PROMERYCOCHCERUS 141 



Foratnina: The infraorbital foramina are above the interval between P 4 and M 1 . The supra- 

 orbitals cannot be positively located, because of the damaged condition of the frontals in this area. 

 The foramen ovale is large. I do not detect a foramen rotundum. As usual in this genus, the 

 posterior palatines seem to be absent. 



Dentition: The teeth are larger than the size of the skull would seem to demand. Superior: 

 The metastyle of M 3 is small. M 2 and P 4 have well-developed internal cingula; on the other 

 molars they are absent or faintly developed. On P 3 the posterior crescent is much larger than the 

 anterior, and on P 2 these crescents are subequal, while on P 1 the posterior is somewhat the larger. 

 The anterointermediate crest is present on the first three premolars. P 1 is not isolated, and the 

 premolars are crowded but do not overlap. Inferior: The metastylid of M 3 is medium in size. 

 The incisors, canines, and premolars are crowded and overlapping. The three anterior premolars 

 are narrow and compressed. The superior molar-premolar index is 0.85 and the inferior 0.875. 



Skeleton: The skeleton of this species is not so robust as that of P. hollandi, although the skull 

 is larger. 



Discussion: This subspecies is certainly closely related to P. montanus, although by no means 

 synonymous. 



Fig. 97. — Promerycochcerus suferbus (Leidy). Fie. 98. — Promerycochcerus suferbus (Leidy). 



Fragmentary maxilla with two molars. GCT. Cat. Inferior view of fragmentary maxilla. GCT. Cat. 



No. 10151 Y.P.M. About 1/2 nat. size. No. 10151 Y.P.M. About 1/2 nat. size. 



Promerycochoerus superbus (Leidy) 1870 

 Figs. 97-105; PI. L, figs. 3-4 



Original Reference: Remarks on a collection of fossils from Dalles City, Oregon. Proc. Acad. Nat. 

 Sci. Phila., XXII, pp. 111-112 {Oreodon suferbus). 



Synonyms: Ef oreodon suferbus Marsh 1875; Eucrotafhus suferbus Cope 1880; Merycochaerus suferbus 

 Cope 1884; Promerycochcerus suferbus Douglass 1901; Paracotylofs suferbus Matthew 1901 ; Merycochaerus 

 temf oralis Bettany 1876. 



Type Locality: Bridge Creek, John Day Valley, Oregon. 



Geologic Horizon: Lower Miocene (upper John Day). 



Types: Genocotypes, Cat. Nos. 516, Condon Collection, University of Oregon, and 10151, 10152, 

 10153, 10153a, 10967, and 10968 Y.P.M., all fragmentary parts of rami and skulls, some with teeth. Plesio- 

 types, Cat. Nos. 10154, 10978, 10983, 10989, and 10991 Y.P.M., skulls and rami. 



Specific Characters: The skull is medium-sized, in length somewhat greater than that of 

 P. chelydra. The maximum zygomatic expansion is just in advance of the glenoid surface. The 

 malar originates above the middle of M 2 , is deep and flat beneath the orbit, and extends well aft. 

 The ridge from the anterior zygomatic pedicle extends forward and upward beyond the infraorbital 

 foramen. The squamous portion extends forward beneath the posterior fourth of the orbit. It is 



