearing broad flat-
tened spines, which are gently recurved. Five of these si)ine8 are seen
on the fragment described, the last of which originates opposite the
fourth segment, leaving space for two or perha[)s three additional ones
between it and the central line of the plate. This woul<l give seven or
possibly eight spines on each side of the plate. Surface of the plate
smooth to the unassisted eye.

"This is one of a group of primordial trilobite pygidiae having affinity
with the genus Dikellocephalus Owen, but not properly belonging
there. They have been variously placed under several genera, but are
equally unlike any of theui, and this one is more extreme in its charac-
ters than any hitherto described. It strongly reminds one of the pygidiiB
of a group of Dalmania which characterize the Lower Devonian of
America, in the aiTaiigement of spines around the outer margin, and is
so very similar that were there any question as to its authenticity I
should have been iu(!lined to pLace it at that horizon."

In all the collecting done at the Parker quarry the past two years
only a few pygidia of this species have been found, and but one imper-
fect head, and nothing is known of the thorax.

The head and pygidium do not belong to the genus Dicellocephuius,
and the pygidium, iu its spinose extension of the segments, approaches
the forms we have referred to Olenoides.

The reference to Dicellocephallus is misleading, as the genus is typ-
ical of the Upper Cambrian or Potsdam horizon and is as yet unknown

iu the Middle Cambrian.

(012)

WALCOTT.I

MIDDLE CAMBttlAK PAtJNA.

187

A similar type of the pyfrldium is fiffured by Angeliii (Pal. Scan., !)!•
xxxili, flff. 11) and donbtfuUy referred to the geiKna Corynexochu8. Tn
Brogger's Die Bilirischeii Etagen 2 und 3, pi. i, a number of pygidia with
u spinose border of this type are referred to the geaera Peltiira.

Formation and locality. — Middle Carabriau. Parker's quarry, town of
Georgia, Franklin County, Vermont ; also, in the conglomerate lime-
stones of Bic Harbor, on the St. Lawrence River, below Quebec, Canada.

OLENOIDES LEVIS D. Sp.
Plate XXV, iigs. 3, 3a.

Of this species we have only the head within the facial sutures. The
glabella is elongate, sides parallel, front broadly rounded, general sur-
lUce moderately convex and marked by glabellar furrows. Occipital
furrows well defined, occipital segment imperfectly preserve<l, but ap-
parently narrow. Free cheeks broad ; the rim of the large eye lobe is
coiilinued across the cheek to form the ocular ridge; frontal limb nar-
row concave and rising rapidly from the front of the glabella to the
narrow frontal rim; laterjilly it merges in the broad, free cheeks;
posterolateral limbs broken away except the inner portion on the left
side, which is narrow, as in 0. typicalis. Although imbedded in lime-
stone the surface is not well preserved; it was probably smooth or
finely granulose.

In the form of the glabella and broad, fixed cheeks this species dif-
I'ers from other known species of the genus.

BnfhyureUus abruptus Billings (Pal. Foss., vol. i, p. 26.'3, fig. 247) is
of this type of head, and is placed as the first species after the generic
description, but it is evidently not regarded as the type of the genus
Bathyurellus, as the generic description is taken from the species B.
nitidus, described after B. abruptm.

This species occurs in a granular limestone with OleneUus Oilbcrti.
At a higher horizon Olenoides spinoaun is found in an arenaceous shale,
and still higher in the se<;tion 0. typicaliny in an argillaceous shale.

Formation and locality. — Middle Cambrian. Pioche, Nevada.

OLENOIDES QUADIUOKPS H. & W.
Plate xxix, figs. 1, lo-o.

IMlellocephaluB quadriceps Hall & Whittield, 1877. Geol. Expl. Fortieth Par., vol. iv,

p. 240, pi. i, figs. 37-40.
DireVoeephalus f qhudriceps Walcott, 1884. Moiiogruphs U. S. Geol. Survey, vol. viii,

p. 4."), pi. ix. fig. W4.

Original description. — "Glabella und fixed cheeks united, quadrangu-
lar in form, with a regularly and symmetrically arcuate front margin.
Glabella elongate quadrangular, a little expanded and rounded in front,
three-fourths as wide across the middle as the length above the occipital

(913)

188

CAMBRIAN PAJNAS OF NOnXII AMERICA.

[nULt. 30.

I *

■■\

furrow, very {gibbous or somewhat inflated ; marked by three pairs of
traT'sverse furrows, wli^cli extend about three-fourths of the distance to
the center, not iu the least oblique, and so faint as to be detected only
on the closest examination or by the reflection of li^ht along the sur-
face; occipital furrow \ery distinct; r'^g strong and robust, support-
ing a strong, thicliencd spine of undeterinine<l lengtli on the posterior
iiargiu. The base of the spine is broad and the spine <lirected bacii-
ward and upward.

" Fixed cheeks of moderate si/e, strongly convex, a little more than
one-third as wide at the eye as the width of the glabella, and rapidly
declining to the antero-lateral angles. Eye lobe small, situated rather
behind the middle of the length of the head ; ocular ridges distinct,
strongly directed forward in their passage from the eye to the glabellti.
Frontal limb very short, not exteu<ling beyond the frontal margin of
the glabella, and strongly curving backward to the point of intersec
tion with the facial sutures.

" Facial sutures commencing at the anterior margin on a line with
the inner angle of the eyelobe, and running directly back to the eye in
a straight line ; behind the eye the direction is outward, but its exact
course has not been ascertained. Lateral limb not observed.

"A pygidiuin associated with the glabella is paraboloid ifi form, and
surrounded on the margins by twelve short, rather strong spines, the
four on the posterior margin being shorter than the others. Axis nar-
row, highlj' convex, two-thirds as long as the shield, and marked by
four rings, exclusive of the terminal ones. Lateral lobes broad, convex,
and marked by four low, rounded ribs, the anterior one much narrower
than the others ; each of the four ribs terminating in one of the lateral
spines.

" There can be no doubt th.at the above-described pygldium belongs
to the same species with the associated glabella, as they are both
equally abundant and are the only trilobitic remains brought from the
locality, except those of Conocephalites xubcoronatus. The glabella is
enlarged to three diameters in the ttgiire, while the pygidium is given
natural size, but is one of the largest individuals seen, while there are
fragments of glabellas in the rock fully twice the size of the specimen
figured. The species bears a very close resemblance to D. gothicvs
herein described, but differs principally in the simple ribs ; while in that,
species they are divided, a feature that will very readily distinguish the
two forms.

"■Formation andlocallty. — In limestone of the age of the Quebec group,
from the base of Ute Peak, Wasatch llange, Utah. Collected by Ar-
nold Hague, esq."

There is little doubt of the generic relations of O. quadricepit with
Olenoides, and it occurs at the same relative geologic horizon in the
Eureka district, and, from all I can learn of the locality on Ute Peak, its
position there is at the same relative horizon as 0. WafMatchensiSf which

(014)

WAt.COTT.l

MIDDLE CAMBRIAN I'AUNA.

189

wo kuuw to bo Middle Cambrian and bolow the rotisdani fauna. The
reference of the .species to the Quebec group Hhowt^ the uoiifuHion then
prevailing as to the paleontologic characters of a group naiiied, but not
existing, as detiued by its authors, in nature.

Tiie head and pygidium are of the same tyi)e as 0. Marcuui and O.
Wuhmtchensis.

Thedifferences between the head of thisspeciesand that of 0. Wahtidtch-
enn'm are not of specitic value, and, except thai the latter species shows in
the pygidium strong pleural grooves, I would unite them as one species.
Tills character is slightly shown in some of the pygidia of (Ktiiiadriccps,
and it is not imjirobable that the specimens in the sliales develop thes«i
grooves mucli more distinctly, owing to the criishing of tin' test aii<l con-
se<pient deepening of all the original depressions. A nood scries of
specimens may yet prove the two species to be identical.

Formation and localities. — Middle Cambrian. Ute Peak, Wasatch
Kange, Utah, and on the east slope of Prospect IVak, Eureka district,
Nevada, 4,000 feet below the typical Potsdam fauna, with OU-nvUm
Oillnrti, &c. A head apparently identical occurs 2,(»0() IVct higher in
the section. The other locality, on the west side of tlie Eureka dis-
trict, is an outlier of limestone, the stratigraphic relations of \vhich are
not known.

Olenoides Wahsatchensis H. & W.

Plato xxix, figs. 2, '2a.

Dikcllocephalus trahnatchenaiii Hall & Whitfield, 1877. (Jcol. Expl. Furtititli I'ar., vol.

iv, p. 241, 1)1. i, fig-. 35.
DikvUocephalus f gothicus Hall & Whitfield, 1877. Geol. Eipl. I'ortiilh Par., vol. iv,

p. 242, pi. i, fig. 30.

Original description of the head, — "Glabella elongatcniiiadrangular,
with parallel lateral margins and slightly rounded front ; height and
width about as four to three; very depressed convex, and nmrked by two
])airs of transverse furrows, which do not (juite meet in the center,
dividing the glabella into three nearly equal portions. Occipital fur-
row narrow, not strongly defined ; ring narrow, distinct, and bearing a
slender spine on the center; <loivsal furrows narrow and poorly dctincd.

"Fixed cheeks wide and flattened; ocular ridges faintly marked,
rising opjmsite the anterior furrow of the glabella, and directed slightly
backward to the eye-lobe. Frontal limb very short an<l wide, the mar-
ginal rim regularly arcuate, narrow, and prominent, closely cutting the
front of the glabella. Facial sutures not fully determined, but are «lis-
tinct on the anterior margin, cutting the rim with a strong outward
curvature, and again recurving to the eye, leaving the limb neaily two
thirds as wide at its widest point as the glabella."

The associated pygidium is described as another si)ecies ; but, from
the character of the head and pygidium of 0. quadriceps and 0. Marcoui,

(915)

m ■

it-

ii!

!Pf

190

CAMBRIAN FAUNAS OP NORTH AMERICA.

[BULT. W.

I have no hesitancy in referring it to the same species as the head asso
ciated with if. The reason given by the authors of the species, thiit
it was not a pygidium characteristic of the genus Dicellocephalus, to
which they referred the head, is not accepted, as tlie head is not typical
of Dicellocephalus. A still more cogent reason is the fact that we have
a crushed and distoi-ted specimen showing the head, thorax, and p.ygi
dium united. The thorax is so badly crushed that only five segments
can be counted, and the head and pygidium are partially crushed on
each other, owing to the doubling up of the thorax.

Original dencription ofthepyffidivm. — "Pygiditim semi-ovate, or short
paraboloid, with a very strong central axis and s))inose margin; ante-
rior margin straightened for about two-thirds tL»e width of the lateral
lobes, where it curves abruptly backward to the lateral angles. Axial
lobe strong, cylindrical, and prominent, forming one-third of the entire
width exclusive of the spines, and reaching almost to the posterioi'
margin of the shield ; obtusely rounded at the «>xtremity, and marked
by six annulations, exclusive of the terminal ones. Lateral lobes very
moderately convex, and marked by four divided ribs on each side, each
terminating in a strong and proportionally long marginal spine; cen-
tral area of each rib depressed, forming a flattened groove, extending
to the base of the marginal spine. Borders of the ribs elevated, the
anterior one strongest and prominent, gradually widening from its ori-
gin to the margin of the shield; posterior border narrow and rounded,
separated from the next succeeding rib by a sharply-dei>ressed, narrow
groove. This peculiar form of rib gives to the shield an appearance
similar to the groining of a Gothic arch. Margin of the shield sur-
rounde<l by twelve long, rather strong spines, four of which, on each
side, aic about equal in size and strength, while the four occupying the
posterior border are shorter and unequal, those in the middle being the
shortest.

"The peculiar feature of the specimen consists in the divided ribs of
the lateral lobes and 8i)inose margin. In these features it differs from
all others known, and may possibly, when better material shall be ex-
amined, showing other i>arts of the organism, require a distinct generic
name."

By comparing the figures of Olenoides Marconi, pi. xxvi, flgs. .'), ort,
with those of pi. xxix, figs. 2, 2a, the types of Dicellocephalus Walisatch-
enais and D. gothicus, the generic identity is evident, although the pleural
grooves on the anchylosed segments of the pygidium are not known to
be present in that of 0. Marconi.

The spe(Mfic relations of O. WahsatcheriHis are with O. qnadriccps, as
has been mentioned un<ler that species.

Fornmtion and localities, — Middle Cambrian. Box Elder ('. Hon,
above (!alls Port, Wasat(!h Mountains, and also in Big Cottonwood
Oafion, one mile below Argenta, in the same mountains.

<916)

WAIXOTT.J

MIDDLE CAMBRIAN FAUNA.

191

Genus BATHYNOTUS ITiill.

Bafhynotut Hall, 1H60. Thirteenth Ann. Kcp. N. Y. Statu Cab. Nat. Hist., p. 117.
Idem, 1B61. Geology of Vormont, vol. i, ji, 371.

To the description of the parts pfiven by the anthor, we are now ahh*
to add that of the eye-h)be an<l the direction of the facial sntiire. The
eye-lobe is narrow, elongate, ami extend.s from opposite the antero
lateral angle of the glabella obliquely backward nearly to the posterior
margin, resembling in this the eye lobe of Centropleura Loveni Ang..
the type of the genns Centropleura (Pal. Scan., p. 95, tab. iii, flgs. 1,
\a, 18.54), and also the eye-lobe of the genus Anopolcnns Salter (Quart.
Jour. Geol. Soc. vol, xx, p. 230, 1804; also, note bj' Dr. Henry Hicks
in vol. xxi, p. 477, 1865). Th<i facial suture passes nearly around the
extended eye-lobe and cuts the margin before rea<!hing the posterior'
extension of the eye-lobe. This is another character of the genns
Anopolenus. Anteriorly it appears to pass around the front of the
glabella and the narrow frontal limb, and, from the fact that the free
cheeks are united with the frontal margin, even when detache«l from the
central portions of the head, there is a strong presumption that the
sutures i)ass around in front within the margin without cutting the
latter, as in the later genera Phacops and Homalonotus. This is not
proven absolutely, but the evidence is very strong in its favor. Nuni
her of segments in the thorax, thirteen.

The genus is related to the Paradoxidaj in most of its characters, and
is well defined from other described ginera.

Dr. Emmons figures, of the typical species, the pygidinm, six thoracic

segments, and the two large genal spines under the name ParaAoooideH ?

qiiafirispinosus (Manual of Geology, 1800, p. 80). In a note on page 280

of the same book, he gives among fossils characterizing the Taconie

slates Paradoxides {Pagura) quadrinpinosm, mentioning at the sair.o time

Panidoxides TJiompsoni und P. V(n'niontava, whi<;h were described by Prof.

Hall in 1850- (Twelfth Rep. N. Y. State Cab. l^at. Hist.), at the san»e

time with Pelfura {Olenu8) holopyga. Why Dr. Emmons failed to note

this fact is unknown. It may be that he intended a new genus by placini";

tli(^ name Pagura as above, but, vithoiit a description or a referenc»s I <lo

not think we are waiTanted in assuming what was meant, and replacing

the generic name Bathynotus based on a description and a figure by the

name Pagura.

Bathynotus holopyga Hall.

Plate xxxi, fijjR. 1, Iff.
Peltiira {Olenua) holopyga Hall, 1859. Twelfth Ann. Rep. N. Y. State Cab. Nat. Hist.,

p. 61 ; Pal. N. Y., vol. iii, p. M8.
Bathynotus holopyga Hall, 18G0. ThirtCLMith Ann. Rep. N. Y. State Cab. Nat. Hist., p

J !; Geology of Vormont, vol. i, p. 371, pi. xiii, Ijy. A, 1861.
Paradoxideg f qiiadriapinogut Emmons, 1860. Manual of Geology, p. 80, fig. 57. On p

280 the name P. (Pagura) quadnKpinosiis occirs.

DettvriptioH. — "Entire form elouj^ate sub('llii)ti<:al, having a length of
about twice and a half the width. Head somewhat semielliptical j the

(917)

fif

192

CAMBBIAN FAUNAS OF NORTH AMERICA.

ruULL. 30.

!"'

i ,1

1 '

■' e

: I

¥:

posterior angles produced in long spines. Glabella strongly lobed, it8
length a little greater than its greatest breadtb, the entire breadth of
the bead when entire, being about twice as great as the length. Ilypos-
toina wider than long.

"Thorax with eleven articulations; the middle lobe prominent and
about twice as wide as the lateral lobes; the articulations strong',
rounded above, and each one nmrked in the center by a node (or the
base of a spine which has been broken off in the Hpecimeus examined).
Articulations of the lateral lobes short (the extremities of the upitcr
ones brokeu ott' in the specimen) ; the lower ones bending abruptly
downwards and ternuuating in spiniform processes, the last pair being
prolonged much beyond the extremity of the i)ygidium.

"r*.Vgidium longitudinally semielliptical; the middle lobe marked by
three annulations, and a fourth obscure one above the terminal lobe;
lateral lobes flat and plain, the exterior margin apparently free from
ornament or inequality."

In his observations on this species in the Thirteenth Report, 1860,
the author adds:

" The rings of tho axis are marked by a row of small spines. The
greatest length of the spines or processes, from the jjosterior angles of
the cephalic shield, is a remarkable feature. In this individual their
extremities must have reached as far as the eighth or ninth segment of
the thorax; and in another individual these separated parts have sim-
ilar proporMous.

" In one imperfect siiecimen of this species, with narrow axis, we
have eleven body rings, including the elongated posterior one; but
behind this there are three annulations of the axis, the two anterior oi'
which have somewhat the appearance of free segments, and are like-
wise niarked upon the lateral lobes, while the i)ygidium below has ap-
parently a single aniinlation extending into the lateral lobe." *

Having obtained several nearly entire specimens of this species we
are enabled to corroborate the description given by Prof. Hall and to
add details of interest.

The position of the elongate eye-lobe and the direction of the facrial
suture have been referred to in our note on the genus. The great length
of the postero lateral spines of the head is even greater than men
tioned by Prof. Hall, as they fully ecjual and pass beyond the entire
length of the thonix and pygidium. The free cheeks are narrow,
united (?) in trout of the glabella, shorter than the length of the fixed
cheek (a character of the genus Anopoleisus Salter), and longitudinally
striate on the margin, a character that extends around the front ami
back nearly to the termination of the spines.

The hypostomais of a peculiar t»vpe. The anterior margin extends

forward from each anterolateral single, meeting at an obtuse angle at

the front margin of the doublure, the latter being cut away to permit

this extension of the hypostoma to cross it. Back of the line of the

• (918)

wAixxyrr.]

MIDDLE CAMBRIAN FAUNA.

doublure the bypostoma is transversely quadraugular iu oatliue and
marked very much as in Centropleura Loveni Angelin. The unly genuH
known to me that has the anterior margin of the bypostoma rising to
an obtuse angle is Cryptouymus, as shown iu C. punctatus Wahl. (Pal.
Scan., Angelin, tab. iv, flg. 6, 1852; also, Quart. Jouru. Geol. Soc., vol. vi,
pi. xxzii, flg. la, 1850). In other respects there is little similarity.

Prof. Hall, in speaking of the median axis, says that "there are eleven
body rings, including the elongate posterior one; but behind this there
are three annnlations of the axis, the two anterior of which have some-
what the appearauce of free segments, an0 are likewise marked upon
the lateral lobes, while the pygidium below has apparently a single an-
nutation extending into the Iu eral lobe. In three examples preserving
the thorax and pygidium united, we find the two segments between the
pygidium aud large- ex tended segment free. Tliey ai'e short, and with
but a slight pleural lobe, the extension of the eleventh segment crowd
ing them into the narrow space between it and the pygidium.

Formation and locality. — Middle Oambrian, Georgia Formation. Par-
ker's farm, town of Georgia, Vermont.

Genus PTYCHOPARIA Corda.

Ptychoparia Corda, 1847. Prodrom. Mod. bobm. Trilobiten, p. 141. Abb. der k. buhm.
Oessell. der Wiasenscbaften.
= Conocephalus Zenker, 1833, not Conocephalua Tbnnberg, 1812.
= Conoc^halitea Barrande, 1852. '

I have given, in Bull. U. S. Geol. Survey, No. 10, p. 34, the history of

the names Ptychoparia and Gonocephalites and my reasons for using

Ptychoparia.

Ptychoparia KiNGi Meek (sp.)

Plate xxtii, fig. 4, 4a.

CoHOcoryphe (Conocephalitea) Kingii Meek, 1870. Proc. Acad. Nat. Sci. Phila., vol.

xxii, p. 63.
Conocoryphe {Ptychoparia) Kingii Meek, 1873. Sixtb Ann. Rep. U. S. Oeol. Surv. Terr.,

p. 487. (Generic reference changed.)
Comcoryphe {Ptychoparia) Kingii White, 1875. Oeog. and Geol. Expl. aud Siirv. West

100th Merid., vol. iv, pt. 1, p. 40, pi. ii, figs. '2a-o.
Conocoryphe {Ptychoparia) Kingii Meek, 1877. Geol. Expl, Fortieth Par., vol. iv, pt. 1,

p. 20, pi. i, fig. 4.

Original description. — " Entire form ovate and much depressed, with
breadth equaling about two-thirds the whole length. Cephalic shield
»eniicircular, or a little wider than long, with the anterior and antero-
lateral borders regularly rounded in outline and provided with a nar-
row, slightly defined marginal rim ; i>oBterior margin nearly straight,
with the lateral angles terminating in abruptly pointed extremities, so
short as scarcely to project as far backward as the posterior margin of
the second thoracic segment. Glabella depressed nearly even with the
BnU. 30 13 (919)

194

CAMBRIAN FAWN-AS OP NORTH AMERICA.

(iiiiM.. no.

1 1
If

,'1 ■

I • i

fli

cheeks, about two-tliirdH as long sih i\w entire heuU, and Itetween one
third and one-fourth the breadth of the stune behind, but narrowint;
forward to its subtrunoated anterior end, and separated front the cheekH
on each side and in front by a shallow furrow ; occipital furrow moder-
ately well defined, and continued as rather deep broad furrows along
the posterior margin of the cheeks out nearly to the points where the
facial sutures cut the margin; lateral furrows not clearly defined in the
si>ecimens, but apparently consisting of four pairs. Facial sutures di-
rected at first, for a short distance, forward from the inner anterior end
of each eye, then curving gracefully outward as they extend forward,
until near the anterior margin of the head, where they are a little wider
apart than the distance between the eyes, but again curving rather ab-
ruptly inward, so as to reach the anterior margin nearly on a line with
each eye; posteriorly these sutures extend at first outward, nearly at
right angles to the longitudinal axis, from the posterior end of eacli
eye, and then curve gracefully backward so as to intersect the pos-
terior margin between one-fourth and one-third the distance from the
lateral angles, inward toward the glabella. Eyes rather depressed,
slightly arched outward, and separated from each other by a space
somewhat less than half the entire breadth of the head, and placed less
than their own length in advance of the posterior margin, and about
once and a half their length behind the front margin of the head ; visual
surfaces narrow, and not showing any lenses under a good magnifier.

" Thorax with its length bearing the proportions to that of the head,
of 79 to 52, and to its own breadth, of 79 to 107, being very slightly
wider near the middle than in front, and narrowing posteriorly, with
gently convex lateral margins, from behind the middle to the pygidiuui.
Axial lobe depressed, narrow, or only about two-thirds the breadth of
each lateral lobe at its anterior end, and narrowing regularly with
straight sides posteriorly ; segments thirteen, nearly or quite straight,
and each with a small node or prominence at each end. (In some speci-
mens thest) nodes seem to be wanting, while in others they do not exist
on all of the segments.) Lateral lobes depressed or nearly flat ; pleuree
almost transverse or arching slightly backward to near the extremities,
which are abruptly pointed; each with a well-defined furrow, which
commences small near the anterior inner end and widens and deepens
for about half way out, and then narrows and becomes more shallow,
so as to die out before reaching the lateral extremities.

"Pygidium subsemicircular, being rounded posteriorly, with a nar-
row, slightly flattened border, and somewhat rounded anterior lateral
extremities; length bearing to that of the thorax the proportions of 30 to
79, and to that of the head of 30 to 52, with a breadth of not quite two-
thirds of that of the head ; axial lobe equaling more than two thirds the
length, narrow, depressed, and showing more oriess distinctly about five
segments ; lateral lobes much depressed, nearly twice as wide at the
anterior end as the middle one, each with about three segments, which

(920)

WAIiCOTT.)

MIDDLE CAMBRIAN FAUNA.

195

curve a little backward and become obnolote before |>n88ing upon the
narrow, smooth border ; segments each provided with'u comparatively
large longitndinal ftarrow, corresponding to those on the pleunv.

<'Entii« surface apparently smooth, excepting fine radiating strite on
tbe anterior and lateral portions of the cephalic shield that are scarcely
visible without the aid of a magnifier.

"Whole length, 1.60 inch ; breadth of thorax, 1.07 inch; breadth of
cephalic shield (somewhat flattened by pressure), about 1.12 inch;
length of thorax, .70 inch ; length of pygidium, .30 in(;h ; breadth of
pygidium .60 inch.''

The very short genal spines of the head and also the peculiar curva-
ture of the posterior margin between the facial suture and the spine, as
shown in Mr. Meek's type specimen, are owing to the breaking away of
t(ie outer marginal rim and outer side of the spines with it, and the
]>08terior marginal rim is crushed and bent out of shape and also partly
broken away. Twenty entire specimens show the spines and marginal
rim as In the figure given by Dr. White and as in the figures on plate
xxvii.

Formation and locality. — Middle Cambrian. House Range, Antelope
Springs, Utah.

Ptyohopaeia Adamsi Billings sp.

Plate xxvi, figs. 1, lo-c.

Conoetphalite$ Adamai BilliDgs, 1861. Geology of Vemiont, vol. ii, p. 950, ds- 355;

Pamphlet (1861) republished (186.'>) in Pul. Fohh., vol. i, p. 12, fig. 15. Idem,

1863. Oeol. Canada, p. 28(i, fig. 294.
Conocephalitet armoaug Billings, 1861. Geology of Yerroont, vol. ii, p. 952, fig. 3.58.

Idem, 1865. Pal. Foss., vol. i, p. 15, fig. 18 ; Geol. Canada, p. 286, fig. 297.

Original description. — "Head broad, semicircular, moderately convex;
glabella oblong-conical, nearly two-thirds the length of the head, the
front obtusely rounded or somewhat straight, the anterior angles nar-
rowly rounded, the sides nearly straight from the anterior angle to the
neck furrow, just in advance of which is the widest part. The neck
farrow well defined all across; the glabellar furrows indistinct; the
dorsal furrow is well defined all round the glabella. The cheeks are
moderately tumid; a line drawn across the glabella about the mid
length would pass through the eyes. The distance of the eye from the
dorsal furrow is equal to the greatest width of the glabella; the eye ap-
pears to be very small. The margin in front of the glabella is equal in
width to about one-third the whole length of the head ; it is bordered
by an obtuse, narrow, elevated rim, just within which is a groove which
is more deeply impressed on each side than directly in front of the gla-
bella, there being at this place a gently convex elevation, resembling
that which occurs in Barrande's species, G, Sulzeri and C. Coronatus.
The ocular ridge is well defined where the surface is preserved, but is

(921)

196

CAMBRIAN FAUNAS OF NORTH AMERK^A.

(huli.:h).

I ':

1^
i

rarely visible iu the Huudstoue cuhIh. MonI of tliu HpceiinciiN arc (lin
tinctly carinate »loiig the iiiedian line of the glabella.

" It is possible that there may l>e a niediau tubercle ou the neck seg
loeut, but none of our speuiuieus have this part suiUcieutly well pre
served to show it.

*' The following are the diineiisioDS of a specimen of the average size:
Length of head, five lines; length of glabella, three and one fourth
lines; greatest width of glabella, two lines; width of glabella at front,
one and one- fourth lines; distance of eye from side of glabella, two lines.

^« Dedicated to the late Prof. C. B.Adams, State geologist of Vermont.

" Formation and locality. — Highgate, Vermont, in the Potsdam group,
about a mile east of the Highgate Springs."

On assembling a large number of specimens of the head of this si)ecieM
from limestone, arenaceous and argillaceous shale, and arenaceous lime-
stone, we find that it is even more variable than as described by Mr. Bil-
lings and that it includes the form given by Mr. Billings as C. arenonus.

On plate xxvi figures of the head are given to show variations.

The frontal limb, between the glabella and margin, varies in breadth
and, in the smaller heads, is very narrow; the frontal rim also varies
very much in thickness and breadth. li\ sfiecimens from a purplish-
colored limestone, the maceration of the test, prior to mineralization, ap-
pears to have gone so far that nearly all the outlines of the glabella,
frontal limb, and rim were lost by the compression accompanying the
consolidation of the sediment.

