1915.] Matthew and Granger, Lower Eocene Wasatch and Wind River Faunas. 1D 
The masseteric fossa is deep and extends forward to a point beneath the 
posterior end of ms, bounded inferiorly by a well defined ridge and antero- 
superiorly by the high crest which runs upward to the anterior margin of 
the coronoid process. 
Neve? S25 
- 
ee : a 
= 
ie mas aoe ae 
Fig. 10. Anacodon ursidens, lower jaw, inner and outer views and crown view of teeth, 
natural size. No. 15711, top of Gray Bull beds, Big Horn Basin, Wyoming. 
No. 16781, lower jaw fragments with ps-ms perfect and unworn, agrees 
with the described specimens save for smaller size. It is from the Upper 
Gray Bull horizon at head of Ten-Mile Creek in the Big Horn Basin. 
The New Mexican specimen consists of parts of the lower jaw with mz_3 
of the left, and m; and mp of the right side, it is slightly smaller and the teeth 
appear somewhat more primitive than A. ursidens from Wyoming, except 
No. 16781. 
