1853.] DAWSON COAL-MEASURES, NOVA SCOTIA. 27 



another erect tree converted into hard shining coal, and reaching to 

 the height of 15 feet, through heds of sandstone and arenaceous shale 

 (fig. 5) . Its roots, which are in the state of coal, spread in an irregular 

 manner through the clay or soft shale, and its top appears to be 

 broken off abruptly. After sand and mud had collected around 

 this tree to the depth of 10 feet, and while its top projected above 

 the surface, a dense brake of Calamites grew around, some of them 

 attaining a diameter of nearly 2 inches and a height exceeding 5 feet. 

 Farther accumulations buried these Calamites in the erect position 

 to the depth of 5 feet, when their tops were broken off and the im- 

 bedded stems decayed and were replaced by sand. Still the erect 

 tree remained undecayed, and though its top was broken off at this 

 level, only the cracks which had formed in its wood were filled with 

 sand, when the whole was buried by farther accumulations of sandy 

 sediment, which contains drift-plants with attached Spirorbis. As 

 this remarkable tree was evidently more durable than the ordinary 

 Sigillarice, and had irregular roots distinct from Stigmaria, and as 

 it had quite lost its surface-markings, I was very anxious to ascertain 

 its internal structure. After many trials, however, I could find only 

 very indistinct traces of cellular tissue, the mass of the fossil con- 

 sisting of compact coal divided by transverse joints, and by an im- 

 mense number of minute vertical cracks with a few larger fissures 

 which seemed to have a concentric arrangement. After abandoning 

 the attempt in despair, I found, in a box of specimens with which I 

 was favoured by Mr. Logan, a piece of fossil wood in precisely the 

 same condition with this tree, but retaining in one part distinct 

 evidence of its coniferous nature. Believing at the time that this 

 specimen was from the beds in question, (though I have since learned 

 that it belongs to another part of the section,) I was encouraged to 

 make farther attempts, and had the whole of the tree taken down by 

 a miner. After carefully selecting the most promising portions, I 

 made new slices, and was rewarded by finding cellular tissue of distinct 

 coniferous character, and in one small portion the hexagonal disks 

 or reticulations characteristic of the Araucarian type of pines (see 

 figs. 6 a, a, & 7). If, as T have no doubt, this tree grew where it now 



stands, we have thus evi- 



Figs. 6 & 7. — Microscopical structure dence that coniferous trees 



of the erect coniferous tree in grew in the same swamps 



Group XXIII. (fig. 5). which produced Sigillaria 



and Calamites, though they 

 had hitherto been found only 

 as drifted trunks in the 

 sandstones. Their compa- 

 rative rarity, however, in 

 connection with their dura- 



Longitudinal section of Transverse section of blc UaturC, SCCmS tO prOVe 



the wood. the wood. i,,i o i i n 



that they lormed only a small 

 part of the vegetation of these swamps. 



Passing over a few beds containing evidences both of growth in 

 place and driftage, we find, near the top of this group, a thin bed of 



