with Descriptions of New Species. 229 



In many respects this species is similar to P. superhus, 

 except for smaller proportions. The incisive foramina 

 are very nearly semi-circular, approach very close to the 

 incisive alveoli, are large, and separated from each other 

 by a very narrow strip of bone on each side of the sagittal 

 plane. The basicranial axis is moderately steep, but 

 much less so than in P. macrostegus. The occiput above 

 the foramen magnum is strongly convex and the trans- 

 verse crests are very close together. The overhang of the 

 occiput is considerable. The molars have an internal 

 cingulum. The skull is low and the cranium fairly wide. 

 The zygomata rise to the top of the brain cavity, which 

 is surmounted by a high narrow sagittal crest. The f ron- 

 tals are flat between the orbits. The side of the face is 

 prominently divided by the upAvard convexity from the 

 anterior zygomatic pedicle. The zygomata form a wide 

 shallow U with the posterior crest turning backward 

 internally and overhanging a position posterior to the 

 postglenoid process. The lateral fossa above the condyle 

 is quite shallow. The orbits are small and round and 

 situated very high. The incisors are small. 



Measurements. 



Cat. No. 10960 



Holotype Y. P. M. 



mm. mm. 



Length of skull 330 331 



Half width across frontal surface 54 54 



Max. diameter from sagittal plane to ex- 

 ternal zygoma 83* 94 



Max. diameter of brain case 73 73 



Width between external surfaces of post- 



glenoids 114 114 



Depth of malar below orbit 40 38 



Vertical diameter of orbit 46 38 



Transverse diameter of orbit 35 



Length of superior dental series, inc. canine 156 



Length of superior premolar series 47.5 



Length of superior molar series 76 



Length of last molar 38 35 



Max. length of ramus 254 



* Approximate. 



Specimen No. 10965, of the Marsh Collection, possesses 

 complete mandibular rami with teeth except incisors. 



