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ON
THI

iC^^ > ' ^

[From the Qcartekly Journal of the Geolooical Society /yr

November 1877.]

ON A SPECIMEN OF DIPZOXYLON FROM
THE COAL-EOllMATION OF NOVA SCOTIA.

r^i

830

J. NV. DWVSON (»N

UCIMKN OK DIl'I.ttWLON

Note on a Rpkcimkn of l)ii'i-oxvi,nx from the Coai.-I'okmaiion nj
Now Stu.TiA. Ky J. W. Dawson, I.L.I)., F.R.S., F.d.S.

In a recent visit to the Soutli .Iog<i;iiis, with the view of further
htudyiii}? the fossils of thiit district, and more espeeially of Kearoliiiii;
for reptilian remains in any erect stump.s of >Siiflll<tri(( Ihat nii^rlit
have been exposed hy the action of tlie w.ives, 1 was zealonsly aided
by my friend Mr. Albert J. Hill. Manaj;er of tlie Cumberland Mine*,
who, after my departure, determined t(j take down ?ome erect trees
occurring in beds lower in the section tlian those containinij: tlie
reptilian remains. In jjursuing this investij:;ation he discovered a'l
erect tree twelve feet in heiglit, having the whole of its woody a.xis
perfectly preserved, in .s/7»«, and showing structure. As thisapjx'ars
to me to be important with retereiue to (juestions now in discus-
sion, I beg to j)resent to the Society Mr. Jiill's description of the
specimen and some remarks on its structure and alKnities.

Mr. Hill thus describes the mode of occurrence of the H])ccimcn : —
" The tree in question stood i)artially exposed near the t(»p ot a per-
pendicular cliff, one hundred and twelve feet above the beach (tig. 1 ).
The means of rejiching and successfully extracting it from the massive
sandstone stratum in which it was still half imbedded, was a pro-
blem of no easy solution. The diflicnlty, however, was overcome by
an adventurous workman, who undertook, by means of a ladder at-
tached by a rope to a small tree upon tlie surface, to descend to a
sloping ledge formed by the jutting-out of a coal-seam and super-
incumbent debris, and to form there a 'standage' from which sub-
sequent operations could be carried on. Having successfully estab-
lished himself in his eyry, the tree, which, from exposure to the
weather and the action of the frost, readily divided itself into sec-
tions, was sent up piece by ])iece in safety to the surface.

" On removing the clay which covered the upjier extremity of the
stump, I was struck with the unusual apjiearance of a well-preserved
stem or axis in the sandstone cast, and which exhiliitcd structure in
a remarkably distinct manner, though here from ex])osure it had l»e-
come somewhat friable. Further down, however, it was perfectly
calcified and showed its structure distinctly, except in the centre,
which was occupied with a core of ])erfectly cylindrical form and
consisting of grey sandstone. The outer surface of the axis is lon-
gitudinally striate, without joints, and occujues a position near tlic
side of the cast, from wliich it is separated tliioughout by rather more
than iis own diameter, or about three inches.

* We were so fortunntp aa to find nn erect Sii/i/Un/d ('(intiiiiiiiig the ri'innins
of no less than fhlrhvn nninfl l>iilriicliiini!», bclonffitif; tn six Hpccics. two nl' lluni
new. So soon as lliese can Ix* worked out fVoni llic nialnx, I liope to bring
them \nider llio intioo ot tliis Society.

*/37l

;jL

FIIOM rilK COAI.-KOUMATIO.V OK NoVA SCOTIA. SH'i

Fjn;. 1. — Sin-fiive of (If CVi(f, nhnvlnif the fvuflfloii of the Tttt,
(From 11 sketch by Mr. A11)itL J. Hill.) "

(7, rt. Coiil-soains. h. Siii>crfici;il Drift.

