EDENTATA OF THE SANTA CRUZ BEDS. 237 



The skull also is of a somewhat peculiar type. The occiput is quite 

 high and slopes forward and upward more than in most species of Hapa- 

 lops. From the occipital crest the upper contour of the skull rises slightly 

 to the parietal eminence, which is quite low, and thence descends very 

 gradually to the muzzle, so that the dorso-ventral diameter of the skull is 

 nearly uniform throughout. The brain-case is broad and capacious, the 

 postorbital constriction shallow and the expansion forward from it unusu- 

 ally gradual ; the sagittal crest is not developed, save for a short distance 

 upon the frontals, which on the sides are uncommonly concave to form 

 the wall of the orbits ; the preorbital fossae are of moderate depth. 



The occiput is broadly convex, with a median ridge for the vermis of 

 the cerebellum and a shallow fossa on each side ; the condyles are quite 

 large, projecting well below the level of the basioccipital and are widely 

 separated by the large foramen magnum. The occipital crest is quite 

 prominent on the sides, becoming inconspicuous dorsally, where the 

 supraoccipital is reflected for a short distance upon the cranial roof. The 

 hard palate is moderately convex between the molariform teeth, flattening 

 anteriorly ; its rugosities receive a somewhat characteristic appearance 

 from their being arranged in three or four longitudinal rows, or ridges ; 

 the median notch for the premaxillary spines is broad and U-shaped. 



MEASUREMENTS. 



Skull, length in median basal line 148 Skull, width over lachrymals 056 



" condyle to anterior nares. .174 Zygomatic arch, length 100 



Cranium, length from condyle to rim of Distance from condyle to glenoid cavity. .027 



orbit 135 " " " " i 087 



Face, length from rim of orbit to anterior Palate, length in median line 060 



nares 043 " width at i 026 



Occiput, height 046 " " " preorbital fossae 029 



" width at base 065 " " <' & 018 



Skull, width at postorbital constriction. .036 " " " & 019 



The humerus differs but little from that of//, longiceps ; the shaft is 

 somewhat more slender, the deltoid area narrower, with less rugose and 

 prominent edges; the distal trochlea is rather wider and has a more 

 hemispherical facet for the radius, while the anconeal fossa is distinctly 

 deeper; the internal epicondyle is quite as massive and prominent, but 

 the bony bridge over the foramen is considerably narrower. 



