574 LAND MAMMALS IN THE WESTERN HEMISPHERE 



the Bridger, shows another imitation of the cats, the flanges of 

 the lower jaw indicating sabre-hke upper canines. 



Another genus, ■\Palce.onictis, of the Wasatch, found also 

 in France, is sometimes referred to the tOxya?nidse and some- 

 times made the type of a distinct family, but is too incom- 

 pletely known for final reference. It had the same number of 

 teeth as ^Oxymna, but the principal pair of carnassials was the 

 fourth upper premolar and first lower molar, as in the Fissi- 

 pedia, the first upper and second lower molar forming the sub- 

 sidiary pair. The first upper molar was hardly sectorial at 

 all ; its two outer cusps were long, sharp-pointed cones, and the 

 posterior cutting ridge was a mere tubercle. The skull had a 

 short, cat-like face. The genus left no successors. 



This concludes the long story of the Carnivora, so far as it 

 has been recovered from the rocks. Incomplete as it is, and 

 full of unsolved problems, it yet enables us to follow, some- 

 what vaguely, but with a general kind of accuracy, the develop- 

 ment of the various modifications which characterized the 

 different families and genera of the group. 



The more ancient and primitive suborder, the fCreodonta, 

 made its first recorded appearance in the lower Paleocene and 

 was, no doubt, derived from Mesozoic ancestors, which cannot 

 yet be distinguished among the very imperfectly understood 

 mammals of that era. In the upper Paleocene, if not before, 

 the fcreodonts had spread over the northern hemisphere and 

 had begun to diverge into a number of families, which con- 

 tinued to diverge more and more widely throughout the Eocene 

 epoch, as they became more specialized and adapted to differ- 

 ent habits of life. From the most primitive group, represented 

 more or less accurately by the fOxycla^nidse, may be traced 

 the several lines of diverging adaptations incorporated in the 

 various families, some of which had become distinctly recogniz- 

 able in the lower Paleocene, others in the upper, while all were 

 in existence in the lower Eocene. In one series, the fMeso- 



