E. L. Troxell — Entelodonts in Marsh Collection. 253 



enough for the cones of the uppers, between each set of 

 the high anterior cusps on the lower molars. 



The actual movement of the teeth, beginning in front, 

 was a shearing inward of the lower premolars, graduated 

 into the shearing, grinding, crushing of the anterior 

 molars, each one in turn from before backward; and fin- 

 ally the movement was ended when M 3 , facing slightly in- 

 ward, came fairly against the face of M 3 turned at an 

 angle outward. This movement of the jaws may be 

 judged from the wear between adjacent teeth, showing the 

 slight movement of a tooth in the jaw with respect to the 

 others, and also from the wear on the inner sides of the 

 upper molars and on the outer side of the lower; in the 

 latter case it amounts sometimes to the shearing off of a 

 large portion of the side of the tooth. 



The incisors are not only worn on the ends but are 

 notched posteriorly, probably by lateral motion of the op- 

 posing teeth. The canines are generally worn off at the 

 tips at right angles. Always the upper canine is worn 

 flat anteriorly and it in turn wears a diagonal groove on 

 the posterior side of the lower canine. On the anterior 

 face of C 1 , specimen No. 10286, there is a horizontal notch 

 probably resulting from transverse movement against the 

 tip of the lower canine. 



In none of the specimens at hand is there evidence of 

 wear by roots drawn across the base of the tooth such as 

 is reported by Scott. 



These apparent movements of the teeth and the lower 

 jaw may offer a clue as to the purpose of the mental 

 tubercles. Writers have hesitated to speculate, even, 

 about the use of the many processes found on the skulls of 

 the entelodonts. Peterson (1909, p. 144) "believed . . . 

 that these processes, at least in the genus Dinohyus, 

 existed for the attachment of muscles in order to give re- 

 quired strength to this portion of the head." Cope 

 (1874A, p. 504), in speaking of the great tubercle on the 

 lower jaw of Pelonax ramosus, says : "The posterior edge 

 is acute and the extremity very rugose as though for the 

 attachment of a horny or cartilaginous cap or apex." 

 Later (1888, p. 1089) he compared the "osseous projec- 

 tions" to the "wattles in old males of the recent hog. In 

 the E. ramosum these tuberosities become processes, and 

 the anterior ones especially are so long that when the chin 

 was stretched, hog-like, on the mud, it was raised well 



