226 M. R. Thorpe — John Day Pr ornery cochoeri, 



middle line, as in M. superhus." This statement is in 

 error, and should read 60°, the angle of both P. superhus 

 and P. chelyclra. The lacrymal fossa is well marked, but 

 not deep. The orbits are more obliqne than in P. super- 

 hus, and their vertical diameter exceeds the transverse. 

 The malar is wide and flat. The squamous part of the 

 zygoma is very heavy and massive, and the inferior 

 surface as wide as in any John Day form in the genus. 

 In our specimens the bullae are slightly larger than in 

 the type, extending to, but not below, the inferior surface 

 of the postglenoid tubercle. This latter process has nearly 

 the same transverse as antero-posterior dimension, with 

 the former slightly the greater. The incisive foramina 

 are large and approach close to the base of the canines. 

 These foramina are wdder than long, in which they differ 

 from those in both P. superhus and P. macrostegus. The 

 sagittal crest is thick and high. 



Measurements of Holotype. 



mm. 



Total length of skull, approx 342 



Bipostglenoid diameter 127 



Bizygomatic diameter 250 



Length of superior molar series 70 



Length of superior premolar series 62 



Length of superior dental series, inc. canine 157 



Depth of malar below middle of orbit 36 



Max. width of cranium 82 



Diameter of postorbital constriction 59 



Max. height of zygoma above glenoid surface 85 



"Width of f rontals above middle of orbits 94.5 



Width of face at infra-orbital foramina 70 



Pr ornery cochwrus macrostegus (Cope). 



Holotype, Cat. No. 7444, Cope Collection, A. M. N. H. Upper 

 Oligocene (upper John Day), Bridge Creek, John Day Eiver, 

 Oregon. Supplementary data from Cat. Nos. 10955 and 10957, 

 Y. P. M. Figured by Scott, Morph. Jahrb., 16, pi. 14, figs. 8, 9. 

 1890. 



Specific characters. — Infra-orbital foramen above inter- 

 val between M^ and P* ; squamous part of zygoma much 

 expanded, edge truncated; malar robust; palate much 

 produced posteriorly ; width of skull equal to length from 

 condyles to P^; maxillary produced anteriorly; frontal 

 plane transverse, diamond-shaped; bullae small, conical. 



