SCLIURIDM—LEX TINCT SPECIES. 935 
posterior diameter of lower incisor 0.17; transverse 0.125. Described and 
figured by Dr. Leidy (/. c.) from the greater portion of a left mandibular 
ramus and several detached molar teeth. From Fort Bridger, Utah, and also 
reported by Professor Cope (¢. c.) from Cottonwood Creek and Black’s Fork, 
Southwestern Wyoming. 
PARAMYS DELICATISSIMUS Leidy. 
Paramys delicatissimus Lewy, Proc. Acad. Nat. Sci. Phila. 1871, 231; Ann. Rep. U. 8. Geol. Surv. Terr. for 
1871 (1872), 357; Extinct Vert. Fauna, 1873, 112, 335, pl. vi, figs. 28, 29.—Corr, Pal. Bull. 
no. 12, 1873, 4. 
Smaller than either of the preceding, and from the same localities. 
Length of the lower molar series 0.50 of an inch ; antero-posterior diameter 
of the lower incisor 0.125; transverse 0.083. Described and figured by Dr. 
Leidy (Z. ¢.) from “the greater portion of the right ramus of a lower jaw, 
containing all the molars, and a second specimen consisting of a small frag- 
ment of another lower jaw containing the second molar”. Fort Bridger 
(Leidy) and Black’s Fork (Cope). 
Genus SCIURAVUS Marsh. 
Sciuravus Marsn, Amer. Journ. Sci, and Arts, 3d ser. ii, 1871, 122. 
Upper molars with two pairs of tubercles, and a minute intermediate 
cone on the outer edge. The lower incisors extend below the entire molar 
series. 
SCIURAVUS NITIDUS Marsh. 
Sciuravus nitidus Mansu, Amer. Journ. Sci. 3d ser. ii, 1871, 122—Leyy, Ann. Rep. U. 8. Geol. Sury. Terr. 
for 1871 (1872), 358. 
“About the size of the Brown Rat (Mus decumanus).” Described from 
a portion of an upper jaw containing the last three molars. Found at Grizzly 
Buttes, near Fort Bridger, Wyoming. 
SCIURAVUS UNDANS Marsh. 
Sciwravus undans Mansu, Amer. Journ. Sci. and Arts, 3d ser. ii, 1871, 122.—Letpy, Ann. Rep. U.S. Geol. 
Surv. Terr. for 1871 (1872), 358. 
Paramys undans Corr, Pal. Bull. no. 12, 1873, 4. 
Rather larger than the Brown Rat (Mus decwmanus); smaller than 
Paramys delicatissimus Leidy. Described by Professor Marsh (/. c.) from a 
portion of a lower jaw containing the incisors and the first three molars, from 
