368 GEOLOGICAL SURVEY OF THE TERRITORIES. 



water, such, as existed in Dakota and Nebraska during tlie tertiary 

 period. 



CROCODILUS. 



Eemains of this genus occur abimdantly in the Bridger Group of 

 tertiary formations in Wyoming. Among numerous fossils from this 

 region sent to tbe writer by Dr. J. Van A. Carter, and in the collection 

 made during Professor Hayden's last expedition, the writer has detected 

 the remains of three species of crocodile. 



Crocodilus cvptus. — A species named from a single vertebra found by 

 Colonel John A. Knight, United States Army, near South Bitter Creek, 

 Wyoming. The animal was about the size of the Mississippi alligator. 

 Remains apparently of the same species have been collected by Dr. J. 

 Van A. Carter in the vicinity of Fort Bridger. 



Crocodilus Elliotti. — The remains of a second species of crocodile were 

 found in abundance, during Professor Hayden's last expedition, on one 

 of the tributaries of Green River, Wyoming. The skull is about a 

 foot and a half in length and bears a resemblance in shape to that of 

 the crocodile of the Nile. The species is named in honor of Mr. Henry 

 W. Elliott, the artist attendant on Professor Hayden's expedition. The 

 remains of a third and smaller species of crocodile are contained in the 

 collections made by Professor Hayden's party in the tertiary deposits 

 of the Bridger Group. Dr. J. Van A. Carter has also sent to the author, 

 from the same locality, a number of vertebrae of this third species. 



BACERTILIA. 



The cretaceous formations of the West teem with the fossil evidences 

 of lacertilian life, forms well expressed in the line " there were giants in 

 those days." These were, however, in many respects so peculiar, or 

 different from the lacertilians of our day, holding as they did a position 

 between the latter and the serpents, that Professor Cope has viewed 

 them as characteristic of a distinct order, under the name of Pythono- 

 morpha. The true lacertilians appear also to have been represented 

 during the tertiary period, as indicated by the following genus : 



SANIVA. 



An extinct genus of lacertian reptiles, with the above name, is founded 

 on remains discovered during Professor Hayden's last expedition, in a 

 tertiary rock at Granger, Wyoming. The vertebrae, as in the living 

 iguanas, monitors, &c, have the body excavated in a cup in front and 

 terminating in a ball behind. The cup and ball are oblique and widest 

 transversely. The animal possessed well-developed limbs with long 

 toes, but the remains are too imperfect to determine their number and 

 arrangement. The teeth were compressed, conical, and doubly trench- 

 ant, indicating carnivorous habits. 



Saniva ensidens. — The species was as large as our largest living 

 iguanas. 



FISHES. 



Numerous remains of fishes have been discovered in the secondary 

 and tertiary formations of the West. Those from the secondary forma- 

 tions of cretaceous age belong to marine forms. Those of the tertiary 

 formations of California, which have been described, also belong to ma- 

 rine forms, mainly sharks. Those of the tertiary formations east of the 

 Rocky Mountains, which have been described, are from Green River, 

 Wyoming, and Castle Creek, Idaho, and belong to fresh-water forms. 



