206 Wortman — Studies of Eocene Mammalia, etc. 



Palceonictis. If this is true — and it would seem to be a very 

 probable assumption from the evidence thus far obtained* — it 

 then follows that the whole series are true Carnassidents, since 

 the first lower molar of the Bridger species is practically as 

 well developed and as exclusively a sectorial as it is in any of 

 the Oligocene Felids. 



The genetic relationship of JElur other iam to the Oligocene 

 Felidse is a matter of the greatest moment, for the reason that, 

 if once established, it gives us the long sought key to the solu- 

 tion of the problem of feline ancestry. Although the material 

 upon which our knowledge at present rests is scarce and frag- 

 mentary, and the evidence correspondingly meager and incom- 

 plete, yet such as this affords appears to be of neither an 

 indifferent character nor uncertain significance. We have 

 already seen (1) that the milk dentition of the lower jaw is 

 surprisingly feline in the make-up ; (2) that the molar and 

 premolar formula for the inferior series is the same as in cer- 

 tain of the Oligocene types, notably Dinictis ; (3) that the 

 structure of the molars and premolars coincides almost exactly 

 with those forms, and (4) that the form of the lower jaw 

 exhibits unmistakable evidences of relationship. The speci- 

 mens do not afford any evidence whatever of a contrary nature, 

 and until such is forthcoming we must look upon this source 

 of feline origin as not only possible but extremely probable. 



If the conclusions herein set forth are well founded, it 

 follows that in the Bridger epoch there were clearly established 

 three of the main lines of modern Carnassident descent, a fact 

 which in itself implies an origin at a much earlier date. 

 Indeed, as the evidence accumulates we are forced to conclude 

 that the beginnings of these phyletic lines are incomparably 

 more ancient than we had formerly thought possible. 



*See Ancestry of the Felidse, Bull. Amer. Mus. Nat. Hist., 1892, p. 94, in 

 which I fully discussed this subject. 



[To be continued.] 



