450 Wortman — Studies of Eocene Mammalia, etc. 



in age to the American White River Oligocene or earlier, our 

 Uinta species of this group may well have been their ancestors. 



At least three species are known, the oldest of which, 

 P. promicrodon, comes from the Wasatch of the Big Horn 

 Yalley. In this species the fourth lower premolar is not 

 reduced but those anterior to it are quite small ; the first 

 premolar is single-rooted and the second and third are two- 

 rooted. A second species, P. ca?iavus, from the Wind River, 

 shows the fourth premolar in the lower series reduced but the 

 second premolar has two roots. 



A fragment of a lower jaw in the collection, which 1 

 provisionally refer to the Uinta species P. Scotti, figure 17, 

 shows the second premolar relatively very small and implanted 

 by a single root. 



It will thus be seen, from a consideration of what has already 

 been said, that there were at least three, and probably four 

 distinct lines of canine ancestry 

 already established in the Bridger. 

 One of these led from Vulpavus 

 through Neovulpamis and Pro- 

 cynodictis directly into the Oligo- 

 cene and Miocene Oynodicfds, 

 which without much doubt was 

 the main axis from which all the 

 living species of Canis have been 

 derived. The second leads out 

 through Uintacyon edax, Dapkm- 

 nus vetus and Temnocyon, into the 

 living Gyon and possibly also into 

 Lycaon. The third passes from 

 Prodaphamus into Amphicyon 

 and thence into the Bears. The fourth is more hypothetical, but 

 was possibly split off from ZTintacyon, passing into Daphamus 

 Dodgei and thence into the succeeding short-jawed dogs of the 

 Miocene and the living Bush Dogs. 



Peabody Museum, Yale University. 



Figure IT. — Anterior portion of 

 jaw of Prodaphcenus Scotti (?) ; three 

 halves natural size. 



