244: M. R. Thorpe — John Day Pr ornery cochceri. 



marked; greatest bizygomatic diameter of any 

 John Day species of the genus; great depth of 

 malar below orbit ; zygoma V-shaped ; no internal 

 cingulum on superior molars P. latidens. 



Orbits small, nearly circular, very short sagittal 

 crest; malar wide; lacrymal fossa deep; face 

 narrow; incisive foramina large, set obliquely 



from sagittal plane ; skull large, massive 



P. marshi. 



Skull long, narrow ; extremely small brain chamber ; 

 very high narrow sagittal crest ; f rontals separate, 

 parallel to a point above condyles before junction ; 

 malar wide; no internal cingTilum on superior 

 molars ; bullae large ; lacr^nnal fossae moderately 

 deep P. microcephalus. 



2. Infra-orbital foramen above interval between M^ and 



Orbits very high ; palate much produced posteriorly ; 

 no internal cingulum on superior molars ; bullae 

 small, conical ; lacrymal fossa small ; skull longer 

 than in P. superbus; incisive foramina large, oval- 

 shaped P. macrostegus. 



Orbits small, looking chiefly outward ; palate moder- 

 ately produced; internal cingulum on superior 

 molars ; lacrymal f osscT very shallow ; malar very 

 wide ; squamous part of zygoma weak, not rising 

 above middle of orbit; bull£e rotund . . .P. inflatus. 



3. Infra-orbital foramen above posterior half of P^. 



Small size ; basicranial axis steep ; lacrymal fossae 

 deep, small ; internal cingulum on superior molars 

 but faintly developed ; crest of zygomatic arch low ; 

 true Pr ornery CO choerus, but close to Eporeodon 

 Desmatochoerus curvidens. 



