PROMERYCOCHCERUS 



25 



other diameter. It is set well in from the posterior border of the ramus. The sigmoid notch is 

 shallow and wide, and the coronoid process is short. 



Foramina: The infraorbital foramina are above P 4 . The supraorbitals are missing, and the 

 foramina of the basicranial region cannot be made out with certainty. The posterior palatines are 

 very minute or entirely missing. 



Dentition: Superior: There is a well-marked internal cingulum on both cones of the molars 

 and on P 4 . The metastyle of M 3 is unusually large. The anterointermediate crest is prominent on 

 P 2 and P 3 , and the anterior and posterior basins are not confluent. Inferior: The metastylid on 

 M 3 , in conformity with the corresponding part of the superior tooth, is very large. The premolars 



Fig. 8 1 .—Promerycochcerus hollandi Douglass. 



Skull and jaw. HT. 

 Douglass, 1907.) 



Cat. No. 1194 CM. 3/8 nat. size. (After 



are somewhat crowded. Pi is large; C has about twice the diameter of I 3 . The incisors are small, 

 spaced, and peg-like. The superior incisors are also spaced and increase in diameter from one to 

 three, as do the inferior ones. The superior molar-premolar index is 0.88 and that of the inferior 

 series 0.85. 



Skeleton: The bones are heavier than in P. montanus grandis, and the limbs are nearly of the 

 same length in both species. 



Discussion: Douglass stated that there is little difference in the actual basal measurements of 

 the type skulls of P. m. grandis and P. hollandi, but the latter is broader and not so high, with the 

 zygomatic arches more widely expanded. The teeth of P. hollandi are not so large and strong. 



Promerycochcerus hollandi hatched Douglass 1907 

 Fig. 82; PI. XIV 



Original Reference: Some new merycoidodonts. Ann. Carnegie Mus., IV, p. 104, pi. XXVI 

 (P. hatcheri) . 



Type Locality: Canon Ferry on Missouri River, about 20 miles east of Helena, Montana. 



Geologic Horizon: Lower Miocene (lower Harrison). 



Type: Holotype, Cat. No. 1303 CM., nearly complete skull and jaws. Collected by E. Douglass in 

 1902 and the specific name given in honor of the late J. B. Hatcher. 