In the collections of the Museum of Comparative Zoology, Cambridge,
Massachusetts, there is a matrix of a nearly entire individual of this spe-
cies IS")"* in length, from Parker's quarry, and the U. S. Geological Sur-
vey collection includes the greater part of a specimen 40^"' long. From
these we obtain a description of the thorax, pygidium, and iiree cheeks of
the head in addition to Mr. Billings's description.

The free cheeks are narrow and terminate posteriorly in sharp spines
that reach back even with the fifth segment of the thorax.

Thorax with sixteen segments, narrowing gradually' to the tenth se;;:
nient and then more abruptly to the pygidium ; axial lobe about three-
fifths the width of one of the pleural lobes; segments narrow, rounded
on the axial lobe, and flattened ou the pleural lobes; the pleural lobe is
flattened about one-half the distance from the axial lobe to its outer
margin and then bent dow^nward, and each segment directed slightly
backward; pleural groove broad, well defined, and extending nearly
to the end of the segment.

Pygidium small ; axial lobe short, obconical, and marked by two or
more rings; lateral lobes showing the pleural grooves corresponding to
the axial rings.

Surface finely granulose under a strong magnifier (Tolles's f-incb
triplet).

(922)

WALcaix)

MIDDLE CAMBRIAN FAUNA.

197

> spines

f-incb

Formation and localitieg.—MidiWe Oambrian, Georgia Formation.
Friinlclin County. Vermont. East of Higbgate Springs the species
rouges through the purpliHli and reddish magnesian limestone and up
into the argillaceous shales, a total distance of over 1,600 feet. It
occurs at the same relative horizon on the Bullard farm east of Swanton,
and also at Parker's quarry in the town of Georgia; also, in the conglom-
erate lime-stones of Bio Uarbor, below Quebec, on the St. Lawrence
River, Canada.

Ptyohopabia Tguobr Billings.

Plate xxvi, fig. 3.

ConovephalUe$ Teuoer BillingM, 1H61. Geology of Vermont, vol. ii, p. 9S1, fig. 366;
Pamphlet (1861) ropiibliHbed in Pal. Foaa., vol. i, p. 13, fig. 16, .< <; Qeol.
Canada, p. i286, fig. '295.

Original description. — " Head semi-oval ; glabella conical, con /ex, well
(letlued all round by the dorsal furrows, about two-thir^^ the v. hole
length of the head, widest just in advance of the neck turrow. sides
gently convex, froit tly rounded, neck furrow well defined all a oss ;
))OHterior furrows commencing at about one-half the length ot tlie gla-
bella, and running inwards and backwards nearly to the neck furrow
and one-third across ; median furrows curved backwards, and extend-
ing one fourth across; anterior furrows short; ocular ridges well de-
tilled; front margin one-third the whole length of head, with a well-
(lefiued groove running across, in front of which there is an elevated
marginal rim, which rises with a flat slope upwards and forwards; the
groove across the margin is situated at about one-fourth the distance
from the front of the glabella to the elevated edge of the rostrum ; the
cheeks are moderately tumid ; the neck segment is well developed, with
a small median tubercle scarcely the fourth of a line in height, which
in some specimens seems to be absent altogether.

"Thorax of 13 or 14 segments; axis strongly defined, cylindrical;
side lobes about one third wider than the axis.

'' The pygidium is very small, being scarcely one-sixth the length of
the thorax. The only specimen in which it has been observed attached
to the thorax is not sufficiently well preserved to enable me to descnbe
it in detail.

"The following are the measurements of two of the specimens: Length
of head, 4^ lines; length of glabella, 3 lines; width, just in advance of
the neck furrow, 2^ lines, and at one-third the leu;:th from front margin
2 lines.

" In a specimen consisting of the thorax and pygidium whe whole
length is 6 lines, of which the pygidium occupies apparently a little
less than 1 line. Width at first segment, 5^ lines; width of axis at same
place, 1^ lines; width at anterior margin of pygidium, about 3 lines.

"The position of the eye is not shown in any specimen that I have
8eei>, but, from the width of the portions of the fixed cheeks which

(923)

■•'■"■SI

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t H

n .i

Ml:
i

■r t

198

CAMBRIAN FAUNAS OF NORTH / ilERICA.

lBUIX.30.

remaio, it must be distaut from the dorsal farrows nearly the width of
the glabella.

*' This species appears to be closely allied to the one above cited from
Shumard's paper, so far as the characters of the glabella are concerned.
As, however, the proportions are a little different, I shall dispose of it
as above until I can have an opportunity of submitting a specimen to
Dr. Shumard.

" Locality and formation. — One and one-half miles east of Swantoo.
in Vermont, in the elates of the Potsdam group."

Mr. Billings describes an entire specimen, but does not figure it, and
we have been unable to obtain any more than the head exclusive of
the free cheeks.

The most marked difference between the head and that of P. Adaimi
is in the form of the frontal limb.

A comparison with specintens of P. Billingsi, from Texas, shows it to
be a distinct species.

Forma f '>on and locality. — Middle Cambrian, Georgia Formation. About
1^ miles east-northeast of Highgate Springs, Vermont; also, in the con-
glomerate limestones at Bic Harbor below Quebec, on the St. Lawrence
River, Canada.

Ptychoparia Vuloanus Billings.

Plato xxvi, figs. 4, 4a.

CoHOoephalitet I'ulcatius Billings, 1861. Geology of Vermont, vol. ii, p. 952, fig. 357;
Puiuphlet IStil, republished (1865) in Pal. Foas., vol. i, p. 14, fig. 17; Oeol.
Canudu, 18K.3, p. 286, fig. 296.

Original description. — "Head broad, moderately convex; glabella
obtusely conical, with the neck segment triangular and extended back-
wards in the middle ; neck furrow not extending across, being inter-
rupted by a stroug carina which runs along the median line ; dorsal
furrow aU round, but not sharply defined. Front margin about one-
third i\\e length of whole head, with a projecting rim, and a traqsvorse
groove situated two-thirds the distance from the front of glabella.
Gheeks moderately convex; ocular ridge well defined; a line drawn
across the head a little in advance of the mid-length of the glabella
would pass through the eyes ; the latter distant from the glabella at
least half the whole lefigth of the head. No indications of glabellar
furrows visible.

" Length of head, four and one-third lines ; of glabella, including the
backward projecting angle of the neck segment, three lines ; width of
glabella just in advance of neck furrow, two and one-third lines; dis-
tance of eye from glabella, two and one- fourth lines.

" This species differs from G. Adamsi in the character of neck fur-
rows and in the greater proportional width of the glabella.

** It was found along with C. Adamsi in the same beds.''

(924)

WALCOTT.]

MIDDLE CAMBRIAN FAUNA,

199

This species varies in tlie 8ba])o of the ghibella, occipital segment, and
frontal limb so much that I am inclined to consider it a little m(»re than
a variety of P. Adamai or P. Teuoer, as it is intermediate to them iu
many of its characters. An illustration is given of an extreme form
and also of one that approaches more nearly to that of P. Adamsi.

It is associated with P. Admnni at ail the localities where it has been
found.

Formation and localities. — Middle Cambrian, Georgia Formation.
Franklin County, Vermont, Parker's quarry, and also one mile east of
Highgate Springs.

Ptychopahia miser Billings. ' '

Plate xxvii, fijj. 2.

Conocephalites mUer Billing^, 1861. Geology of Veriuoat, vol. ii, p. 950, fig. 354 ; »1ho
in pamphlet. Idtm, 1863. Geology of Cauada, p. 286, fig. 293. Idem, 186.').
• Pal.Fo88.,vol. i,p. 12,ttg. 14.

Original description. — " Glabella elongate, conical, very convex, most
elevated at about the mid-length, slightly narrowed at the neck segment,
widest in the middle, narrowly rounded in front, well defined all round
by the dorsal furrows. Neck segment strongly convex and bearing a
short broad-based spine directed upwards and backwards. Neck fur-
row extending all across; the posterior glabellar furrow well defined
across, forming an obtuse angle backward iu the median line ; median
glabellar furrow also running across, but not so strongly defined as the
posterior; anterior furrows extending one-third across.

"Length of glabella, two lines; width in the middle, about one-half
the length.

" There is no described species to which this one bears any close re-
lation, on account of the peculiar character of the posterior and median
furrows running quite across the glabella."

In looking over the collection of the Canadian Geological Survey with
Prof. J. F. Whiteaves, we found a more perfect example of the head
than that figured by Mr. Billings, and I was kindly permitted to havo
a tigure made of it. The frontal limb, fixed cheeks, palpebral lobes, and
posterolateral limbs are shown in addition to the i)arts described by Mr.
Billings.

Formation and locality. — Middle Cambrian. In limestone, associated
with fosails characteristic of the Georgia Formation of Vermont, I/Anse
au Loup, on the north side of the Straits of Belle Isle.

Ptychoparia quadrans H. & W.

Plate xxix, tigs. 4, 4a, b.

CrepicephaUs f {LogaHeUiia) quadrans Hall & Whitfield, 1877. Geol. Expl. Fortieth

Pur., vol. iv, J). 238, pi. ii, figs. 11-13.
Compare P. Adamai aiiJ P. Kiiigi.

Original description. — *' Form of entire body unknown. Glabella and
fixed cheeks together broadly quadrangular, about four-fifths as high

(925)

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'M,

*.■.,

11 »■-:

^'^

200

CAMBRIAN FAUNAS OF NORTH AMERICA.

[BULL. 30.

W M.

as wide and quite uniform in many individuals, very depressed-cou-
vex or quite flattened, as occurring on the surface of the shale in which
they are imbedded; glabella distinctly conical, moderately tapering
above the occipital furrow, and broadly rounded in front; marked
by three pairs of distinct transverse furrows, which are directed ob-
liquely backward from their outer ends ; the posterior pair almost or
quit« meeting in the middle, the others shorter and situated at almost
equal distances from each other. Occipital furrow well marked, propor-
tionally wide and shallow ; occipital ring narrow, not well defined.

" Fixed cheeks very broad, nearly two-thirds as wide as the glabella,
depressed-convex; frontal limb short, the broader and inner part of
nearly the same width ; sides of the limb in front, wide, and slightly
rounded at the anterolateral angles ; posterior limb wide at its junc-
tion with the glabella, and rapidly narrowing outward, being a1)ont
once and a half as long as its greatest width ; ocular ridges slender, aut
very distinct, rising from the anterior angle of the eye and uniting
with the glabella near the anterior furrow, forming a slightly curved
line parallel with the marginal furrow of the head.

"Facial sutures directed inward from the anterior margin of the head,
to the eye- lobe, behind which they are directed outward and backward
to the posterior margin of the head, at an angle of about forty degrees
to the occipital line.

"A form of movable cheek found associated in considerable numbers
with the glabellas, and corresponding in size and character, is narrowly
triangular, the posterior extremity terminating in a short, blunt spine,
slightly curved; inner angle strongly notched for the reception of tbe
eye-lobe, and the outer margin bordered by a thickened, rounded rint,
which gradually increases in width to the base of the spine. The facial
suture corresponds to the margin of the fixed cheek above described,
and, on the under side, the anterior border is prolonged in the form of
an acute process, to extend along the anterior border of the frontal limb.

"The pygidium associated with the above specimens is minute, trans
versely subelliptical in form, most strongly rounded on the front border,
with a wide axis terminating obtusely a little within the posterior mar-
gin. The axis is marked by five rings, exclusive of the terminal ones.
Lateral lobes convex, marked by three or four divided ribs, (exclusive
of the anterior single one.

" Surface of the head and cheeks marked by fine anastomosing lines,
radiating from the eye and front of the glabella."

This species, as far as we know its structure, is closely allied to Pty-
choparia Kingi, and, with the latter species, to P. Adamsi. They are
the representatives of the same specific type in the distinct localities at
which they occur.

P. quadrata is associated with Olenoid^s Wahsatchensis in a dark,
shaly argillite.

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MIDDLE CAMBRIAN FAUXA.

201

The figure of the head on pi. ii, fig. 11, Geol. Expl. Fortieth Par., vol.
iv, is that of an unusually elongated specimen, and not the form that is
most abundant. We give one that is the average form of a number of
heads found at the type locality.

Formation and localities. — Middle Cambrian. Above Gall's Fort, north
of Box Elder Caiiou, and one mile below Argenta, in Big Cottonwood
Cafion, Wasatch Mountains, Utah.

Ptychopaeia Housensis, n. apt

Plate XXV, fig. 5.

Head small, transversely quadrilateral exclusive of the free cheeks ;
moderately convex. Glabella rather small, of almost uniform width
from the posterior margin to the rounded front ; furrows shown only by
a posterior pair; occipital ring strong and bearing a short small spine
that extends obliquely' upward and backward ; occipital furrow of mod-
erate depth and continued out as a strong groove on the lateral limbs;
dorsal furrows broad and well defined. Fixed cheeks wider than the
glabella;, palpebral lobes small; ocular ridges strongly defined; frontal
limb concave, of medium width, and rising to a strong frontal rim;
postero lateral limbs short. Surface finely granulose. j.

Free cheeks, thorax, and pygidium unknown.

This peculiar little liead is associated with Ptychoparia Kingi and
Asaphiscus Wheeleri, and, while we have over one hundred perfect spec-
imens of these two species from the same bed, but one fragment of
P. Housemis has been found. This is so strongly characterized by its
form and occipital spine that I do not hesitate to give it a specific
uame.

Specific name derived from the House Range.

Formation and locality. — Middle Cambrian. House Eaiige, Antelope
Springs, Utah.

Ptychoparia Piochensis, n. sp.

Plate xxvi, figs. 2, 3a, b ; pi. xxviii, figs. 1, la-«. x -I

General form ovate, moderately convex, usually much depressed by
being flattened in the shaly matrix.

Head transverse, semicircular ; frontal margin comparatively narrow
iu young individuals, becoming broader and more flattened with the
increase in size of the animal; posterolateral angles prolonged into
slender spines. Glabella of medium size, truncato conical, and marked
with three pairs of short glabellar furrows that increjtse in size and also
in obliquity to the central axis on the larger heads , occipital groove
shallow and rounded downward from the base of the glabella and up-
ward to the moderately strong occipital ring ; a small point or node
occurs at the center of the latter. Fixed cheeks of medium width ; they
merge in front into the broad frontal limb and posteriorly into the

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202

CAMBBIAN FAUNAS OF NORTH AMERICA.

[BULUaO.

elongate, narrow, postero-lateral limbs ; palpebral lobes small ; ocular
ridges well defined and terminating nearly at the front of the glabella;
frontal limb comparatively' narrow in the young and broader in the older
and larger specimens.

Thorax with 19 segments in two specimens 30""" and 40"*"' long, re-
spectively ; another specimen, 18""" long, shows 17 segments ; the seg-
ments are nearly transverse, except at the geniculation on the pleural
lobes, where the falcate extremities bend slightly backward ; axial lobe
moderately convex ; pleural lobes flattened half-way out and then curved
downward to their margin ', pleural groove of medium width and cou-
tinued well out towards the extremity of the segment.

Pygidinm small, semicircular ; axial lobe with 3 or 4 segments ; lat-
eral lobes small and marked by furrows indicating about 3 united seg-
ments.

Surface apparently smooth except on the frontal limb and free cheeks,
where fine, irregular striae radiate towards the margin.

The large number of segments in the thorax, 19, is a marked peculiarity
of this species, t^e usual number of segments in the gonus being from
13 to 15. The expansion of the frontal limb with the increase in size
is also very suggestive, as, in the adult, we have the broad, compauu
late limb, and, in the young, the narrow limb with an elevated outer
margin ; a variation that would be given as specific if the intermediate
forms were absent. The small pygidium resembles that of Ptychoparia
Emmrichi (see Syst. Sil. Boh6me, vol. i, pi. xi, fig. 4), except that it is
proportionally smaller.

Formation and locality. — Middle Cambrian. In an argillaceous shale,
at the (JLisholm Mine, on the southwest slope of the Ely Mountains ;
also, on the western slope of the Highland Eauge, 8 miles north of Ben-
net's Spring, Nevada. . .

Ptychoparia sp. !

Associated with OlentUiis G'dherti in a gray, granular limestone, at
Piocbe, there is a species of Ptychoparia that is closely allied in the
head parts to P. Adamsi. The material is too imperfect to determine
satisfactorily, at present, its specific relations.

Ptychoparia ! Prospectensis Walcott. -

Plate xxvii, Ag. 5.

Ptychoparia f Proapectenais Walcott, 1884. Monographs U. S. Geol. Survey, vol. viii,
p. 46, pi. ix, flg. 20.

The general outline of the head is moderately convex, semicircular,
the width being about twice the length.

The glabella is subconical, truncate in front, and marked by three
pairs of short, slightly impressed, glabellar furrows; occipital ring dis-
tinctly defined by a narrow, lightly inii)ressed, occipital furrow; fixed
cheeks broad, of equal elevation with the glabella, and extending be-

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WALCOTT.I

MIDDLE CAMBRIAN FAUNA.

203

row: fixed

youd it anteriorly, the space between them on the oroad A'ontal limb
being occupied by a small swelling or boss that, but for the slight trans-
verse dorsiil furrow between it and the glabella, might be mistaken for
u continuation of the latter ; the eye lobes are comparatively large for a
species of this character and occupy a prominent position on the outer
margin of the cheeks, a distinct ocular ridgo crossing the latter from the
anterior margin of the eyes to the dorsal furrow on a line with the front
of the glabella; the lateral limbs are narrow, rather short, and slo))e rap-
idly downward back of the eye-lobes ; frontal limb broad at the center,
narrowing in front of the fixed cheeks, and bordered anteniorly by a not
very distinctly defined rounded margin. The facial suture curves a
little inward in front of the eye and appears to terminate on the front
line somewhat in advance of a line passing through the center of the
tubercle in front of the glabella ; behind the eye it extends obliquely
outward and backward to the posterior margin of the head, outlining
an elongate triangular postero lateral limb.

Under a strong magnifying power the surfifce is seen to be finely
granulose (see p. 32).

Free cheeks, thorax, and pygidium unknown.

Its associated species are mentioned in the introductory remarks of
this bulletin.

Formation and locality.— ^Middle Cambrian. Mountain shale band of
the Prospect Mountain section, on the east slope of Prospect Peak,
Eureka District, Nevada.

Ptychopabia trilineata Emmons (sp.).

Plate xxvii, fig. 1, la-c.

Atopa trilineatua Emmons, 1844. Taconic system, p. '20, fig. 1, pi. ii, fig. 3. Idem, 1847.

Agrl. Rep. N. Y., vol. i, p. 64, fig. 8; pi. xiv, fig. 3. Idem, 1849. Proc. Amer.

Assoc. Adv. Sci., vol. i, pp. 16, 17. Idet 1855. Amer. Geol., vol. i, pt. 2, p.

115, pi. i, fig. 16.
Atopa trilineatua Haldemau, 1848. Amer. Jour. 8ci., 2d ser., vol. v, p. 107.
Atopa triliiuatua Barrande, 1861. Bull. Soc. G6ol. de Franco, 2" s^r., t. xviii, p. 26J»,

pi. v, fig. 1.
Cahimene Beck 11, 1847. Pal. N. Y., vol. i, p. 252, ;>1. Ixvii, tigs. Aa-i: Idem, 1848.

Amer. Joar. Sci., 2d ser,, vol. v, p* 322.
Calymene Beckil Fitch, 1849. Trans. Agrl. Soc. N, Y., vol. ix, p. 865.
Cahimene Berkii Walcott, 1879. Pamphlet in advance of vol. x, Trans. Albany Inst.,

p. 23.
Atopa puiictataa Emmons, 18.59. Manual of Geology, p. 88, fig. 71.
Atopa punciatua Barrande, 1861. Bull. Soc. G6ol. do France, 2" 8<<r., t. xviii, p. 271,

pi. V, fig. 3.
CoHOcephahiM {Atopa) trilineatua Ford, 1871. Amer. Jour. Sci., 3d si>r., vol. ii, p. 33.
Conocephalitea trilineatua Ford, 1873. Amer. Jour. Sci., 3d ser., vol. vi, p. VXi.
Conocephalitea (Atopa) trilineatns Ford, 1875. Amer. Jour. Sci., 3d ser., vol. ix, p. 205.
Triarthrua trilineatua Miller, 1877. Cat. Amer. Pal. Fosh., p. 223.
Cnnocorjiphe Foul, lii80, Amer. Jour. Sci., 3d ser., vol. xix, p. 152. ...

This trilobite has an interesting htstory that connects it with the
Taconic controversy. First charac/terized by Dr. Emmons as typical of

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204

CAMBBIAN FAUNAS OF NORTH AMERICA.

(BULL. 30.

tbe Taconic system, it was considered by Prof. Hall the same as the
Triarthrus Benki of the Utica slate, and not of importance in estab
lishing a different geologic horizon for the Taconic slates. It was not
until Mr. Ford, in 1871, published a list of the fossils known to him
from the conglomerate limestones east of Troy, N. Y., that the question
was satisfactorily settled, a fact overlooked by the writer in prepariiij[r
a list of the synonyms of Triarthrus Becki in 1879 (Trans. Albany Inst.,
vol. X, p. 23).

The original specimens figured by Dr. Emmons were fragmentary and
very much compressed, and the figures of the head and three segments
of the thorax of the best specimens are not so good as the original
specimen that is now preserved in the collection of the American Mu-
seum of Natural History, New York, a figure of which is given on plate
xxvii, fig. 1. Subsequently (Araer. Geol., p. 115, 1855) Dr. Emmons
descnbed a much more perfect specimen, as follows:

''Crust granulated, cephalic shield semicircular, with its anterior and
lateral edges turned ifpwards ; posterior angles rounded, facial suture
beginning at the outer angle of the cephalic shield and runs nearly par
allel with the anterior margin to the middle lobe, when it turns at a
right angle and runs parallel with that lobe; eyes undistinguishabU',
body con)])osed of seventeen or eighteen rings, narrowing very gradu
ally to the caudal extremity ; pygidium a fiat expansion of the crust,
and is provided with a single ring; axis narrower than the lateral lobes;
rings seventeen, each of which is separated by a groove about as widt;
as the rings. Axis armed by a row of short spines ; lateral lobes pro
vided with a row of tubercles or prominences along the median line ;
margins of the rib groove run parallel as far as the tubercle, when they
diverge; tubercles become obsolete towards the tail ; caudal shield very
small and provided with one or at most two rings."

The figure which we reproduce on plate xxvii (fig. Ic) is that of the
specimen described; it is crushed, and if the same liberty was taken in
making the drawing that was used in that of the first figure we cannot
place much reliance on the details. The whereabouts of the specimen
Is unknown to me.

Dr. Emmons afterwards considered this specimen as belonging to a
distinct species, A.punctatus; but, from the fact that the original does
not preserve the outer shell and that from the parts preserved we can
not judge of its specific distinction, I have considered them as belong
ing to one species.

The first type specimen shows an ocular ridge and traces of the direc
tion of the facial sutures the same as in typical species of the genus
Ptychoparia.

The generic name Atops preceded that of Ptychoparia, but it was
not until years after Ptychoparia had been thoroughly <lescribed, illus
trated, and published that Di*. Emmons so defined Atopa trilineatm
that even the specific characters could be determined. The simple pro

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IfALCOTT.l

MIDDLE CAMBRIAN FAUNA.

205

po8al uf a name without figures or descriptiou by which cougeuerin
forms could bo iucluded within it is not sufficient to warrant our ub« ot
the name Atops in ])lace of Ptychoparia.

Formation and locality. — Middle Cambrian. Beynold's Inn, sev^n
miles north of Union Village, Washington County, New York ; in the
conglomerate limestones on the ridge east of the city of Troy, New
York ; also, in conglomerate limestones of Bic Harbor, below Quebec, on
the St. Lawrenc<» Eiver, Cauada. .

Ptyohopaeia subcoeonata H. & W.

Plate xxviii, fig. 4.

Conocephalites subooronatua Hall & Whitfield, 1877. Geol. Ezpl. Fortieth Par., tuI.
iv, p. 237. pi. ii, fig. 1.

Original description. — " Glabella short, conical, with straight lateral
margins, regularly converging from the base upward to the rather
squarely truncated summit ; height above the occipital furrow scarcely
exceeding the breadth of the base, and the width at the summit equal
to about two-thirds of the height ; marked by three pairs of very oblique,
.subequally distant, and moderately distinct transverse furrows. Oc-
cipital furrow narrow and well marked ; ring distinct, widest and some-
what pointed on the center of the posterior margin.

"Fixed cheeks wide, separated from the glabella by distinct dorsal
furrows, prominent and rounded between the glabella and eye-lobe,
almost equaling the convexity of the glabella ; ocular ridges slender
and curved. Frontal limb wide and concave, destitute of a thickened
marginal rim, as long as the glabella, and obscurely trilobed from an
extension of the dorsal furrows, forming a convex, boss-like area in
front of the glabella, which is divided transversely by a double de
pressed line, or narrow fillet, midway of the limb and parallel with the
anterior margin of the head. Eye-lobes about half as long as the gla
bella, obliquely situated, and separated from the fixed cheek by a deeply-
depressed ocular sinus.

" Facial suture cutting the anterior border on a line with the front
angle of the eye, which it reaches by a broad convex curvature, giving
rounded lateral maigins to the frontal limb ; posterior to the eye it is
directed outward, the actual course not determined. Posterior lateral
limbs not seen. Surface of the crust in front of the glabella strongly
striated.

" The species is only known by the glabella and fixed cheeks. The
specimens are all minute, but readily recognized by the peculiar formed
boss in front of the glabella."

This species is associated with Olenoides quadriceps in the same pieces
of rock. Its nearest allies are P. Prospeetemis and P. f Linnaraaoni
(Monographs U. 8. Geol. Survey, vol. viii, pp. 46-48). They all have a
cylindro-conical glabella, with a rounded boss on the frontal limb; rather

(931)

i-^ii

iff

' 'r

; ■ t

'I'll

^:n

206

CAMBRIAN FAUNAS OP NORtH AMERICA.

(mni.ML

wide fixed chcckH, and nicdinm-sized eye lobes. Specifically P. nvheorfh
nata differs from tlie other two species very decidedly.

Formatian and locality. — Middle Cambrian. Ute Peak, Wasatch
Range, Utah.

This species was originally referred to the Qnebec Group, but, as
mentioned under the description of Olenoidea quadriceps, the reference
is now known to be incorrect.

Genus OREPICEPHALUS Owen.

Crepii ephaluB Owen, 1852. Rep. Geol. Surv. Wisconsin, Iowa, and Minnesota, p. 576.

Original description. — " Generic character. Some rich Trilobite slabo,
occupying the position of the third Trilobite-bed at the Mountain Island
section, contain numerous fragments of a Trilobite, a portion of the
cephalic shield of which is seen on the medal-ruled slab, fig. 16 of Tab.
I. A., on the left corner, as well as by figs. 10 and 18 of the same plate.
These, as far as preserved, approach somewhat in form to the genera
Solenosema, Micropyge, and Endogramma ; but if the caudal shields, fig.
8 of Tab. I. and fig. 16 of Tab. I. A., correspond, which seems improb-
able,^ as they are abundantly disseminated in the same bed and are min-
eralized in the same manner into a brown, ferruginous crust, contrast-
ing strongly agai'Mt the gray gritstone, then this Trilobite of Mountain
Island must constitute a genus distinct from either of these, and for
which the name CrepicephaUis is proposed.

" The rather flat, slipper shaped glabella is tapering and slightly
acuminated anteriorly, with a faint ridge in the median line ; two small
and very superficial depressions, and a posterior faint furrow, very
partially divide the glabella. The facial sutures run nearly parallel to
the margin of the glabella, and join a thickened, cord-like, anterior
narrow border, inclo ing a convex area, narrower in front than at the
sides. Oblique plications can sometimes be traced on the cheek-plate,
in advance of the eye, converging towards the apex of the glabella.

" If the associated pygidiums, fig. 8 of Tab. I. and fig. 16 of Tab. I.
A, belong to Trilobites of this species, they are relatively larger than
those of any of the above genera. The axal lobe has four segments;
side lobes bounded by a slightly concave border, which widens pos-
teriorly, and of which the confines are almost rectangular, with rounded
comers."

From a careful reading of the author's description of this proposed
genus and a study of all the figures referred to it and also of a series
of specimens from the type locality, there is but little doubt that P.
{Crepiceplialus) lowensis is the species to be taken as the type of the
genus.

' This is undoubtedly a typographical error, as the sentence is rendered meaning-
less unless the wotAprohdble is used. — C. D. W.

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WALCOTT I

MIDDLE CAMBRIAN PAITNA.

207

inesota, p. 576.

