.Q>^ ^^> .v'^i. IMAGE EVALUATION TEST TARGET (MT-3) A L^*- [>. :/. fA 1.0 I.I 1.25 ^ m m ■;" IM |||||22 * 2,0 1.4 1= 1.6 V] <^ /}. ^;. (3 ^^. om Photographic Sciences Corporation 23 WEST MAIN :>TREET WEBSTER, NY. 14580 (716) 872-4503 L ' ^ [From the Qcartekly Journal of the Geolooical Society /yr November 1877.] ON A SPECIMEN OF DIPZOXYLON FROM THE COAL-EOllMATION OF NOVA SCOTIA. r, r^i 830 J. NV. DWVSON (»N UCIMKN OK DIl'I.ttWLON J 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 .IogSiifllliilriicliiini!», 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 I '■^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 ]»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!iF 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(jiHS'. linm'nii, are allied to {yymnosperms. Prof. Newberry and (he writer have adduced stroTij; circumstantial evidence to show that i^i;illlkhulnuh-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. ■■■k^i. :;,^( *^ , k , '?■;' ■<1 ■' U^ ■ ■'; \ ^ ^'H ■ ^ 1 m * k' r r, 1 UL ■ I TJ?5K^ :^ ' . ' ' .♦ .,»-^. ' »> ; , • -; "-I .' P -^r- .-^N i