8 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I3I 



number of serrations of smaller size and the associated ridges are less 

 clearly defined. U.S.N.M. No. 21280 is certainly much closer to 

 Carpolestes dubius than to any of the other known carpolestids, and 

 it seems, moreover, that C. dubius is somewhat more removed from 

 Carpodaptes in the form of P4 than is the genotype Carpolestes 

 nigridens. 



Carpolestes dubius is recorded by Jepsen (1930) from the Clark 

 Fork beds as well as the Tiffanian portion of the Polecat Bench 

 sequence. 



The Almy P4 measures 2.9 mm. from its anterior margin to the 

 posterior root at the alveolus. The width is approximately 1.8 mm. 

 across the posterior portion of the base of the tooth. 



CARNIVORA 



ARCTOCYONIDAE 



ANACODON? NEXUS,3 new species 



Plate I, figure i 



Type.—Leit ramus of mandible (U.S.N.M. No. 21282) with Mi 

 and M2. 



Horizon and locality. — Buckman Hollow Clark forkian Paleocene 

 on La Barge Creek, NW^NE^ sec. 12, T.26 N., R.114 W., Lincoln 

 County, Wyo. 



Specific characters. — Size considerably smaller than Anacodon ursi- 

 dens, but teeth only slightly larger than in type of Claenodon mon- 

 tanemis. Primary cusp pattern of lower molars better defined than 

 in Anacodon ursidens or A. cidtridens, but trigonid less elevated above 

 talonid than in Claenodon montanensis. Also, anterior crest from 

 hypoconid low but joins protoconid at a completely lingual position 

 so that inner wall of first two lower molars shows little flexure mid- 

 way of its length. 



Discussion. — Anacodon? nexus is considered as possibly repre- 

 senting that genus rather than Claenodon as earlier (Gazin, 1956 and 

 in press) supposed, because of the lowness of the trigonid on Mi as 

 well as M2. Also the crista obliqua has entirely lost its oblique char- 

 acter or has been overshadowed by the development of a distinctly 

 lateral spur or crest extending forward from the hypoconid to the 

 posterolateral surface of the protoconid, one of the several possibili- 

 ties afforded by the crenulated character of the principal cusps in the 



^ ncxtis (L.)=:tie, bind, with reference to its intermediate position between 

 Claenodon and Anacodon. 



