E. L. Troxell — Entelodonts in Marsh Collection. 431 



Art. XXIX. — Entelodonts in the Marsh Collection; by 

 Edward Leffixgwell Troxell. 



[Continued from p. 386.] 



PART III. THE LARGER GENERA AND SPE- 

 CIES. 



Pelonax potens Group. 

 Pelonax potens (Marsh) Peterson. 



Holotype, Cat. No. 12042, Y. P. M. ? Upper Oligocene, Colorado. 



This specimen (figs. 13, 14), originally described by 

 Professor Marsh, in 1893 (p. 410), consists of the lower 



Fig. 13. — Pelonax potens (Marsh) Peterson. Holotype. Cat. No. 12042. 

 One-fifth nat. size. 



jaws without ascending rami and has only the tooth series 

 P 4 -M 3 ; it is from Colorado and of probable Upper Oli- 

 gocene age. 



The very large anterior mental tubercles, for which this 

 specimen is noted, point downward, forward and outward 

 equally. Because of their great length these processes 

 resemble those of P. ramosus Cope. They are oval in 

 section but have a strong ridge on the upper edge. The 

 second set of tubercles below P 4 Mj are compressed trans- 

 versely, extend downward strongly and are correspond- 

 ingly long. 



The first premolar is situated close to the canines and is 

 single-rooted. The second premolar is double-rooted, but 

 because the roots are small and not deep-set, one supposes 

 the tooth was vestigial. Premolar three, which was con- 

 fusingly shown in Peterson's drawing (1909, p. 60), is a 



"Am. Jour. Sci. — Fourth Series, Vol. L, No. 300.— December, 1920. 

 32 