" Tlu^ slum]) WMs found to ori^'iiiMtc in a six-inch conly seam, thirty-
five feet five inches below that worked in the ('um])erland Mine in coal-
^roup 'l\)ii of Dr. Dawson's section, or division 4, section xi. f>f Sir
\V. K. liOiran's seitioM*, and se[tara1ed hy an nndcrclay of \\ feet
4 inches from tlio uiKkrlyinj; seam of coarse coal in group IJO. The
downward termination of" the tree exhihited s|)r(iidin}i; roots, which
were, liowever, in a fiialde condition and not wtdl preserved, hut
exhihited on the surface, insido tlu; coaly hark, a tine transverse
striation, scarcely visilde t » tli(> naked eye. The surface-markings
of the trunk are also indistinct ; hut it shows a coarse longitudinal
striation and indications of hroad tlat ril)a. The accompanying
drawings (tigs. I and '1) will illustrate the mode of occurrence of the
tree in the clitf, and also the principal dimensions of the trunk and
axis, with the position of tlie latter in the cast."

The axis of this remarkable stem is ab'ut six centimetres in ita

* Auadiiiu (ioolotjy, 2ii(l edi .in, p. 171.

838

jr. W. DAW80N ON A SPECIMEN OF DIPLOXVLON

proatest diameter, and consists of a central pith cylinder and tv^o con-
centric coats of scalarit'orm tissue (fig. 3), The pith cylinder is replaced
by sandstone, and is about one centimetre in diameter. The inner

p- 2. Jjonffitudirud and Tratisvei'se Sections of the, Trunh, sJiowhuj

*hp rmition of the Axis. (Scale 2* feet to 1 inch. Drawn by

the postt
Mr. Hill.)

a, a, a. Internal axis.

cylinder of 83alariform tissue is perfectly continuous, not radiated,
and about one millimetre in thickness. Its vessels are somewhat
crushed; but have been of large diameter. Its outer surface, which

'■^4

FROM THE COAL-PORMATION OF NOVA BCOTIA.

839

reaflily separates from that of the outer cylinder, is striated longi-
tudinally. The outer cylinder, which constitutes by much tho
lai'goHt i)art of the whole, is also composed of scalariform tissue; b>it
this is radially arranged, with the individual cells quadrangular in
cross section. The cross bars arc similar on all the sides and usually
simple and straight, but sometimes branching or slightly reticulated.
The wall intervening between tho bars ha? extremely delicate lon-
gitudinal waving lines of ligneous lining, in tho manner ftrst de-
scribed by Williamson*, as occurring in the scalariform tissue of
certain Lrpidodenifra (fig. 4). A few small radiating spaces, par-

Fig. 3. — Aa Is of Diploxylon, as seen
on tveathend surface. (Natural
size.)

Fig. 4. — Portion of
Scalariform Tissue.
(Magnified.)

a. Medullary cylinder, filled with siindstone.
6. Medidiary sneath of scalar! t'orin tissue.
c. Exogenous cylinder of scalariform tissue, radi-
ally arranged and with concentric lines.

tially occupied with pyrites, obscurely represent the medullary' rays,
which must have been very feebly developed. The radiating bundles
passing to the leaves run nearly horizontally; but their structure is
very imperfectly prese"vcd. The stem being old and probably long
deprived of its leaves, they may have been partially disorganized
before it was fossilized. The outer surface of the axis is striated lon-
gitudinally, and in some places marked with impressions of tortuous
fibres, apparently those of the inner bark. In the cross section, where
weathered, it shows concentric rings; but under the microscope these
appear rather as bands of compressed tissue than as proper lines of
growth. They are about twenty in number. Though apparently
of very lax tissue, the wood of the outer cylinder may, in con-
sequence of the strength of the vertical rods and transverse bars of

* Monthly Microscopical Journal, August 1809.

840

J. W. DAWSON ON A HPECIMKN OK DII'I.OXYLON

lij»ncou3 liniiif?. liiive Ijocn of roiiHidcraMo firninoss, which would, in-
dfcd, Hocin to 1)0 iinplit'd in thu inaiiiKT of its jircstTViit ion within the
hollow bark.

