E. L. Troxell—Entelodonts in Marsh Collection. 371 



cle. This tubercle is entirely different from that of A. 

 davits clavus in form, but resembles more the knob-like 

 process of A. marshi: round,heavy at the end, and slightly 

 recurved. The posterior mental tubercles are unusually 

 long, about 30 mm. from the side of the ramus, slender, 

 rounded, pointed, and curved upward; they are com- 

 pressed at the base and attached widely on the ventral 

 borders of the rami. 



The coronoid process arises well outside the line of the 

 molars ; it is compressed rather than rounded, but sends 

 wide branches downward and also backward on the front 

 and upper sides of the masseteric fossa. This fossa is 

 deep and oval in form, extends to the condyle, and its 



Fig. 8. — Arcliceotlierium clavus darbyi, subsp. nov. Holotype. Cat. No. 

 10032. Crown view of (A) upper, and (B) lower teeth. One-half nat. size. 



ventral border is gentle, not an abrupt edge. On the 

 inner side of the coronoid and just in front of the mandi- 

 bular foramen, there is a marked rugosity for the inser- 

 tion of the temporal muscle. The condyle is rather blunt 

 on both ends. 



The crown of P 3 has a long protoconid and is high on 

 its roots ; it is- thick, recurved, short antero-posteriorly, 

 and is separated from P 4 by 4 mm. The tooth is much 

 worn, but probably never was very rugose even on its pos- 

 terior heel. 



P 4 measures 25 X 14.8 mm. It is relatively very short 

 and thick. The heel is a shelf of moderate extent. The 

 widest part of the tooth is through the hinder part of 

 the main cone, while the heel narrows instead of increas- 

 ing in width as in A. clavus clavus. 



M 2 , although the entoconid is weak, seems to show little 