On pp. oiSQ of Bulletin 10, U. S. Geological Survey, I bave spoken of
the relations of tbe genera Ptycboparia, OrepiceplialuH, &c., stating tbat
Ci-epicepbalus migbt be used as a subgenus on account of its peculiar
pygitliuai. Tbe projecting postero-lateral spines of tbe pygidium are
also present in otber genera of trilobites, but not just in tbe same way.
Tlie nearest I know of is tbe pygidium of Cerat<ypyge forJumUt Sars
(Die sil. Etagen 2 und 3, &c.; W. C. Brogger, 1883, pi. 'ii, flgs, 19-22),
where tbe spines are tbe extension beyond the border of tbe second
ancbylosed segment of tbe central axis. Tbe bead of tbis species is
entirely distinct from tbat of P. (0.) lotcensin. We now have, in tbe
Geological Survey collections, three well-marked species of the group ;
one from the Potsdam horizon is represented by entire specimens, some
of which have a length of 15*"" (p^ inches), exclusive of the two postero-
lateral spines of the pygidium, which give an entire length of 20*"". This
18 the largest species of tbe Gonocephalidie tbat is known to me. It
will be illustrated in tbe study of tbe Upper Cambrian faunas.

Ceepicephalus Liliana n. sp.

Plato xxviii, flgH. 8, 3a-c.

Head semicircular in outline and terminating in round, sharp, postero-
lateral spines of moderate length. Glabella truncato conical, tapering
moderately to the front, height and width at tbe occipital furrow
about equal ; marked by three pairs of furrows ; the two posterior ex-
tend obliquely inward and backward and tbe anterior pairs are nearly
transverse in direction ; the anterior pair is often very faintly indicated,
and on the glabellas of young individuals, 2""" or 3- " in length, the
furrows show only as faint depressions on tbe smooth surface ; occipital
farrows broad and well defined ; occipital segment strong and moder-
ately elevated ; dorsal furrows distinct.

Fixed cheeks broad as tbe glabella opposite tbe eyes; posteriorly
they broaden out in the short postero-lateral limbs, and anteriorly
merge into the frontal limb, which is of moderate width, slightly convex,
and bordered anteriorly by a flattened margin about as broad as the
distance from the front of the glabella to tbe slight but distinct depres-
sions between the frontal limb and tbe margin ; postero-lateral limbs
grooved near the posterior margin by a distinct furrow. Eyes lunate,
about one-third as long as tbe length of the glabella ; a strong ocular
ridge extends from tbe anterior end of tbe narrow palpebral lobe with
a slightly forward direction, touching the dorsal furrow nearly, but not
(juite, opposite the antero-lateral angle of the glabella. Facial sutures
cut the anterior margin on a line with the sides of tbe glabella, and ex-
tend obliquely inward and outward across the margin and then curve
inward and extend to the eye ; curving around the palpebral lobe, they
extend obliquely outward with a slightly sigmoidal course to tbe poste-
rior margin. The associated free cbet;k is irregularly triangular; mar-

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208

C4MBRIAN FAUNAS OF NORTH AMERICA.

[HUM.. 10,

giual border strong and produced behind into u niudiiiui sized, 8barp
npine ; central area slightly convex, and marked by strite that radiate
from the base of the eye towards the margin ; anteriorly the border
narrows to a slender point.

Thorax unknown.

Pygidium subqnadrilateral in outline, with strong, slightly-diverging
spines extending back from the postero-lateral angles ; sides nearly
straight, slightly converging posteriorly to the base of the spines ; pos-
terior margin a little concave between the spines ; axial lobe promi-
nent, convex, and reaching five-sixths of the distance between the front
and back margins ; the sides converging very little towards the ob-
tusely-rounded posterior end ; divided by fine transverse furrows into
five segments and an obtuse terminal point; the pleural lobes are
grooved by the extension of the grooves crossing the axis ; the termi-
nal spines appear to arise from the extension of the anterior segment
of the pygidium. There is considerable variation in the strength and
direction of the postero-lateral spines, but I find this to be true of the
corresponding spines on Crepicqthalva lowensis.

Surface of head and pygidium with papillsB of different size scattered
over it, sometimes so thickly as to give a granulose appearance to it.

This and associated forms are the only ones we know of this type in
the Middle Cambrian. The type is found in the Potsdam horizon of
Nevada, Wisconsin, and Alabama, and will be fully described in the
review of the Potsdam or Upper Cambrian fauna.

Formation and localities. — Middle Cambrian. In limestone associated
with Ohnelliis Qilberti, near Pioche, and also eleven miles north of Ben-
net's Spring, on the west side of the Highland Range, Nevada.

Ceepicephalus Augusta n. sp.

Plate xxviii, figs. 2, 2a, b. ; ■■

Glabella and fixed cheeks sub- quadrilateral in outline exclusive of the
postero-lateral limbs; glabella truncato-conical, sides tapering moder-
ately to the front, height and width at the occipital furrow about equal;
marked by four pairs of glabellar furrows ; the two posterior pairs ex-
tend obliquely inward and backward, the third pair being opposite the
anterior end of the palpebral lobe and transverse to the axis of the gla
bella; the fourth pair are very minute and resemble elongate pits oppo-
site the terminations of the ocular ridges; occipital furrow well defined;
occipital segment strong, thickened at the center, and showing a small
central node or point near the back margin; dorsal furrows distinct.

Fixed cheeks broad, convex; posteriorly they broaden out into the
short postero-lateral limbs, and anteriorly merge into the frontal lobe,
which is narrow in front of the glabella, expanding a little laterally;
frontal margin slightly convex, and broadest in front of the glabella,
narrowing towards the facial sutures, separated from the frontal lobe

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MIDDLE CAMBRIAN FAUNA.

209

by a narrow groove that arches slightly forward on each side of the
center; in young individuals thin groove is nearly obnolete, and the
frontal limb appears broader in proportion to the width of the margin.
I'oHtero lateral limbs very short in the small heads and of medium length
in the larger; a welldcUned groove occurs just within the posterior
margin. Palpebral lobes of medium length ; ocular ridge narrow, strong
on the adult and less distinct on the small heads; starting u little back
of the antero-lateral angles of the glabella, they cross the cheek, trend-
ing obliquely backward to the anterior ends of the i)alpebral lobes
Facial sutures cut the anterior margin on a line with the sides of the
jjlabella, and extend obliquely outward and across the broad margin,
curving inward as they cross the frontal limb and extending to the eyes,
around which they curve on the margin of the palpebral lobe and then
extend obliquely outward and backward, with a slightly sigmoidiil
carve, to the posterior margin. Free cheek unknown.

Thorax unknown.

Pygidium with a short strong axis crossed by three furrows; pleural
lobes flattened and marked by the extension of the axial furrows; poste-
riorly the lobes extend into points, leaving an arched posterior border
between the two points of the pygidium.

Surface of head and pygidium papillose; the papillre are scattered
aud vary in size; on the smaller beads they are often not present.

This species is distinguished from the i)receding, C. Liliana, by the
elongate form of the head, the more rounded frontal margin, and the
character of the associated pygidium ; the latter has a short axis, a
broader space back of the axis, and the posterolateral angles terminat-
ing in points instead of long spines. The two species are closely re-
lated, but we have a large number of specimens of the head of each,
and the diflferences hold good in distinct localities and in different sized
beads down to those 3""" in length. The small heads of C. Augusta are
quite smooth .and the groove between the frontal limb and margin is
nearly obsolete.

Formation and localities. — Middle Cambrian. Very abundant in lime-
stones of the Olenellus horizon, both in the vicinity of Pioche, and also
eleven miles north of Bennet's Spring, Highland Range, ISTevada.

Genus ANOMOCAEE Angelin.
-Inomocore Angelin, 185a. Pal. Scand., p. 24.

Anomooaee? parvum Walcott.

Plate XXV, fig. 1.

Anomocare t parvum Walcott, 1885. Monographs, U. S. Geol. Snrvej-, vol. viii, p. 50,
pi. ix, flg. 17.

This is the same species described in Monographs U. S. Geological
Survey, vol. viii. No new material has been obtained since the discov-
ery of the original specimen in 1880.
Bull. 30 14 (936)

Kth

■i

■ 1 i
■ ^

^ i

■ '-
. 11

■i^^

210

CAMBRIAN FAUNA8 OF NORTH AMP^RICA.

(HUM. .10.

: .

Formation and locality. — Middlu Cainbriaii. In a liiut>Hton«,aH8fK!iatc(l
with OleneUuH Oilherti^ beneath the areiiaceouM shale carrying Olenellut
OHherti and 0. Iddingsi, West Bh>pe of Prospect Mountain, Eareka DIh-
triot, Nevada.

Genns OBYOTOCEPHALUS n. gen.

(dpvKT<>c, fiirrowt^d. 1111)1 Kr^uAf/, huu<l.)

Glabella oblong, transversely lobed ; eye central, with a narrow ocu-
lar ridge connecting it with the axial furrow about the glabella; facial
Butnre marginal in front and cutting the posterior margin within tlui
posterolateral angles ; free cheeks spinous.

Thorax unknown.

Pygidium with segmented axis and pleural lobes; margin spinous.

This genus is founded on numerous s]>ecimens of the head and pygid-
ium of a small trilobite that, in its generic and family relations, a])
proaches Parabolina of the family Olenidte. The combination of char-
acters shown in the head and pygidium serve to distinguish it A>om any
generic form known to me.

Type Oryctocephalus primus.

OBYOTOCEPHALUS PRIMUS n. Sp.
Plate xxix, iigH. 3, 3a.

Entire head as restored by the union of the free cheeks to the central
portions of the head, transverse subsemicircular. Glabella elongate,
quadrilateral, sides parallel, front broadly rounded and, in some speci-
mens, showing a slight indentation midway; surface marked by four
transverse furrows that terminate in little pits within the margin of the
glabella; a shallow de])ression unites the pits on each side within the
margin, and there is on some glabellas a very shallow depression run-
ning obliquely backward from each pit to the axial furrow ; the trans-
verse furrows uniting the pits are strong and arch a little backward
at the center ; anteriorly a shallow pit occurs a little back of the antero-
lateral angles of the glabella that opens out into the axial furrows; the
occipital furrow is represented by the posterior pair of pits and connect-
ing furrow, and the strong occipitJil segment is united to the glabella at
each end within the axial furrows; axial furrows strongly defined.

Fixed cheeks nearly as broad as the glabella ; they narrow slightly
in front and broaden out posteriorly into the short posterolateral limbs;
frontal limb practically obsolete ; a narrow raised margin bonlers the
front of the head ; palpebral lobe narrow and with a deep groov«! be-
tween it and the fixed cheek; a narrow ocular ridge crosses the fixed
cheek from the palpebral lobe to the axial groove opposite the small an-
terior depressions on the side of the glabella. Free cheeks elongate,
convex, bordered by a narrow rounded rim that extends backward as a
short spine; visual surface of eye broken away.

(936)

Hi'':

WAI.COTT. 1

IflDDI.K CAMBRIAN FAUNA.

211

Tlionix unknown.

AH80ciate<l pygidium with a strong axial lobe and divided into tlvo
riiiiTH and into. a terminal elongate ring by Ave tninHverNii rnrrowN;
pleural lobes strongly grooved by four anttliyloHed pleural ttegnie' tH that
feriiiinate in strong, elongate iioints; a ilfth Negnient (eriniiuiteM inn
])oiut on each side of the posterior end of the axial lobe.

Surface of the head and i>ygidium apparently Hlightly giauulo.se.

This trilobite is so distinct in its character that, beyond referring the
(Tonus to the Olenidae, there are few couipariHons to make Nave those
iiinted at under the generic description.

Formation and locality. — Middle Cambrian. In limeHton(> just above
the quartzite, east of Pioche, Nevada.

Genus PR0TYPU8 n. gen.

T.v|)o Protypui Eitohoooki Whitfield.

The only entire example of an individual of this genuH is the type of
the typical species, and, until more is known of other species referred
to it, the description of the species gives the generic characters.

PEOTYPrS HiTOHCOCKI Whitfield (sp.)

Plate zxxi, ^k- 4.

AngeHna HUoheooki Whitfield, 1884. Bull. Amer.Mus. Nat Hist., vol. i, 148, pi. xiv,
fig. 13.

Original description. — "Body ovate in outline, largest across the base
of the head and gradually narrowing bdiind ; distinctly trilobcd lon-
gitudinally.

"Head broad, semicircular in outline, being about twice an wide
across the base as the extreoie length from the front margin to the pos-
terior side of the occipital ring. Glabella proportionally large, with
parallel sides and rounded front. Surface convex and apparently des-
titute of any glabellar furrows. Frontal limb narrow in front of the
glabella and bordered by a narrow rounded rim. Fixed cheeks ])ro-
portionally broad, crossed in front of the eyes by a distinct ocular
ridge, which is curved and runs nearly parallel to the margin of the
head. Lateral limba large, triangular, and extending nearly to the
origin of the cheek spines. Eyes large, reniform, and the palpebral
lobes flattened. Occipital ring narrow and divided from the glabella
and fixed cheeks by a narrow groove- Movable cheeks elongate tri-
angular, curved on the outer margin, moderately convex over the
central area, and projected backward at the -posterolateral angles in
short spines. Facial suture passing a very little outward in its course
from the eye to the anterior margin, which it cuts nearly at right angles
to the border ; behind the eye it passes obliquely outward and back-

(937)

« . 'U

212

CAMBRIAN FAUNAS OF NORTH AMERICA.

[BOLL. 30.

.:vj'!:

ward with a slight curvature to just within the cheek spine, forming a
very broadly triangular lateral limb.

" Thorax nearly once and a half as long as the head, consisting of
twelve segments, and nearly twice as wide at the anterior as at the poa-
terior end ; strongly trilobed, the axial lobe forming one-third of the
width anteriorly, but rapidly tapering backward ; at the twelfth seg-
ment its width dees not exceed one-fourth of the whole. Axial lobe
convex, the segments well marked, narrow and rounded, separated by
broad grooves; pleura straight, direct and flattened for nearly two-
thirds of their length, from which point they are rapidly narrowed to a
point, which is not recurved, but which is a little back of the central
line of the rib. Surface of the i)leura broadly channeled, the furrow
occupying nearly the entire width of the rib and extending to the ex-
tremity.

"Pygidium small, semi-elliptical, and transverse, about four times as
wide as long, and marked by three furrows, both on the very small axis
and on the lateral areas. Axis terminating within the posterior margin
of the plate.

" Surface of the test smooth.

" The generic relations of this trilobite are not exactly those given by
its author to the genus Angelina, but they are more nearly like them than
of any other described. The general form and proportions are very sim-
ilar, as is also the general appearance; but in the head parts it differs
principally in the possesion of very distinct glabellar furrows, which is in
direct opposition to the generic diagnosis, and the eyes are larger than
those of the typical species. In some lights the specimen figured seems
as if it had possessed two pairs'of glabellar furrows,^ but they are so very
unsatisfactorily defined that I have chosen rather to consider them as ab-
sent. The great difference, however, is the nature of the furrows of the
pleura and the pointed extremities of these parts. In the A. i^edywicld
the furrow is narrow at each end and broadest and angular at the genic-
ulation, which is near the middle of the length, while in this one the
furrow is broad at the inner end of the pleura, and retains its breadth
and depth for the entire length, only narrowing as the extremities of
the ribs are narrowed, while the extremities of the ribs cannot be fairly
said to be bent backward to any degree. These points of difference,
although considerable, I have not deemed of suflflcient importance to
constitute a distinct genus, rather considering that the typical species
was followed too closely in the original generic description."

After reviewing the character of the genns Angelina and those of the
species under consideration, I am led to differ with Prof. Whitfield and
to consider the diffferences of generic importance.

Briefly enumerated, thej' are: The presence of strong ocular ridges.

I The author probably meant ooulur rw^M.
(938)

II .

Kjular ridges,

WALCOTT.]

MIDDLE CAMBRIAN FAUNA.

213

the difference in the type of the pleural lobes of the thoracic segments,
and the pygidium of Angelina, which has a spiuose margin.

In a second species found at Parker's quarry, P. parvulus, very faint
glabellar furrows are shown in a natural mold of the glabella.

The only specimen yet known to me of P. Hitchcocki is the one de-
scrib' by Prof. Whitfield, and now in the American Museum oi y^tural
History, New York.

Formation and locality. — Middle Cambrian, Georgia Formation. Par-
ker's quarry, town of Georgia, Franklin Cmmty, Vermont.

Pkotypus senectus Billings.

Plato xxxi, lij»8. 2, 2a-e.

Balhjurua senectus Billings, 1861. Geology of Vorinont, vol. i', ji.9o3, figs. 059, 360.
Painpblet (1861) republished (1865) in Pal. Foss., vo;. i, p. 16, 1863. Geol.
Canada, p. 266, figs. 298 a, 6.

Compare Bathyurns parvulus Billings, 1861, Geol. Vermont, vol. ii, p. 953.

Original description. — "Glabella subcylindrical, clavate, strongly con-
vex, one-fourth wider at the front margin than at the neck segment,
sides nearly straight, front obtusely rounded and presenting a strong
convex elevation, neck furrow extending all across, three pairs of gla-
bellar furrows represented by small but distinct and obtuse indenta
tions in the sides. Fixed cheeks, rather strongly convex. Eyes of mod
erate size, semicircular; a line drawn across the head at about one third
the length of the glabella from behind would pass through them, and
they are distant from the side of the glabella about the width of the
neck segment. The front of the neck is surrounded by a narrow border
which appears to be flat; thfu appefirs to be some evidence of a spine
on the neck segment.

" The pygidium found iu ^lie same fragment of stone with one of the
specimens of the glabella of this species is iu all general characters that
of a Bathyurus. It is semicirculiir, convex, axis cylindrical, strongly
••onvex, terminating behind with rn abruptly rounded descent, six an-
nidations, the first three or four most strongly defined. The lateral
lobes have four segments each, separated by strong rounded furrows;
there is a narrow entire margin all round, with a distinct groove inside,
which appears, however, to be interrui)ted at the end of the axis.

"The dimensions of the most perfect specimens are as follows:

"Glabella, length three and one-half lines; width at neck segment
one and one-half lines, at the front two lines; distance of the eye from
the side of the glabella one and one-half lines. The eye appears to be
about three-fourths of a line in length.

"Pygidium, length three lines; width at anterior margin five and
one half lines; width of axis one line.

^^ Locality and formation. — Anse an Loup, on the north shore of the
Straits of Belle Isle. Limestone of the Potsdam group."

(939)

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214

CAMBBIAN FAUNAS OF NOBTH AMEBICA.

[BULL. 30.

In the more arenaceous and calcareous layers of the upper portion of
Parker'8 quarry the heads and pygidia of this species are quite abuu-
dant, and, on comparing them with the figure and description of P. se-
nectus, we place them under that species.

The figure and description given by Mr. Billings require the pres-
ence of short obtuse glabellar furrows, and these we find on two
specimens ; ten other specimens of the head do not show them. lu
other particulars the head appears to be the same, and the associated
pygidium is similar to that found with P. seneetua; and, as they are
from the same relative geologic horizon, I prefer to place the Yermont
species under P. aeneotua rather than to make a new species for its recep-
tion. The species Bathyurua parvulua is associated with P. aenectua at
UAnse au Loup, is almost identical in appearance with some specimens
of the head of P. aeneotua as found in Vermont, and it is, as yet, uncer-
tain whether the latcer should be referred to P. aenectua or P. parvulm.
The condition of preservation is the cause of the two forms in the Yer-
mont rocks.

P. parvulua is placed as a variety of P. seneotu^y as I am unable to
clearly understand the type of P. parvulua.

In studying broken fragments of trilobites it is difficnlt t4> determine
generic, much less specific, relations ; but, from a study of the type of
the genus Bathynrus, I do not think we can refer any known species
from the Middle Cambrian to that genus.

In some respects this species approaches quite closely to Corynexochm
apinuloaua Angelin (Pal. Scan., p. 59, p]. xxxiii, figs. 9, 9a); but, until we
have a more complete description and better figures of that species, it
would be hazardous to make a generic identification.

Formation and loealitiea. — Middle Cambrian, fltet rgia Formation . Par-
ker's quarry, town of Georgia, and one and one half miles east of Swan-
ton, Franklin County, Yermont ; also, on the Labrador coast, as men-
tioned above.

Genus SOLENOPLEUBA Ai «elin.

Solenopleura Augelin, 1852. Pal. Scan., p. 26.

SOLENOFLETJBA NANA Ford.

Plate xxvii, fig. 3.
Solen&phura ^ana Ford, 1678. Amer. Jonr. Soi., Sdser., vol. xr, p. 126.

Original deacription, — <' The largest and best-preserved specimen con-
sists of a nearly perfect glabella and the greater portion of the fixed
cheeks, and is but two lines in length. The glabella is neatly four-flftbs
the total length of the head and is especially characterized by its great
relief. It is obtusely conical, slightly widest behind, and is well defined
aU aroaud by the dorsal furrows. In a specimen two lines in length its

(MO)

WALCOTT.]

BODDLE CAMBBIAN FAUNA.

215

highest point is nearly one and one-half lines above the base of the
fixed cheeks. It is marked on either side by two or three faint furrows.
The fixed cheeks are notably convex, bat their relief does not exceed
one-third of that of the glabella. The eyes are sitnated slightly in
advance of the mid-length and are connected with the front of the
glabella by an obscure ocular fillet. The distance from the eye to the
glabella is nearly equal to. the width of the glabella at the mid-length.
The front margin is narrow and is bounded by a feebly convex rim,
inside of which there is a narrow furrow which gradually deepens on
either side of the median line in passing outward. Between this furrow
and the glabella there is a somewhat angular ridge which widens in
passing outward to the sutures.

'< The course of the facial suture is nearly the same with that of
Solenopleura brachymetopa of Angelin (Palseontologia Scandinavica, pi.
xix, fig. 1), but is directed more inward in front of the eye. The neck
farrow is continuous all across. The exact form of the neck-segment
cannot be made out, owing to the damaged condition of all of the speci-
mens at this point. It is seen, however, to be less elevated than in the
majority of the species, not rising above the surface of the fixed cheeks.
The entire surface is covered with a tine regular granulation."

Specimens in the United States Geological Survey collection show
that the occipital segment rises towards the center to form the base of
a short spine that projects backw^ard and upward to the base of the
tumid glabella. In a head T*"*^ long the furrows of the glabella are
shown very distinctly.

Formation and loeality. — Middle Cambrian
on the ridge east of the city of Troy, New York.

Oonglomerate limestone,

Genua BATHrURISOUS Meek.

Bathyuriaous Meek, 1673. Sixth Ann. Bep. U. S. Oeol. Snrv. Terr., p. 484.

Bathyuriscus was proposed by Mr. Meek at the end of the description
of Bathyurm t Raydeni in event that the latter species was found to be
non-congeneric with Bathyurus extans, the type of the genus Bathyurus.
Mr. Meek says : " If further comparisons show it to be generically or
subgenerically distinct from all of the groups mentioned, as t believe it
to be, it may be designated by the name Bathyuriscus.^^

Having found that two other species are generically allied to B. Hay-
deni and distinct from any described genus, I refer them to Mr. Meek's
genus; and from the three species, Bathyuriscus Haydeni, B. producta,
and B. Howelli, the following description is drawn :

General outline ovate. Head medium size, semicircular. Glabella
Htr£ right or slightly expanded in front, marked by three or four pairs of
glabellar furrows. Byes elongate. The facial sutures cut the anterior
margin of the head a short distance each side of the line of the greatest
expansion of the glabella, and extend obliquely iuwMd to the anterior

(941)

111

»l

' :»

•

! ■

216

CAMBRIAN FAUNAS OF NORTH AMERICA.

IBULL.80.

bases of the eyes; encircliDg the latter, they extend obliquely outward,
cutting the posterior margin so as to leave a narrow elongate lateral
limb. Free cheeks unknown.

Thorax with from seven to nine segments; axis strong; pleural lobes
well defined ; pleural groove broad.

Pygidium semicircular ; axis strong and crossed by several furrows ;
lateral lobes marked by the extension of the furrows crossing the axis.

Hypostoma of B. producta irregularly ovate; broadest a little forward
of the center ; posterior marginal rim raised ; a strong sulcus extends
around inside the rim ; muscular scars well defined.

In many respects the head is similar to that of the genus Olenoides;
the thoracic segments recall those of Ptychoparia, and the pygidium
might be taken for that of a species of Bathyurus, or perhaps Ogygia.
The general assemblage of characters points to a generic type distinct
firom any known to the writer.

The geologic rangs of the genus is from the Middle to the Upper Cam-
brian. Bathyuriseus produeta is associated with Kutorgina pannula,
Olenoides typiealis, and Ptychoparia PioehemiSy &c., in a band of shale
2,000 feet below a typical Upper Cambrian or Potsdam fauna, such as
B. Haydeni is found with in Montana. The intervening strata between
the two specifcs iu the Highland Eange, Nevada, are massive limestones.
(See Highland Range section, p. 34.)

Bathyubiscus Howelli n. sp

Plate XXX, figs. 3, 2a.

General form ovate. Entire form of head unknown, but from the
parts preserved it appears to have been semicircular. Glabella clavate,
expanding in front of the second pair of glabellar furrows; posteriorly
the sides are subparallel to the occipital segment ; the posterior pair of
glabellar furrows are directed obliquely backward nearly to the oc-
cipital furrow ; the second pair are less obliquely inclined backward,
and the third pair penetrate directly in, one-third the distance on each
side. Occipital furrow well defined ; occipital ring rounded and rather
strong. Eyes large, lunate, the extremities close to the glabella.
Fixed cheeks very narrow; postero-lateral limbs narrow elongate;
frontal limb narrow, slightly convex, and expanding but little in front
of the glabella. The facial sutures cut the anterior margin and trend
obliquely in to the anterior end of the eyes ; encircling the large palpe-
bral lobes, they extend outward from the posterior ends of the eyes and
out the posterior margin of the head well out towards the genal angle.
Free cheeks unknown.

Thorax with eight segments. Axial lobe convex, tapering very grad-
ually from the anterior segments to the pygidium ; each segment is well
defined and arches slightly forward ; pleural lobes moderately convex;
the segments curve gently backward from the genal angl« <md i^vmi'

(942)

WALCOTT.]

MIDDLE CAMBRIAN FAUNA.

217

nate in short falcate points ; 'pleural groove rather broad and deep, and
continued nearly to the extremity of the segment.

Pygidium subelliptical in outline ; axis prominent, elongate, subcon-
ical, divided by four transverse furrows into four rings and a terminal
segment; the pleural lobes are less convex, and, towards the margin,
flattened out so as to form a broad, slightly convex border across which
tbe four anchylosed segments, with their pleural grooves well defined,
extend nearly to the margin.

Surface not preserved so as to show any surface striae.

{mm •

head, 9°"" ; thorax, 8"

Dimensions : Length of entire body, 23"
pygidium, 6°"".

The pygidium of this species is much like that of several referred to
the genus Bathyurus, but in all other characters it is far outside that
genus.

From the associated species, B. prodiicta, it differs in having a difi'er-
ent type of frontal margin to the head and in the extension of the
pleural groove of the thoracic segments out nearly to their extremities.
The pleural lobes of the pygidium also show the anchylosed segmental
division much more strongly. The difference of one segment would not
be of specific value in all cases, but, united with the other difierences,
it serves to distinguish the species.

The type specimen is the only one yet discovered that shows head,
thorax, and pygidium. It is entire, with the exception of the free cheek,
and the form is but slightly compressed.

Formation and locality. — Middle Cambrian. In an argillaceous shale
at the Ghisholm mine, on the southwest face of the Ely Mountains,
near Pioche, Nevada. A pygidium was found in the Highland Range
section twenty miles farther West.

Bathyuriscus pr'oductus H. & W.
Plate XXX, figs. 1, la-4.

Ogygia producta Hall & Whitfield, 1877. Geol. Expl. Fortieth Par., vol. iv, p. 244, pi.

ii, figs. 31-34.
Ogygia parabola Hall & Whitfield, 1877. Geol. Expl. Fortieth Par., vol. iv, p. 245, pi.

ii, fig. b5.

The original dtscription of the species is unsatisfactory, as it is drawn
from imperfect material. I have before rae all the type specimens, also
a large collection made by Mr. J. E. Clayton for the Wheeler Survey,
and a collection obtained the past season in the Highland Range of
Central Nevada, where the stratigraphic position of the fauna was de-
termined; the same horizon was also found in Big Cottonwood Canon
of the Wasatch Range in this same relative position just above the Ole-
nellm Gilherti zone.

Form ovate. Head of medium size and nearly semicircular; margin
bordered by a narrow ritn that, at the genal angles, is prolonged into a
rather strong spine. Glabella elongate, and expanding slightly near

(943)

; '-hi

Bi 'i"!'l

)\l;

I ':

^ *

218

CAMBRIAN FAUNAS OF NORTH AMERICA.

