CONCLUSION. 



191 



The Dinocerafa now known may be placed in three genera : Dinoceras, 

 Thioceras, and Uintafherium. These may be separated by characters of 

 tlie skull, vertebra?., and feet. There are also indications of several 

 intermediate forms, which may, perhaps, be found to represent sub-genei'a, 

 when additional specimens in good preservation are secured for comparison. 

 Twenty-nine species may be distinguished, mainly by the skull alone, 

 which, at joresent, offers the best distinctive characters. 



Sub-order DINOCERATA, Marsh. 



Family Tinoceratid/E, Marsh. 



Uintatherium, Leidy. 



Teeth, thirty-six. 

 Lower premolars, four. 

 Base of canine tusk, 



nearly vertical. 

 Parietal protuberance 



above post-glenoid 



process. 

 Cervical vertebrae of 



moderate length. 

 Lunar articulating with 



trapezoid 1 



Dinoceras, Marsh. 



Teeth, thirty-four. 

 Lower premolars, three. 

 Base of canine tusk, 



nearly vertical. 

 Parietal protuberance 



above post-glenoid 



process. 

 Cervical vertebrte less 



elongate. 

 Lunar articulating with 



trapezoid. 



Tmoceras, Marsh. 



Teeth, thirty-four. 

 Lower premolars, three. 

 Base of canine tusk, 



horizontal. 

 Parietal protuberance 



behind post-glenoid 



process. 

 Cervical vertebras short. 



Lunar not articulating 

 with trapezoid. 



These three genera clearly represent three stages of development of 

 the Binocerata, and these stages correspond to the successive horizons of 

 the middle Eocene in which the remains of these animals were entombed. 

 Uintatherium, the most generalized type, is found at the lowest level ; 

 Dinoceras is from a somewhat higher stratum ; and Tinoceras, the most 

 specialized of all, occurs in the latest deposits. 



Lit the Synopsis which follows this chapter, a systematic list of all the 

 species of the Diuocerata is given in detail. In connection with the 

 preceding pages, and the Plates at the end of the volume, this will place 

 before the reader everything of importance now known in regard to the 

 Binocerata. 



