422 O. C. Marsh—Fossil Mammals and Birds 
The only known specimens representing this species were 
found by the writer in the Pliocene strata, near Camp Thomas, 
on the Loup Fork river. 
Sciuravus nitidus, gen. et sp. nov. 
vuride, and hence the present fossil may be referred pro- 
visionally to that group. The genus is apparently distinct from 
any known, and will be more completely defined in the 
description. The upper molars are composed essentially of two 
pairs of tubercles, with a minute intermediate cone on the outer 
edge. ere is a strong basal ridge in front, and the inner 
margin is bifid. The species was about the size of the common 
brown rat, Mus decumanus. 
' Sciuravus undans, sp. nov. 
The present species was somewhat larger than the preced- 
ing, but probably a near ally. A single specimen only can now 
oh ot Ag J. 4 Bing: 
c 
fo 
in question is part of a right lower jaw containing the incisors 
and nce 
smooth, and somewhat, convex, and the inner face, where ine 
two teeth meet, is mar y a succession of delicate wave-like — 
impressions. The tubercles of the molars are more prominent 
than in those of the last species. : 
Measurements. 
Length of portion of lower jaw, containing first three 
molars. 
Transverse diameter of third lower molar,......__---- ae 
Transverse diameter of lower incisor, 6 
This specimen was found by the writer at the same geological 
the same locality 
Johan: and near the same that afforded the species 
