SCIURIDJE— EXTINCT SPECIES. 935 



posterior diameter of lower incisor 0.17; transverse 0.125. Described and 

 figured by Dr. Leidy (I. 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 (I. c.) from Cottonwood Creek and Black's Fork, 

 Southwestern Wyoming. 



PARAMYS DELICATISSIMUS Leidy. 



Paramys delkalissimm Leidy, Proc. Acad. Nat. Sci. Pliila. 1871, 231 ; Ann. Rep. U. S. Geol. Surv. Terr, for 

 1871 (1872), 357; Extinct Vert. Fauna, 1873, 112, 335, pi. vi, figs. 28, 29.— Cope, 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 (/. c.) 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. 



Sciurarus Marsh, Amer. Jouru. 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. 



Seiuravus nitidus Marsh, Amer. Journ. Sci. 3d ser. ii, 1871. 122. — Leidy, Ann. Rep. U. S. Geol. Surv. 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 

 Bultes, near Fort Bridger, Wyoming. 



SCIURAVUS UNDANS Marsh. 



Sciuravm undans Marsh, Atuer. Journ. Sci. and Arts, 3d ser. ii, 1871, 122. — Leidy, Ann. Rep. U. S. Geol. 



Surv. Terr, for 1871 (1872), 358. 

 Paramys undans Cope, Pal. Bull. no. 12, 1873, 4. 



Rather larger than the Brown Rat (Mus decumanus) ; smaller than 

 Paramys delicatksimus Leidy. Described by Professor Marsh (I. c.) from a 

 portion of a lower jaw containing the incisors and the first three molars, from 