IBULL. 30.

the anterior end of the eyes and on towards the front, where it k
broadly rounded ; three pairs of furrows are well defined on small speci-
mens and more faintly shown on the larger heads; the posterior pair
penetrate obliquely backward nearly tf the occipital furrow; the second
and third pair extend transversely about one-third the distance acrosS|
the third pair are opposite the anterior end of the eyes. Occipital fur-
row well defined, both across the glabella and out on the lateral limbs;
occipital segment broad and convex in uncompressed specimens. Frontal
limb narrow and usually liitle moi e than a thickened rim. Fixed cheeks
narrow and, except on the posterolateral limb, almost obsolete. Free
cheeks subtriangular, rather large, and produced posteriorly in the genal
spines of the head.

Thorax with seven segments; axis moderately convex; gradually
tapers from the anterior segment posteriorly; segments well defined;
pleural lobes gently convex ; the pleurse curve backward near their
pointed extremities; pleural groove broad and distinctly marked about
two- thirds the distance out from the axis; the flattened extremity shows
no trace of it.

Pygidium broad, subelliptical in outline ; proportions oC length and
breadth varying very much, owing to distortion by compression in the
shaly mat ix; the normal form ap])ears to be less than twice as wide as
long; axial lobe less than one-third the width anteriorly and tapering
graduallyfo the posterior extremity, which is about one-fifth the dis-
tance of the length of the pygidium from the posterior margin; margin
rather broad and usually well detint d ; axis marked by about six rounded
rings, tliat vary in strength in dilierent specimens: pleural lobes de-
pressed ct)nvex and marked by four or five pleural grooves on well-
preserved specimens. The surface characters are usually destroyed,
but on some of the better-preserved specimens it is seen to have been
very delicate and much like that of the genus Olenellus, having inos-
culating, subimbricating striae over nearly all portions of the test except
on the free cheeks, where irregular lines radiate from the base of the
eyes to the margin.

We rarely meet with a species that shows a greater variation in
the form and character of the glabella and pygidium than this; it all
appears to be owing to the extent of the maceration of the shell before
the solidifying of the sediment, the character of the sediment, and the
subsequent distortion by compression and lateral movement in the ma-
trix. The several figures tell the story better than any description. On
the specimens showing the broad rim, the grooves are removed by com-
pression and the reflex margin or doublure beneath gives the outline to
the rim on the upper surface. On the better-preserved specimens, the
axial rings, pleural grooves, and margin show much as when in their
original condition.

It was owing to these distortions that Messrs. Hall and Whitfield
were led to describe » second species, Ogifgia parabola, from the impep'

(944)

WALUOTT.]

MIDDLE CAMBBUN FAUNA.

219

feet material at their command. The study of the variation of form
under different conditions of preservation is an essential one and is
often disregarded by paleontologists, more especially in relation to the
greater or less convexity of form. This remark is caused by reading
the description of trilobites preserved in shales when the form is given
as depressed, flattened, &c., as a specific character.

Formation and localities. — Middle Cambrian. Just above the Olenel-
las-bearing strata, one mile below Argenta in Big Cottonwood Cafion ;
also, at City Creek, Wasatch iMountnins ; East Canon, Oquirrh Mount-
ains, Utah ; and at the Olenoides horizon, 2,000 feet below the Potsdam
horizon of the Highland Bange section, near Pioche, Nevada.

AMphiaeuB Meek, 1873.
1872.

Genus A8APH1SCUS Meek.
Sixth Ann. Rep. U. S. Geol. Survey Terr., p. 485, foot-oote.

Original description. — "Asaphicus differs from the typical forms of
Bathyurellus Billings, to which it is nearly allied, << in having its conical
{>labella decidedly depressed and the niargiif of the head in front of it
first convex and sloping forward into a deep transverse mesial furrow,
then rising in the form of a convex margin to the front. The mesial
lobe of its pygidium is also proportionally longer, and the free margins
of the same much narrower and less flattened and alate. It probably
only forms a subgenus under Bathyurellus. From AsapJius, with which
it agrees in general form and proportions, it differs in its decidedly con-
ical, well-defined glabella, without lateral furrows or lobes, the extended
and transversely furrowed character of the anterior margin of its head,
its less arcuate eyes placed more remote from the glabella, and partic-
ularly in having nine body segments, instead of only eight. As in
Asaphus, its pleurae are distinctly furrowed, but they are more pointed
than is usual in that genus, though not falcate. Its surface is smooth.

" The generic and specific characters will be given in full, with illus-
trations, in Lieutenant Wheeler's Report.

" Several American species with a similar depressed, conical glabella,
without traces of lateral furrows or lobes, have been described from
more or less complete specimens of the head, under the name Conoceph-
alites. It is evident, however, from its smaller number of body seg-
ments, large pygidium, and differently formed plural grooves, that
Asaphiscus is entirely distinct from that group."

From reading the descriptions of the genera Batbyurus, Bathyurellus,
and Asaphiscus, I considered that the two latter genera had been sepa-
rated on specific rather than generic characters (TM'enty-eighth Ann.
Rep. N. Y. State Mus. Nat. Hist., p. 94, 1879), but now that I have ex-
amples of the typical species of Bathyurus {B. extans) and Asaphiscus
(A. Wheeleri) before me their generic differences are readily appreciated.
The pygidium of Asapljisgu^ is identical in ch^rscter with thflt of B^thy-

(946)

220

CAMBRIAN FAUNAS OF NORTH AMERICA.

[BL'LUSO.

\ t

i 1

»!!

" ' 'I

urns, and from the pygidium alone the reference would be to Batbyuru8.
The head, however, shows strongly marked diiferences, as mentioned
by Mr. Meek. Witli Bathyurus it is more difficult to decide.

Mr. Billings gives as a distinction between Bathyui-us and Bathyu-
rellus that the latter has a conical or pointed glabella without traces of
glabellar furrows, while Bathyurus has a subcylindrical glabella, rounded
in front and marked by obscure furrows, " the pygidium of which also
difters in not being strongly convex, in having a shorter axis, and iu
general a wider border."

Another marked diffei-ence between the two genera is in the configu-
ration of the frontal limb; it also occurs between Bathyurellus mX
Asaphiscus; this, together with the differences in the pygidium, sti ..s
to distinguish the two latter.

When reviewing the Potsdam fauna, the relations of the genera
Bathyurus and Bathyurellus will be discussed and figures of the typ-
ical species given.

AsAPHiscus Wheelebi Meek.

Plato xxxi, figs. 3, 3a. ■

Bathjfurellut (Aaapkiaous) Wheeleri Moek, 1873. Sixtb Ann. Rep. U. S. Oeol. Snrv.

Terr., p. 485, foot-note, 1872.
AaaphisciM IVheeleri White, 1875. Geog. and Gcol, Expl. and Surv. West lOOth Merid.,

p. 43, pi. ii, tigs. 1 a-f.

The description of this species by Mr. Meek has already been given
under the genus Asaphiscus. Subsequently Mr. C. A. White described
the species from the type specimens as follows :

"Body oblong-ovate in outline; surface smooth. Head depressecl
convex ; front margin regularly rounded ; posterolateral angles ab-
ruptly rounded, without cheek spiues; exterior margin bent shortly
upward all around, producing a raised border of considerable width,
and also a rather deep linear depression, or groove, parallel with that
border and between it and the remainder of the cheeks. Glabella coni-
cal, much wider behind than in front, depressed; space between its
anterior end and the marginal groove about equal to the width of the
raised marginal rim in front of it ; outline well defined by the narrow
dorsal furrows ; sides nearly straight ; anterior end abruptly and pos
terior end broadly rounded, without lateral furrows, or at least they are
hardly discernible ; occipital furrow shallow, broad, but somewhat dis-
tinct and uniform, extending entirely across the glabella, and continuous
with furrows similar to itself that extend to the posterolateral angles
of the head ; the latter furrows lie i)arallel with and near to the pos-
terior margin of the head, giving that margin also a raised border,
somewhat like the one upon the exterior margin. Eyes comparatively
small, crescentic, situated nearly opposite the mid-length of the gla'
bellft; and nearly equidistant from it and the posterior margin,

(946)

WAUX>TT.]

MIDDLE CAMBRIAN FAUNA.

221

" Thorax Iiaviug nine segments ; its length not quite so great as that
of the head ; axis broadest anteriorly, more strongly convex, and about
one-third narrower than the lateral lobes are; segments extending
Htraight across the lobe; lateral lobes depressed, their greatest con-
vexity along the middle ; pleurte bluntly pointed at their outer ends,
the points not being directed very strongly backward ; their inner ends
80 joined to the axial segments that they have the appearance of lap-
ping a little upon them just inside the dorsal furrow ; grooved, the
jjroove being deepest about mid-length, where the outer and inner
l)ortion8 of its front border meet at a distinct but very obtuse angle ;
j;rooves extending from the dorsal furrow nearly to the extremity of
tlie pleurae, where they disappear.

"Pygidium somewhat semicircular in outline, distinctly trilobate;
segmentation indistinct, so much so in some of the specimens that the
surface appears nearly as plain as that of an Aaaphm, but the seg-
mentation is usually more distinctly shown upon surfaces from which
the crust has been removed; axis prominent, especially at its distal
end, where it terminates abruptly at the inner edge of the broad mar-
ginal border; segments of axial lobe eight or ten; lateral lobes much
depressed, a little wider than the axial lobe at the anterior end, and
narrowing to an incurved point at the end of the axis; the whole exte-
rior margin having a broad, flat border of nearly uniform width through-
out ; the under surface of this border marked by fine, somewhat irregular,
longitudinal striae, such as are usually seen upon corresponding parts
of Asaphus.

''The largest specimen in the collection is about seven centimeters
long.

"These specimens are the same that were used by Mr. Meek in his
(lesciiption of this species, and upon which he also based his genus
Amphiscus." '

All the specimens are more or less flattened by compression; but
from a few that show portions of the original convexity it is proven to
have been about as in the genus Bathyurus. The strongly marked
border of the pygidium also arises from the compression of the doublure
up against the upper surface. In an uncompressed specimen the slope
from the central axis to the margin is unbroken by any marked line.

Formation and localities. — Middle Cambrian. House Range, Antelope
Springs, Utah. An identical form of pygidium also occurs at Pioche,
Nevada, associated with Olenoides typicalis.

Genus DOETPYGE Dames.

Dori/pyge Dames, 1883. China, Richthofen, vol. iv, p. 23.

It was not until the last pages of this report were put in type that I
had the opportunity of reading Dr. Dames's description of the genus

(947)

222

CAMBRIAN FAUNAS OP NORTH AMERICA.

[kULu 3a

Dorypyge and his reference of JDikellooephalus quadriceps and D. gothicun
of H. & W. to Uiat genus (China, Bichthofen, vol. iv, p. 24).

On pages 187 and 189, 1 have placed the two species under the genuH
Olenoides while waiting for proof of the character of the border of the
pygidium of the genus. I have very little doubt of its being spinous,
and if it is so the species described by Dr. Dames will probably fall
within its limits, and the genus Dorypyge be placed as a synonym of
Olenoides.

In the event of Olenoides Nevadensis being generically distinct from
J>orypyge Riehthofeni Dames, then Olenoides typicalis, 0. Mareoui, 0.
spinosus, 0, Levis, 0. flagricaudus, O. expansus, 0. quadriceps, and 0.
Wahsatehensis may be referred to the genus Dorypyge.

It is hoped that this question will be settled during the present year
by the acquisition of large collections of fossils from the typical localities
in Utah and Nevada.

(948)

DESCRIPTION OF

A PTEROPOD
CAMBRIAN.

FROM THE UPPER

PTEROPODA.

Genus MATTHEVIA Waloott.

Matthevia Waloott, 1885. Amer. Jour. Sci., 3<l Her., vol. xxx, p. 17.

Shell conical; aperture sinuous; transverse section ovate, elliptical, or
rounded subquadrate; interior with two elongate chambers diverging
from the apex and opening into a large, single, terminal chamber; both
of the interior chambers are crossed by a single imperforate septum;
calcareous ; surface papillose. Operculum calcareous, nucleus eccentric,
lines of growth concentric.

Type, Matthevia variabilis.

The generic name is proposed in honor of Mr. G. F. Matthew, who is
doing so much good work on the St. John Cambrian fauna.

This peculiar shell is so distinct from all described forms referred to
the Pteropoda that a new family, Matthevidae, is instituted to receive
the one genus now known.

In form and surface markings it approaches the genus Gonularia;
the operculum may be compared to that of Hyolithes and the imperfo-
rate transverse septum allies it to both Hyolithes and Gonularia. Its
thick shell is observed in the genera Gonularia, G.feeunda Barr. (Syst.
Sil. Boh^me, vol. iii, pi. viii, fig. 8) ; Hemiceras, H. cylindricm Eichwald
(Lothea Ross., vol. i, atlas, pi. xl, fig. 17; pi. xlii, fig. 29); and Hyolithes,
H. impar Ford (this Bulletin, pi. xiv, fig. 1). When we come to trace
a relationship to the two inner chambers, we are at once at a loss for
comparisons. The genus Pterotheca has a shelf-like projection that
may indicate a division of the animal, and we may look to the shelf-
bearing gasteropods, Grepidula, &c. ; but, while these may indicate the
origin of the dividing shell between the two chambers of Matthevia, the
latter remains clearly and distinctly a type by itself.

There is a curious form described as Tetradium^ Wrangeli Schmidt
(M^m. Acad. Imp. Sci., St.-P^tersbourg, vii« s6r., t. xxi, No. 11, p. 42;
t. iv, figs. 3-8, 1874), which Lindstrom suggests is by the thiek-shelled
Gonularia femnda linked to the Gonnlarise and made to stand in affinity
to them (Sil. Gasteropoda and Pteropoda of Gotland, p. 41, 1884).

'The genus Tetradium being preoccupied (Dana, 1846; Safford, 1856), I propose
Palaonigma in place of Schmidt's Tetradium, 1874, for the species under diBcnBsion, P.
Wrangeli.

(940)

W79

.If w

V . II'

i l' 1"

»il

224

CAMBRIAN FAUNAS OF NORTH AMERICA.

lBIILL.30.

From onr comparisonH Matthevia appears Htill more to nerve an a con-
necting link between Palamif;ma and the genera Connlaria and Uyo
Utiles. If i*. Wram/eli I'au chambers running up into the shell, as jh
suggested by the cross-sections, and a septum that caused the \i]m'r
portion of the shell to be decollated, as we are led to believe by the nat-
ural section shown by tig. 2b, pi. ;(xxiii, and by the fact that each speci-
men has lost its apex, the relations between Palu)nigma and Matthevia
are quite close, and Paltenigma may be, provisionally at least, groui)ed
with the Paleozoic genera Matthevia and Goinilaria.

Matthevia variabilis Walcott.

Plate xxxii, ilgn. 1-12; pi. xxxiii, Hkb. 1. la-/.

Matthevia variaMUn Wulcott, 1885. Aiuer. Jour. 8oi., 3d aur., vol. zxx, p. 18, figs. 1-6
of p. 20.

On a side view the outline of the shell varies from broad to narrow
conical, and the end view shows an elongate-conical to a broad-conical
outline; the cross-section varies from elliptical to oval to rounded quad-
rangular; aperture varies in outline with the proportions of the shell;
a sinus, varying in depth and curvature, extends aoi'oss the ends of the
shell; in the more elliptical apertures the sides are nearly straight and
parallel, while in those with a subquadrangular outline they are strongly
curved, and the sinus at the ends is very profound. A longitudinal
cross-section shows, in the larger number of shells, a sect.on similar to
that represented by fig. la of pin, ^ xxxiii ; figs. 1, 16, Id, exhibit the
variations in section taken at the samt ^ ' '>e in different shells that vary
in outline. The shell thins out at the ed^v and is not thick over the
exterior of the interior chambers, but between .lem a connecting mass
of shell unites the sides and gives strength and solidity ; a section cross-
ing the center of the shell at right angles to the preceding shows a solid
shell to the outer chamber, where it gradually thins out to the margin.
The positions of the two inner chambers var,\ in relation to each other,
as may be seen in the figures, from subpaii^Uel to widely divergent; the
chamber that is more at right angl^ss !> the aperture than the other is
usually larger and is always prominent, while the oblique chamber is
sometimes filled up by shelly matter and only the outer portion remains;
both chambers are usually flattened on the inner side and more or less
expanded where they enter the large outer chamber. The septum cross-
ing the inner chambers is thin and varies in shape with the form of the
chambers; it is usually slightly concave-convex, concave towards the
outer chamber, and marked, usually, by a raised scar of varying char-
acter, as is shown in the figures; the septum is usually a short distance
from the outer chamber, l""*" to 4°"".

The substance of the shell is calcareous, and in thin sections appears
to be vesiculose, as in figs, le, If, of plate xxxiii.

(950)

WAunn,]

tTtftOtOD FROM ThE UPPEfe CAMBRIAN.

225

Surface marked by undulating lineu of growth parallel to the margin
of the aperture, a few radiating lines UHUuUy on the sides, and several
floe papilltiB arranged in lines that cross each other at right angles on
some shells ; on others the papillte are arranged in lines parallel to the
lines of growth and without reference to the order of those in the ad-
joining lines; the interior surface is covered with a fretted surface
brought out by depressed, irregular, inosculating lines; this surface
varies in force and character, and some shells are almost smooth in-
side ; a narrow, smooth space extends all around the margin of the in-
side of the aperture.

The associated opercula vary in form and outline ; the shell is calca-
reous, concavo-convex, rising to a blunt point more towards one end
than towards the other ; from this point, which is the center of the con-
centric undulations of growth, narrow, radiating undulations extend to
the margin. Surface with concentric and radiating undulations; fine
inosculating lines subparallel to the concentric undulations and flue
papilla) on the spaces between the inosculating lines ; interior surface
convex, smooth, or showir ?; the undulations of the outer surface ; at the
center, corresponding to the apex of the outer surface, a small round
Hcar appears to be indicated on some specimens.

There are two forms known to me that correspond in a measure to
this: one is that figured by Eichwald (Lethea Koss., pi. xl, fig. lOo-c*)
as Hyolithes paradoxodtia, which appears to be the cast of a portion of
the outer chamber and one of the conical inner chambers ; it may be,
however, only a superficial resemblance. The second was discovered
when examining the type of Metoptoma anomala Billings (Pal. Foss.,
vol. i, p. 89), in the collection of the Geological Survey of Canada. I
found it to be the cast of the chamber of habitation of some species of
Matthevia. It may be that of M. variabilis, but it is impossible to iden-
tify it from the specimen. It was found in a bowlder of limestone at
Point Levis, Canada.

Formation atid locality. — Upper Cambrian. Limestone resting on
Potsdam sandstone, one mile northwest of Saratoga Springs, New York.

The species is associated with Cryptozoa poriferum Hall (Thii ty-sixth
Adn. Kep. N. Y. State Mus. Nat. Hist., description of pi. vi, 1884), Pla-
tyceras minutismmim Walcott, Ptychoporia {L.) calcifera Walcott, Dicel-
locephulus Hartti Walcott, and 1). speciostis Walcott.
Bull. 30 15 (961)

imi

Jlil *

J '

PLATE I.

Fig. 1. Ethmophtllum'profunpom

1. Enlargement of a portion of a transverse section of specimen in which
the growth appears to have been in layers. Collection U. S. National
Mnsenm.

la. Outline of the section from which fig. 1 was enlarged.

lb. Enlargement of a portion of the section shown by fig. 36 of plate ii.
The vesiculose stracture is well shown. Collection U. S. National Mu-
seum.

lo. Secciou of solid stem. Natural size. Collection U. S. National Museum.

88B (962)

n. 8. OEOLoo-.cAL iiaavEY

> in which
National

f plate ii.
tional Mu-

1 Museum.

BOLLETIN N'O 3J l-L I
1(1

,S*»'.-'

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, ^ d;

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t'f , il

I'l

■ft

t ' t ■

PLATE n.

Paga

Fig. 1. ARCHiEOCTATHi. ' T , tticUS 73

1. Transverse section *.ype specimen now in the Museum of the Geo-

logical Survey of Cii da.
la. Longitudinal section of 1. At "a" the growth within the cup, spoken
of in the text, is shown. The elongate body, " b," is probably a foreign
body introduced into the cup.

Fig. 2. Lkptomitus Zittku 89

2. View of the typo specimen. Natural size.

2a. Enlargement of a portion of 2, between the dotted lines. Collection U.
S. National Museum.

Fig. 3. ETHMOPHYLLUM PROFTJNDUM 84

3. Portion of a cast of the interior of the outer wall, showing the openings
in the septa. Collection U. S. National Museum.

3a. View of the cup of a small specimen. Collection U. S. National Mu-
seum.
. 3b. Longitudinal section showing the depth of the cup and the vesiculose
character of the space betwt.^n the walls. An enlarged view of the
lower portion of this figure is shown on pi. i. Collection U. S. National
Museum.

230 (956)

Ur n.zi.or.'^.Ai.Biii'vzi

fCLLKTIN NO, SO I L.

fPi^H^i:iil/

wlm?f

'^if[

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I 4

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*'ii

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l:lk^i

PLATE III.

Page.

Figs. 1,2. Arooaiooyathus Atlantious 73

1. Tranaverae section of apecimen from L'Anae an Lonp, Labrador, en-

larged to abow the irregular openings. Collection U. S. National

Museum.
la. Longitndinal section showing more regularity in the arrangement of

theskeleton than in the type apecimen, pi. ii, fig. la. Collection U. S-

National Mnaeum.
lb. Longitndinal section of a apecimen fr pa Silver Peak, Nevada.

2. Longitudinal section of specimen from silver Peak that shows still more

regularity in the interior structure than either la or lb. Collection
U. S. National Museum.
2a. Tranaverae section of fig. 2.

Pig. 3. Abch^ocyathus Billingsi

3. Transverse section of a small specimen. Collection U. S.' National

Museum.
3a. L iigitudinal sectiou showing the central cavity, transverse septa,

etc. The outer walla are mostly worn away. CollectionU.S. National

Museum.
3b. Enlargement of a few transverse septa, showing the irregular vertical

septa, pore openings in the septa, and the spicula-like pieces in the

interaeptal spaces.
3e. Enlargement of the spicula-like bodies in the onp and interaeptal

■paces.

834 (960)

C B QtOLOGlCAL irjKVET
1

'■rTLLETlM i;0. 3J PL. lU

O'Mm

^^1

■ 'if^ i

if •'' !^

•■■a.

i^'l.

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m'l

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.1 '

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PLATE IV.

Fig. 1. Ethmophyllum Whitneyi

1. Enlargeniout to two tliaincterH of one of the type speoimenH. Colleotion
U.S. National MiiHenui.

la. Enlargement of Mie outer Hinf'are to lOdiaineterH. Collection U. 8. Na-
tioiial MuHeuni.

lb. Longitudinal motion of a Hpeciuien ^bowing the vemcuIoHe inner wall,
whicb, whtn the outtr wall and septa are broken away, gives the form
described by Mr. Metik n^; K. yraoUia. Collection U. S. National Mu-
seum.

Ic. Transverse siction showing +he structure mentioned of fig. 1ft still
more clearly ; also, the septa and poriferous outer wall. 37 septa. Col-
lection U 8. National llusenni.
. Id, le. Two transvuiso sections of a very small Hpecimeu, in which the walla
and septa are tbickcniMl.

y, Trnnsverae section, l..")""" in diameter, showing eight septa. Collec-
tion V. 8. National Museum.

\g. Similar section to 1/', with 14 septa. The two sections represented by
tigs. \il, \e, indicate irregular growth, and 1/, \g, the uninterrupted,
natural growth of the s]H>cies. Collection U. 8. National Museum.

\h. A largin- transverse section, with .')8 septa ; numerous partitions b jtween
the septa, the outer ]>oriferons wall, an<l the openings between the
septa. (,'olle(ttion U. 8. National Museum.

Fig. 2. ETH.MOPII YLI.U.M

2. Diagriimmatic vertical section through the ceuteron the line of the septa,
to show the writer's view of the poriferous system. If the outer wall is
removed, the large jiores on the line of the septum would be shown as
in lig. 1, pi. i v, and tig. 2, pi. v. The inner wall is perforated by smaller
openings, and fewer of tbeui, than the outer wall.

Ethmophyllum pkokundum 1

3. Enlargement of a portion of the section represented by fig. 1, pi. i, to
show the complicateil stfUCture more clearly.

838 (964)

Page.

u. a. aE0L03:cAL bohve?

1/>

^ ,^f;;*

^Ufl

«i •

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i^B-

■'

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PLATE V.
Fig. 1. Ethmophyllum Rrnssklakkicum

Fftge.

la.

Id.

1. A nearly perfect specimen, sbowiog the summit and the outer poriferous
surface. Collection U. S. N^^tioual Museum.

A speciiuen witli portions of the outer wall removed, so as to show the
septa and the poriferous surface of the inner wall. Collection U. S. Na-
tional Museum.

Transverse section showing 12 septa and the pores of the inner and
outer walls, enlarged. Collection U. S. National Muiteum.
Transverse section of the upper end of lo, with 18 septa. Collection
U. S. National Museum.
Transverse section, where the walls and septa are thickened by addi-

tional layers. Collection U. S. NatioPbl Museum.

le. Enlargement of the outer poriferous surface.

If. Drawing of the type specimen, by Mr. S. W. Ford. The poriferous sur-
face in worn off on the raised portion. I am not satisfied but the dis-
sepimeiits are of accidental origin. There are about 20 septa in the
transverse secti' >n of the specimen. Collection S. W. Ford.

Fig. 'i. Ethmophyllum rarum

2. View of the only specimen that can be referred to this species in the col-

lection of the Geological Survey. The outer surface is entirely re-
moved. Collection U. S. National Museum.

2a. Transverse section of the lower end of 2, showing 9 septa.

26. Drawing of the type specimen, by Mr. S. W. Ford. There are about 21
septa and the outer surface is removed. Collection 8. W. Ford.

Fig. 3. EOCY8TITE8 ? f LONGIDACTYLU8

3. Enlargement of one of the plates occurring at Pioohe, Nevada,
tion U. S. National Museum.

Colleo-

(968)

8 GEOLOaiCAI- ECRVEr

BULLETIN NO. 30 FL V

it »

■^1
.11

SPONGI02CA.

iCHl.\CL:Ef^!v'ATA.

5 ■-:

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'I'^j;: K^iK

1 1 fii''

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i ■' .

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i
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'ifil

PLATE VI.

Fig. 1. EOCTSTITES t f LONOIDACTrLUS

1. Upper half of the body of a large specimen, pieserring several of the
long, slender arms. The summit is crushed on the right side, causing
the arms to bunch together. Natural size. Collection U. S. National
Museum.

la. Outline figure, natural size, of a specimen with the plates crushed in on
each other.

lb. Enlargement of the summit of a specimen from which the plates have
been broken away, showing the structure of the arms and the casts of
the short pinnulse. Three times natural size. Collection U. S. National
Museum.

lo. Enlargement of a group of plates from a large specimen, to show varia-
tion in size, outline, surface markings, and the differences in the open-
ings or pores on the margins of the plates.

Fig. 2. Protosponoia 1 fbnbstrata f 90

2, 2a, 2h. Three forms of spiculaa. 2a is the form rarely met with. Colleo-
tion U. S. National Museum.
846 (972)

U. B. CEOl^OClCAL DOKVEi

BOLLEXII! in. 39 FL. VI

SPONGlCZOA. ECH'NGDE = 'v'ATA.

! (

IM'

I 1.*

PLATE VII.

P»ge.
Fig. 1. litNOULELI^ C^LATA 95

1. Ventral valve, enlarged U> 2 diameters. (Drawing by 8. W. Ford.)

Collection 8. W. Ford.
la. Hide view of same, with a view of the beak, looking from behind.
lb. Enlargement of a small dorsal (t) valve. Collection U. S. National

Museum,
lo. Dorsal valve, enlarged. Collection U. S. National Museum.
Id. Surface of dorsal valve, greatly enlarged. *

Fig. 2. LiNOULELLA Ella 97

2. Ventral valve, showing the area, deltidial opening, and oast of the ex-

terior surface of the valve. Enlarged. See pi. viii. Collection U. S.
National Museum.

Fiff. 3. KUTORQINA PANNULA lO.'i

3. Ventral (?) valve, enlarged. The type specimen. Collection U. S. Na-

tional Museum.
3a. Enlargement of a portion of the surface of 3. if ^i plate viii.

Fig. 4. IPBIDEA BELLA 100

4. Copy of the original figure given by Mr. Billings. Ventral (f) valve.

Collection Geological Survey, Canada.

Fig. 5. ORTH181NA TRANSVERSA 121

5. Ventral valve, enlarged to 2 diameters. Collection U. S. National Mu-

seum.
5a. Another specimen, showing the area. Collection IT. S. National Mu-
seum.

Fig. 6. Orthisina Orientalis 120

6. Ventral valve, natural size. (After Whitfield.) Collection American

Museum Nu.tural History, New York City.

Fig. 7. Orthisina FE8T1NATA 120

7. Ventral (?) valve and outline, natural size. Collection U. S. National

Museum.
7a. Dorsal (?) valve, enlarged. Collection U. S. National Museum.
76. View of area of 7a. Collection U. S. National Museum.

