DAKOTA AND NEBRASKA. 179 



Posterior view. — The inion is less deep than in the Hog, and in its proportions 

 is more like that of the Hippopotamus. Its summit, narrower than in the 

 Hog, presents, as in this animal, a pair of wing-like plates, less divergent and pro- 

 portionately more prominent posteriorly. The concave surface between the wing- 

 like processes, though much smaller, is proportionately deeper than in the Hog. 

 Lower down the surface appears to have been transversely convex, being broken in 

 the only specimen in which it is partially preserved. 



The lateral border of the inion forms an acute edge, descending obliquely from the 

 summit and curving outwardly and slightly upward to the top of the archway 

 enclosing the external auditory meatus. 



The sides of the inion are deeply depressed, and form a deep concavity between 

 the upper part of the ex-occipital, the supra-occipital, and the edge of the squamosal. 

 The lower border of the ex-occipitals curve outwardly and downward from the con- 

 dyles to the external part of the archway leading to the auditory meatus, where they 

 terminate in the paramastoids. 



The occipital foramen is transversely oval, and is larger and looks more downward 

 than in the Hog. 



The condyles are less sessile than in the latter, and resemble more those of the 

 Hippopotamus and Glioerodes. Their upper border is nearly horizontal, and they are 

 separated at their lower extremities by a wide notch, part of the occipital foramen. 



The paramastoid processes, or par-occipitals, hold a much more external position in 

 relation with the condyles than in any of the living suilline animals. Thej' are too 

 much broken in the specimens under examination to determine their character, but 

 they appear not to have been better developed proportionately than in the Peccary 

 and Hippopotamus. Their base, in association with the less well-developed mastoid 

 process, forms the posterior wall of the archway leading to the external auditory 

 meatus. 



Inferior view. — The base of the skull is proportionately broader than in the Hog, 

 and bears more resemblance to that of the Hippopotamus. 



The basi-occipital is more convex than in any of the recent suilline animals. It is 

 proportionately long and thick. Narrowing anteriorly in conjunction with the basi- 

 sphenoid, it forms a pair of tuberosities for muscular attachment. The basi-sphenoid, 

 narrower than the former, ascends from it forward to a comparatively large aperture 

 above the position of the internal pterygoids, which are suturally connected in an 

 arching manner across the position of the pre-sphenoids. 



The anterior condyloid foramen occupies a corresponding position with that in the 

 Hippopotamus. The glenoid cavity is remarkable for its extreme outward position. 

 It resembles more that of the Peccary tlian that of the Hog or Hippopotamus. It is 

 not so low relatively as in the former, being only a little below the level and on a 



