524 CARNIVORA 



premolars, and the lower carnassial may retain its inner cusp. 

 .Elurictis, of the French Phosphorites, with p /^r^j, in gzsjp together 

 with several American Miocene genera, such as Nimravus (p f, 

 m i), Archcdurus (p ~^y m |), Pogonodon (p f , m }), and Hoplo- 

 phoneus (p ^^, m \}, approach more closely to the modern Cats, 

 although many or all of them retain the alisphenoid canal, and have 

 not yet developed the anterior lobe to the upper carnassial, or lost 

 the talon to the lower one. Hoplophoneus has a descending flange 

 to the mandible ; and its scapholunar bone has a line indicating its 

 dual origin; while the femur still retains the third trochanter, 

 of which all traces are lost in the modern Cats. 



On the other hand, some of the extinct Felidte show a most 

 remarkable tendency towards a specialisation not occurring in any 

 of the surviving members of the family, viz. an enormous develop- 

 ment of the upper canines, with which is usually associated an 

 expansion downwards and flattening of the anterior part of the 

 ramus of the lower jaw, on the outer side of which the canine lies, 

 when the mouth is closed. In Machcerodus nceogeus, the Sabre- 

 toothed Tiger, from the caves of Brazil and also from Pleistocene 

 deposits near Buenos Ayres, an animal about the size of a Tiger, 

 these teeth are 7 inches in length, greatly compressed, and finely 

 serrated on the trenchant anterior edges. Similar serrations are 

 seen on a much fainter scale in the unworn teeth of modern Tigers. 

 Many modifications of this commonly-called " machaerodont " type 

 have been met with both in the Old and New World. In M. 

 cultridens, of the Upper Pliocene of Italy and France, the upper 

 canine is long and narrow, with smooth cutting edges ; the smaller 

 form described as M. meganthereon being apparently the female 

 of this species. M. creiiatidens, of the same deposits, is distinguished 

 by the shorter and broader upper canine, in which both edges are 

 strongly serrated ; the same feature occurring in the closely allied 

 or identical M. latidens of the English cavern-deposits. The Italian 

 Pliocene form described as M. nestianus has serrations only on the 

 hinder edge of the upper canine, and the third lower premolar 

 is separated by a long interval from the fourth. M. necator, 

 of the Pleistocene of South America, is remarkable as being the 

 only member of the family in which the humerus has no ente- 

 picondylar foramen. A very remarkable form, Eusmiliis, from the 

 Upper Eocene Phosphorites of Central France, differs from all other 

 known Felines in having only two pairs of incisors in the lower jaw, 

 and a small canine separated by a very long diastema from the 

 cheek-teeth, which consist only of one premolar and one sectorial 

 true molar. The lower jaw is enormously expanded towards the 

 symphysis to protect the large upper canines. This animal then, 

 although of Eocene age, appears to form the culminating develop- 



