REPTILIA. 



CROCOD I LI A. 



CROCODILUS. 



Crocodilus aptus, Leidy. 



Contributions to Extinct vertebrate fauna of the Western Territories, p. 126. 



Henr3''s Fork. 



Crocodilus Grinelli, Marsh. 



American Journal of Science and Arts, vol. i., p. 465. 



From Cottonwood Creek. 



Crocodilus ELLiOTii, Leidy. 



Cont. to Ex. Vert. Fauna, p. 126. 



Represented by a perfect skull, and several vertebras. 



This fossil exhibits a form of skull which shows characters 

 of both crocodile and alligator; the latter to a less marked 

 degree. That it properly belongs to the former genus is 

 shown by the notch in the upper jaw which receives the 

 canine of the lower. 



The entire skull is remarkably flat on its upper surface, 

 the face and cranium being nearly in the same plane without 

 the descent at the frontals usual in these reptiles. The jaw 

 is deeply notched at the sutures between the maxillaries and 

 pre-maxillaries, and the second maxillary notch is well marked. 

 All the bones of the upper surface of the head are deeply 

 pitted. 



The borders of the cranium are rounded as they approach 

 the orbits ; the superior temporal orifices are almost perfectly 

 circular, the fore-and-aft diameter exceeding the transverse by 



