99° The Reptu Poeene. [December, 



occurs in the Bridger formation, the Anostira of Leidy (Fig. 7). 

 Its two species differ from the existing snappers in having the 

 marginal bones of the carapace united by suture with the plas- 

 tron, in which they resemble Clidostcrna, and in being elegantly 

 sculptured as in the Triony chides. 



The Clidostema are represented by three families, the Baenidee, 

 the EmydideB, and the Testndinidce. The first named family is of 

 much interest, as it displays marked points of resemblance with 

 the Plenrodira and the Ckefydrida:, as well as with Emydida. 

 Like the first named, it has the additional scuta of the plastron 

 (integulars) ; like the second, it has the caudal vertebrae concave 

 behind instead of in front, and has an additional row of scuta on 

 the plastron, in contact with the marginals of the carapace. Then 

 it has an additional bone on each side of the plastron (intersternal) 

 as in Pleurodira. This family appeared in' Europe in the Jurassic 

 period {Platychelys), and has been found in the American Laramie 

 Cretaceous {Polytliorax Cope). In the Eocene we have the genus 

 Ba'ena Leidy, with four species, one of which is figured below 



f Ba'ena range from the si 



ze of a red belly 



loggerhead (B. hebra'ica). 



The genus is oi 



:ch and Bridger. 





