490 SINCLAIR— ENTELODONTS FROM THE 



tooth from Pelonax, where it is either small and single-rooted {P. 

 ramosus) or small and double-rooted (P. potens). P3 is a very 

 large tooth, imperfect at tip and posterointernally, and lacks a heel, 

 so far as can be judged in its present worn condition. P4 seems 

 small by comparison with the tooth in front. It has no anterior 

 cuspule (surface worn), but a good-sized heel. The molars are too 

 worn and too much reconstructed to warrant description. The gap 

 between p4 and the first molar is accidental, due to distortion and 

 stretching of the specimen. The canines are worn to stumps and the 

 few incisors remaining point straight forward, the chin being ex- 

 ceedingly procumbent, perhaps accentuated by crushing. 



The anterior mental process is very long, projecting outward and 

 forward, with roughened distal end, and is attached to the ramus 

 by a triangular neck with concave faces, the anteroexternal one con- 

 cave in all directions, the posteroexternal larger and more broadly 

 concave, and the inferior one concave proximo-distally and undu- 

 latory transversely. The posterior process is strong, expanded dis- 

 tally to a bulbous tip which is no wider anteroposteriorly than the 

 neck supporting it, and directed downward and outward. 



Additional characters are the forward slope of the upper incisors 

 and the extremely long and slender face. 



Other Forms. 

 Remains of entelodonts of a smaller size than those just de- 

 scribed occur in the Protoceras beds, as shown by specimens in the 

 Princeton collection, but most of the material is too incomplete to be 

 even generically determinable with certainty. No. 11 124, the front 

 of a skull with complete premolar and molar dentition, collected by 

 Mr. Hatcher in 1894 from the Protoceras beds on Cottonwood 

 Creek in what is now Washington County, South Dakota, differs 

 from all other entelodonts except Megachceriis zygornaticus and 

 Entelodon magnum in almost completely lacking the notch in the 



Fig. 20. Undetermined entelodont from the Protoceras Beds, No. 11 124, 

 showing upper dentition of the left side, one third the natural size. P4 lacks 

 the notched anterior border. 



