530 LAND MAMMALS IN THE WESTERN HEMISPHERE 



fMiacidse. The White River species are referred to the Euro- 

 pean genus ^Cynodidis, those of the John Day and lower 

 Miocene to fNothocyon, and it has been suggested that this 

 series gave rise to the foxes, a suggestion which may prove to be 

 true, but the very long gap in time between these animals and 

 the most ancient known foxes prevents any conclusion. 



To determine the mutual relationships of the six phyla of 

 Canidse which, from the Eocene onward, inhabited North 

 America in such numbers, is a task of great difficulty and only 

 a tentative solution of the problem can be offered. The central 

 stock would seem to be nearly represented by the White 

 River 'fDaphoenus, leading through '\Cynodesmus and ^Tephro- 

 cyon, of the Miocene, to the wolves. A short-lived series, 

 apparently given off from jTephrocyon, was that of the fhyena- 

 dogs, which flourished greatly in the upper Miocene and lower 

 Pliocene and then became extinct. Another branch, that of 

 the fbear-dogs, was derived from '\Daphoenus, through fDa- 

 phoenodon to \Amphicyon, \Dinocyon and ^Borophagus, the 

 gigantic Miocene and Pliocene forms, ending perhaps in 'fHyoe- 

 nognathus of the California Pleistocene. A third branch, 

 represented by ^Mesocyon and '\Temnocyon, is believed to be 

 continued to-day by the Asiatic Dhole and the Brazilian Bush- 

 Dog. The fshort-faced dogs {^Enhydrocyon) are still very 

 obscure. The last phylum, that of ]Noihocyon, '\Cynodictis, 

 \Procynodictis, had become distinct in the upper Eocene and 

 possibly gave rise to the foxes, but this is highly conjectural. 



2. Felidce. Cats 

 The only other fissipede group whose development in North 

 America may be followed for a long period is that of the 

 ^Sabre-Tooth Tigers, the subfamily '\Machairodoritinw, which 

 have been extinct since the Pleistocene ; the history of the True 

 Cats (Felinse) is much more obscure. In most respects the 

 two subfamilies agreed closely and, as they became separate 

 at least in the early Oligocene, they furnish instructive parallel 



