94 



which is so marked in the ordinary alligator. The rami, 

 however, do not diverge at such an open angle. The jaw 

 is very stout, and is deeper and thinner than in Crocodtlus 

 Elliot a ; and is of about the same proportionate thickness, but 

 deeper than in the alligator. The splenial ends obtusely, and 

 approaches the symphysis somewhat more closely than m 

 the alligator, but does not enter into its formation. The 

 teeth are stout and obtusely conical, not striate, and im- 

 planted very close together ; they exhibit about the same 

 alternation of size as do those of the alligator. What appears 

 to be the canine is small ; it is preceded by a much smaller, 

 and succeeded by a slightly smaller tooth. The dermal scutes 

 are quadrate in shape ; they are deeplyand irregularly pitted, 

 and have a low but distinct longitudinal keel ; they are 

 suturally united by their lateral borders. 



CHELONIA. 



The Bridger beds have yielded a great abundance and 

 variety of land, marsh, and fresh-water chelonians. They 

 present much variation of form and size ; and, owing to the 

 great pressure in the strata, scarcely any two specimens of the 

 same species are alike ; occasionally, however, an undistorted 

 specimen is obtained. 



The most abundant remains of turtles are those of a spe- 

 cies of the recent genus Eviys, which are found in all the 

 beds, and are, perhaps, the commonest fossils of the basin. 

 The genera Trionyx and Hadrianus {Tcstudo, Leidy) follow 

 next in order. 



HADRIANUS, Cope. 



Resembles Tcstudo in form, but has two analscuta, as have 

 most Eniydidce. 



Hadrianus allabiatus, Cope. 



U. S. Geol. Survey of Territories, 1872, p. 630. 



Represented by two ungual phalanges which resemble 

 the claws of Testiido, but are proportionately shorter, broader, 

 and not so pointed at the ends. They are oval in section, both 



