284 The American Geologist. May, 1896 
genus is more advanced and more modern in its development 
than its predecessor Vaphon-nus of the White River.* 
HYPOTEMNODON. Eyerman (No. 2. p. 321). 
Talon of inferior sectorial trenchant; inter- 
nal cingulum greater and more pronounced 
t h a n i n T e m n <> c y on; i n f e r i o r s e c o n d ra ol a r t u- 
b e r c u I a r, w i 1 1> i n f e r n a I <■ n s p s e q u a 1 1 i n g in size 
those- of t h e e x t e r n a 1 si d e. 
Hypotemnodon coryphaeus. 
{Temnocyon coryphaeus Cope, No. I, p 906.) 
Description and comparison with T. altigenis ('ope. — 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 . coryphams 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 their 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^js 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. fever has preserved the parts which are missing 
from the mandible of the former species. 
