FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 



167 



which enter entoconid and h3^poconulid and on which other, variable 

 cuspules are probably developed, although obscured by wear on the 

 known specimens. 



The horizontal ramus of the mandible resembles that of Plesiadapis, 

 but the symphysis (and incisor) are less inclined, and the constriction 

 at the diastema of Plesiadapis is absent, as is the diastema. The 

 larger anterior mental foramen is beneath P2 and the smaller posterior 

 foramen beneath P4. 



The single upper jaw fragment referable to this species has only 

 P*-M", and these are much worn and somewhat corroded. P* has 

 the paracone and metacone as well separated as in Plesiadapis, a large 

 conule mass usually considered a protoconule in this group, but from 

 its central position it could be either this or a metaconule, and a dis- 

 tinct protocone apparently higher but less expanded than in Plesia- 

 dapis. The molars seem to resemble those of Plesiadapis closely but 

 to be somewhat simpler, with few or no secondary cuspules and crenu- 

 lations. The anterointernal corner is more evenly rounded, not 

 emarginate. No mesostyle can be seen. It may have been removed 

 by wear, but probably was absent. 



Table 36. — Individual measurements of Pronothodectes matthewi 

 Lower Jaws (all known) 



Upper Jaw (unique specimen) 



Genus PLESIADAPIS Gervais, 1877 



PLESIADAPIS REX (Gidley) 



Plate 9, Figures 4, 13 



Tetonius rex Gidley, 1923, p. 11. 



Type.—U.^.^M. no. 9828, isolated M2. Collected by A. C. 

 Silberling. 



119212—37 12 