Fig. 8. Camarella (?) antiquata 122

8. Ventral yalve, enlarged. Collection U. S. National Museum.

260 (976)

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PLATE VIII.

Fig. 1. ACROTRETA OKMMA 98

1,1a. Summit und side views of the dorsal valve, enlarged 3 diameters.
Collection U. 8. National Museum.

lb. Ycntra! valve, enlarged to '\ diameters. Collection U. S. National Mu-
seum.

Fig.2. KUTORGINA PANNOLA 105

2, 2a. Side and summit views of the dorsal valve, enlarged 3 diameters. Col-
lection U. S. National Museum.

26. Ventral valve, enlarged to 3 diameters. Collection U. 8. National Mu •
Houm.

2c. Enlargement of the svrface of 2b.

Fig 3. Orthis (?) Highlandemsis 119

3. Dorsal valve, with most of the exterior shell worn away. Collection

U. 8. National Museum.

3<(. Cast of the interior of the ventral valve. Collection U. S. National
Museum.

3ft. Exterior of the ventral valve, with the side restored from another speci-
men. Collection U. S. National Museum.

Fig. 4. LiNGULELLA Ella 9T

4. View of the type specimen, enlarged to 2 diameters. Collection U. 8.

National Museum.
4o. Cast of the interior of the dorsal valve, showing the position of the

muscular scars. Collection U. 8. National Museum.
4ft. Cast of the interior of a very small dorsal valve, enlarged 6 diameters.

Collection U. S. National Museum.
4t> Cast of the interior of a very small ventral valve, enlarged 6 diameters.

Collection U. 8. National Museum.
4rf. '".ompressed ventral and dorsal valves from the shales of the Chisholm

mine. Natural size. Collection LT. 8. National Museum.
4e. Enlargemeiit of the snrl'ace of a specimen from the shales at the Chia-

hoh 1 mine. Collection U. 8. National Museum.

Fig. 5. Lepkrditia Argknta 146

5. Crushed specimen of the left valve of the carapace. Natural size. Col-

lection U. S. National Museum.

Fig. 6. SCENELLA conula 127

6. tia. Side and summit views of the type specimen, enlarged to 4 diametera.

Collection U. S. National Museum.

«4 (980)

Ptg^

diameters,
tional Mu-

itere. Col-
/ional Mu-

105

'^b

Collection
. National
tber speci-

ion U. S.
on of the
Liameters.
iameters.
Chisholm
the Chis-

ze. Col-

lameten.

119

146

127

;!/(

-,achi!Jp:>ja.

.CEA.

■i. J

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PLATE IX.

Pagoi

Fig. 1. KUTORGINA CINGULATA 102

1, la, lb. Yentrul, lateral, aud dorsal views of a large shell tbat is mostly
denuded of the outer surface. Collection U. S. National Museum.

Ic. Lateral view of a sniall shell, to compare ' 'ith la, the height of the
dorsal valve being much less than that of la. Collection U. S. National
Museum.

Id. Cast of the. interior of the dorsal valve, showing muscular scars. Col-
lection U. S. National Museum.

hu Dorsal valve, enlarged. Collection U. S. National Museum.

If. Interior of dorsal valve. Collection U. S. National Museum,

lij, Ih. Compressed shells from shales of Parker's quarry ; probubly ventral
valves. Collection U. S. National Museum.

Fig. 2. KUTORGINA .lAHUADOKlCA 104

2, 2a. Ventral valves, enlarged. Collection U. S. National Museum.
2b, Dorsal valve, tnilarged. Collection U. S. National Museum.

Fig. 3. KUTORGINA PjtOSPECTKXaiS 106

3. Ventral ''alve, enlarged. Collection U. 8. National Mviseum.

13a. Dorsal valve, enlarged. Collection U. S. National Museum. *

Fig. 4. ACROTHELK SUBSIDUA 108

4. Ventral valve from Pioche, Nevada, showing exterior surface, enlarged.

Collection U. S. National Museum.

4a. Interior of dorsal valve, enlarged. Collection U. S. National Museum.

46. Ventral valve fiom Antelope Springs, Utah, with exterior surface re-
moved, enlarged. Collection U. S. National Musonrii.

4o. Cast of interior of dorsal valve, enlarged. Coliection U. S, National
Museum.
a58 (984)

BDLLETIN NO. 33 PL. IS

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PLATE Z.

Figf. 1. ObOLBLLA CRA8SA 114

1. Tentral valve, abowing well-preserved exterior surface, enlarged to 3

diameters. (Drawing by 8. W. Ford.) Collection 8. W. Ford,
la. Dorsal valve, with the outer surface exfoliated, enlarged. Collection

U. 8. National Museum.
lb. Dorsal valve, preserving outer surface, enlarged to 2 diameter . (Draw-
ing by S. W. Foxd.) Collection 8. W. Ford,
lo. Cast of interior of dorsal valve ; notation same as Id. Collection U. 8.

National Museum.
Id. Diagrammaticdrawingof the interior of dorsal valve. (Drawing by 8.

W. Ford.) «, cardinal; c, central, and d, lateral muscular scars; x,

area,
le. Cast of interior of ventral valve ; notation same as 1/. Collection U. 8.

National Museum.
if. Diagrammatic drawing of the interior of ventral valve. (Drawing by 8.

W. Ford.) a, cardinal; c, central, and d, lateral muscular scars; p,

pedicle groove.

Fig. 2. Obolella ormma 116

2. Exterior of a somewhat macerated specimen of the ventral valve, from

Bic Harbor, enlarged. Collection U. S. National Museum.

2a. Ventral valve from Troy, New York, enlarged to 6 diameters. (Draw-
ing by 8. W. Ford.) Collection 8. W. Ford.

2b. Interior of ventral valve from Bic Harbor, a, cardinal; d, lateral, and
0, central muscular scars ; p, pedicle groove. Collection U. 8. National
Museum.

2o. Interiorof ventral valve from Troy, New York. The differences between
26 and 2o are largely owing to the condition of preservation of the shells.
Notation same as 2b. Collection U. S. National Museum.

2d. Interior of dorsal valve from Bic Harbor. Better spr^cimens will be re-
quired in order to make out the details of structure. Collection U. 8.
National Museum.

2e. Exterior of dorsal valve from Troy, New York. Collection U. 8. Na-
tional Museum.

All figures of 2, enlarged.

Fig. 3. Obolella CiRCK 118

3. Interior of dorsal valve. Compare with Ic, Id. Notation same as fignres

lo. Id. Collection U. 8. National Museum.
3a. Interior of ventral valve (f ) ; 3 and 3a from L'Anse aa Leap. Collet*
tion U. 8. National Museum.

868

(088)

n. OEOLOaiCAL bdrvei

H -ih

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, • PLATE XI.

Fig. 1. OBOLEI.LA CHHOMATICA 112

1. DoTBal valve from L'AnHe an Loup, enlarged. Collection U. S. National

Miiaeuni.

la. Ventral valve from L'Anse au Loup, enlarged. Collection U. S. Na-
tional Museum.

lb. Interior of dorsal valve, enlarged. Scars the same as in O. oraata.
Collection U. 8. National Museum.

Fig. 2. OBOLELLA NITIDA 118

2. Dorsal f valve, enlarged to 5 diameters. (Drawingby 8. W.Ford.) Col-

lection S.W.Ford.

Fig. 3. FORDILLA Tboyensis , 125

3. Kiglit valve, enlarged. Collection U. 8. National Museum.

3a. A shorter right valve than that of 3, enlarged. Collection U. S. Na-
tional Museum.

36. Cast of the interior of the right valve, enlarged. Collection U. 8. Na-
tional Museum.

3c. Left valve, enlarged. Collection U. 8. National Museum.

Fig. 4. DiPLOGRAPTUS f SIMPLEX 92

4,4a. Two fronds, natural size, from the fine-grained argillites of Parker's
quarry. Collection U. S. National Museum.

Fig. 5. Climacograptus ? ? Emmonsi 93

5. The only specimen known to mo. Collection of Mr. E. Hurlbart.

(992)

•J. B. 0E0L03ICAL QCRVEY

BOLLBTIN NO. SJ PL. X:

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PLATE Xn.

Page.

Fig 1. StENOTHKCA RUGOSA 128

1. Lateral view of a nicdiuiu-Hized specimen. Collection U. 8. National

Mnseuui.

la. Lateral view of a more elevated and coarsely aunulated specijueu than
1. Coll»>ctioii U. S. National MuHenni.

16, 1<!. Summit views of two apocinieus, to show eccentricity of apex. Col-
lection IT. S. National Museum.

Id, le. Side and summit views of a very small shell. Collection U. S. Na-
tional Museum.

All the specimens iij^ured are from Troy, New York.

Fig. 2. SCKNKI.I.A ? VARIANS 127

2. Summit and lateral views of specimen with concentric apex. Collec-

tion TJ. S. National Museum.
2a. Lateral view of s])ecimcn with eccentric apex. Collection U. S. Na-
tional Museum.

Fig. W. SCRNKI.LA RKTUSA 12ti

[i. Smumit and lateral views of the type specimen ; enlarged 3 diameters.

(Drawing? by S. W. Ford.) Collection S. W. Ford.
3a. Sunmitt view of a s|)ecimen iVoiii Troy, New York, doubtfully referred

to the species. Collection II. S. National Museum.

Fig. 4. Stknotheca icloxgata l-Xt

4. Summit view of specimen from L'Anao an Loup. Collection U.S. Na-

tional iMusenm.
4a, 4/). Sunnuit and lateral vii^ws of specimen from the £<ireka District,
Nev.ada. Collection U.F. National Museum.

Fig. 5. ri.ATYCKUAS PKIM^VU.M 130

5. View of cast, right side. Collection U. S. National Museum.

r)a. Left side, enlarged to show characters of the outer surface of the shell.
Collection U.S. National Museum.

Fig. <). SCENKI.I.A KETICtTLATA 125

G, Ga. Enlarged figures of the two supposed type specimens from Topsail
Head, Newfoundland. Collection Geological Survey of Canada.

Fig. 7. Salterkli.a pulchem.a I44

7, 7a. C.istsof specimens in the "Red Sandrock," east of Highgate Springs,

Vermont. Collection U.S. National Museiun.
76, 7f'. Specimens from the "Winooski" marble, near Swanton, Vermont.
These probably belong to a ditt'erent sjiecies. Collection U. S, National
Museum.
PO (00(5)

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PLATE XIII.

Page.

Fig. 1. Hyolithes Billingsi 134

1. la, lb. Lateral, ventral, an<l dorsal views of a sitecimon from Pioche,

Nevada. Collection U. S. National Musoum.
lo. Transverse section of specimen from Pioche, Nevada. Collection U. S.

National Museum.
Id. Operculum associated with 1 in same fragment of rock. Collection U.

S. National Museum.
le. Specimen from L'Anse an Loup. Dorsal view and outline of transverse

section. Collection U. S. National Museum.

Fig. 2. Saltkreixa rugosa 145

2. Enlarged view of a specimen fron; l/Ause au Loup. Collection U. 8.

National Museum.

Fig. 3. Salterella pulchella 114

3. Lateral view of a specimen fioni a pebble in the Point Levis limestone

conglomerate. Collection U. S. Nitioual Museum.
3o. A specimen from same locality, showing the aperture and one of the
inner tubes. Collection Geological Survey of Canada.

Fig. 4. Hyolithes sp. uudt., from Troy, New York. Collection U. S. National
Museum. '

Fig. 5. Hyolithes prixceps 135

5, 5a. Dorsal and side view (natural size) of specimens from Bic Harbor.

Collection U. S. National Museum.
56. Outline of transverse section of a more convex tube. Collection U. S.
National Museum.

Fig. 6. Hyolithes Americanus V3'/

6. Ventral view. Collection U. S. National Museum.

6a. Dorsal view of a narrow specimen. Compare with 6f. Collection U.

S. National Museum.
6b, 6o. Transverse sections showing dilfereuces in outline. Collection U.

S. National Museum.
6d, 6e. Opercula. Collection U. S. National Museum.
Of. A small, unusually broad specimen. Collection U. 8. National Museum.

All specimens of 6 from Troy, New York.

274 (1000)

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PLATE XIV.

Pig. 1. Hyolithes impar '. 139

1, la. Lateral and ventral views of the type specimen. (Drawing by 8.

W. Ford.) Collection 8. W. Ford.
lb. Outline of cud of tnbe at point of septnm, and transverse section of

same, enlarged. Collection U. 8. National Museniu.
lo. Transverse section of 1.

Id. Operculum from Troy, New York. Collection U. 8. National Museam.
le. Cast of tube, showing constriction at the septum. Collection U. S.

National Museum.

Pig. 2. Hyolithellus micans 142

2. A fragment of the shell remaining in a natural mold, enlarged to show

the annulations. Collection U. 8. National Museum.

2a. Enlargement of the terminal portion of » tube. Collection U. S.
National Museum.

26. A crushed specimen in shule. Presented by S. W. Ford. Collection
U. 8. National Museum.

2o. Exterior of operculum. Collection U. 8. National Museum.

2d. Cast of the interior of an operculum. Collection U. 8. National Mu-
seum.

2e. Interior of nn operculum. Collection U. 8. National Museum. All
specimens from Troy, New York, except 2b, which was found one mile
below Schodack Landing.

Fig. 3. Hyolithes communis 138

3, 3a. Dor.sal and side views of specimen from Bio Harbor. Natural size.

Collection IT. 8. National Museum.

3b. Another specimen from Bic Harbor, Collection U. 8. National Museum.

3c. Operculum from Bic Harbor. Collection Geological Survey of Canada.

3d, 3e. Specimens from Troy, New York. Collection U. 8. National Mu-
seum.

3/, 3g, Transverse sections to show irregularities of thickness of shell.
Collection U. 8. National Museum.

Fig.4. Hyolithes communis var. Emmonsi 187

4. Dorsal view of specimen showing evidence of three layers of shell and

a septum. Collection U. 8. National Museum.
4a. Ventral view of a specimen, showing the constriction at the point of
decollation of the apex. Collection U. 8. National Museam.

S78 (1004)

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PLATE XV.

Paca

Fig. 1. Protooaris Marshi 148

1. Figure given in Bnlletin 10, U. 8. Geological Survey, plate x. Descrip-
tion on page 50. Reproduced here in order to show the Bfiddle Cam-
brian fauna, as known to me, in one series of plates. Collection U. 8.
National Museom.

(1008)

C. B. OEOLOQICAL BCRVET

EOLLETIN NO. 3) rL. S.7

148

>e8orip-
le Cam-
n U. 8.

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PLATE XVI.

Pig. 1. MiCRODISCtTS L0BATU8 l&C

1. Head, very muc]« enlarged. Collection U. S. National Mnaeum.

la. Head, shovriug considerable variation ft'oni 1. Collection U. S. Nation-
al Mnaenm.
1ft. Pygidiuro, very mnch enlarged. Collection U. S. National Mnsenni.
Original Bpecimens from Troy, New York.
Fig. 2. MiCRUDiscus Pabkbri V>7

2. 2a. Head and pygidium, enlarged. Collection U. S. National Museam.

Fig. 3. MiCRODISCUS 8PECI08U8 154

3. 3a. Top and side views of a specimen, enlarged to 2 diameters. (Draw-

ings by S. W. Ford.) Collection 8. W. Ford.
3ft'. Pygidium, similarly enlarged. (Drawing by 8. W. Ford.) Collection

8. W. Ford.
3o. Very perfect hrad from Troy, N. Y. Collection U. 8. National Museum.
Fig. 4. MicRODiscuH Mkrki , ir>5

4. Type specimen, enlarged to abont 3 diameters. (Drawing by 8. W.

Ford.) Collection 8. W. Ford.

Fig. 5. Lbperditia Trotbnsis 14(>

5. Sketch of the type specimen, enlarged to 3 diameters. (Drawing by 8.

W. Ford.) Collection 8. W. Ford.

Fig. 6. AGNOSTUS INTKR8TB1CTU8 149

6. 6a. Top and side views of the type specimen. Collection U. 8. National

Musenm.

Pig. 7. AGNOSTU8 NOBILI8 150

7. Copy of Mr. Ford's original figure. Original specimen lost.

286 (1012)

V. B. lEOLOJIOiI, 8tTR7Er

BULLETIN NO. ») PL. X7:

15C

. Ntttion-

isenni.

useniu.

154

(Draw-

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[useum.
155

' S. W.

146

gbyS.

149

ational

150

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PLATE XVIL

FigB. 1, 2, 4, 9. Olrnkllus Tiiompsoni

1. Heiul with an unusually broad liorder, fWxn Swanton, Vermont. Col-
lection U. S. National MuMMiin.

2. Entire npccinien from line arKillacoous abales at Parker's quarry. Col-
iKctinn U. 8. National MuHeuui.

4. ThIhou or pyK><liii<>i found in tbo Wiuooaki marble series, weut of Park
er's quarry. Collection U. S. National Museum.

9. A very iwrfect bead, preserving tbe natural convexity, from the de-

comiHised niiignesian limestone east of Swanton. As portions of tbe
specimen were broken away otber specimens were used to aid the
drauKbtsman in reiiresenting nn entire bead. Collection U. S. National
Museum.

FigB. 3, ,5, 6, 7, H, 10. Olenkllus asapiioid!:^

3. Telson associated with fra^i'Heuts of this species at Troy, New York.

Collection U. 8. National Museum.

5. Tbe youngest stage of dovelopuiont yet observed by tbe writer. Length,

fonr-fifthN of one millimeter. Collection U. 8. National Museum.

6. A slightly larger specimen, l.TG'"'" in length. Collection U. S. National

Museum.

7. Adult form. (After Ford.) Collection S. W. Ford.

8. Young form. (After Ford.) Collection 8. W. Ford.

10. Hypostoma associated with, and supposed to belong to, thia speoiM.
Collection U. 8. National Museum.

290 (1016)

Page.
167

168

H. aC0LO<llCAL 8CRVET

bOLlCriN NO. U L. X7:

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PLATE XVm.

Fig. 1. Olenellus Oilbbrti

1, la. Top and lateral views of type specimen from Pioohe, Nevada. Col-
lection U. S. National Museum.

lb. Fragment of a large head from the Eureka mining district, Nevada.
Collection U. S. National Museum.

le. Free cheek found detached from fixed cheek. The direction of the
suture in front of the eye is well defined ; its direction, posteriorly,
may be along the line of fracture, oo} but it is impossible to satisfac-
torily determine it ; if as in fig. li of pi. zz, it would follow the dotted
line 0, X. Collection U. S. National Museum.

294 (1020)

Pag&

170

f. B. GEOLOOICAL BCRVET

bcllet::; i:o. 30 pl. sviir

i,(

la. Col-
Nevada.

n of the
Bteriorly,
satisfao-
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p.t£Cilcpod;

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i M

PLATE XDL

Pftge.
Fig. 1. Olenellus Idoingsi 170

1. View of the type specimen, enlarged to 2 diameters. Collection U. 8.

National Musenm.
Pig. 2. Olenkixus Qilbbrti 170

2, 2a, 2b, 2k, Figures of the type specimens illnstrated by Dr. White, from

Pioche, Nevada.

20, 2g, 2h. Specimens from the Eureka district, Nevada.

2d. A portiou of a head referred to this species, showing the same carrying
forward of the genal angles that is shown in specimens from the Eurelta
district. Oroom district, Nevada.

2e. A worn specimen of a young individual of this species, or Olenellus
Iddingai. Qroom district, Nevada.

S^. Hypostoma associated with this species in the Eureka district, Nevada.

21. Prolonged pleura of third (f) segment of this species. Associated with S^.

All originals of 2 are in the collection of the U. S. National Mnsenm.

(1024)

'J. B. CtEOLOJIOAL b"RVE?

Page.
170

U. S.

, from

170

BCLLETUI NO, 30 I'L. Xl

2«

Tying
ureka

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vada.

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FCECILOPODA.

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PLATE XX.

Pig. 1. Olenkllus Gilbkrti.

1, 1<^ iSiiiiilIest H|iHciiii('ii (if tbe head iu the collection; eyea distant from

P»g<i.
170

la.

the glabella.

16.
Id.

1/.

A larger Niieciiiien than 1, hut with the geual angles curried forward,
whilo the eyes are close to the glabella.

Goniil Hiiglos normal, hut eyes united to the glabella by un ocular ridge.
Head showing the anterior position of the genal spines, gg, and the an-
gles of the posterior nuirgiu, xx, extravagantly developed. The dift'er-
ence in the length of the ocular ridges of the right and left sides is also
very marked. Natural size.

le. The smallest individual ni which the posterior course of the facial sut-
ure was observed. The outline of the head is much like that of fig. 1.
Natural size.

A specimen from Southern Nevada, with the genal spines still further
advanced than those of Id,

Form intermediate In contour of head l)etween figs. Irf and le. gg, Ge-
nal angles and spines ; xx, angles of the posterior margin. Natural
size.

Ih, The eyes in this specimen are no longer pedunculated or united to the
glabella by an ocular ridge, aud the genal angles are more posterior.
Thd course of the facial suture, in front of the eye, is also seeu for the
firHt time. Natural size.

Example in which the genal angles are in the same position as in the
adult individual in species of this genus. The eyes ore more omliry-
onic in character than ir. the preceding example. Natural size.
Broader and more common form, showing the sumo peculiarities as flg.
Im. Natural size.

The right and left sides are irregularly developed, the genal spine on
the loft side being more anterior iu position. The course of the lacial
suture is traced in accordance with its position, as observed iu fig. 6.
Natural size.

Narrow form, with the eyes of the adult type, and having the genal
angles carried forward, as in the younger individuals, Ic, If, Ih, Nat-
ural size.

The originals of the above are iu tho collection of the U. S. National Mu-
seum.

2. Paradoxides Kjerulfi

2. Outline of head showing the position of the genal angles and angles of

the posterior margin, xx, with the interocular spine ; also, the ocular
ridge (o) uniting the glabella and eyes. (After Linnarsson.)
Fig. 3. OLENELLUS A8APU0IDES

3. Embryonic form showing the circular outline, the genal spines in close

proximity to the facial suture, and the interocular spines, enlarged 3^

diameters. (After Ford.) Collection 8. W. Ford.

Auotber phase of tbe development of this species, succeeding with

lirobably intermediate forms, flg. 3. The position of the genal spines,

gg, and the sutures cutting the posterior margin at the angles, xx, is
comparable to tbe same in flg. le, enlarged to 5 diameters. (After Ford.)

Collection S. W. Ford. (See plate xvii.)

Normal adult type of the head of this species, enlarged to 2 diameters.

(After Ford. ) Collection S. W. Ford.

Olenellus Gilberti

Narrow fonn of head that shows the angles in the posterior margin, xx,

slightly developed. Natural size. (After White.) Collection U. S.

National Museum.
302 (1028)

li.

Ifc.

Im.

Fig.

3a.

Fig.

36,

4.
4.

178

168

170

O. B. OEOLOIICAL 8CHVBT

BOLLETIN NO. 30 PL. XX

'»

\i I

if ■

PCECILOPODA,

.1^:

::|

;.]"■

:||

';:11

i*:*'^;*

PLATE XXI.

Pigs. 1 and 2. Olenellus Oilbbrti

1. Normal form of the species, except the unusual prolongation of the third
segment. Collection U. S. National Museum.

la. Outline of the specimen from which fig. 1 was enlarged. Natural size.

2. Specimen broadened by longitudinal compression. The head shows
features observed in the series of heads figured on plate xx. The long,
slender extremities of the genal spines and the terminations of the third
thoracic segments are not often observed. Collection U. S. National
Museum.

2a. Outlined figure from which fig. 1 was enlarged. Natural size.

306 (1032)

Page.

170

Page.

170

ion of the third

Natural size.

le bead shows

XX. The long,

ann of the third

U. S. National

A size. '

f :

I 'I'ti

,ilp]

ft m

',> I

III

iOii

»;iiJM

< ■ -t

l'!' Ei

'■I'J^l'

;.!;*.:■•

PLATE XXII.

Pig. 1. Olenellus Thompsoni 167

1. A nearly eutire specimen from Parker's quarry. Natural size. Collec-
tion U. S. National Museum.

310 (1036)

i'' I

1 1* .'.I

L". J. QEOLOiZCAL S'JR7L2

BDLLETIN l;0. 30 } L. SXi:

Page.

167

Colleo-

vMm
|J|i;l

PCICiLOPOCA.

PLATE XXIII.

P«ge.
Pig. 1. Olbnellus Thompsoni 167

1. A specimeu allowing au uuusual prolongation of the third segment.
Collection U. S. National Mnseuui.

314 (1040)

-t

U H OF.'LO-II'JAL !^"?,':E7

pollet::! v). si fl. :•:;%::

::ecil:poc;

PLATE XXIV.

Fig.l. ME80NACI8 Vkrmontana 158

1. Copy of the original fl(;ure of tbb type specimen of the Hpecies. Collec-

tion American Museum of Natural History, New Yorlt City.
la. A very perfect specimen from the collection of Mr. E. Hurlhurt. The

matrix is in the U. S. National Museum collection.
lb. Enlargement of the posterior portion of In. The spine ])rojccting from

the tifteenth segment is flattened down on the thorax more than is

shown in the flgnre.

Fig. 2. Paradoxidks rugulosus ,. 162

2. Pygidium and four posterior thoracic sc, lents, enlarged after Barrcnde

(Syst. Sil. Bohfime, vol. i, pi. ix, fig. 31, . '"), which is introduced for
comparison with fig. lb,

318 (1044)

es. Colleo-

Iburt. The

ectiiig from
iore tbau is

r Bnrrunde
roduced for

158

162

■0

F
o

■D

o
>

o
e

i: i

llt«*

bit!

m
m

>u>

Fig.
Fig.

Fig.

3
3,

4.
4.

5.
5.

6.
fi.

Fig. 7.

Fig.

PLATE XXV.

Page-

AnOMOCARK ? PA1{VUA[ '. 209

View of t,v]>e N[i(i!imt!ii, ('nlin>;cil Collection IJ. S. National Mnaeum.

Olknotdks typicaus 183

View of tyi»o spccimon, iMil:ir;;(Ml to "i dijiniotors. Tim free cbeeks are
displaced iu tlie original and arc n-storod from another sp»^cimen. Col-
lection U. S. National Museum.

A very small head, greatly enlarged. The ditt'ereiices^jif* compared with
fig. 2, are in the form of the glabella and glabellar furrows. Collection
U. S. National Museum.

OlKNOIDES LEVIS 1S7

View of the type specimen. Collection U. S. National Mn.seum.
. Lateral view- of 3.

OLKNOIDKS ? FLAGinCAUDUS ItfS

View of the ty])P specimen from Pioclie, \(!vada. Collection U. S. Na-
tional Museum.

Ptyciiopakia Housknsis 201

View of the type specimen IVoiu Auteloi»e Springs, Utah. Collection U.
S. National MiiscMim.

Olenoidks spinosus 184

View of tyi)e specimen froin the I'.nrclid districi, Nevada. Natural size.
C(dlection U. S, National Museum.

. Head of this or a closely allitd species fiom I'ioulK', Nevada. Preserved
iu an arciiiiceous shale. Colicctinn l^ S. N.Uinnal Museum.

Olenoides Nkvadkxpis 181

View of the type specimen of thci genus and species from Antelope
Springs, Utah. Collection U. .S. National Mnsenm.

Olexeli.us asapiioidks 108

Enlargemenli of a bit of the shell of th<! free, cheek. From Troy, Now
York, Collection U. S. Nation;il Museum. (See plate xvii.)

ASAPIIISCUS WlIKKI.ERl 220

Hypostoma, enlarged. (Sei^ plate xxxi, fig. 3.) Collection U. 8. Na-
tional Museum.

(1048)

U, 8. GEOLOjICAL husve?

BULLETIN NO. 3J FL SX7

Page.
209

[nseum.

183

jlieeltH are
len. Col-
lared with
Collection

167

lir?5

I U. S. Na-

201

lection U,

184

tural size.

Preserved

....... 181

Antelope

1G8

roy, Now

220

U. S. Na-

PCEC'LOPOiTA.

'iil

ki.A

PLATE XXVL

Fig. 1, Ptychoparia Adamsi 195

1. Head from the "Kwl Saudrofk,'.' east of Highgate Springs. Collection
U. S. National Museum.

la, 1ft. Narrow and broad form of head from the limestone "lentile," two
miles east of Swnnton. Collection U. S. National Museum.

lo. Nearly entire specimen from Parker's quarry. Original in the collec-
tion of the Museum of Comparative Zoology, Cambridge, Massachusetts.

Fig. 2. Ptychoparia Piochbnsis 201

2, 2a. View of two heads that vary a little in detail. Collection U. S. Na-
tional Museum,
2ft. Free clieek a jsociated with 2, 2a. (See plate xxviii. ) Collection U. S. Na-
tional Museum.

