288 LLOYD’S NATURAL HISTORY. 
VIII. GENY> POGONODON. 
Pogonodon, Cope, Amer. Naturalist, vol. xiv. p. 843 (1880). 
This genus is characterised by the great depth of the flange- 
like expansion of the lower jaw, and its remarkably broad 
anterior surface, coupled with the presence of three pairs of 
lower pre-molars, and the absence of the small last molar. 
The two known species, P. platycopis and P. brachyops, come 
from the Upper Miocene strata of the John Day River, Oregon. 
As they were both of large size, and furnished with long tusks, 
they would appear to have been the most powerful beasts of 
prey that flourished in their epoch. 
IX, GENUS: ARCHAIEURUS, 
Archelurus, Cope, Amer. Naturalist, vol. xiii. p. 798, a (1879); 
vol. xiv. p. 841 (1880). 
Characterised by the remarkably short muzzle of the skull, 
which descends abruptly from the forehead, this North Ameri- 
can genus differs from all the Cats hitherto noticed in possess- 
ing four pairs of pre-molar teeth in the upper jaw, there being 
also a small second lower molar. The lower carnassial tooth 
has no inner cusp, and only a very small posterior heel. It is 
represented only in the Upper Miocene of the John Day River by 
A. debilis, a species of the approximate dimensions of a Leopard. 
X. GENUS HOPLOPHONEUS. 
Hoplophoneus, Cope, Rep. U.S. Geol. Surv. for 1873, p. 509, 
(1874); id., Amer. Naturalist, vol. xiv. p. 849 (1880). 
Although the skull is very similar to that of mravus, this 
genus differs from all the preceding members of the group in 
the reduction in the number of the teeth, which are numeri- 
cally the same as in Lusmilus and the True Cats; that is to 
say, there is no second molar in the lower jaw behind the car- 
nassial tooth, while there are only two pairs of pre-molars in 
the same jaw, and either two or three pairs of upper pre-molar 
teeth. In this respect, therefore, the genus forms a connect- 
