1862.] 



HTJXLEY CARBONIFEROUS LABYRINTHODONT. 



63 



field and then described, were necessarily Ichthyosaurian, — seeing 

 that I had mnch reason to suspect that they might belong either to 

 Labyrinthodonts, or to some genus of intermediate characters, be- 

 tween Labyrinthodonts and Ichthyosaurians. 



"Within the last few days Mr. Russell has sent me the vertebra of 

 which an outline-view is given in fig. 2 (one-half the natural size). 

 It was found in the same bed as that which yielded the skull of 

 Anthracosaurus, and corresponds very well in size with what one 

 might expect would be the dimensions of a dorsal vertebra of that 

 animal. Associated with it on the same slab are several other less 

 complete vertebraa and the remains of two ribs. 



Fig. 2. 



A. Dorsal vertebra of Anthracosaurus, viewed from behind. 



B. Rib of the same Amphibian. 



A. 



i< 



A.- 



B.- 



Body of the vertebra. 



The longer division of the transverse process, and 



The shorter division. /. Spinous process. 



Anterior zygapophysis. g. Neural canal. 



Posterior zygapophysis. 



Capitulum. b. Tuberculum. 



The body of the vertebra is greatly flattened from before back- 

 wards, as the subjoined measurements will show. The exposed 

 articular surface is concave, and a section which I have had made of 

 a similar vertebral body shows that it was equally concave upon both 

 sides. The concavity, however, is not conical in section like that of 

 a fish's vertebra, but its sides are a little convex, rising slightly, within 

 the margin. Hence the section of this vertebra has very much the 

 same appearance as that of Mr. Marsh's problematical vertebra repre- 

 sented in the figure which accompanies his paper*. 



The contour of the vertebral body is not circular, but is slightly 

 angulated, so that it would tend to be octagonal were not the place of 

 * Am. Journ. Science, n. s., vol. xxxiv. pi. 2. fig. 2. 



