1880. } On the Extinct Cats of America. 843 
The first description of this species was given by myself under 
the head of the Nimravus brachyops (Macherodus brachyops. 
Palzontol. Bulletin, 30, p. 10, Dec., 1878), from a skull found by 
0. AS. 
Fic. 4.—Archelurus debilis, one-half nat. size ; inferior aspect of Fig. 1. Foramina: 
AS, alisphenoid ; O, ovale; PG, postglenoid; C, carotid; Co, condylar, 
Mr. Sternberg, under the impression that it might belong to a 
female of that species.’ Subsequently a nearly perfect cranium. 
obtained by Mr. Wortman, demonstrated the distinctness of the 
animal both as to species and genus, 
Horizon and Locality. The remains of the Archelurus debilis 
have so far been only found in the Truckee Miocene formation of 
the John Day river, Central Oregon. Judging from the remains, 
it was, after the Vimravus gomphodus the most abundant feline of 
that region. 
Nimravus Cope. 
This genus has the dental formula and characters of Hoplopho- 
neus, with the addition of a tubercular inferior molar tooth. It 
is, moreover, not a true sabre-tooth, as is that genus, since it 
does not display the inferior anterior flange of the mandible. This 
is represented by an obtuse angular border, quite as in the species 
of Archelurus, in which genus Nimravus finds its nearest ally. 
The constant absence of the anterior premolars in both jaws dis- 
tinguishes it sufficiently from that genus. On this account, and 
in view of the larger development and denticulated edge of the 
Superior canine teeth, Vimravus may be considered as occupying 
a position between the two genera above named. 
Two species are known to me, a larger and a smaller, both 
from the Middle Miocene formation. 
