1884.] The Creodonta, 347 
River or Oligocene horizon, and no species is known from later 
formations. The species range in size from that of the Æ. vul- 
pinus Gerv., which equals a red fox, to that of an American black 
bear, as the Æ. heberti Filhol, and H. horridus Leidy (Fig. 12). 
The latter species is from the bad lands of Nebraska. 
LEPTICTIDÆ.? 
This family is very nearly related to the Centetidæ, which are 
now living in Madagascar. The only character by which I dis- 
WAITS 
aiy 
AY 
NA \ 
“Ay uur 
Stypolophus whitie Cope, skul 
river, W thirds natural size. F; igs. a-b from the Wasatch beds of the Big Horn 
a y i £ : a : 
CSS oe ee ae dey ee 
P 
“ 
yw 
| 
Figs. 
oR ak i right mandibular ramus. Fig. d, left tarsus minus cuneiform bones, from 
Hayden, "ginal, from Vol. 11, Report U. S. Geological Survey Terrs., F. V. 
Poe it is by the presence of the zygomatic arch, a part of the 
Which is absent in the Centetidæ (Fig. 13). The Leptictide 
Th: ae 
Pia family is included in the Centetidæ in the first part of this paper, p. 261. 
