V ' MUBIDiE— SIGMODOKTES— NEOTOMA. ■'- T 



of the t^ipical genus Mus, — not being indigenous to this country, and being, 

 moreover, among the best-known of mammals, will not be treated in the 

 present paper, .» . . 



Tribe SIGMODONTES. 



Under tliis head come all tlie Murince indigenous to America. Those 

 of the northern division of the hemisphere may be grouped under four 

 genera, — Neoloma, Sigmodon, Oclietodon, and Llesperomijs ; the latter with 

 three subgenera. Full descriptions of these and of their respective species 

 follow. • 



Genus NEOTOMA, Say & Ord. ;"' 



Miu'ap., Say & Oiii), 181B-a3.— Dksmauest, ISiS. |}.j jj -,,. 



ylri'ico/a, sp., llAltLAN, 1825. 



Lemmiu, up., KiscilKU, l&Jti. 



Xcoloma, Bay &, Onu, Journ. Acad. Nat. Sci. Pbila. iv, pt. ii, 1825, 34C (typo, X. Jloritlana).—Avi>. & Bach., 



Qiincl. N. A. i, 1849, 31.— Baihd, M. N. A. 1857, 486.— CouES, Proc. Acud. Nat. Soi. Pliila 



1875, 174. 

 Hyoxm, Bp., RicilAliDSON, Zoiil. Journ. iii, 1828, 517 (N. cinerea). 

 Teonoma, J. E. Gray, Proc. Zoiil. Soc. Load, 18—, p. — (xV. cintrea). 



CiiAHS. — Embracing sigmodont rats of the largest size ; highly murine 

 in general aspect ; peculiar to North and Middle America. Snout pointed, 

 mobile; whiskers very long (the longest ones reaching to or beyond the 

 siiouldcrs) ; eyes large and full (as in Dipodomys) ; ears very large, orbicular, 

 nearly naked. Tail long, nearly equaling the body with or without tiie head, 

 either scant-haired (nearly as naked and scaly as in Mm) or bushy (much as 

 in Myoxus). Feet small, but broad for their length, with short toes ; the fore 

 with four perfect clawed digits, which in length run 3d, 4th, 2d, 5th ; and a 

 rudimentary tiiumb bparing an abortive nail; the hind with five perfect 

 clawed digits, tiie middle three of which are subequal and longest ; the 5th is 

 not much siiorter, its claw reaching about to the base of the 4th claw, while the 

 1st reaches about to the median node of the 2d. Palms naked, 5-tuberculate ; 

 one tubercle postero-external, another postero-intemal near base of poUex ; 

 two at bases of 2d and 5th digits, respectively, and one at base of 3d and 4th 

 digits together. Soles naked at least for their anterior two-thirds — the pos- 

 terior third hairy in northern species, mostly naked in tropical forms; fur- 

 nished with seven tubercles, thus : one near postero-external angle of foot, 

 only evident in naked-soled species ; * a larger one a little farther in advance 

 on internal border; another (smaller) in advance of this externally; throe 



'ILirdly n true tiiburelu, howovor; being mutol; oaiued by protuberance of tbe lattjaccnt bone, 

 ovot which the skin ia not particularly thickened. . ' 