Fig. ;?. Ptychoparia Tkuckr ■ 197

:?. View of specimen from the " Red Sandrock," east of Highgate Springs.
Collection U. S. National Museum.

Fig. 4. Ptychoparia Vuicanus 198

4. Compressed specimen from Parker's quarry. Collection U.S. National

Museum.
4rt. More perfect specimen from the " Red Sandrock," east of Highgate
Springs. Collection U. S. National Museum.

Fig. T). Olenoides Marcoui 186

5, .5o. Head and pygidium from the arenaceous shales of Parker's qnarry.

Collection U. S. National Museum.
5ft. Interior of pygidium. Collection U. S. National lifaBeaiD,

386 (1052)

-ii

BOLLEflN "0. 30 PL. S.TTI
1'-

H'*

'§

iii

PTClLOPODA.

/ I

i\ ''I

PLATE XXVn.

Pig. 1. Ptychoparia trilineata 20a

1. Figure of one of Dr. EintnoDH's original specimens, now in the Amer-

ican Museum of Natural History, New York City,
la, 16. Drawings, by S. \V. Ford, of the species as ho identified it at Troy,

New York, enlarged to 2 diameters. Collection S. W. Ford.
Ic. Copy of figure in Aniericun Geology, vol. i, pt. 2, pi. i, fig. 7. Original .

specimen unknown to the writer.

Fig. 2. Ptychoparia MI8KR 197

2. Figure drawn from the type specimen in the collection of the Geological

Survey of Canada.

Fig. 3. SOLENOPLEURA NaNA 214

3. Enlarged figure of specimen from Troy, New York. Collection U. S.

National Museum.

Fig. 4. Ptychopaiua Kingi 193

4. 4a. Views of the type specimens. Collection U. S. National Maseum.

Fig. 5. Ptychoparia? Prospbctensis 202

5. View of the type specimen, enlarged. Collection U. S. National Mnsenm.

330 (1056)

r. n. oEoLOTioAL sorvet

Bl'LL-hTIN NO. v'J I'L. s:;r!i

4(1

PCF-CILCPODA.

■'i ill

Fig.

Fig,

PLATE XXVIII.

1. PTYCHOPARIA P1OCHEN8I8

1. Largest bcatl observed. The gradual narrowing of the frontal limb and

margin is hIiowii by ligs. 1, la, 16, \c, Id. Collection U. S. National Mu-
seun.i.

Specimens showing decrease in size: la, 19 thoraci(! segments; 16, 19
thoracic segments; Ic, 17 thoracic Hegments; Id, 16 segments pre-
served.) Collection IT. S. Nauionul Museum.

le. Hypostoma associated with this species. Collection U. S. National Mu-
seum.

See plate xxvi, figs. 2, '2a.

2. CUKPICKPIIALUS ArOT'STA.

2. Head, natural ^;ize. Collection U. S. National Museum. '

2rt. Pygidium assoeiattd with the heads of this species. Collection U. S.

National Museniii.
26. A much smaller head showing variations from tig. 2. Collection U. S,

National Museum.

Page.
201

Fig.

\ CHEPICEPHALUS LlMAXA

3. Large head, with j^rm-.i'.lose surface. Collection U. S. National Museum.
36.'. Pygidium associated with 3 in the same fragment of rock. Collection

U. S. Nation;;! MtisfMim.
35. Cast «ii" a smaller head. Collection U. S. National Museum.

4. PTYCHOPARIA SUUCOKONATA

4. Figure of the type specimen figured by Hall & Whitfield, enlarged to 4
diameters. CollectJon U. S. National Museum.

334

(1060)

206

207

20.'>

^ * * t

* • * .

O. 8. OEOLOOICAL BDRVE?

BOLLETIN NO. 30 Tl.. y.XTW

• la

rWm

P-

•CECIUOPODA.

.1'

iiU'

ti;

iifi

PLATE XXIX.

Pig. 1. OlBNOIDES QVABRICBPS 187

1. Original figure of Dikellocej)halui> quadriceps Hall & Whitfield, enlarged

to 3 diameters. Collection U. S. National Museum.
la. Side view of fig. 1.
16, Ic. Top and side views of iissocialedpygirtimn. CollectionU.S. National

Musenm.

Fig. 2. Olenoides Wahsatchensis 189

5j. View of the type speciniun of DikcUocephalns Wahsatchensis Hall & Whit-
field. Collection U. S. National Museum.
2a. View of type specimen of DilieUovephatasf yothicus Hall & Whitfield.
Collection U. S. Niitioual Museum. ,

Fig. 3. Okyctocephalus primus 210

3. Head with the free cheeks in outline; the latter are raised up and ap-

pear broader than when attached to the central partis of the heatl. Col-
lection U. S. National Museum.
3a. Pygidinm that is associated in the same piece of rock with the head
wherever the latter is found, enlarged to 4 diameters. Collection U. S.
National Museum.

Fig. 4. Ptychoparia quadhans 199

4. Central portions of the head with the free cheeks restorcvi in outline.

This figure varies from that given in vol. iv, Geol. Expl. Fortieth Par.,
pi. ii, fig. 11. It is drawn from a specimen marked as the type of the
' species.
4a. Associated pygidinm.
46. Associated free cheek-

338 (1064)

O. 3. OE0LO:3;CAL SDRVEI

BnLLETIN NO. 3:) PL SSIX

4rt

1-^

'^M^

PCECILCPOCA.

III.'

I-

PLATE XXX.

Pagft

Fig, 1. BaTHYURISCUS PRODDCTU8 217

1, la. Narrow and broad forms of the head. Wasatch Mountains.
lb. Free cheek associated with la.

Ic. Large head from the Highland Kauge.

Id. Pygidinm associated with Ic. ;

le. Type of Ogi/gia parabola Hall & Whitfield.
If, Iflf, Ifc. Pygidia showing variation in form.

li. Restoration from specimens obtained in the Oqnirrh Range. Originals
in collection U. S. National Mnsenm.

Fig. 2. Bathyukiscus Howelli 21C

2. Type specimen, enlarged to 2 diameters. Collection TJ. S. National Mn-

senm.
'2a. Central portions of head, enlarged tn 'i diameters. Collection U. S. Na-
' tional Museum.

342 (1068)

ffl

0. B. OEOLOOICAL STRTET

BOLLEn.V NO, ,iD PL. aSS

Iff

217

/«»

1«

a^inals

IMu-
!. Na-

21C

1,7

l/t

PCEGiLOPODA.

<!'■'

if'!

I'f-fk

PLATE XXXI.

Fig. 1. Bathynotus holopyoa « 191

1. View ot'a nearly perfect Hpeciinen; the lr)ngeye-lobo8 are crnshed down,

Natural HJzc. Collectiou U. S. National MuHeiiiii.
la. View of the free chi^ekn and hypostotna in pOHitioii. C'nlloction U.S.
National MuHeuui.

Fig. y. PROTYPUS 8ENECTUS '. 213

2. View of tiattoned Hpecimen. Collectiou U. S. National MuHenni.

'-'a. Siteciimui laterally compressed. Collection U.S. National Museum.
'2b, '2c. Pygidiuni associated witk the beads 2 and 2a. Collection U. S. Na-
tional Museum.

Fig. :5. A.sAPin8CU8 Wueei.kki 25M)

3. A tignre partially restored, as a portion of the pygidium and free cheeks

is broken away in the typo specimens. Collection U. S. National Mu-
seum.
;Ja. A head that has a strongly-marked glabella. Free cheeks broken away.

Fig. 4. PkOTYPUS HiTCHCOCKI 211

4. Figure of the typo specimen. (After Whitfield.) Collection Amerioan

Museum Natural History, New York City.
346 (i072)

c. e. oeoloj:jai bcrve?

BOLLBTIN MO. SJ S'C. Sf^l

191

pddown,

ioD U. S.

213

Moum.
U. S. Na-

220

e chtieks
)nul Mu-

m away.

211

merioan

p.'ecilopo::a.

PLATE XXXII.

Figs. 1-12. MaTTHEVIA VARIABILIS

1, 2, 3. End, Hide, and BUDimit views of the inoflt characteristic form, en-
larged.

4. Associated operculum, with portions of the shell removed.

f). A mere conical form than 1.

6. Cast of the interior of another oporculnm.

7, 8, 9. Summit, end, and side views of the conical variety, having a deeply
sinuous margin.

10. Transverse seiitum crossing the inner charaher of the shell, as at »' in
fig. la, pl.xxxiii.

11. Section of the apex broken oft' at the septa, in the inner chambers.

12. Enlargement of the inner Surface of the chumber of habitation.

The originals of the above are in the collections of the U. S. Nationttl
Museum.

Pago.
222

350

(1076)

U. B. OEOLOaiCAL RnRVF.T

bdllet::! i.'o. so fl. xssii

'■■I

orm, en-

; '

PTEROPOi/A.

Il4l

\i\i

PLATE XXXin.

Page.
Pig. 1. Matthbvia variabilis 222

1, la, It. Casts of the chamber of habitation and the inner chambers. The
septa are seen at a, a', and the oiitline of the shell is traced. Collection
U. S. National Mustmin.

End view of a conical specimou. The cast of an inner chamber and
the relative thickness of the outer shell are shown ; also, the character
of the outer surface. Collection U. S. National Museum.
Diayrammatic transverse section to show the shell (o a) ; the inner
chambers (c, c) ; the chamber of habitation (6), and the septa (a «) be-
tween the latter and the iuncr chamber ; (t), transverse section of the
shell and inner chambers.

le, ]/. Enlarged sections of the shell to show its peculiar vesiculose struct-
ure. The section (Ir) is oblique to the axis ff the shell, -which gives it
the irregular form. Collection U. S. National Museum.

Ic.

Id.

Fig. 2. Paljenigma Wkanoeu

2,2a. Side view and section of summit of a specimen, the apex having

been broken away.
2b. Summit view of what is probably the line of a septom.
2o. Side view of a smaller specimen than 2.

354 (1080)

221

BULLETIN NO, 3:j PL. XT. 21: 1

ra. The
allectiou

ber and
iaracter

e inuer
[a 8) be-
ll of the

222

»'tl

struct-
Ejives it

having

921

PTEROPOCA.

A
A

INDEX.

m.r.. io heav,fac^ type ina.c.te the pa«e onwh,„j the deception U «,.«„ „r ,„po.tant mention

Anrothele, 52, 107.

comnioD to Lower amd Middle Cambri»D, 62.
Spj'ciiH of, in Cambrian, 60.
Bohemica, 107,

Bolieruicn=Obolu8» Bohemlous, 107.
coiiacea, 107, 108.

'ilicliotoma, 107. '

granulata, 107, 108, 109.

Matthowi, 107, 108, 100.

siibsiduB, 35, 40, 46, 09, 107, 108, 108.

siibsidna, E.xpIanation of flgares of, on plate

Aorotreta, 52, »8, 100.

common to Lower, Middle, and Upper Cam-
brian, 62.

Species of, in Cambrian, 60.

attennata, 88.

j:erama, 32, 33, 35, 46, 40, 50, 98.

gomma ExplanaUon of figures of, oa plate
Tui, 2o4.

pysidioula, 98.,

snbconica, 88, 89.

Janbsidna, 108.
Adirondack region, Potsdam fauna of the, 23.

Rection correlated, 44.
Adirondacks, Submergence of the, 24.
Aglaspis, 54.

iu Fpper Cambrian, not in Middle or Lower
Cambrian, 62.

Species of, in Cambrian, 61.
Aj;uostidtB, 55.
Agnostas, 19, 48, 149.

common to Lower, Middle, and Upper Cam
brian, 62.

sp. f, 26, 47.

Species of, in Cambrian, 61.

Acadious, 55.

bidens, 32, 33, 150.

communis, 32, 33, 150.

integer, 150.

interstrictns, 40, 47, 55, 149, 150.

iutorstrictus? 32.

intorstrioliis, Explanation of figures of on

pinto xvi, 'iSB.
Josepha, 55.
Ijevigatus, 104.
lobatiis, 151, 153, 156.
Neoii,, 32, 33.
iiobiliH, 27, 47, 55, 150.
nobilis. Copy of original figure of, on plate xvi

Orion, 17.

;:083)

Agnostns— Continued,
parills, 65, 151.
pisifonnis, 65, 160.
prolongus, 33.
Richmondensis, 32.
seclusuB, 32.
tnmid08n8,33, 150.
tumifrons, 33.
Agranlos, common to Lower and Upper Cambrian.

Species of, in Cambrian, 61.
AlgtB, 72.

Distribution of species of, in Middle Cam-

brian, 45.
Genera and species of, 48.
Genera and species of, in Cambrian, 62
Genera of, iu Cambrian, 59.
Ampbion, 185.
»8p.?, 19.

doubtfully identified iu Cambrian, 63.
» Species of, in Cambrian, 61.
» in Upper Cambrian, not in' Middle or Lower
Cambrian, 6-'.
Angelina, 212.

Hitchcoclii, 211.
Sedgwiciti, 212.
Annelid trails in Middle Cambrian 72
Annelida, Distribution of species ot, in Middle
Cambrian, 46.
Genera and species of, 48.
Genera and species of, in Cambrian fauna. 62.
Genera of, in Cambrian, 59.
Anomocare, 56, 209.

limited to Middle Cambrian, 02.
Species of, in Cambrian, 61.
parvum, 32, 48.
? parvum, 107, 209.

'r"'T.:.^'P''""'"°° "^ *'"■»'« < o» plate
Anopolenus, 165, 101.

limited to Lower Cambrian, 62.

Species of, in Cambrian, 61.

Salteri, 165.
Anthromorpha, 80.
Apu8 cancriformls, 148.

glacialis, 148.

panotatns, 204.
Archteocyatliellus, 75, 76, 87, 88.

Eenssclaericua, 84, 88.

? Krns.selaeiiciis, 85.
ArcLaioe.vntbina', 51, 80.
Arcbffioc.vathus, 36, 72, 75, 83, 87.

common to Lower and Middle Cambrian, «.

3&7

358

INDEX.

ArohnooyatbiiH— Continoed.

Species of, in Cnmbrian, SO.

■p. uudt,, 38.

up. }, 4n.

Atlanticns, 20, 38, 46, 80, T8, 74, 75, 77, 78. 70, 84.

AtlaDti(su8, Explanntion of IlKnrcH of, on plato
ii, 2!t0; on plate iii, !i84.

BilUnKHl, 2U, 4.^ 7», 74.

BlllingHi, Explanation of flgurea of, on plate
ill, 234.

Kracilis, 81, H3.

HinKaueusiH, 75, 77, 78, 83.

profuntluH, 78, 79, 83, 84.

Whltni-yl, 81, 83. . .

Archean, 44.

Arenlcolites, common to Lower, Middle, and Up-
per ^ambrian, 63.

sp. ?, 46.

SpecieH of, in Cambrian, 50.
Aretbiisina, in Upper, but not in Middle or Lower,
Cambrian, 62.

Spccien of, in Cambrian, 61.

Americana, 33, 33.

Eoninvki, 176.
ArgilloceoiiB slate, Primitive, 13.
Asapbidee, S6.
Asaphiacus, 319,221.

limited to Middle Cambrian, 62. '

Species of, in Cambrian, 61.

Wlieeleri, 40, 48, 56, 57, 109, 201, 210, 220.

Wheeleri, Explanation of figures of, on plate
XXV, 822 ; on plate xxzi, 840.
Asapbu.'), 219,221.
Atops pnnctatus, 203.

trilioeatUB,203,204.
Avicula 1 desquamata, 114.

same as Obolella desquamata, 110.

Barrande, M., 53.

as to genns Fordilla, 53, 124.
Barrandia, 162, 163.

Thompsoni, 167.

Vormontana, 158.
Bathyuotus, 20, 55, 101.

limited to Middle Cambrian, 62.

Species of, in Cambrian, 61.

holopyga, 15, 47, 56, 150, 1»1.

bolopyga, Explanation of figures of, on plate
xxxi, 34«.
Batliyurellus, 210.

abmptus, 187.

nitidus, 187.

(Asapbiscns) Wheeleri, 220.
Batbyurida), 56.

definition of family, 66.
Bntbyuriscus, 215,

limited to Middle Cambrian, 62. ■> '

Species of, in Cambrian, 61.

Hiiydeni, 215, 216.

1 1laydoni, 215.

Howelli, 34, 48, 50, 215, 216.

Huwelli, Explanation of figures of, on plate
XXX, 842.

prodnoto, 84, 30, 40, 48, 57, 95, 2] 5, 216, 217.

(1084)

BatbyuriHCUs— Continued.

producta. Explanation of fignrvs of, on plate
zxx, 842.
Bathyuru8,213,210,321.

doubtfully identified in Cambrian, 63.

1 in Upper Cambrian, not in Lower or Middle
Cambrian, 62.

sp. t, 19.

) Species of, in Cambrian, 01 .

extans, 20, 215, 219.

parvulus, 213, 214.

senectus, 213.
Bellerophon, in Upper Cambrian, not In Middle
or Lower Cambrian, 63.

Species of, in Cambrian, 60.

antiquatus, 35.
Bennett's Spring, Xev., Section near, 33.
Beyrichona, limited to Lower Cambrian, 62.

Species of, in Cambrian, 60.
Bio Harbor, Conglomerate limestones of, 24,

List of species of, 26.
Big Cottonwood Cafion, Great Cambrian section

of, 88.
Big Cottonwood section, 38, 41.
Billings, E., 40, 64, 114.

As to certain species recognized and de-
scribed by, 2».

Middle Caml>rian fauna Classified as Lower
Potsdam by, 49.
BUlingsia, in Upper Cambrian, not In Middle or
Lower Cambrian, 62.

Species of, in Cambrian, 60.

Saratogensis, 21.
Bonne Bay, Georgia fauna of, 29.

section, by Sir William Logdn, 20.
Bornemann, J. G., 51, 80.

papers published by, 81.
Brachiopoda, 62, 96.

Distribution of species of, in the Middle Cam-
brian, 46.

Genera and species of, 48.

Genera and species of, in Cambrian fauna, 62.

Genera of, in Cambrian, 60.
Braintree fauna, 44, 40.

C.
Calathium, 70.
Calciferons fauna, 63.

formation, 22.

fossils, 24.

horizon, 21.
Calymene Beckii, 203.
Camarella, 48, 122.

common to Middle and Upper Cambrian, 02.

Species of, in Cambrian, 60.

sp. » , 26.

tsp. »,46.

antiqnata, 19, 122.

fantiqnata, 46.

(f) antiquata. Explanation of figures of, on
plate vii, 260.

varians, 122.

"Volborthi, 122.
Camarotheca, 131.

Cambrian, Conditions ueveloping Middle fanna
of, peoaliar to Kortb America, 57.

fl)Oirf« of, on plate

mbrian, 6».

D Lower oi- Middle

iaii, Dot In Middle

1 near, 3S.
Cambrian, 62.

stonef) of, 24.

Carobriaii seotioD

cogniznd and de-
asaifled as Lower
not in Middle or

INDEX.

359

In, 29.

the Middle Cam-
nbrian fauna, 62.

• Cambrian, 82.

figures of, on

Middle faana
»,57.

Cambrinn — Continned.
Doiibtl'ul pennra of, (Ki.
Ulntrict ofCuniilurande in Sardinia, 80.
I'auim, SpecinH of, tH,

fiiiinuH, BH (lorit'lBtfd !)> P'- •»'. Whitfield, 1.1.
I'niinatt of North AimTica, l>.
fHUiiiiH of North America, Siiiiimnrv of, 30.
forniiitioii, Totnl thtclcui'HS ot', 11.
r)riii>raoftheOI('iiidiii of Aini^ricaii Middle, niS.
Lower and Upper. Oeuernrouiiiiou to the, tl'i,
Ixiwer, Gfiiorii aud BpccicH < '' III.
Lower, Genera enmmon to il ti'2.
Lower, (Joiiera limited to thr, (I'i.
Lower, Uuiiura of the Upper not ocourring

ill tlie, iVi.
Lower, Middle, and Upper, Genera coiiimon

to the, (I'i.
Lower, of Sedgwick, (18.
Lower, or I'nrndoxideg fimna, U.
Lower, Period of oronion of, i'.t.
Lower, St. .lohn HuriuH, 14.
Lower, SvMteniatic poHilioii of, <W.
Middle, at XluUing IIorHO Laliu, lU'itiHh

America, 40.
Middle, Central hori/.on of, 44.
Middle, Desciiptioii of I'aniia of the, 72.
Middle, denignated aa Lowir Potmlaiu by

Billings, 49.
Middle, Fauna of, I7.'>.
Middle, Genera and Npecloaof the, 01.
Middle, Genera common to the Lower and, 02.
Middle, Genera limited to the, 62.
Middle, Geiu'ia of the Upper not occurring

ill the, 02.
Middle, or Georgia horizon. Review of the

Htiata and fauna.s referred to the, 12.
Middle, Period of erosion ol the, 43.
Middle, Species id' Kutorgiua in the, 101.
Middle, Systematic position of the, OX
Mi<ldle, Table of distribution of fauna of the,

4.5.
Middle, Total of (be fauna of the, 41.
M iddlo, -- Georsffa or Olenellus, 44.
Middle, Trails of annelids in, 72
Middle and Upper, Genera common to the, 62.
Reason for using (he term, 11.
locks. North American, ClasdiUoation of the,

seas. Life of the older, 58.

strata of the Grand Canon, 41.

system. As to the data for dividinK the, 13.

system of Europe, 57.

system of North America, As to the stratig-
raphy of the, 12.

system of North America, First systematic
arr.ingement of the, 64.

Upper, 32.

Upper, Description of a Pteropod from the,223.

Upper, Genera of, not occurring in tbo Middle
and Lower Cambrian, 62.

Upper, Genera and species of the, 61.

Upper, Mixing of fauna of, witli the Lower
.Silurian (Ordovici.in), 12.

Upjier, or Potsdam fauna. II.

Upper, I'assage fauna between the Georgia
iiud Potsdam, 'H,

(10

Cambrian — Continued.

Upper, Species of Kutorgina in the, 101.

Upper, Species in the, 32.

Upper. Systematic position of the, 69.

Upper, Upper limit of the horizon of the,
44.

Upper, - Potadam or Dicellocephaliis, 44.
Citstlnton slate, 14.

Cutlinite beds probably pre-Cambrian, 30.
Centropleura, 101.

Loveni, 101.
Ceratiocaris. 148.
Ceratopyge fortlciihi, 207.
Cliamplaiii Group, 00, 67.

ChariocephaluH, in Upper, but not in Lower or
Middle, Cambrian, 02.

Species of, in Cambrian, 61.

tumifrons, 32. .

Chazy formation, 23.

limestone, 24.
Chondrites, 72.
Clitiar foi-matiou, 43.
Classitli^ation of North Ai eriean Cambrian rocks,

(l:t.
Clayton, J. E., 36.
Climacograptus, 93, 04.

?, Si>ecie» of, in Cambrian, 59.

(0 Kmnionsi, !.'>. 51.

■>! Emmonsi, 40. )>3.

?f Emmonsi, Explanation of hgure of, on plate
xi, 26».
CliniactichnitcH sp. !, 21.

Species of In Cumbrian, 00.

in Upper Caralirian, not in Lower or Middle
Camlirian, 02.
Coleulus, 131.
Coleopriim, 131.

Conglomerate limestones of Bio Harbor, St.
Simon, St. Lawrence River, Island of Or-
leans, &c.,24.
Conglomerates at Point Levis, of Calciferona age,

23.
Conocephalidae, 56.
Conocephalitos, 21B.

Adamsi, 195, 108.

arenosus, 195, 196.

coronatus, 195.

miser, 199.

snbcoronatns, 188, 205.

Sulzeri, 195.

Teuoer, 197.

trilineatns, 203.

( Atops) trilineatns, 203.

Vulcanus, 198.
Conocoryphe, 203.

Uniit<>d to Lower Cambrian, 62.

Species of, in Cambrian, 61.

(Conocephalitos) Kingi, 193.

(Ptychoparia) Kingi, 193.
Conophrys, 153, 157.
Connlaria, 131, 223.

fecunda, 223.
Conularidffi, 131.
Correlation of sections, 40.
Corynexochns, 187.

spinulosus, 214.

So)

360

INDEX.

C'nNcinocyntliiiH, RO.

• 'rnnin (Kiitoritiiiu) Lubrndorlcu, id.

Cic]iiu('ijliului), 30, Ad, '20tt.

coiimuiii lu Middle iind Upper Cumbriun, 02.

SpucicH of, in Cumbrian, 61.

AiiMUHtit, Kxpliiuattuii of flitiireii of, on plato
xxviii, iiiU.

AuKiiNtn, n. tp., .'lit, 4H, 208i

IowouhIh, 208.

Ltltana, !l.\ 48, 207.

I^llluuu, Kxplanatiou of flgureR of, on plate
xxviil, 334.

I (IjOkuduUuh) quad raOH, 100.
Crinoidea. UiHti'lbutlon of Hpocleii of, 4tt.

Qonera and Hpecles of, 48.

Genera and Hpeoieg of, in Cambrian, 62.

Oenora of, in Canibrinu, SU.
Cructtucea, A4, I4H.

ViHtrlbution of apRcies of. In the Middle Cum-
brian, 47.

Genera and apecios of, 48.

Genera and apecioa of, In Cambrian, 02.

Genera of, in Cambrian, 60.
Cnizinua, 72.

common to Middle and Upper Cambrian, 62.

Spcciea of, in Cumbrian, 59.

ap. (.'),34,30,4.').
CryptozoA proliferum, 21, 225.
CtonocephaluH, limited to Lower Cambrian, 02.

Speciea of in Cambrian, 61.
Cypbaspia Hunneistor, 184.

1).

Dulmuuia, 180.

Dnna, .T. D., conHiilersEuiraona'aTaconicaa Lower

Silurian, 70.
Dawaon, George M., 40.
Dawson, J. W., 70. <

UenilrograptUH, !S0.

eomnion to Lower and Upper Cambrian, 62.

SpecioH of, in Cambrian, 50.
Dicelloceplialus, 30, 181, 185.

in Upper, but not in Middle or Lower, Cam-
lirian, 02.

S)ieciea of, in Cambrian, 01.

ap. ?, 3.'5.

Minneaotensis, type of, 35.

nngustifrons, 33.

bilobus, 33.

Hartli, 21, 225.

Lodenaia, 21.

Marconi, 180.

Marica, 33.

?na8utu8, 32,33.

Osceola, 33.

ropincnsia, 21, 35.

? quadriceps, 187.

Uicbmondunais, 32.

s]>ecioaua, 21, 225.
Uicellomus, 109.
Dikellocephalus nothioua, 188, IflO, 222.

( Sotliicua, 189. [

magniflruB, 185.

quadricepa, 187, 222.

Wabsatcbensls, ISO. 190.

?gorax, 185,

UiploKraptua, 03.

SpecioH of, in Cambrian, SO,

ae«:alinua, 02, 03.

(t) simplex, 15, 40, 51, 03, 03.

(?) simplex. Explanation of fl){nre of, on plate
xl, 20«.
Dlplotbeca, 131.

limited to Lower Cambrian, 62.

Rpooiea of, in Cambrlau, 60.
Dlscina, doubtfully identified In the Cambrian, 63.

In Upper, but not in Middle or Lower, Cam-
brian, 62.

Species of, in Cambdan, 00.

Acadioa, 128.
Diaolnella, 141, 142.
Dorypyge, 221.

Ricfathofeni, 222.
Dwi^lit, W. B., deacrlbca belt of Ilmeatone near

FouKbkecpaio, 23.

B.
Echinodennata, M, 94.
Kchinognathua Clevelandl, S4.
Kllipsocepbalus, 162.
Elllptocopbula, 102.

aaapboides, 108.
EUiptocepbaluH, 102.

usapbotdea, 108.
£ly Mountains, Olenoldos fanna in the, 86.
Emmons, E.,72,04.

concct in claaaifying Upper Taconio as pre-
Potadam, 05.

Extracta from works of, 60, 67, 68, 69, 70.
Endo);ranima, 200.
Eocoryne, limited to Lower Cambrian, 62.

Species of, in Cambrian, 59.
Eocyatites, 04.

? common to Lower, Middle, and Upper Cam:
briun, 02.

Genua of, in Cumbrian, 50.

1 ap. 1, 40.

?? longidactylua, 34, .35, 40, i>l, »»<,95.

?? longidaotylns. Explanation of tigures of, on
plate V, 242 ; on plate vi, 24».
Eopterin, liichardsoni, 53.

? ornata, 53.

typica, 53.
Eospongia, 79.
Eozoiin, 79.
Ethmophyllum, 51, 73, 75, 80, 82.

Explanation of figure of, on plate Iv, 288,

limited to Middle Cambrian, 02.

Species of, in Cambriun, 59.

Billingsi, 80.

gracile,30,81,83,g4, 85.

