1902.] Matthew, Neao Miocene CanidcB. 283 



horizon of the two is different, and I hardly think that they 

 are really allied, although the distinctions on known parts 

 may appear rather slight. 



From Pseiidarctos it differs in the presence of the two ac- 

 cessory cusps on the trigonid of the carnassial, in the larger 

 premolars with well-marked deuteroconid, the slender jaw 

 and small third molar. 



From Amphicyon the genus differs in the bicuspid heels of 

 the molars, greater reduction of pr'', and presence of accessory 

 external and internal cusps, long slender jaw, and cynoid 

 premolars. 



From Ursavus it differs in the less reduction of the pre- 

 molars, presence of accessory cusps on pg, p^, and p^, and the 

 much more cynoid character of molars 2 and 3. In Ursavtis, 

 judging from Dr. Schlosser's figures and description, the 

 cusps on mg are nearly obsolete, and the surface flat and 

 wrinkled, while mg is a round, peg-like tooth with flat, wrinkled 

 crown. The jaw of Ursavus is deep and short like that of the 

 bears, and the coronoid directed nearly upward as in the 

 Ursidse. 



The foregoing description is based on a nearly perfect pair 

 of lower jaws found in the Loup Fork (Pawnee Creek beds) of 

 Cedar Creek, Colorado, by Mr. Brown of the American Mu- 

 seum Expedition of igoi. A single lower carnassial in the 

 Cope Collection from the Colorado Loup Fork probably rep- 

 resents the same species. No upper teeth are known, and 

 the position of the genus is therefore uncertain. Judging 

 from the characters of the lower teeth it would seem probable 

 that it must be placed with the Canidae, and cannot be con- 

 sidered as near to Ursavus, which is unmistakably a bear. As 

 far as can be determined from the lower jaw characters, it 

 seems to be partly intermediate between Ursavus and Can is, 

 with some primitive characters retained, no doubt, from its 

 Oligocene ancestors. If this be borne out by the characters 

 of the upper teeth, Cynarctus will help to bridge the most 

 serious gap in the series of extinct genera connecting the 

 Ursidae and Canidae. Amphicyon, as Dr. Schlosser has shown, 

 does not fulfil the requirements for a direct ancestor of the 



