AMPHIBIA: ASPIDOSAURUS 13 



twenty pairs of ribs are visible, either at their ends or from above; 

 and doubtless this was nearly the full number of presacral vertebrae. 

 A fragment of the left ilium is present, and on the right side there 

 appear to be two sacral ribs, though this is doubtful. The tail 

 was wholly lost before fossilization. The ribs, as will be seen from 

 the photograph, have the uncinate process characteristic of Eryops, 

 Euchirosaurus, and Aspidosaurus, differentiating the form at once 

 from the Trematopsidae and Dissorophidae. These processes are 

 more slender in front, where they approach the proximal end of the 

 rib. Posteriorly they become progressively broader and more 

 remote from the proximal end till, at about the tenth presacral 

 vertebra, they are merely distal expansions of the ribs themselves. 



Among the material at the American Museum there are several 

 small skulls, not twice the size of the present species, which have 

 been referred to juvenile specimens of Eryops. In one of these I 

 observe that the otic notch is relatively large, with tabular processes 

 much like those of the present species. I suspect that this skull, 

 at least, is really that of a species of Aspidosaurus. 



From an examination of the tail vertebrae in the mounted 

 specimen of Eryops of the American Museum, I find the same 

 structure as that figured by me in a late paper as coming doubt- 

 fully from the tail of either Eryops or Trimcrorhachis. The figured 

 vertebrae are too small to belong with an adult Eryops, but the 

 structure is identical. 



An examination of the type specimen of Otocoelus mimeticus 

 convinces me of the absolute identity of the genus with Dissorophus, 

 as previously recognized by Case. 



} Aspidosaurus pel tat us, n. sp. Plate XXXII, Fig. 7. Craddock 

 bone-bed, Baylor County, Texas. 



Among the material secured from the bone-bed on Craddock's 

 ranch, as described on a previous page, there are at least two, and 

 possibly three, species of temnospondylous amphibians which may, 

 provisionally, be referred to this genus. Most characteristic of 

 these remains is the dorsal spinous expansion herewith figured. 

 This dorsal plate has, as a part of it, the upper end of a thin dorsal 



