Wortman — New American Species of Amphicyon. 201 



After careful examination of the material at hand, I fail 

 to find any characters which would warrant me in placing 

 the present specimen in a genus distinct from Amphicyon, 

 although the specific characters seem to be somewhat unusually 

 accentuated. I propose, therefore, to refer to it under the 

 name of Amphicyon americanus. 



The chief interest in the Amphicyon group lies in the fact 

 that it is through them that the ancestry of the modern bears 

 has been traced directly to a canine origin, apparently by the 

 most exact and satisfactory evidence. This evolution is sup- 

 posed to have taken place in Europe, and the conclusion has 

 been reached that from this exclusive area of origin they have 

 gradually spread to nearly all parts of the world. However 

 this may be, it is a matter of considerable interest to find one 

 of the ancestral links of the phylum in this country, and one, 

 moreover, which, so far as the superior molars are concerned, is 

 the most primitive yet known. 



It is desirable, therefore, to inquire further into the rela- 

 tionship between this Amphicyon and certain other extinct 

 types of the Canidse found in deposits of preceding age in this 

 country. I am led to undertake this now for the sake of clear- 

 ness, however brief and imperfect the results may be, pending 

 a more complete study of the Eocene Carnivora which I hope 

 soon to publish. 



One of the prime essentials in the way of relationship which 

 these earlier extinct Canidse must exhibit, is the possession of 

 three true molars in the upper jaw, as the disappearance of 

 the last molar in any of them would certainly mean a two- 

 molared successor. The possession of three superior molars is 

 undoubtedly an archaic feature among the Canidse, and this 

 condition was retained by some of the phyla until compara- 

 tively late in their developmental history. Others again suf- 

 fered an early reduction in the number of molars, particularly 

 in the superior series, but in the great majority of instances 

 this reduction has consisted in the disappearance of the last 

 molar only. It is somewhat remarkable to find that the molar 

 formula which characterizes the great bulk of the species of the 

 Canidge to-day was fixed at least as early as the Upper Eocene ; 

 and not only has the number, but the general form and pro- 

 portions, of these teeth remained, up to the present time, 

 unusually constant in that phylum from which the modern 

 genus Ganis was derived. 



Of those types possessing three true molars in the superior 

 series, Paradaphcenus, a genus established by Matthew and 

 myself,* is the only one which has thus far been found in the 



*Bull. Amer. Mus. Nat. Hist, New York, June, 1899, p. 129. 



