402 EOCENE. CATS CHAP. 
jaw. Finally, Hoplophoneus has acquired the dentition of exist- 
ing Cats. 
The Machaerodons, however, show examples with a yet more 
reduced dentition than that of the most reduced existing Cat, viz. 
the Lynx, which has only two premolars in each jaw and one molar. 
In Eusmilus the molar in both jaws is single, and there is but 
one premolar in the lower jaw. 
The genus Jlachaerodus itself, which appears to include 
Smilodon, is referred by Cope to the true Cats, and not to the 
Nimravidae, as he terms the family which we have called here 
the Machaerodontidae. These creatures are known as “ Sabre- 
toothed Tigers,” and were of very wide distribution, occurring in 
South America as well as in Europe and North America. “ As 
nothing,” remarks Professor Cope, “ but the characters of the canine 
teeth distinguished these from typical felines, it is to these that 
we must look for the cause of their failure to continue. Professor 
Flower’s suggestion appears to be a good one, viz. that the 
length of these teeth became an inconvenience and a hindrance 
to their possessors. I think there can be no doubt that the 
huge canines in the Smilodons must have prevented the biting 
off of flesh from large pieces, so as to greatly interfere with 
feeding, and to keep the animals in poor condition. The size of 
the canines is such as to prevent their use as cutting instruments 
excepting with the mouth closed: for the latter could not have 
been opened sufficiently to allow any object to enter it from the 
front. 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 being 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. neogaeus, Lund, whose skull was found in Brazil by Lund, and 
which is familiar to us through the figures of de Blainville.” 
Machaerodus is placed among the Felidae on account of the 
fact that the condyloid and carotid foramina unite with the 
foramen lacerum posterius. But as in at least one species, 
M. palmidens, there is an alisphenoid canal, which, however, has 
disappeared in the more recent American forms, it seems per- 
missible to retain the genus in the family Machaerodontidae 
though its existence reduces the differential character of that 
family to a minimum. The genus goes back to the Eocene. 
d 
