92 



This exceptional combination of characters points to the propriety of sep- 

 arating Adocus as the type of a family equally distinct from the Emydidce iiin\ 

 the HydraspididcB^ to be called the Adocidce. 



Further characters of the genus have been already pointed out in the later 

 essays above quoted. They are: the free lobes of the plastron narrowed and 

 shortened, furnishing extensive posterior and anterior entrances to the carapace; 

 a series of intermarginal scuta on the bridge; costal capitula reduced or 

 wanting. 



No recent or even Tertiary form of the Testudinata has yet been discovered 

 which possesses the remarkable combination found in this genus; and I think 

 it must be regarded as a generalized group, and as such of much interest to 

 the student of paleontology. 



Adocus (?) lineolatus, sp. nov. 



Estai)lished on a number of fragments from ditlerent exposures oi' the Lig- 

 nite beds, primarily on a vertebral and sternal bone, from the Dinosaurian 

 locality in Colorado. As the diagnostic portions of this specimen are 

 wanting, it is referred to this genus provisionally, and because the structure 

 and sculpture of the parts resemble most nearly known species of it from the 

 Cretaceous greensand of New Jersey. 



The sternal bone is Hat, and presents the median and tran^fverse sutures 

 forming the usual right angle, and of a rather coarse character of a median 

 serrate keel, with pits on each side, for the reception of corresponding pits. 

 The vertebral bone is rather thick, and is shallow ]y emarginate in front. The 

 sculpture consists of delicate, obscure, parallel lines, which are more or less 

 interrupted, and occasionally joined, so as to inclose, faintly marked areolae. 



Measurements. 



M. 



Width of the vertebral bone iu front 0. 013.') 



Width of the vertebral bone (greatest) 0. 0:>80 



Thickness of the vertebral bone 0. 0070 



TIjickness of the sternal bone 0. OOf^O 



From Lignite of Colorado, and mouth of Big Horn River, Montana. 



PLASTOMENUS, Cope. 



This genus has been discovered to embrace tortoises having characters 

 of both Trwni/.r and Eniijs. The carapace is like that of the former, in the 



