126 



THE MERYCOIDODONTID.^ 



Specific Characters: This skull is one of the smaller and narrower types. The general 

 form and proportions are much like those of P. hollandi on a much smaller scale. The maximum 

 zygomatic expansion lies at the anterior part of the glenoid surface. The malar is of average depth, 

 while the squamosal portion of the zygomatic arch is light and slender and rises almost vertically to 

 the posterior crest, which does not extend above a line through the upper portion of the orbit. The 

 nasal bones are long and slender, with the widest part near the maxillonasal notch. From this 

 point aft the width gradually decreases to the posterior truncated terminations, and forward of this 

 point decreases rapidly. The nasal bones are moderately convex transversely and nearly straight 

 anteroposteriorly. The lacrimal fossa is deep but small. The frontals are wide, unreduced, and 



Fig. 82. — Promerycochcerus hollandi hatcheri Douglass. Skull and jaw. 



Douglass, 1907.) 



HT. Cat. No. 1303 CM. 1/2 nat. size. (After 



moderately flat, except for the downward curvature above the orbits. The latter are moderately 

 small with the vertical diameter the greater, and they look mainly sidewise. The temporal ridges 

 unite near the postorbital constriction. The sagittal crest is narrow and high, with a length of about 

 a fourth that of the skull. The supraoccipital crest is well produced aft, with the wings moderately 

 closed. The small brain case is narrow, with faint lateral convexities. The external auditory meatus 

 is small. The narrow palate is slightly vaulted, with the U-shaped palatonarial border somewhat 

 behind a line across the posterior of M 3 . The basicranial axis is moderately shallow. The glenoid 

 articular surface is anteroposteriorly wider than that of P. hollandi and transversely shorter. The 

 postglenoid processes are robust, and the anteroposterior diameter is nearly as great as the transverse. 

 The bullae are moderately large, are oval in outline, and extend in advance of the postglenoid 

 tubercle. The paroccipital processes are long and twisted and curve forward below the auditory 

 meatus as far as the posterior of the postglenoid process. Index: 0.53. 



