98 



A thin, inconspicuous basal ridge occupies the inner half of the back part 

 of the crown; a thicker festoon extends from the summit of the posterior 



lobe externally to the bottom of the middle lobe; and a short, prominent 

 ledge occupies the middle of the front of the crown. 



The fore and aft diameter of the crown of the last lower molar is 1£ inches; 

 the transverse diameter in front is 14 lines; behind, 12£ lines. 



Associated with the other specimens referred to Uintatherium, there was 

 found, the isolated tooth represented in Fig. 12, which I suppose to be a first 

 upper molar. It has the same constitution as the last upper molar above 

 described, but is smaller. In the present condition of the crown, the poste- 

 rior lobe is more prominent than the anterior, and it exhibits a broad horseshoe- 

 shaped exposed tract of dentine extending upon the summits of both lobes. 

 The dentinal surface is concave from side to side, and inclines forward. The 

 outer extremily of the anterior lobe, broken in the specimen, is considerably 

 thicker than that of the posterior lobe. Back of the inner conjunction of the 

 lobes, just below the summit, the rounded tubercle is visible, such as exists 

 in a corresponding position in the last molar. It is worn so as to exhibit a 

 small circular islet of dentine. 



The basal ridge, as in the last upper molar, is thick in front and behind, 

 but feeble upon the inner and outer sides. ■ 



The first molar was inserted by a pair of fangs. The anteroposterior 

 diameter of the crown is 16 lines ; the transverse diameter at the hinder lobe 

 is 15| lines. 



The upper molars of Uintatherium above described bear considerable 

 resemblance to the last upper molar of Lophiodon parisiense, as represented 

 in Fig. 3, Plate XVII of Gervais's Paleontologie. They differ especially in 

 the absence of the offset from the middle of the anterior part of the front lobe 

 of the crown. 



The upper molar teeth, attributed by Gervais to L. parisiense, represented 

 in his Figs. 3, 4, so nearly resemble the corresponding teeth of Uintatherium 

 and so decidedly differ from those of Lophiodon, as characterized from the 

 typical species L. isselense, that it may be questioned whether it belongs to 

 the same genus. The characters presented by the teeth referred to L. parisi- 

 ense, are sufficiently distinct and well marked to consider them as indicating 

 a genus differing from Lophiodon and Uintatherium, and probably more nearly 

 related with the latter than the former. 