Mlnganensla, 51, 75, 77.

profundum, 20, 38, 45, 'M, 73, 74, 75, 77, 84.

profundura. Explanation of figures of, on plate
i, 22« ; on plate ii. 230 ; on plate iv, 238.

rarum, 27. 45, 87.

rarum. Explanation of figures of, on plate v,
242.

Ronsselaericnra, 27, 76, 85, 80.

Renaselaericum, Explanation of flgares of, on
plato V. 242.

Whitneyi, 30, 38, 45, 75, 76, 81, 83, 84, W,

(1086)

:i){nre of, on plate

the Cambrian, S3.
5 or Lower, Cam

f limeHtone near

in the, SB,
' Xaconio aa pre-
r, 68, 60, 70.
irian, 82.

md Upper Cam:

,95.
if figures of, on

Lto iv, '288.

5, 77, 84.

ree of, on pUte

late iv, 238.

of, on plate v.

f flgarea of, on
84,86,

INDEX.

361

Etbinopliyllum — Couttiiiie<l.

Whttnnyl, Kxplaiiation of flgiirtw of, on plnte
Iv, '2.1H.
EiicliaHiim llliinioiibnclii, .'^3.
KiiomplialiiH, in ITppo ■, Imt not in Middle or Lower,
'.'uiiilii iun, fl.'.
.Spcoli'H of, ill Ciinilirian, 60.
Euri'kit Ciiuiliriuii Niti'tion, )t3.

roiTi'liitnd, 41. II,
Eiirotldir, 80.

Europe, (luiiibrinn HVHtrm of, W.
Eiirypterida, .'>4.

F.
Fiiiino, Urainlrri-, 411.

DeNoriptiou of the .Middln Cainbriaii, 72.
OcutM'u of Olt-nido) of Aninric.tn Middle Cam-
brian, n<i.
Georgia, L'O, 'i\t.
Middle Cainbriuu, 11,-i.
Middlo Canibrlnu, Table of diHtribiition of

(be, 4,').
X(!wf(iundlaud ParadoxideR, 40,
of Geor;:ia «bab!H, 'JO.
of Olputdlim liorlzon, itant of 8wantoii, 10.
PaluoutoldKic t'baractpra of, 50.
rotHdnni, 23.

Potsdam, of tbe Adirondack region, 23.
Saiatofjia PotHdam, conipnrvd with WiacouHin

Potsdam HandHtone fauna, 21.
Second, Oil.
St. Jobn, 40.
StratiRrapbio poHitioii of tbu Middlo Cam-

l)rian, 4!).
Summary of tbe Middle Cambrian, 48.
Wiaconsin Potadam sandxtone, rompared with
the Saratoga Potsdam fauna, 21.
Faunas, Cambrian, of Korth America, II.

of North America, Summary of tbe Cambrian,

Review of tbe strata and, referred to tbe Mid-
dle Cambrian or Georgia horizon, Vi,
Ford.S. W.,64, 115, 123.

Section doscribod by, 27.
Ford illu, 123.

limited to Middle Cambrian, 02.

Species of, in Cambrian, CO.

Troyensis, 27, 46, 53, 124, 125.

TroyonsiH, Explanation of tlguroa of, on plate
xi, 2tl«.
Formation, Calciferous, 22.

Absence of C^'azy, 23.

Georgia, 13.
Fucoidal remains of Middle f'r.jibrlan, 72.
Fucoidcs sccalinus, 02, 03.

simplex, 02.
Fusuliua, 82.

Gasteropoda, 53, 125,

Distribution of species of, in the Middle Cam-
brian, 40.

Genera and species, 48.

Genera and species of, in Cambrian, M.

Genera of, in Cambrian, 60.
Georgia fauna, 20, 20.

(Vt Ponno Bay, Newfonpdland, 29.

I Georgia Fauna — (;ontinue<l.

of tlie(.)aiiibrian, 44. '

((oorglit formation, II, 13.

lis developed in the town of Georgia, Vt., 14.

placed below tbn Potsdam sandstone, 14.

tliiekiiesH ol'. In V'urmont, 20.
Georgia group, Ueamin for using tbe teim, 14.
Georgia bori/oii. In Cambrian sertlon of Enroka
iiiliiini; diMtrict of Central Nevada, HO.

relation to Potsdam h<u'l7,on,33.

llovlew of the strata aiid faunas referred to the
Midilli^Caiiibvlaii or, 12.
Georgia section, ID, 24, 43.

at j'arker's (iiiari y, 15, 17.

correlated, 44.

flgure of. Hi.
Geoigia series, Straligraphic relations to Potadam

series of, 20.
Georgia sbitlus, 1.5. 18, 23.

Kauna of, 20.
(leiirgia slate, Mtbologlcal nbarneters of the, 14.

Views of difl'orent writers as to tbe ago of
tbe, 14.
Gilbert, (i.K., 30, 41.
Grand CaGoii Cambrian strata, 41, 57.
Grand Cation section, 43.

(Correlation of the, 44.

Fossils of the, 43.
Grand ('aDoii series probably of pre-Cambrlan

age, (i4.
Graiitolltes, 91.

in the Saint Tohu Group, 51.

Tttconic, 92.
Graptolitbus, 02.

Hamburg limestone and shale, 30.

Harttia, genus limited to Lower Cambrian, 02.

Species of, In Cambrian, 60.
Hemiceras, 131, 223.

cyllndricuB, 223.

HexactinellldcD, SI.
Hlghgate see- n, 19, 24.

section 'j1, Hitchcock, 20.

Section near, described by Dr. Emmons, 70.

Springs, Section taken cast of, 18.
Highland Itange section, 41.

Higher strata of tbe, 36.
Hiko, Nevada, 36.
Hipponicbarion, limited to Lower Cambrian, 62.

Species of, in Cambrian, 00.
Hitchcock, C. H., Sections by, across New Hamp-
shire and Vermont, 20.
Holopea, in Upper Cambrian, not in Middle or
Lower Cambrian, 02.

Species of, in Cambrian, 60.
Homalonotus, 191.
Hunt, T. Sterry, as to tbe Cambrian system, 13.

Views of, as to the term Taconie, 70.
Hyatt, Alphfcus, 50, 138.
Hydrozoa, 51,01.

Distribution of species of, in the Middle Cam-
brian, 40.

Genera and species of, 48.

Genera and sjiecies of, in Cambrian, 02,

Genera of, in Cambrian, SO,

(1087)

362

INDEX.

Hj-tnenooaris, 147.

vennicauda, 54, 147.
IlyolitbeUldffi, 131.
Hyolithellus, 131, 141, 142.

limited to the Middle Cambrian, 62.

?, 15.

Species of, in Cambrian, 60.

mioans, 15, 20, 27, 47, 130, 142.

micanH ?, 28.
Hyolltbes, 131, 138. 142, 143, 223.

common to Lower, Middle, and Upper Cam-
brian, 62.

Distribution of the genus, 132.

Species of, in Cambrian, 6U.

u. Bp.3, (36).

gp. ?, 18, 27.

sp. undt.,47, 141.

■p. ondt.. Figure of, on plate liii, 274.

(D'plotbeca) Acadica, 132.

(Dlplothe'^a) Anadicn var. crussa, 132.

(Diplotbeoa) Acadica var. obtusa, 132.

(Uiplotheca) Acadica var. serioea, 132.

aclis, 132.

(Theca) acule-tus, 132.

Auiericanus, 26, 27, 47, 131, 132, 133, 134, )25,
137, 139, 141.

Amc.Ic::,! .4, Billings's desciiption of, 133.

Americanns, Explanation of figures of, on
pla'.« xiii, 274.

BlUingsi, 29, 34, 35, 39, 47, 54, 132, 134.

Billingsi, Explanation of figures of, on plate
X' I, 274.

carbonaria, 132.

centennialis, 132.

cinctus, 141.

nommnnie 26, 27, 47, 54, 131, 132, 130, 138, 139,
140, 141.

communis var Emuionsi, 27, 47, 132, 137, 139.

communis, Explanation of figures of, on plate
xlv, 2;8.

commi^nis var. Euunonsi, Explanation of fig-
ures of, on plate xiv, 278.

(Camarotheoa) Daniana, 132.

eljj^uaa, 135.

EmmoDsi, 131, 136, 137, 138, 139, 141.

excellens, 131, 132, 135.

gibbosns, 131, 132.

(Camai-otheca) grac'lis, 1?^.

(gregaria), 132.

gregarins, 131.

(Diplotheca) EyattiAna, 13',.

(Diplotheca) Hyatt iana v/.r. oandata, 132.

impar, 27, 47, 54, Iril, l?i, 136, 138, 139, 141,
223.

impar, Explanation of Jgnres of, on plate xiv,
278.

ligea, 132.

micans, 141.

micana, I^xplanation of figures of, on plate
xiv, 278.

(Camarotbeca) Micmao, 132.

obtnsa, 134.

paradoxus, 225.

parviusculus, 132.

primordlalls, .T2, 83, 131, 182, 138, 134, 141.

priroordial4st,134.

Hyoli'.ties— Continued.

priDCeps, 20, 38, 47, 54, 84, lUl, 132, 186.
princeps, Txplauation of figures of, on plate

xiii, 274.
principalis, 132.
Sbaleri, 132.

singuluB, 132. '

striatus, 132.
teres, 139.
triliratas, 182.
Vanuxemi, 132.

lUniearus, in TTpper, but not In Middle or Lower,
Cambrian, 62.

sp. ?, 35.

Species of, in Cambrian, 61.
Iphidea, 52, 100.

limited to Middle Cambrian, 62.

Species of, in Cambrian, 60.

beUa, 26, 29, 46, 49, 100, 101, 126.

bcUa, Explanation of figures of, on plate vii,
250.

depressa, 32.

Labradorlca, 106.

omatella 101.

Keweenaw formation, 57.

probably of pre-Cambiian age, 64.
Finderbook Creole section, 28.
Kutorgina, 101.

common to Lower, Middle, and TTpper Cam-
brian, C.
Species of, in Cambrian, 60.
oingulata, 15, 18, 19. 20, 26, 29, 38, 46, 52, 101,

102, 104, 106, 135.
cingulata, Explanation of figures of, on plate

ix, 258.
cin(>nlata vai . pusilla, 102.
Labradorlca, 15, 18, 19, 20, 29, 46, 101, 102, 104,

106.
Labriulonca, Explanation of figure? of, on

plate ix, 258.
(like K. cingulata), 38.
minutissima, 32, 33.

pannnla, 34. 35, 39, 46, 99, 101, 102, 105, 106, 216.
pannula. Explanation of figures of, on plate

vil, 269 ; on plate vili, 254.
Frospetlonsis, 32, 46, 101, 104, 100.
Prospectensis, Explanation of figures of, on

plate ix, 258.
sculptilis, 101, 102, 106.
Whitfleldi, 32, 101, 102

Lamellibranchiata, S3, 123.

Distribution of species of, in Middle Cam-
brian, 46.

Genera and species of, 48.

Genera and species of, in Cambrian, 82.

One genus of, in Cambrian, 60.
L'Anse nu Loup. 32, 38, 74.

Hcction 2tt.

Species from, V9
Leutile, 17, 18.

(1088)

..J"

1, 132, 186.
jares of, on plate

Middle or Lower,

, 62.

126.

a of, on plate vli,

ge, 64.

and Upper Cam-

29, 38, 46, 52, 101,
giires of, on plate

46, 101, 10?, 104,
figures of, on

102, 105, 106, 216.
nrea of, on plate

106.

of figures of, on

in Middle Cam-

ibrian, 82.

INDEX.

363

Leperditia, 14(1.

common to Middle and Upper Cauibiiun, 6J.

Argen'-sia, 47, 54.

Argi-ita, Explanation of ttgiiro of, on plate
viii 234:.

1 Ar«inta, n. sp. 140.

Solvensis, 146.

Troyon8i8,2;,47,54, 14«.

Troyensis, Enlarged ttjuro of typo specimen
of, <in plate xvi, ' rt.
Lepidilla, limited to Liiwdr Cambrian, 92.

Species of, in Ciiinbriim, 60.
Lepiditta, limited 'o i^ower v>'ambrirtu, 6J.

Species of, in f'ainbriiiii, CO.
Leptien:'. Species of in Caml)rian, 60.

? in Upper, but not in Middle or Lower, Cam-
brian, 02.
Leptoniitus, n. pren., 89.

Iimite<l to Middle Cambrian, 62.

Species of, in Cambrian, 59.

Zitteli, 4.5, 51, W>.

Zittoli, Kxplanation oi' tigures of, on plate ii,
230.
Limestone near Poiigbkeepsio, N. Y., '£t.
Linguln, 97, 104.

in Upp'.^r, but not in Middle or Lower, Caui-
briaii,62.

np. ?, 19.

Spe<!ics of, in Cambrian, 80.

calumet, 30.

I'Vistmanteli, 104.

nianticula, 32.

? manticula, 32, 3;i.
LinguJella, 19,»5, 111.

common to Lower, Middle, and Upper Cam-
brian, 62.

Species of, in Cambrian, 60.

eaelata, 20, 27, 28, 46, U5.

cffilata. Explanation of figures of, on plate vil,
250.

Davisii, 96.

Ella, 34, 35, 39, 40, 46, 52, »7.

Ella, Explanation of liirures of. on plate vil,
250 ; on plate viii, 254.
Lingnlepis, in Upper, but not ir Middle or Lower
Cambrian, 62.

Species of, in Cambrian, 60.

aoaminata, 21.

Maera, 32, .33.

minima, 21.

minnta, 32, 33.

pinnKfoimis, 21.
Lingalidai, 52.
Linnarssonia, 107, 111.

limited to Lower Cambrian, 62.

Species of, in Cambrian, 60.
Llano seried, probably of pre-(;ambrian age, '14.
Logan, Sir William, 64.

Section at Trois Pistoles described by, 26.

Section taken by, east of Swanton, Vi'rniont,
19.
Lower Silurian (Ordovician), 14,

Maclurea, In Uppei', but not in Middle '
Canibrian, 02.

.r Lower.

Maclurea — Continued.

Species of, in Cambrian, 60.
, mi>gna, 22.

Marcon, Jules, 72.
I Lentile of, 17.

Strata referred to Potnlam by, 18.
I Matthevia, 131. 22iJ.

variabilis, 21, 223, 224.

vaiiabilis. Explanation of Uguresiif on plato
xxxii, 350; on plate xxxiii, 354.
M:-..tliovidie, 131.
Matthew, G-. F., ,53.
Met;k, F. B., 3<i.
Mesonacis, L'O, .55. 15S.

limited to Middle Cambrian, 62.
Itelation of, to Paradoxides and Olencllus, 185.
Species iif, in .anibrian. 01.
j Vermontana, • './, 93, ISS.lOl, 162, UiO, 173, 178.

I Vermontana, i.xpbinatiou of figures of, on

I plate xxiv, Ills.

Metopton'a, in Upjier, Imt not in Middle or Lower,
CJambrian, 62.
I Specii'.".. of, in Cambrian, 60

I anomala, 224.

I cornutiforme, ;;1

? rugoaa, 128.
I Rimplex. 21,

I variabilis, 225

! Microdiscus, 55, 152, 154, 157.
j ! ciimmon to Lower, Middle, and Upper Cam-

brian, 02.
Species of in Cambrian. 01.
* Uawsoui, 55, 1.53, 1,54, 15,5.
l';batUM, 20, 27, 47, 1.5:!, 154, 155, 158, 157.
lobatns. Explanation of figures of, on platt

xvi, 2S8.
(Agnostiis) lobatua, 156.
Meeki, 27, 47, 153, 1.54, 155
Meeki, Explanation of ti,;ures of, on plate xvi,

2S8.
Parkeri, 15,47, 1,53, 1.54, 157.
Parkori, Exi)lanation of figures of, on plate

svi, 2!S8.
pulchelliis, 153,154,155.
pulcbellus (=M. punctatus),55.
I unotatus, 5.5, 152, 1.'-:!, 154, 155.
quudricostatua, 152,
sculptus, 153, 154, 157, 158.
speciosua, 20, 27, 28, 47, 1,53, 154, 1.55, 157,
s))eciosus, Explanation of liguriut oi', on plate
xvi, '2m.
Micropyge. 2(i6,
Modiolopsis, 123.
Murray, Alexander, 49.

Nevada, 30.
Xewfoundland, 211,44.

Nolhozoe, in UitjKT, but not in Middle or Lower,
Cambrian, 62.
Species of, in Cambrian, 60.

Obolella, .30,107, 109.110.
'.) »p,. 1.5.
eonimiin to Midilleaud Upper (Jainbrian, 92.

' i

(]0,S!))

364

INDEX.

Obololla- -Continuert.
(like O. pretioea), 32.
.Species of, in Cambrian, 60,
! arabifjiia, 111.
coelata, 1.51.

ca2lata=0rbicula cielata, 111.
(Orbiciila) ftelata, 95.

cbromaticB, 29, 48, 90, 101, 109, 111, 112, 114, 116.
chroinatica. Explanation of figures of, ou plate

xi, nn.

chroniatica. Kigures of, 110.

(iiusulata, 102.

(Kutoi'^inu) cingulata, 102.

Circe, 20, 40, 111, 118.

Circe, Explaoatiou of figures of, on plate x,

202.
crassa, 26, 27, 46, 97, 113, 114, 115, 116, 118.
crassa, Explanation of figures of, on plate x,

202.
cra8sa=0rbicula ? crassa, HI.
(Orbicula?) crassa, 114.
desiderata, lU.
desquamata. 111, 114, 118, 151.
do8qnan)ata= Avicula ? desquamata, 110.
discoidea, S3, 111.
gemma, 26, 27, 40, 111, 113, 11«, 118.
gemma. Explanation of figures of, on plate x,

2U2.
Ida, 111.
1 1da, 111
manticula, 5'/.
miser. 111.
Nana, 111.
nitida, 27, 46, 118.
nitida. Explanation of figures of, on plate xi,

2»«.
()) PhiUipsi, 102.
polita. 111.
pretiosa, 111.
prima, 21.
transversa. 111.
ObolidiD, r)2.
UboluH ApuUinis, 110.
ObohLS Labradoricus, 100, 104, 105.
Osyg'i'i doubtfully identified in the Cambrian, 63.
? in Upper Cambrian, not in Middle or Lower

Cambrian, 62.
f Species of, in Cambrian, 61.
parabola, 217, 218.
? problematica, 32.
producta, 217.
1 spiudsa, 184.
t.ypioalis, 184.
OldUamia, 72.

Olenellus, 20, 30, 55, 160, 162, 166, 181.
limited to Middle Cambrian, 62.
ftelations " to I'aradoxtdcs and Mesonaois,

KiS.
Relations of, to other itinera, 104.
sp. f, 29.

Species of, in Cambrian, 61.
asapboidn.^, 27, 47, 151, 164, 105, J«S, 109, 177.
a»ap)'.iiid(^H, Explanation iif li^uresof, on plate

xvii. 2U0; <m plate xx. ;I02; on plate xxv,

322.
fj;niptnv(^plialurt) asapboidr", 162.

Olenellus— Continued.

tiilberti, 32, 34, 35, 30, 38, 39, 40, 47, 55, 84, 95, 105,

107, 109, 127, 134, 135, 101, 161, 10.5, 106, 169, 1(0,

171, 173, 174, nr>, 176, 177, 178, 179, 1?0, 1^7, 181»,

208,210,217.
Gilbertl, Explanation of figures of, on plate

xviii, 21(4 ; on plate xix, 29S ; on plate xx,

302 ; ou plato xxi, 30tl.
Gilbert!, Observations on, 173.
Gilberti (=0. HowcUi), 164.
Howelli, 107, 164, 170, 171, 173.
Iddingsi, 32, 34, 35, 30, 47, 107, 170, 174, 178, 210.
Iddingsi, Explanation of figure of, on plate

xix, 21tS.
Tbompsoni, 1.5, 18, 19, 26, 29, 32, 3«, 47, 89. 93, 95,

104, lOJ, 111), 121, 141, 158 159, ISl, 10;i, 165, 166,

107, 168, 169, 171, 173, 17,5, 176, 178, 179.
Tbompsoni, Explanation of figures of, on plate

xvii, 290 J on plate x.\ii, 310; on plate xxiii,

314.
typicalis, 50, 95.
Vermontana, 158. 159, 176.
(=MeHonaci8) Vermontana, 167.
Ollenellus borizon— Georgia or Middle Cambrian,

44.
east of Swautoii, 19.
Fauna of, east of Swanton, 19.
Relation of, to Potsdam horizon, 33.
Separation of the, 33.
Olenida;, Genera of, iu Middle Cambrian, 55.
Olenoides, 30, 55, ISO.

fauna in Ely Mountains, 35.

Genus itroposed, 183.

limited to Middle Cambrian, 62.

Species of, in Cambrian, 01.

expansu.s, 222,

flagricaudua, 47, 181 , 222.

? flagricaudus, 1S5.

tflagricaudus. Explanation of figure of, oh

piate xxv, 322.
levis, 20,35,47, 1>T, 222.
levis. Explanation of figures of, on plato xxv,

322.
Marconi, 1,5, 26, 47, 56, 95, ISO, IbU, 190, 222.
Marcoui, Explanation of figures of, on piato

xxvi, 320.
Nevadensis, 40,47, 1S1,22&.
Novadensis, Explat)''tioii of figure of, on plate

x.NV, 322.
q":uii i-^eps, 32, 47, 1J»7, 188, 189, 100, 20.5, 222.
quad,,ticps, Exidanatioc of figuie.Hof, im plate

xxix, 33S.
spinosus. 32,47, 181, 1S4, 1H7, 222.
spiuosuH, Explanation of figures of, on plate

xxv, 322.
typicalis, 34, 47, 180, 181, 1S3, 187, 210, 221, 222.
typicalis, n. sp.. Explanation of figures of. on

platt^ xxv, 322.
Wahs.itcliensis, 47, 188, ISO, 200, 200, 222.
Walisatobcusis, E.vplauatiou of figures of, on

plato xxix, 33S,
Olenus, 102,104,105.

? ia Upper, but not in Middle or Lower, Cam-
brian, 02.
Spoi-icH of in Cambrian, 61,
a.saphoides, 108.

(1()«>0)

INDEX.

36^

I, 55, 84, 95, 105,
1,5,106,169,170,

ro, iFO, le", is'.t,

38 of. Oil plate
; oD plato XX,

>, 174, 178, 210.
•e of, on plate

3S,47, 89, 93,95,
01,16,), 165,166,
178, 179.

ires of, on plate
o!i plato xxiii.

ildle Cambrian,

1, 33.
ibrian, 65.

ii^urfi of, OH

on plato XXV,

, 190, 2'J2.
<!.s of, on iViato

no of, on plato

00, 'J0.5, 222.
i>.s of, on plate

■a of, on plate

21tj 221 222.
figures of, on

206, 222.
llHUVcH of on

I.owiT, f'ani-

Olonus — Coiitiniiid.

(OIpucUus) Gilbertl, 170.

(Olent'llua) Howelli, 171.

NevadensiH, 18,1.

Tlioiupsoni, 167.

Vcrmsntana, 158.
Opbilta, in Upper, but not in Middle or Lowor,
Cambrian. 62.

Species of, in Cambrian, CO.

conipacta, 22.
Orjnirrh Range, Cambrian secition of, 'M,
Orbicula csrlata, 95.
Orbiciila ? cra.smi, 114.

Manio as Obololla crasaa. 111.
Ordovioian, 44.
Ortbia, 48, lUt.

• genus 1 jiutnoft to Lower, Middle, and TTpper
Cambrian, 62.

n. sp., 26.

?Hp.,29.

a^. I 27.

SpVicies of, in f'ainlirian, 60.

Eurekcnaia, 3L'.

Higblaud ns'.s 35,40

? IligblaiidenHi.s. n, aii., 11!),

? Higblaudcnuis, Explauation of ligurea on
plate viii, 2o4.

Orientalia, 15.

Ch' - -(, 48, rid.

» jnii' i.n to Middli' and Tppcr Cambrian, 02.

sr {-., 15, ]?, 20, 4ti, 99.

sp. iindt., i'l'i.

Spccii's of, in Cambrian. 60,

featinata, 1.5, 18, 19. 4ii, .52, 120.

festiuata, K.^pUmation of iignrea of, on plali^

vii, 2.">0.
Orienfalia, 19, 40, 49, I'iO.
lOrientalia, 119.
Orient ali.'^, Kxplanatiou of ligiuv of on pliite

vii, 'ioO.
I'opina, 49, 119, 120.
tranavoraii, 15.
transveraa, Kxplanation of figures of, on plati-

vii, no.

.'transversa, 40, 1'21,
Ortbocciatitea, lliR.
Orycloccpbalus. od.

limited to Middle Cambrian, 02,

Sjiecies of in Can)brian, 61.

piimuH, AH, 'ilO.

prinitix, Kx]ilaiiation of Mgurea ol'. on plate
xxix, :t'>S.

I'agiira, 191.

I'aliniiia'iat liange, Silurian of :10.
I'alieaeniea, in I'piier, Init not in Middle or Lower,
C:ii]ibrian, 02.

SjHM-iva of ill Cambrian. 00,

typiea, 21,
rali'clionla, inT'p])ei, but not i;, Mid'!. i.' or Lower,
Cambrian, 62.

Speeiea of in (,'anilii iaii, 59.
Pabenignia, Kll.

proposed in place of 'I'etriidiuiii, 223.

>Vrangeli, 224,

PaliEnignia — Con! iuued.

Wrangeli, Explanation of flguros of, on plate
xxxiii, :t5t.
Paleo])bj-cus, 72. •

eonimon to Middle and ITppor Cambrian, 62.

Spoci(^s of in Cambrian, 59.

<-ongregatua, 15, 4,j, 72.

iucipiens, 15, 27, 29, 45, 72.
Paialiolina, 181!,

Nevadensia, 18:(.
Paradoxii'ea, 44, 160. 102, 164, 165 166, 181, 182, 183.

fauna, i ; , 49, 5S.

fauna of .St. John, Braintreo, and Newfound-
land, Stratigraphic relations of, 40.

limiti d to Lower Cambrian, 62.

lieiationa of, to Mesonacia and Olenellna,
1«5.

Speeies of in Cambrian, 01.

aaapboides. 168.

Barberi, 29.

expectaua, 162.

Forcliammeri, 104.

Kjenilli, 101, 162, 166, 178.

lijerulti, Explanation of figure of, on plate

XX, ao'i,

L.velli, 162.

niaerocephaluB, 167, 188.

JXevadenais, 180, 181.

Oelandicus, 162.

(luadriajiinoauH, 191.

?quadrispinos«is. 191.

(Pagura) iiuadiispinosus, 191.

rugulosua, 161, 162. 166, 183.

ruouloaus. Explanation of figure of, on plate
xxiv, 31S,

K.ieberi, 161.

spinosua, 161.

Tliofnp.soni, 167, 191.

Verniontana, 1.58, 191.
I'.irailoxidea liorizon, Oeuera of American, 50.
TarUer'a farm, 17.
I'arUcr's nuarrv, Fossils in sbales of, 15.

G<'orgia section at, 13-17,
Peltocaria. 148.
Peltura, 187.

(t)lenus) liolopyga, 191.
Pempliigaspia, in Upper, but not in Middle or
Lower, Cambrian, 62.

Speeies of in Cambrian, 61.

b\illata, r>:>, 153, 154.
Phacops, 191.

Pbillipsburg formation, 22.
i'hragmotbeca, 1,'il.
Pioelie. Xev., Sjieeies fnun, 35.

Tliickneaa of quartzito at, 36.
riautn', 48, 50.
I'lat.veeras, i;;0.

common to Middle and irpjier Cambrian, 62.

Sjipcies of, in Cambrian. 60.

Koyti, 21.

n\iuntia,siniiim, 21, 131,225.

primaviini. 20, 27, 46, .53, ISO, 131.

primavuni, Explanation of ligures of, on
j)late xii, '270,
Plenrotomaria, doubi fully idciitillcd in Cambriuii,
03,

(1001)

366

INDEX.

W \

*
,?

Pleurotouiai'la — ('i)iitiiiuocl.

?, in XTppnr, Imt not in MidiUo or Lower Cam-

brinii, G2.
'Species of, in Cambrian, OU.

Hp. iindt. (i). ■'!•">■
I'cpcilopoda, M, I ll>.

Di.strilmtion of species f)f, in Middle Cam-
brian, 47. IS.

(icncra and sjiceii^s of, 48.

(ienera and iii)i<eie:4 of, in Cambrian, (!2.

(jinera of, in C:imbrian, lil.
I'oiut Levin, 'JO.

eoiiiilonierntes of Caleiferons afje, 'J3.

(tliaU, Ajio of, 'J4.
I'otHdani epocli, i;i.
Potsdam fauna, 11, 2:!.

of (lie Adirondaelv region, 2.1.

Coi relation wifb Xew Yoik of, ;).■!

of the ('amlirian. 44.

Saiiitoga, C(>n)]iared witli Wiscousiu Potsdam
■(itndHtone I'auna, 21.