No traco remains of the tliick inner bark, which is represented by
Handstone ; and, us usual in these trees, the outer bark consista of
Hlruetureless coal. The outer surface of the sandstone cast shows lon-
gitudinal Htriution ; but the ribs, if presetit, arc very indistinct ; und
only a few sonu'what remote and indistinct depressions remain as
indications of the leaf-scars. The roots, as stated by Mr. ]lill, show
a delicate transverse wrinklin;;, which may be an cHect of pressure.
In oiw small jtortion only could 1 recognize on them the remains of
the stif^marioid areoles.

When treated with an acid, the calcareous mutter is removed and
the wood renuiins as a crumblin<; dark brown mass, whioli shows the
structure very i)ertectly when diffused in water or Canada l)aLsam.
When this Itrown substance is if^nitcd it burns with scarcely any
tianu', and leaves a reddish ash, in which the bars of the scalariform
tissue are still (piite a]>i)arcnt.

In sonu; jjiivts of the axis the medidlary cylinder becomes reduced
in size, and the inner scalariform cylinder proportionally thickentd.
Towards the top of the axis there is an indication of l)ifurcation, which
may, however, be a d'-ceptive appearance resulting from mechanical
splitting due to decay.

The structures above described are obviously those of DIpIo.rijhm
of ('orda ; and the tree may be regarded as a Slijilhirin of this type,
the only well-characterized <me yet found in the Nova-Scotia coal-
field. In eoniijarison with the axes of Si<fillaria' which I have de-
scribed in fornuT papers presented to this Society, it agrees in the
general anaiigement of the tissues, but differs considerably in their
character. The pith cylinder is smaller and not Stcrnbergian. Tho
scalariform tissue of the inner woody cylinder and medidlary sheath
is nuu'h coarser. The outer cylinder, instead of ])seudo-8calariform
and porous tissue, like that of Cycads, has coarse scalarifonn ti8.sue.
In these respects the trunk resembles those recently described by
^Villiamson*, aiul is also like specinuns from Arran shown to me
some years ago by Mr. C'arrutliers. From the examples given by
the fonner, 1 cannot doubt that such trees come within the limits of
the genus ISiffilhirla, as determined by tho ii. -.rkings of the bark ;
and that they belong to that low type of these trees in which tho
woody matter, while arrang( d in an exogenous manner, is wholly
scalariform, and with the nuduUary rays little developed. As Wil-
liamson has shown, these trees a]>]»r()ach closely to Liqiidixhwlra in
their structure. On the ctther hand, the tSitjillaritB of the type of
S. I'hyatis of l{r(mgniart, and of /S.NpinnlihSd of Renault and Grand'-
Kury, have a somewhat higher organization, and point to tho still
more elevated type descril)ed by me in 1M<>. There would thus
appear, as I pointed out in my paper on the structures of coal in
18.')1), and in that on the conditions of accumulation of coal in 1865,

* 'ri!0)sii('tio!i<s (()■ tlie iliival Sociit}'.

^ffiii'ihh^'i i

KUKM nil; COAl.-HiKMATION (>F NmVA SIOTIA.

