236 M. R. Thorpe — John Bay Pr ornery cochoeri, 



postglenoid processes relatively small; palate moder- 

 ately produced; wide interval between paroccipital and 

 postglenoid processes; infra-orbital foramen above P"^- 

 M^ interval ; exceedingly liea^^ metastyle on M^. 



The type consists of a skull only. It is peculiar in 

 that the bone of all parts of the skull is slightly spread 

 apart and the interstices filled with matrix. 



Measurements of Holotype. 



mm. 



Total length of skull, approx 400 



Bipostglenoid diameter 170 



Bizygomatic diameter 254 



Length of superior molar series 94.3 



Length of superior premolar series 78.5 



Length of superior dental series, inc. canine 200 



Depth of malar below middle of orbit 49.7 



Width of palate at P^ 78 



Width of palate at protocone of M" 69 



Max. width of cranium 138 



Diameter of postorbital constriction 82 



Max. height of zygoma above glenoid surface 58 



Width of frontal above middle of orbits 140* 



Width of face at infra-orbital foramina 130 



* Approximate. 



Promerycochcvrus marshi, sp. nov. 



(Figs. 4 A, B.) 



Holotype, Cat. Xo. 10999, Y. P. M. Upper Oligocene (upper John Day)^ 

 Haystack Valley, John Day River, Oregon. 



Specific characters. — Malar below orbit very wide and 

 heavy; orbits small; lacrymal fossae deep; zygoma very 

 heavy; nasals project to a point above the anterior 

 portion of the canines ; infra-orbital foramen above P^ ; 

 masseteric fossae very deep ; face narrowed in advance 

 of the orbits more than in any other species; frontals 

 flat and decnrved above orbits ; temporal ridges have 

 their junction above a line throngh postglenoid processes, 

 which is more posterior than in any other species of the 

 genus ; incisive foramina large and separated by a trian- 

 gular wedge of the palate, the apex of which is close to 

 the incisor border. In all the other species, the proximal 

 sides of the foramina are parallel to the sagittal plane^ 

 instead of being markedly oblique as here. 



The holotype consists of the skull and jaws of a fully 

 adult animal, as well as the atlas, axis, fsNQ cervicals, two 



