536 



LAND MAMMALS IN THE WESTERN HEMISPHERE 



to those of other fissipede families ; the upper one, the fourth 

 premolar, was relatively smaller than in '\Machairodus and 

 its blade less effectively trenchant ; the accessory antero- 

 external cusp was present, though extremely small, and the 

 internal cusp, which in ]Smilodon had almost disappeared, was 

 quite large. The lower sectorial, the first molar, though already 

 cat-like and consisting of two thin, broad and trenchant 



Fig. 264. — White River fsabre-tooth tiger {tHoplophoneus primcevus). Restored from 

 a skeleton in the American Museum. tOreodonts {fMerycoidodon) in the back- 

 ground. 



cusps in line, yet had vestiges of the heel and sometimes of the 

 inner cusp. These vestiges were a connecting link between 

 the highly specialized sectorial of the cats and the type usual 

 among the Fissipedia, which is exemplified by the dogs. The 

 small upper molar was less reduced than in the Miocene and 

 Pliocene genera and plainly consisted of a larger external and 

 smaller internal cusp. 



Compared with that of other Fissipedia, the skull was short 

 and broad, but in comparison with that of the modern cats 

 and of fSmilodon, it was decidedly longer and narrower and 



