190 



THE CARBONIFEROUS SYSTEM. 



existence of animals of that tribe at so early a period. These inter- 

 esting remains were all found in the interior of an erect tree, mingled 



Fig. 33. — Fossil Land SJiell — Jogrjins Coal Measures. 



Magnified three diameters. 



with the sand, decaying wood, and fragments of plants which had 

 fallen into it after it became hollow. The bed of argillaceous sand- 

 stone, nine feet in thickness, which enclosed this tree, contains a 

 number of erect plants (Fig. 34). Three erect trees in the form of 

 sandstone casts and erect Calamites were observed in it, with many 

 Stigmaria roots. There was also a tree not in the form of a cast, 

 but of a mass of coaly fragments surrounded by a broken and partly 

 crushed cylinder of bark ; the whole being evidently the remains of 

 a trunk which has been reduced to little more than a pile of decayed 



Fig. 34. — Section of middle part of Suhdivison XV. in which the Dendrerpeton, Land 



Shells, etc., have been found. 



1. Underclay, with rootlets of Stigmaria, resting on gray shale, with two thin coaly seams. 



2. Gray saTidstone, witli erect trees, Calamites, and other stems: 9 feet. 



3. Coal, with erect tree on its surface : 6 inches. 



4. Underclay, with Stigmaria rootlets. 



(a) Calamites. (c) Stigmaria roots. 



(6) Stem of plant undetermined. (d) Erect trunk, 9 feet high. 



pieces of wood before the sand was deposited ; consequently it must 

 have been either an older or more perishable plant than those which 

 stand as pillars of sandstone. The wood of this tree shows, in the j 

 cross section, a cellular tissue, precisely similar to that of the Conifers ; fl 



