ORDER UNGULATA. 



I3S9 



P, 



■7 5 



-, M. - ; but according to Professor Cope the lower incisors 

 3 3 



may be wanting. The genus may be divided into a Dinoceratine 

 and a Tinoceratine group. The former, which includes Dinoceras 

 of Marsh and Octotomus of Cope, comprises the smaller forms from 

 the typical Bridger, in which the nasals are not greatly produced, 

 and their prominences are comparatively small (figs. 1261, 1262). 

 According to Professor Marsh, the base of the upper canine is 

 vertical, and the lunar has a small facet for articulation with the 



trapezoid (fig. 1262, b) ; the neck 

 /' \ being comparatively short. In the 

 / second group, comprising Tinoceras 

 of Marsh, and Eobasileus and Loxo- 

 lophodon of Cope, all the species are 

 of huge size, and have the nasals 

 overhanging the premaxillae, with the 

 prominences very large (figs. 1260, 

 1262). These 

 species are con- 

 fined to the 

 upper Bridger, 

 and have the 

 base of the 

 upper canine 

 horizontal, the 

 trapezoid not 



Fig. 1263.— Right lateral aspect of the skull 

 of Uintatherhim cornutum; from the Bridger 

 Eocene. Reduced. (After Cope.) 



articulating with the lunar, and the neck longer. The species, of 

 which the skull is shown in fig. 1262, is remarkable for having the 