841

nnd Ktill in«»re fully in (hat on Sliflllariit iiiul its iiIUi-h in 1>7<**,
BC'voriil (liHtinct typi'8 ot' Sif>;illiiri<)i(l trees ; thoujrh whether wc ean, an
Hiifff^ested in those papers, weparate those with the Chil/irttrin aiitl
I'avuUtria styles of inarkiii;j:s from the other Si(jiH<iriif, is st ill douht-
ftil. The FreJieh authors iihove cited rej^ard their S, ilfijitns and
S. HitinuloHd, whieh are of the Faviiltirln type, us true .S'/'/////fn(P, and
hohl that their woody eyliiuler, with its Hltres in radial s«'ries and
with medullary rays and radiatiufjhundles proceediii;; t'roui (he inn»'r
eylinder, allies these trees with the f^yiunospenuous e.\o;;eus. Wil-
liaujHon rof^ards his Si<iilhiri.<f of the iJi/ila.viflon type of structure as
prohahly eryi)to};an)()us and allied to Lipiifodi inlron, thou{?lj nuiin-
tuiiiing tliat the structure of tlu^se stems is truly exo<;eiious. There
can scarcely be any doultt that the hijjher type of SiijiUtifia, which
I dcscrilted in 1^7<', and which, I thiuk. rei)resents the ordinary
coarsely-ribbed s])ecies of the type of my >S'. linm'nii, are allied to
{yymnosperms. Prof. Newberry and (he writer have adduced stroTij;
circumstantial evidence to show that i^i;illl<irl<f produced the fruits
known as Tri'/onocdr/Ki, found so constatitly witli their renuiins.
(ioldenberg, on the other !iand, has tiffined a sort of strobile as at-
tached to iSitfiU'iria. Williamson luis ti<j;ured fruit-scars, which he
repiards as attachments of cones. I have tif^uredt wcU-pn served
fruit-scars of two species which cannot have borne strobiles, but may
very probably have l)orne l^-ii/imocai'jm or racemes of such fruits.
These facts, 1 think, taken alonj? with those of structure, tend to show
that there may l)e included in the {^enus Sli/illarin, as orifiinally
founded on the markings of the surface, species widely dilfering in
organization, and of both gymos])cnnous and acrogenous rank. This
conclusion is further confirmed by the fact, which 1 have long ago
amply demonstrated in my papers on the structures and nxale of
accumulation of coal, that in the great coal-beds tissues of gymno-
spermous character, but distinct from those of Conifers, exist to nii
enormous amount, while no other trees are found in connexion with
these beds to which such tissues can 1)e referred excejjt iho S I fjH /arid' .

Should this view be finally established, these trees will present an
interesting link of connexion between the gynuiospenns and the
higher cryptogams. They connect the Lcj>khulnuh-d with the Cycads
and Conifers in the gradations of exogenous structure seen in their
wood and bark, and also in the remarkable transitions which they
exhibit between woody tissues of the discigerous type and those sca-
lari form tissues which, tliongh resembling scalariform vessels ])ro-
perly so called, yet in these plants are evidently arranged in the
manner of woody fibres, and take the place of these in the construc-
tion of the stem.

The tendency of investigation of late has been to convey (he im-
pression that the Sigillarioid and he]»idodendr()id trees of the coal-
formation were of one somewhat uniform aiul monotonous tyjte. On
the other hand, the great number of species of these trees indicated

* Qanrt. .Touni. Oenl. Soc. toI. xx\ii. (1S71) p. 147.

t Quart. Joiirii. Oeol. ^oc vol. xxii, Kvport 'm I'\)f»^il Plants nf tlio Lower
Carboniferous: 1873.

842

J. W. D\W80N ON A DIPLOXTLOX FROM NOVA SCOTIA.

by cxtorniil murkiiigH,tlio number of kinds of gymnospcrmous fruits
and cryi>t<)}?'inn>UH HtrobilcH iwsociiitcd with tlicni, und tho grout
riingo of orgunization i)roHont('d by their HtcniH, indicato a consider-
able variety of j^encric and specifie tyi>eH, probably bridf^iiig over,
l)y means of the class of (lymnospcrms, tho }!;reat gap at present ex-
isting lietween the Angiospermous and Acrogenous trees, and giving
an amount of diversity to tho forests of the coal-])oriod of which wo
have as yet little conception. A further illustration of this is pre-
sented by the remarkable species of Conluitis recently described by
M. (jlrand'Kury, and which furnish another varied scries of (jymno-
Bpermous type.

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