I'ppcr, S|i( ciis in, I!,').
I'oi.ud.ini format i(pn, nrar tiie Adlronda<d;H. rejire
■senloil as a .sandstone, 24.

not (d)Herved in Nortlioin Vermont as ;t exists
in New York, 2i.
Potsdam fossils, 24.
Potsdam horizon, 2!l.

Hiialion >>f, to Georgia or Oleuellns, U.'t

l'])I'er liMiit of tlie, 14.
I'otrtdam limi'stone. 4').

!'ot,sdaiii Lower, Funua of fleorpia sIialoH referred
to the. 20.

iiivriiHjiiven by liilliii);stoiridd!e''ainbrian, 4!*.
I'otsfl.im or Tlici'lloceplKiliis ITjiper Oambi'fiin, 44,
IV)tsdi'.m sandsKme, 21), 23.

I'riinonlial Zone of Life perhaps equivalent t>
the, 14.
I'ofsdaiM series, Strati;;iaphir relations to Georiii i

series, 20.
Pre-Candirian. 14.

Callinile beds piiibably belons to the, 'M.

fitrnta of the fliaiid Ciifion, 41.
Primitia!, Species of in Cambrian, tiO.
Primordial fa>:n.i of liarrande, ii.'i.

or (-"anibrian I'eiio.l, 12. \'i.
Pr'^tns decoviis, 170.

vemistna. 176.
Prospeet Mountain limestone. 32.
Prii.-ipeel Mouutiiiii <]iuirtziti'. IHI,
ProapevI M,)unt.iii! shale, ;|(i,
Protiehnites, in Upper, but not in Middle or
Lower. CamViri/.n, 02.

,Spe<ie*of, in Cambrian, 01.
Protoearis, 1

limited l,i Miildli Cambrian, 02.

Speeici of, in Cambrian, I'd.

Marsbi. 47, 54. 80. t):i, 147. <4»i.

Miirshi, Explan.ntioii of tl'.-'ires of, on plate
XV, Wi.
Protocyntlins. 7."i, 70.

ranis, 87.
Protoeystites Menevensls. ft."

;/ lonsi'laetybis, it"
Protojjruptns, luniled to Lower Caiir^mii. uJ.

Species of i« ViMnliiian. ,'<M,

Protospongia, 110.

common to Lower. Middle, and Vlpjwr Cam-
brian, 02.

Spoeies of, in (Cambrian, 50.

fencstrata, :!2, 4r,, 49, oO, f>\, ttO.

/ fnnestrata ?. Explanation of fignrcs of, on
plate vi, 240.
Protypns, .5(1,

limited to Middle Cambrian, 02.

n. <;en.. 'ill.

Species (if, in (Cambrian, 01.

exp,insnH, ,'t2.

llitcbcocki, l."i, 48, 211, 21.'!.

Ilitcheoeki, Bxplauaticm of tiguie ot', on plat«
XX xi, ;i4(i.

parviilns, 213, 214.

8en»etU8, 1.5, 19, 20, 2!), .'(2, 40', 4S, fy"., 213.

^enectus, Explanation of IttMiri^s of. on plato
xxxi. 34t».

seuectus var. parvnlns, 1."). 28, 29, 48, <t9, 126.
Plnrojiort, Deseriptiou of a, from the Upper Cam -

biian. 'in.
PteroiMida, .")4, l^l, 'i'i:!.

Distribution of species of, in Middle Cam-
brian, 4T.

(renc ra and 8])eo!es of, 48.

tienera and species of, in Cambrian, 02,

Genera of, in Cambrian, ftO.
PteroHieca. '31.
Pterotbecidie, 131.

Ptyehaspis, in TTjijier, but not in Middle or Lower,
("ambrian, 02.

Sjiet ies of, in (Jambriau, 61.

miiiut»,, 3:>
Plychoparia, 19, 35, 48, llt3.

and subgenera, common to Lower and Middle
Cambrian, (i2.

and subgenera. Species of, in Cambrian, 61.

common to Lower, Middle, and Tipper Cam-
brian, 62.

sp ? 32, 3.5, 4.8. 202.

sp. nmU.,26.

Adaiu'i, 1,5, 17, 18, 1ft, 20, 26, 47, 4ft. 141, 105.
199, 200.

Adntnsi. Explanation of ftgures ol. on plato
XX ri, 320.

iilUuis, 33.

bella, 32.

Billingsi. 198.

brevicep 33.

calcifera. 21.

(i=('ouoiephft!ite8), 193.

(— (./'onoeepbalns), 193.

dissimiliH, .<2.

(Enlotiin ?) dissimilis, 36.

Emmrichi, ?02.

griinulosji, 3.'t.

Uaguei, 32, 33.

Ilousensis, 40, 47, 201.

HouHen;*is, Explanntinn of fignres of, on]dat4<
XXV :{22.

(Crepi'i'pliii'.uH) Iowens\s, 200, 207.

Kiu«i, 40. 47. 10ft, 103, '200. 201

Kin:.:!. KxTilanution oi ligures of. on plate
xxvii, 330.

Itevieeps, i^i. '

St
S(

.Sn

(100-')

id Upper Cam-
ngurc» of, on

iincof, on plat«

48, O'l, 213.

ivus o)'. oil V'"'**

5, 2'J, 48, 4tt, Vi6.

in Middle Cam-
mbriuii, 02,

Middle or Lower,

Lower and Middle

1 Canil)riai>, 61.
aud Tipper Cam-

47, 4!), 141, 10,5.
'rtres ot, ou plato

flanreHof, onplato

iOfi, 207,
ill.
unw ol', <•" pli'*f

INDEX.

t^.yoboparia— Continued.
latic»jpp, 32.
LincamHoni. ^12.
JLiuaarsuwiii, 205.
(Lonohocopbalvii*) oalcifeni, 226.
miuoi, 34, 35.
mlnnte, 21.
mi^fcr, 29, 47, 1«».
mioer, Esp^.aration of fleuroi ol', ou plate

xxvii. 880.
occidfUtJiliig, ;i2.
Oweni, 32, 33.
Owcnl (ot'Ha'.l), 21.
perniiauta, 32.

PiocUensia, 34, 47, 5tt, 95, 201, 2i0.
Piochousis, Explanfltion of flr,Dre8 of, on plate

xxvl, 32tf ; on plate xsviji, 334.
ProsipectunBlH, 32, 20ii.
I Prospectenais, 47, 'iO'i,
1 Proapectensis, Explanation of figures of, oo

plat« xxtrij, ;i;{0.
quadrans, 39, 47, 11)!».
quadraus, Kxplanation nf fijriireB of, oj plate

xsix, 338.
(Agraiilos) Saiatogennifl, 21.
(Agianlos) atrenuus, 2(5, 47.
seueotus, 214.
Blmilis, 32.
aininlata, 33.

siibcoroniita, 47, ^0.5, 206.
sultforonata, Eiplaiiationof ftsareof, on plate

xxviii, 3.?4.
Teucer, 18, 26, 197, 199.
Tencer, Exp'iauatiou ol figure of, on plate

ixvi, :in.
tviliucata, 20, 27, 48, 20.3.
ti'ilini>ata, Kxplanation of flgur^^a of, ou ylAto

xsvii, 330.
uDisulcata, 32, .33.
Vnlcanuif, ir,, 26, 48, 1
Vulimnii8, Ksplanatiou o.' B};ur'!.s of, on plate

xxT! 326.
V/i8Coiii*enais, 21.
PughiDcnlas, 131.

lienaselaer County, Sections ip,de8cribiM! by Win-

luona, 70.
libyuchonoliidtB. 53.
Khyaospougia. 70

St, .folni fa'inn, •)!».

St, Joliu G'oup. Gviiptolitos in, 51.

Hyo'iitlies from, liavc uintin< t •^t i>ta, I3f.
St. Lav.rciii'o Valley, 24.
St. Simon, Coujtlorji'rate liniesiones of, 24.

List of species from. 2G.
Snlteri'll". 131, ]■(«, 137. US.

limiifd to Middle Cauibiian, 62.

Mil., •jtl,

.Spi'cits of, in Catubriau. 60. j

iilitnsii, 134, 144.

l>nlr(i«lla, 26, 20,47 134,111, )>^,.

fiiiU'liilla. Kxi'ldniitiidi of tijnio.H of, or plate

xii. 270: on plafu xiii, 274,
pnlcliella {!). I'l, 18. IB.
rugosa, 2», 47. 144, 14.'.

iW'Jo)

SalfceroUa — Con t.niiod .

rPKOs*, KxpSanal'ion of fsore of, on plate xiii,
274.
Salterelhda), J 31.
SftrMogft Potsdain fi»nn«. compared with the Wis-

conaiu PotRdani 8a.ndatone fauna, 31.
Saiwroga Spi ingu. Section west of, 22.
Gaidinia, 57.

Caiubriun diHtrtci, of Canalgrande iu, 80.
SceiteUa, 125.

limited lu Middle Cambrian. 62.

Species of, 11 Cambrian, fiO.

conula, 32, 4C, 136

conula. Explanation of figures of, or. pbite
viii, 251.

? conula, 127,

reticuLita, 20, 46, 49, 125, 126, 127.

ruiiculattt. Explanation of flguri's r,f, on plate
xii. 2T0.

retasa, 20, 27. 46, 12-5, J2«.

retus-i, E:cplunation of Hruii'm uf, ou plato xii,
270.

variana, 18 12.').

? varans, 4(;, 127.

1 variana. Explanation of ti^nros of, on plate
xii, '>7ft.
Schi^iimboii, yennfi, 52, 107,

SchjdacTi Landing, Stction aouth of, by S. W.
Eor.l, 2V, 2S.

Spocies Iroai, 27
Scolitlirs, in Upp'n- Imt not in Middle or Lower,
C.iinibi''iin, 82.

Spocios of, in Cambrian, .W.
Pcyphia, 79.
Second far.na. 63.
Sei-'et Caflon shale, 30.
Section, at '/Ause aii fxiuj . 21'/.

at Trois Pistoles, de<<oribed by Sir WilKam
Logan, 2H.

at f ro>', l>y S, W. Fold, 27.

Big Cottonwood CaBon, 41.

Camt>rian, Euroka mining district. Central
Ncva«ia, 30,

CiimbriiD, Wbile's Peak, Xevada,41.

east of HighgKto SpringH. Vermont, 18.

oast of Swanlon. Vennont, 18.

Eureka t^anihriw). H.'i,

Georgia. 19, 1,4, 43

Oeorgiii, it Parker » (|narry Ac, 15-17.

Georgia, rignrf of, IW,

Grajjd Oafion, fo.-isils ol, 4t.

Great Cambrian of ( ot'onwood CaOou, «8.

Higher strata ot Ui^hiand Range. 36.

Highgate, 19, 24.

Highuiate, ot Hitcheoek. 20.

Higiiland Raugu. m>vcA of Eureka, 33.

illu«tratiiig the Tueouic HvAteni <T7.

Kiiidcrliiiok Creek, above .St«5tej«rt, N. ?'. 38.

Oquinli Ufingo, 31t.

south of 9ii4to<iHek Landing, by H. W 9aBt. 27,
2n

.Swanton. 24.

'akeu eitar of .Swautou by Hir WiUiam Logan,
10.

WauMf h or Bi„' Cotton wo««, UK

west jf Saratoga Sprin-s. '£t.

ill-

368

INDEX.

P' < tS

SeotloDB at different points, from Hi^bgate, in
Northern Yermont, to Bensselaer Comity,
New York, by Dr. Emmona, 70.
Cambrian, Table showing correlations of, ii.
Correlation of, 10.

Group of, taken across New Hampshire and
Yermont, by Prof. C. H. Hitchcock, 20.
Selwyn. A. E. C, 24, 26, 71, 145.
Serpulites, in Upper, bnt not in Middle or Lowen
Cambrian, 62.
SpecleH of, in Cambrian, 60.
dissolutns, 89.
Shumardia, 153, 157.
iSilurian, Lower (Ordovician), 11, 12.

Hixinf; of, with Upper Cambrian, 12.
Silver Peak, Nevada, 36, 74.

species from, 38.
Siphonin, 79.
Solenopleura, 10, 56, 214.

common to Lower and Middle Cambrian, 62.

sp. 1, 26.

Species of, in Cambrian, 61.

brachymetopa, 215.

Nana, 27, 48, 214.

Nana, Explanation of figure of, on plate xxvii,

880.
(like S. Nana), 20.
Solf nosema, 206.
Spongiffi, 50, 72.

Distribution of species of, in Middle Cam-
brian, 45.
Genera nod species of, 48.
Genera and species of, in Cambrian, 62.
Genera of, in Cambrian, 59.
Stampede Gap, section near, 33.
Steuotbeca, I2H.

coroniou to Lower, Middle, and Upper Cam-
brian, 62.
Species of, in Cambrian, 60.
Acadica, 53, 128, 12».
cornucopia. 128, I2U.
elongata, 29, 32, 46, 49, ."50, 125, 129.
elongata, Explanation of figui-es of, on plate

xii, 270.
pauper, 128, 129.

rugosa, 2(i, 27, 29, 46, 40, 53, 120, 128, 129, 139.
rngoaa, Expliinatiou of figures of, on plate
xii, 2iO.
Straits of Belle Isle, Georgia fauna occurs at the,

29.
Sirapnriillina. Spoclesof, in Cambrian, 00.
Streplioclietu.s, 91.

■Species of, in Cambrian, 59.
i sp. (, 38, 45, 91.
oseellatllH, 01.
Slrophimicniiln?, 52.
Stvlioln, i;,i.
Swauton, section east of, 18.

Serticin east of, by Sir WiUlani Logan, 19.
Section, 24.

Taconlo— Continued. ,

rocis, Upper division of the, 70.

serief, 66.

8lat<^, 13. ' .

system, 65.

system, Dr. Emmons's seotion illustrating the,
67.

system. Position and relation of, by Emmons,
66.

system, Proposition by Dr. Emmons to divide
the, 69.

Upper, 23.

Upper, classified by Dr. Emmons as pre-
Potsdam, 65.
Tontaculidio, 131.
Tentaculites, 131.
Tetradium, Palienigma proposed in place of, 223.

Wrangell, 223.
Theca, 131.

triangularis, 132, 133.
Topsail Head, Georgia fauna occurs at, 29.

limestone, correlated by Murray, 49.
Trails of annelids, in Middle Cambrian, 72.
Tromatis, 102.

? pannula, 1U5.

l)unctata, 105.

Siluriana, 105.
Trenton limestone, 24.

Triartlv. ella, in Upper, but not in Middle or
Lower Cambrian, 62.

Species of, in Cambrian, 01.
Triarthi-us, Bocki, 176, 204.

trllineatus, 203.
Trichospougia sericea, 78.
Trilobita, 55.

Trinucleus concentricus, 152.
Trinucleus ornatuB, 152.

Triplesia, in Upper, but not in Middle or Lower,
Cambrian, 62.

Species of, in Cambrian, 60.

primordi.ilia, 53, 122.
TrocbocyHtitos Bohemica, 95.
Trois Pistoles, List of species from, 2H.

section, as described by Sir William Logan,
20.
Troy, N. Y., 20.

section, b.> S. W. Ford, 27.

Upper Camlinan, 19, 99.
Utica sbalo, 24, 43.

Vaginelirt, 131.

Yermont, Xortbm t, Potsdam formation not ob-
served in. as it exists in New York, 23.

section, 28.

sections, by C. II. Hitchcock, 20.

Western, sections, 13.
Von Jlieruig, 138.

Tacouie, On tlio use of the mime, C5.

of Eiiiinoiis cdiisiileieii by Dana as Lower Si-

Inriait, 7(1. Wasatch section, 3S.

grai)toliUs. 02. I "correlated, 44.

(1094)

1,70.

>n illustrating the,
n of, by Emmona,
Bumona to divide

Emmona as pre-
I in placo of, 223.

lura at, 29.
rray, 49.
lubiian, 72.

>t in Middle or

Middle or Lower,

om, 2rt.

orra.ition not oli-
ew Yorls, 23.

i, 20.

Ix\i)EX.

369

Wbitllcld, n. p., Cambri;

13.

Ill I'iltlll -.A ((UTI)I.lIcd l,v,

Whitney, J. D., 36.
Wlnchell, N. H., 29.
Wiuooftki niarlde, 23, 145.

Wisconsin Potsdam sandstone fauna compared
with Saratoga Potsdam fauna, 21.

Bull. 30 24

Zittfll, Dr., 80.
Zoanthcria perforata, 7B,
Zoologio r6sum6, 62.

(1095)

!■•

'U 1 ■il

\i\

mm I'

Slip',
Si' v

-m !

I», "«

A-DVERTISKIVLTCNT.

[iJullotin No. 30.]

Tilt pulilicatioDs of the United States Geological Survey are iHHueil in accorilaiice with tlio statute,
approved Marcli 11, 1871), wliifli declaroB that —

" The iiublicatiouHot' the Geological Survey nlmll coiiHist of I he a:iuuHl rejjort of oiienitioiis, acdloirical
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of said Survey shall be iHSiied In uniform (piarto series if deemed ueeeH.siiry by th(( l)ire(^tor, hot ot hiM-
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On July 7, 1S82, the following joint resolution, referrinc to all Government publications, was passed
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' ' That whenever any document or rcportshall be ordered printed by Congress, there shall be printed,
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Under these g«'neral laws it will be seen that none of the Survey jjoblicaticns are furnished to it for
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legislative and e.'cecutivo departments and to stated deiiositories throughout the TTuited .States.

Except, therefore, in those cases where an extra number of any j)uldiration is specuiUy 8up|died to
this Office by the Secretary of the Interior, the Survey has no copies of any of its publications for gra-
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ANNUAL KEPORTS.

Of the Annual Reports there h.ivo been already published :

I. First Annual Report to the Hon. Carl Sehurz, liy Clarence King. 18P0. 8°. 79 i»]). 1 map. — A
preliminary report describing plan of orgauizati n and publications.

II. Report of the Director of the United States Geohigical Survey for lb80-'81, by .1. \V. Powell.
1882. 8°. Iv, 58S pp. (U pi. 1 map.

III. Third Annual Report of the United States Geological Survey, 1881-'82, by .7. W. Powell. 18K».
8°. xviii, 5C4 pp. 07 ]il. and maps.

IV. Fourth Annual Report of the United States Geological Survey, 1882-'83, by J. W. Powell. 1884.
8°. xxxii, 473 pp. Sn pi. and maps.

"V. Fifth Annual Report of the United States Geological Survey, 1883-'84, by J. W. Powell. 1885.
8". xxxvi, 46!) pp. 58 pi. and maps.
The Sixth Annual Report is in press.

MONOGRAPUS.

Of the Monographs. Xos. II,III, IV, V, VI, VII, VIII, and IX are now published, viz:

II. Tertiary History of the Grand (^auon District, with atlas, by Clarence E. Dutton. Capt. U. S. A.
1882. 4°. xiv, 264 pp. 42 pi. and atlas of 24 sheets folio. Price $10.12.

III. Geology of the Conistock Lodo and the Washoe District, with atlaa, by George F. Becker.

1882. 4°. XV, 422 pp. 7 pi. and atlaa of 21 sheets folio Price $11.

IV. Comstock Mining aiul Miniirs, by Eliot Lord. 1883. 4"^. xiv, 4.")1 pp. 3 pi. Pri«e$1.50.

V. Copper-bearing Rooks of Lake Superior, by Roland D. Irving. 1883. 4°. xvi, 4H4 pp. 1.5 1.
29 pi. Price $1.85.

VI. Contributions to the Knowledge of the Older Mesozoic h'lora of Virginia, by AVni. M. Fontaine.

1883. 4°. xi, 144 pp. 54 1. 54 pi. Price $1.05.

VII. Silver-Leatl Deposits of Eureka, Nevada, by Jose|di S. Curtis. 1884. 4°. xiii, 200 pp. IC pi.
Price $1.20.

VIII. Palcimtology of the Eureka District, by Charles D. Waloott. 1884. 4°. xiii, 298 pp. 24 1.
24 pi. Price $1.10.

IX. Braehiopoda and Lamellibranchiata of the Raritan Clays and Greensand Marls r)f New Jersey,
by Robert P. Wliitficld. 188.J. 4°. xx, 338 pp. 35 pi. Price, $1.1.5.

*f"i.*

,' I

ADVERTISEMENT.

The followlnsnrn In prow, viz;

X. DlnucKratu. A M<)iio){raph of an Extinct Urdor of Oigantlu Mamniali, by Othulel Charlns Martb.
1885. 4°. xvill, 237 pp. 50 pi.

XI. OeoloRlcal History of I.ako LRliontiin, a Quaternary Lake of NDrthwestern Nevada, by hraal
Cook liuBRcll. 1885. 4°. xir, '.'88 pp. 40 pi.

XII. GeoIo);,v and Mining: luiluHtry of LeadvlUe, with atlas, by 8. F. Emmons.
Tho following are in prciiaration, viz:

I. The PiecioUB Metals, by Clarence ICiug.

— Ueulo^y <il' the Eureka Mining District. Nevada, with atlas, by Arnold Hagne.

— Lake Uuunuville, by U. K. (rill)ei't.

— Sauropoda, by Prof. O. (!. Marnh.

— StetfOH.mriii, by Prof. O. I'. Marsh.

— Geolouy of the Quicksilver Depo.sits of the PaoiUo Slope, with atlas, by Oeorge F. Booker.

— The Penolfee-nnj^eljio IronDoaring Series of North Wisconsin and Michigan, by Roland D. Irving.

— Description of New Fossil Plants from the Dakota Oroap, by Leo Lesquerenx.

— Youn>;ur Muuozoic Flora of Vir^^lnla, by William M. Fontaine.

— Report on the Denver Coal Basin, by Samuel F. Emmons.

— Report on Ten-Milo Mining District, Colorado, by Samuel F. Emmons.

— Report ou Silver Cliff Mining District, by Samuel F. Emmons.

— Flora of the Dakota Gronp, by J. S. Newberry.

BULLETINS.

The Bnllutinit of the Survey will contain such papers relating to the general pnrpose of its work as
do not properly come unilerthe heads of Annual Reports or Monographs. -

Kach of those Bulletins will eoutain but one paper and will be complete in itself. They will, how-
ever, bo numbered in a coutinuouH series, and will in time be united into volumes of convenient sizes.
To facilitate this, each Bulletin will have two pagination-^, one proper to itself and uuotherwblch be-
longs to it us part of the volume.

Of this series of Bulletins Nos. 1 to 30 are already published, viz :

1. On Uyperstbene-Anilesite and on Triclinic Pyroxene in Augitie Rocks, by "!^^hitman Cross, with
• GeologiealSkotehofBuiruloPoaks, Colorado, by 8. F. Emmons. 1883.8°. 42i)p, 2 pi. PricelOceuts.

2. Gold and Silver Conversion Table.s, giving the coining value of troy ounces of line metal, (to,, by
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3. On the Fossil Faunasof the Upper Devonian, alongtho meridian of 70° 30', from Tompkins County,
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4. On Mesozoic Fossils, by Charles A. White. 1884. 8°. 30 pp. 9 pi. Price 5 cents.

5. A Dictionary of Altitudes in the United States, compiled by Henry Gannett. 1884. 8°. 325 pp.
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6. Elevations in the Dominion of Canada, by J. W. Spencer. 1884. 8°. 43 pp. Price 5 cents.

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8. On Secondary Enlargements of Mineral Fragments in Certain Rocks, by R. D. Irving and C. R.
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9. A Report of work done in the Washinzton Laboratory during the fiscal year 1883-'84. F. W.
Clarke, chief chemist; T. M. Chatard, assistant. 1884. 8°. 40 pp. Price 5 cents.

10. On the Cambrian Faunas of North America. Preliminary studies, by Charles Doolittle Walcott.

1884. 8°. 74 pp. 10 pi. Price 5 cents.

1 1. On the Quaternary and Recent Mollusca of the Great Basin ; with Descriptions of New Forms, by
K. Ellsworth Call; introduced by a sketch of the Quaternary Lakes of the Groat Hasiu, by G. K. Gil-
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12. A Crystallographic Study of the Thlnolite of Lake Lahontan, by Edward fe. Dana. 1884. 8°
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13. Boundaries of the United States and of the several Stales and Territories, by Henry Gannett,

1885. 8°. 135 pp. Price 10 cents.

14. The Electrical and Magnetic Properties of the Iron Carburets, by Carl Barus ami Vincent
Strouhal. 1885. 8°. 238 pp. Price 15 cents.

15. On the Mesozoio and Cenozoio Paleontology of California, by Dr. C. A. White. 1885. 8°. 33 pp.
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10. On the higher Devonian Faunas of Ontario County, New York, by J. M. Clarke. 1885. 8°.
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17. On the Development of Crystallization In the Igneous Rooks of Washoe, by Arnold Hague and
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18. Ou Marine Eocene, Fresh- water Miocene, and other Fossil Mollusca of Western North America,
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19. Notes on the Stratigi'aphy of California, by George F. Becker. 1885. 8°. 28 pp. Price 5 cents.

ADVERTISEMENT.

1 Charlos Marth.
roTnda,by brael

F. Booker,
iolaurt D. Irving.

086 of its work as

Tlioj' will, how-
cunvonient nizes.
mother which bf-

traan Cross, with
)1. Price 10 cents,
ne motal, ( tc, by

['ompklnsOounty,

). Price 5 cents.

Its.

.8«4. 83. 325 pp.

■ico 5 cents,
orth iind South),
cents.
Irving and C. R.

1883-'84. F. W.

(oolittle Walcott.

f Now Forms, by
liu, by G. K. OU-

:)nna. 1884. 8°

I Henry Gannett,

rus and Vincent

IsSS. 8°. 83 pp.

lurke. 1885. 8°.

lnold Hague and

l^orth America,

Prim 5 cents.

90. Contribntions to the Mineralogy of the Rocky Mountains, by Whitman Crou and W. F. niUe-
brmnd. 188S. 8°. 114 pp. 1 pi. Price 10 cunts

21. Tho Lignites uf tlie Urwkt Sioux Keservatlun, by Bailey WUlia. 1885. 8°. 16 pp. b pi. Price
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22. On New Cretaceous Fossils from Culifuniia, by Charles A. White, H. D. 1888. 8°. 25 pp. 5 pi.
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23. The Junction botwuuu the Kastem Sandstone and tho Keweenaw Series on Keweenaw Point, by
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24. List of Marine Mollusca, comprising the Quaternary fossils and recent forms ftvm American
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25. The Present Technical Condition of tho Steel Indnatry of tho United States, by Phineaa Barnes.

1885. 8°. 82 pp. Price 10 cents.

26. Copper Smelting, by Ilonry M. Howe. 1885. 8°. 107 pp. Prire 10 cents.

27. Work done in the division of Chemistry and Physics mainly during the fiscal year 1884-'8S.

1886. 8". 80 pp. Price 10 cento.

28. The Gabbros and Associated Hornblende Rocks occurring in the neighlmrhood of Baltimore, Md.,
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29. On the Fresh-water Invertebrates of the North American Jurassic, by Dr. C. A. White. 1880.
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30. Second contribution to the studies on the Cambrian Fannas of North Amerio*, by Charles D,
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Numbers 1 U) 6 of the Bulletins form Volume I j Numbers 7 to 14, Volume II; Numbers 16 to 23,
Volume I II J and Numbers 24 to 30, Volume IV. Volume V is not yet complete.
1 lie following lire in press, viz:

31. A NVMtematio review of our present knowledge of Fossil Insects, including Myriapods and Arach-
nida, bv Samuel H. Scndder.

32. Mineral Springs of the United States, by Albert C. Peale, M. D.

33. Notes on the Geology of Northern California, by Joseph S. Diller.

34. On the relation of the Laramie MoiluHc^an Fuuna to that of the succeeding Fresh-water Eocene
and other j^'oups, by Dr. Charles A. White.

35. The Physical Properties of tho Iron Carburets, by Carl Barus and Vincent Stroubal.

36. The Subsidence of small particles of Insoluble Solid in Liquid, by Carl Barus.

STATISTICAL PAPERS.

\ fourth serios'of publications, having special reference to the mineral resonrces of the United
States, has been undertaken.

Of that series the following have been published, viz :

Mineral Resources of the United States [1882], by Albert Williams, jr. 1883. 8°. xvli,813pp. Price
50 centH.

Mineral Resources of the United States, 1883 and 1884, by Albert Williams, Jr. 1885. 8°. xiv, 1,016
pp. Price 60 cents.

In pre|)aration :

Mineral Resources of the United States for calendar year 1885, by Albert Williams, Jr.

Correspondence relating to the publications of the Survey, and all remittances, which must be by
POSTAL NOTK Or MONBY ORDBH (not stamps), should be addressed

To THE DiHECTOB OK THK

Unitkd States Gkoi.ogicai. Suuvkt,
. Washington, D. C.

Wabhinotok, D. C, September 1, 1886.