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



ent shape, and approach much more closely to the incisor 

 border; sagittal crest very much shorter; greater con- 

 vexity above foramen magnum, and lateral fossae deeper ; 

 zygomatic crest not so high and the outer margin of the 

 process less robust; face not so clearly divided by the 

 convex prolongation of the zygoma. Width of the malar 

 below the orbit, 53 mm. ; in P. macrostegus, 38 mm. ; in 

 P. clielydra, 40 mm. ; and in P. latidens, 58 mm. 



The specific name is given in honor of Professor 0. C. 

 Marsh. 



Measurements of Ilolotype. 



mm. 



Length of skull, approx 380-385 



Bipostglenoid diameter 136 



Bizygomatic diameter 244 



Length of superior molar series 85 



Length of superior premolar series 76 



Length of superior dental series, inc. canine 186 



Max. width of cranium 116 



Max. width of postorbital constriction 68 



Max. height of zygoma above glenoid surface 69 



Width of frontals above middle of orbits Ill 



Height of skull above parapet of M-' 115 



Width of face at infra-orbital foramina 86 



Length of nasals 166 



Depth of paramastoids below inferior edge of postglenoids . 36 



Distance from nasion to junction of temporal ridges 138 



Length of inferior molar series 92 



Length of inferior premolar series 81.5 



Length of inferior dental series, inc. canine 173.5 



Depth of ramus from condyle to angle 1 46 



Length of ramus 294 



Max. width of atlas 126 



Length of centrum of axis, exc. of odontoid process 52 



Length of centrum of third cervical 32 



Height of third cervical, exc. of spine 52 



Length of centrum of fourth cervical 34 



Length of centrum of fifth cervical 35 



Length of centrum of sixth cervical 33 



Length of centrum of seventh cervical 33 



Length of centrum of first dorsal 33 



Length of centrum of second dorsal 33 



Length of centrum of third dorsal 35 



Width of spine at top of neural arch, fifth cervical 12.7 



Width of spine at top of neural arch, sixth cervical ... 18 

 Width of spine at top of neural arch, seventh cervical.. 18 



Width of spine at top of neural arch, first dorsal 29.5 



Width of spine at top of neural arch, second dorsal . . . 26.5 

 Width of spine at top of neural arch, third dorsal 24.8 



