284 
The American Geologist, 
May, 1896 
genus is more advanced and more modern in its development 
than its predecessor DaphcedVus of the White River.* 
HYP0TEIY1N0D0N. Eyerman (No. 2. p. 321). 
Talon of inferior sectorial tren c h ant; i nte r- 
n a 1 cingu1u m grenter a n d more pronounced 
than in T e m n o cy on; inferior second molar t u- 
bercula rj w i t h i n t ernal cusps equalling in size 
those of the external side. 
Hypotemnodon coryphaeus. 
(Temnocyon coryphaeus Cope, No. 1, p 906.) 
Description and comparison with T. altigenis Cope.—The 
anterior bones of the jaws supporting the dentition are con¬ 
siderably less elongate. The diameter across the malar bones 
is equal in both species and hence proportionately more ro¬ 
bust in the new genus (being the smaller). The premaxilla 
extends to a greater distance beyond the nasal, the incisors 
and canines inclining forward and outward to a greater de¬ 
gree than in Temnocyon , in which they are erect. The supe¬ 
rior dentition shows marked differences in position and devel¬ 
opment. In the type of Temnocyon the largest incisor and 
the canine are placed close together in a direct line, whereas 
in II. coryphaeus they are separated .and the incisor is ante¬ 
rior to the internal edge of the canine, in this respect resem¬ 
bling somewhat the position in T.ferox. The canines have a 
greater base development and equal that of the considerably 
larger species ( T. ferox ) , but only at the base, for the height 
is nearly three times less than in the larger species, and p. 1-2 
are simple teeth varying only in size, those of T. altigenis be¬ 
ing more elongate in proportion to thei r width : p. 2 , however, 
in this latter species, is formed nearly in the shape of a right 
angle, the anterior portion pointing forward and the posterior 
outward^ 
In p^_3 there is a minute cusp at the posterior in both species, 
and, while the antero-posterior diameter in T. altigenis is con¬ 
siderably greater than in the new genus, the transverse diam¬ 
eter is less, and, further, while the greatest transverse diame- 
*Ithas been noticed above that T. ferox instead of the type, T. altige¬ 
nis , is frequently used for comparison with Daphcenus ; this is due to 
the fact that the mandible of the type, T. altigenis, is incomplete,* 
whereas that of T. ferox has preserved the parts which are missing 
from the mandible of the former species. 
