* 
854 On the Extinct Cats of America. [ December, 
Even when it opens so far as to allow the mandible to pass behind the 
apices of the canines, there would appear to be some risk of the 
latter’s becoming caught on the point of one or the other canine, 
and forced to remain open, causing early starvation. Such may 
have been the fate of the fine individual of the S. xeog@us, Lund, 
whose skull was found in Brazil by Lund, and which is familiar 
to us through the figures of De Blainville, etc. 
Drepanopon Nesti. (Macherodus Kaup). 
This genus as understood by most authors, belongs to the later 
Miocene and Pliocene, and has had numerous representatives in 
Europe and Asia. No species has as yet been found in America. 
‘Some of the species described by authors are only known from 
fragments, so that much remains to be ascertained as to the 
prevalence among them of the characters I have assigned to the 
genus and family. Those given are derived from the two species 
best known, the D. cultridens and D. megantereon, which have 
been readily obtained from the descriptions and figures of authors. 
t is difficult to ascertain the number of European species. 
Pomel’s catalogue is generally cited, and this is, with some sub- 
tractions and additions, the basis of the list already given. 
SmiLopon Lund. 
Besides the family characters already given, this genus differs 
from the Nimravide in two other important respects. In bot 
points it differs also from such existing members of the Felde — 
with which I have been able to compare it. In both S. fatalis and 
S. necator, the posttympanic process of the skull is codssified with 
_ the postglenoid, thus closing the auricular meatus below. It thus 
differs from other Felidæe as the genus Khinocerus differs from 
various other members of Rhinoceride. The second point has 
been indicated by Prof. Gervais. There is no epitrochlear arte- 
rial canal, such as belongs.to cats and Mimravide generally. 
This I have only verified on the S. necator. 
` This genus represents in America the Drepanodons of the Old 
World. The known species belong to the Pliocene period, and 
were the cotemporaries of the gigantic sloths and G/yptodoms, 
which at that time ranged over the entire American continent. 
Their powerful limbs terminated by immense claws, bespeak for 
them exceptional force in striking and tearing their prey, and tae 
long compressed canine teeth are well adapted for penetrating za 
