HISTORY OF THE CARNIVORA 543 



Cheeta may have been derived from some member of this 

 ''false fsabre-tooth " series, though the connecting links are 

 unknown. These cursorial cats quite displaced the leaping 

 fmachairodonts of the jHoplophoneus type, at least in the 

 Oregon region at a time when, it will be remembered, that 

 region had a remarkable variety of dogs. In other parts of 

 the continent, of which we have no record, the true fmachairo- 

 donts must have been thriving, as may be inferred from their 

 comparative abundance in the later formations. 



Concerning the habits of these cursorial cats. Professor 

 Merriam says: "When the canines are not developed to the 

 dagger-like form for stabbing, the premolar teeth serve a more 

 definite purpose in the destruction of prey and would be less 

 subject to reduction. The view suggested above finds support 

 in that such evidence as we have indicates that during the 

 deposition of the Middle John Day beds this region was in the 

 main a country of open plains, offering advantages to running 

 types of carnivores, and that during this epoch the Archcplurus- 

 Nimravus type of feline was by far the most common form 

 [i.e. of cats]." The derivation of these cats is still obscure, 

 but their likeness to certain forms of the European Oligocene 

 suggests that they were immigrants. 



The true cats of the subfamily Felinae include the great 

 variety of living forms, large and small, from the Lion and Tiger 

 at one extreme to the Domestic Cat at the other. There is 

 great difference among naturalists with regard to the nomen- 

 clature of the Recent cats ; some make a considerable number 

 of separate genera, while others include all the species, except 

 the lynxes and the Cheeta, in the genus Felis. For the pur- 

 poses of this book the latter practice is the more convenient 

 and will be followed. In Felis the dental formula is: i^,c\, 

 p^^, rn\, X2 = 28-30; the canines are large and strong, of 

 oval section, and the upper one is but little larger than the 

 lower ; there are two large and functional premolars in each 

 jaw, and an additional very small one may or may not be present 



