402 EOCENE CATS 



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 Eusinilns the molar in both jaws is single, and there is but 

 one premolar in the lower jaw. 



The genus Machaerodus 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 l>e no doul)t 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 sufhciently 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, wdiose skull was found in Brazil l)y Lund, and 

 which is familiar to us through the figures of de Blainville." 



Machaerodus is placed among the Felidae on account of the 

 fiict that the condyloid and carotid foranuna unite with the 

 foramen lacerum posterius. But as in at least one species, 

 M. jjalmidens, there is an alisphenoid canal, which, however, has 

 disappeared in tlie more recent American forms, it seems per- 

 missiVjle to retain the genus in the family IMachaerodontidae 

 though its existence reduces the differential character of that 

 family to a minimum. The genus goes back to the Eocene. 



