406 M. R. Thorpe — Leptauchenia Leidy and 



Description of Species. 

 Leptauchenia decora Leidy 1856. 



This species is represented in the Marsh Collection by 

 more than forty individuals. Apparently the elements 

 of the skull which were most resistant to destruction were 

 the rami and maxillae with molars. Specimens of this 

 species have been found on the North Platte River, at 

 Crow Buttes, Fort Mitchell, Lawrence's Fork, Court 

 House Eock, Scott's Bluff, Omaha Creek, Rattlesnake 

 Butte (near Chadron), and many from Pumpkin Creek — 

 all in Nebraska ; and one specimen from Spring Creek, 

 near Camp Baker, Montana, collected by Edward S. Dana 

 and George Bird GrinnelL The description is taken 

 from various individuals, but especiallv from Cat. Nos. 

 10119 and 10121. 



Specific Characters. — ^^The skull is somewhat smaller 

 than that of Oreodon gracilis, and broader, shorter, and 

 lower. The lacrymal fossa is small and shallow, and the 

 infra-orbital foramen is above the middle of P^. The 

 malar is remarkably robust. The bullae are much inflated 

 and oval in outline. The palate is nearly flat, while the 

 palatonarial border is opposite the posterior margin of 

 iP. The orbits are large, oval-shaped antero-posteriorly, 

 and look chiefly outward; the facial vacuities are large 

 and extend somewhat posterior to the anterior orbital 

 border; the ramus is similar to that of Oreodon, except 

 that the posterior area is of greater proportionate width 

 and depth; the masseteric fossa is large and relatively 

 deep; the inferior border is straight; the auditory 

 meatus is large, situated a little in advance of and well 

 above the line of the occipital condyles ; the paramastoids 

 are plate-like, are in contact with the bullae, and extend 

 downward but slightly below the inferior border of the 

 bullae. The dentition shows the full number of teeth 

 common to Oreodon, that is, forty-four. Both molar- 

 premolar series are crowded and the latter somewhat 

 reduced. The molars are more nearly uniform in size 

 reduction from M-^ to M^ These teeth are very hypso- 

 dont and the external styles are very well developed. 



