124 MONOGRAPHS OF NORTLL AMERICAN RODENTIA. 



Ucaperomya lecontii, Wagner, Wieg. Arch. 1843, pt. ii, 51 (after Aud. & Bach.). 



Iteithrodon leoontii, LeConte, Proc. Acad. Nat. Sci. Phila. vi, 185:?, 413. 



f Mus carolinetiHi, Aud. & Bach., Journ. Acad. Nat, Sci. Phila. viii, pt. ii, 1842, 306 ; Q. N. A. iii, 1854, 332. 

 (South Carolina, in inundated lands, rare. "Tail longer than tho body, ears long and hairy, 

 color light plumbeous; * * under surface scarcely a shade lighter. Length of head an'' 

 body 2.33, of tail 2.75, ear 0.33, tarsus 0.54.") 



f llrxperomys carolinensis, Wagner, Wieg. Arch. 1843, pt. ii, 51 (a'ter Aud. & Bach.). 



T Rcithrodon carolinensis, Baikd, M. N. A. 1857, 452 (after Aud. & Bach.). " 



Iteithrodon megalotis, Baiisd, M. N. A. 1857, 451 ; Eep. U. S. aud Mex. Bound. Surv. ii, pt. ii, 1859, Mam- 

 mals, 43, pi. vii, fig. 4a-c, and pi. xxiv, fig. 4a~g. (Sonora. Largest of North American 

 species. Head aud body, 2^-3 ; tail, 2J ; sole, £-$ ; ear, 0.43 high. Colors as in E. humilc.) 



Diagnosis. — O. mure musculo minor seu staturd subaquans, Cauda trun- 

 cian subcequante kirsutd, sub-bicolore, auriculis prominulis, liirsutis, plantis 

 semi-nudis, vellere molli, supra murino, infra griseo-albido, lateribus fulves- 

 ccnlibus. 



Habitat. — South Atlantic States. Gulf States into Sonora. Up the 

 Mississippi Valley to Saint Louis. Iowa. Kansas. Nebraska. 



Numerous excellent examples, from the South Atlantic States, of this 

 diminutive Rodent, which, with the general appearance of a small house- 

 mouse, is instantly distinguished by its generic characters, present very little 

 variation either in size, shape, or color. None show the peculiar proportions 

 attributed by Audubon and Bachman to their Mus carolinensis. The tail is 

 always a little shorter than the trunk. The hind feet range from 0.50 to 0.60 

 in length ; the ears project beyond the fur, and have a somewhat character- 

 istic shape, difficult to describe, represented with indifferent success in Audu- 

 bon's plate above cited. They are rather obovate in shape, and narrow for 

 their length ; the antitragus is valvular ; the interior below is nearly naked 

 and flesh-colored ; this part is overlaid by the long hairs of the cheeks ; the 

 rest of the ear is rather coarsely hirsute than closely pilous. The fur is soft 

 and silky; above, the color is exactly as in the house-mouse and nearly uniform, 

 being merely a little darker along the middle of the back ; but all along the 

 sides the brown is enlivened with a decided wash of fulvous or pinkish-gra}', 

 never seen in M. musculus. Generally, this tinge is diffuse, but it sometimes 

 forms quite a striking lateral stripe. The tail is distinctly bicolor, but not 

 very sharply so. The under parts are whitish, obscured by the plumbeous of 

 the roots of the hairs showing through, and generally also noticeably washed 

 over with a dilution of the fulvous that tinges the sides. The lips, however, 

 are pure white; and the whole oral and mental region, with the upper sur- 

 face of the feet, are likewise white. The absolute size, and to some extent 

 the range of variation, of this species appear from the table given below. 



