DAKOTA AND NEBRASKA. 95 



broad. The orbits are quaclrately rotund and the transverse diameter shghtly exceeds 

 the vertical. The lachrymal foss£B are comparatively of moderate depth. 



The specimen retains the lower jaw and nearly all the teeth in both jaws, which 

 closely resemble those of Oreodon Culbertsoni. 



2. The greater part of a skull without the lower jaw. It agrees with the corres- 

 ponding portion of the preceding specimen, both in size and details of form, except 

 that the face is less convex above and is not so high. The posterior nasal half-elUpse 

 is five lines long in the median line and seven and a quarter -wide. 



3. A specimen resembling the last, but with, a flatter forehead, and with the upper 

 jDart of the face wider and flatter. The posterior extremities of the nasal bones 

 depart somewhat from the more common arrangement. For a short distance back of 

 the ends of the frontal angular processes they are nearly parallel at the sides, and 

 then terminate in an irregular obtuse triangle, with one bone at the apex shorter than 

 the other. The length and breadth of the two bones enclosed between the frontals 

 is eight lines. The lachrymal fossse are slightly deeper than in the preceding 

 specimens. 



4. A mutilated skull, without the greater portion of the cranium and with the 

 greater portion of the lower jaw. The forehead and upper part of the face are as flat 

 as in the preceding specimen, but the posterior portions of the nasal bones form the 

 usual half-ellipse, which is six lines long and nine lines wide. The right orbit, nearly 

 entire, is shghtly transversely oval. The lachrymal fossae are more shallow than in 

 any of the other specimens. 



5. The greater part of a much fractured skull, rather more robust than the pre- 

 cedmg specimens, but with proportionately much larger teeth. The true molars are 

 as large as those of the smallest variety of skulls appertaining to Oreodon Culbertsoni. 

 The back part of the nasal bones form the usual half-ellipse, slightly notched at the 

 summits of the bones. The orbit is I'otund. The lachr;)Tnal fossa of the usual depth 

 in the species. 



6. The greater part of a skull, -without the lower jaw, of about the same fonn and 

 proportions as the preceding specimen, and with teeth equally lax'ge. 



7. The fore part of a skull, with portion of the lower jaw, nearly agreeing iu its 

 proportions Avith the corresponding part of the j)receding pair of specimens, but with 

 teeth of the usual size. The back extremities of the nasal bones form a half-ellipse, 

 slightly notched at t^ie summit. In this specimen the sagittal crest appears to have 

 been uniform to the anterior border of the parietal, as the di\'ei'ging temporal ridges 

 commence at the summit of the frontals. 



