132 



Fig. 3, Plate VIII, represents a specimen of a first caudal vertebra of a 

 smaller species of crocodile than those indicated by the preceding specimens. 

 It was obtained by Professor Hayden's party near Little Sandy River. The 

 length of the body with its double ball is 21J lines. Several other vertebra? 

 from Black's Fork of Green River, and from near Church Buttes, Wyoming, 

 from their size and conformation, would appear to belong to the same species. 



Order Chelonia 



No other Tertiary deposit in North America has yielded such an abun- 

 dance of remains of different species and genera of turtles as the Bridger beds. 

 The fossils represent a large proportion of fresh-water and paludal forms ; the 

 others pertain to land tortoises. Fragments of turtle-shells are the most fre- 

 quent of the vertebrate fossils met with, strewed on the bare tops and sides of 

 the buttes or among the debris at their base. Entire shells are comparatively 

 rare, and if they have been complete as fossils, they soon undergo disintegra- 

 tion after exposure on the Inittes. Most of them have been much crushed, 

 while embedded, under pressure of the superincumbent strata, and now when 

 exposed from the softening of the matrix they readily fall to pieces. 



The greater quantity of the turtle remains are referable to a species of fresh- 

 water terrapin of the genus Emys, the shells of which present sufficient variety 

 as to have at first misled me in referring them to several different species. 

 The next most abundant remains are those of one or two species of soft-shelled 

 turtles of the genus Triouyx, and after these the remains of a large land-tor- 

 toise. Besides the species and genera described in the succeeding pages. 

 Professor Cope has recently indicated a number of others from the same for- 

 mation. 



TESTUDO. 

 Testudo Corsoni. 



Among the many remains of turtles from the Bridger Tertiary beds are 

 those a^jparently of a large land-tortoise. Small and for the most part un- 

 characteristic fragments of the shell were obtained by Dr. Carter in 1869 

 and during Professor Hayden's exploration of 1870, but it was not until I 

 received the specimen represented in Fig. 7, Plate XV, that I recognized the 

 character of the species to which they pertained. 



The last-mentioned specimen was discovered by Dr. Corson at Grizzly 



