THE TEETH. 49 



In Dinoceras lucare (number 1038), the iipper molar teeth agree with 

 those already described, in their main characters, but as this individual 

 was considerably older than the type of Dinoceras ■niirahUe, the teeth 

 show a greater degree of wear, as represented in Plate IX, figure 2. 



In the genus Tinoceras, the upper molar series is essentially the same 

 in position and structure as in Dinoceras. 



In Tinoceras ingens (number 1041, Plate XVIII, figure 2), the upper 

 series of molar teeth is shown, with a still greater degree of wear than in 

 those above described. In figure 53, page 47, the upjjer molar series 

 of Tinoceras stoiops is represented. 



The Lower Premolars. 



In each ramits of the lower jaw of Dinoceras, there is a close series of 

 six teeth, three of which are premolars, and three true molars. These are 

 all inserted each by two roots. This is also true of the genus Tinoceras. 

 In these two genera, so far as known, there is no indication of any 

 prenu)lar in front of this series. 



The first premolar of the typical inigulate dentition has not been 

 detected in any specimen, young or old, of these genera. In the lower 

 jaw of Uintatlieriniii, as this genus is here defined, there were four 

 premolars. The first lower premolar is here present, situated somewhat 

 in front of the others, and but little separated from the lower canine. It 

 was a small tooth, inserted b}' two roots, and in all probability had no 

 predecessor. The position of this tooth is shown in fig-ures 41 and 42 on 

 page 39. 



The second lower premolar, tlie first of the series in Dinoceras, was 

 inserted by two roots. Its crown consists of a large anterior lobe, and a 

 small posterior one. There is a distinct basal ridge on the external 

 surface, wliich curves around upon the anterior and posterior faces, but 

 is wanting on th6 inner surface. 



