1888.] 87 [Cope. 
ity of the crown (Fig. 5). The anterior of these crests is pretty clearly the 
anterior cingular crest of Corypho- 
don, but the homology of the pos- 
terior 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 Uinta- 
theriide, we find the anterior tri- 
angle of the tuberculo-sectorial 
type, but with the anterior limb 
rudimental. The posterior part of 
the crown differs from that of the 
Coryphodontid in having no pos- 
terior transverse crest, but in its 
stead the diagonal crest which con- 
.nects the external extremity ofthe | Fic. 5.—Dinocerata teeth, one-fourth nat. 
* * Fi size. Upper figures superior molars of Uin- 
posterior transverse with the inte- tatherium leidianum, one-fourth nat. size. 
rior extremity of the anterior trans- aacthee ucla er ie oo ed 
verse. crest. This oblique crest born, memoir on Uintatherium and Loxolo- 
< phodon, 
wears the posterior crest of the su- 
perior molars on its anterior face, as the anterior transverse crest wears 
the anterior crest (cingular) of the superior molar on its anterior face. 
(Fig. 6). : 
Comparison with the dental structure of Pantolambda (Fig. 1-2), shows 
which crests of the two series stand in this relation to each other. The 
diagonal crest of the inferior molar in this genus shears in front of the 
posterior limb of the anterior V of the superior molar. Guided by this 
fact we may regard the posterior cross-crest of the superior molar of the 
Uintatheriide, as the posterior limb of the anterior external V. We must 
then suppose that the anterior limb of this V has disappeared from this 
type of molar, and the anterior cingular crest has taken its place, thus 
forming a long V with the posterior limb. The tubercle between the 
crests at their open external valley, may be a remnant of this external 
crest. A low tubercle on the crown behind the inner extremity of the 
posterior crest, may be a rudimental fourth tubercle, or even the apex of 
the posterior external V. 
The homology of the posterior crest of the superior molar here proposed 
is sustained by the fact that there is no posterior transverse crest on the 
lower molar.* Had the crest in question been part of the posterior V of 
the superior molar, the posterior crest of the inferior molar would have 
had use, and would not have disappeared. 
If this homology is correct, the Dinocerata were derived directly from 
the Pantolambdide, and not through the Coryphodontidee, 
* The raised heel on these inferior molars is not the posterior transverse crest. 
