No.2.] THE HARD PARTS OF THE MAMMALIA. 241 
As is well known, the crowns of the superior molars in this 
family support two cross-crests, which converge and nearly join 
at the internal extremity of the crown (Fig. 66). The anterior 
of these crests is pretty clearly the anterior cingular crest of 
Figure 65.— Coryphodon latidens Cope, lower jaw, one-third nat. size; from the 
Wasatch epoch of New Mexico. Fig. a, right ramus from internal side. Fig. 4, both 
rami from above. Original, from Report U. S. G. G. Surveys W. of tooth Mer., 
G. M. Wheeler in charge. This specimen has an anomalous premolar. 
Coryphodon, but the homology of the posterior crest is less 
obvious. In order to determine this point, recourse must be 
had to the inferior molars, which are more readily understood. 
In the lower molar of the Uintatheriidze, we find the anterior 
