VERTEBRATE FOSSILS 579 



Pareiasauridae. — Very doubtfully present in North America. 



Among the amphibians — 



Eryops. — Closely related in the rhachitomous character of the 

 vertebrae to AcHnodon and Euchirosaurus from the Permian of France. 



Trimerorhachis. — No close relative of this form is known except in 

 the character of the vertebrae, 



Cricotus. — This resembles Archegosaurus in the embolomerous 

 character of the vertebrae which occurs in the caudal series of Arche- 

 gosaurus and throughout the column in Cricotus. 



Dissorhophus and Diplocaulus. — Have no equivalents. 



Crossotelos, Case. — This shows the characters of fringed dorsal 

 and haemal spines in the caudal series such as occurs in Urycordylus 

 and OesteocepUalus both from the Carboniferous. 



The numerous smaller amphibians from Texas are so imperfectly 

 known that it is impossible to make profitable comparisons with 

 other forms. 



Among the fishes — Janassa {Thoracodus), Orthacanthus, Ctenodus, 

 Ptyonodus (Sagenodus), have been discussed above. 



Didymodus. — Known from the Carboniferous of Europe. 



Gnathorhiza. — Known from Texas only. 



Sagenodus perienuis, Eastman. — Known from the Permian of 

 Russia {fide Broili) . 



Ectosteorhachis. — Known from Texas only. 



We may now reject all the evidence furnished by the fishes except 

 Sagenodus perienuis, because they occur both in the Carboniferous 

 and Permian, or because they do not occur outside of North America. 



We may reject all of the amphibians except Eryops and Cricotus 

 for the same reason. 



We may reject all of the solid-roofed forms, Cotylosauria {Chely- 

 dosauria), Pariotichidae, etc., because they have no close relatives 

 known outside of North America. 



We may reject the Clepsydropidae as the only possible European 

 representative is Triassic. 



There remains only the family Poliosauridae, the genus Nao- 

 saurus, and Sagenodus pertemiis, worthy of consideration. Sageno- 

 dus has been identified from Texas (Eastman) and from Russia 

 (Broili). The latter locality, the banks of the Lusa, a tributary of 



