152 Geological Society. 



gation clearly relegate it to the latter group*. It leans, indeed, 

 whollv to the Spioiiidse in minute structure, and especially to such 

 forms as Prionospio and Heterospio ; though it is true that in the 

 marked regional distinctions, and the great length of the posterior 

 division of the body, it approaches SjnocJuetojjterus. While it con- 

 forms to the Spionidae in the structure of its body-wall and bristles, 

 it differs in regard to the absence of the dorsal branchiae ; and 

 further, the short, pinnate and ciliated anterior branchial organs 

 of Prionospio appear to be the nearest approach to its elongated 

 tentacles. In the mechanism of its proboscis and in the structure 

 of its snout and circulatory organs, again, it presents features sui 

 generis. 



GEOLOGICAL SOCIETY. 



February 21st, 1877.— Prof. P. Martin Duncan, M.B., F.E.S., Pre- 

 sident, in the Chair. 



" Note on a Specimen of Diploxylon, from the Coal-formation 

 of Nova Scotia." By J. W. Dawson, LL.D., F.E.S., F.G.S. 



The author described the occurrence in Coal-measure sandstone 

 at the South Joggins of an erect stump of a SigiUarian tree 12 feet 

 in length. It originated in a coaly seam 6 inches thick, and termi- 

 nated below in spreading roots ; below the coal-seam was an under- 

 clay 3 feet 4 inches thick, separating it from an underlying seam of 

 coarse coal. The stem, which tapered from about 2^ feet in dia- 

 meter near the base to 1| foot at the broken end, was a sandstone 

 cast, and exhibited an internal axis about 2 inches in diameter, 

 consisting of a central pith cylinder, replaced by sandstone, about 

 i- inch in diameter, and of two concentric coats of scalariform tissue, 

 the inner one J^ inch in thickness, the outer constituting the re- 

 mainder of the axis. The scalariform tissue of the latter was radi- 

 ally arranged, with the individual cells quadrangular in cross sec- 

 tion. A few small radiating spaces partially filled with pyrites 

 obscurely represented the medullary rays, which were but feebly 

 developed : the radiating bundles, passing to the leaves, ran nearly 

 horizontally ; but their structure was very imperfectly preserved. 

 Th.e cross section, when weathered, showed about twenty concentric 

 rings ; but these under the microscope appeared rather to be bands 

 of compressed tissue than true lines of growth. The thick inner 

 bark was replaced by sandstone, and the outer bark represented by 

 structureless coal. On a small portion of one of the roots the 

 author traced the remains of stigmarioid markings. From the above 

 characters the author identified this tree with Diploxylon of Corda, 

 and stated that it was the first well-characterized example of this 

 type of Sigillarians hitherto found in Nova Scotia. The author 



» Proc. Roy. Soc. Edinb. 1875-76, vol. ix. no. 94, p. 123. 



