MAMMALS OF MINNESOTA. 189 
Vesperimus sonoriensis LECONTE. 
THE SONORA MOUSE. 
Mus leucopus RICHARDSON, Zool. Journ,, 1818; Fauna Bor. Am., 1829. 
Hesperomys sonoriensis LECONTE, Proc. Acad. Nat. Sci. Phila., 1853. 
AUDUBON AND BACHMAN, Quad. North America, 1854. 
RAIRD, Mam. N. A., 1857; U.S. and Mex. Bound. Surv.,1859. 
Hesperomys leucopus sonoriensis CoUES, Monogr. N. Ain. Rodentia, 1877. 
The little animal known as Hesperomys sonoriensis is a resident 
of the western interior region and might be regarded as a per- 
manent prairie variety of H. leucopus but for the fact that the 
two species are associated at the limits of their geographical 
range instead of fading insensibly into each other as geographical 
varieties of recent origin might beexpected to do. Our collec- 
tion embraces a considerable number of specimens collected at 
Brown’s Valley and other points near the western line of Min- 
nesota where this form is the most abundant mouse. There is 
a very remarkable uniformity in size and coloration which both 
are sufficiently unlike the deer mouse to be easily distinguish- 
able. On the whole, the colors may be said to be considerably 
lighter and less conspicuous than in the deer mouse, but still 
they are bright and attractive. The white parts encroach 
more upon the dorsal area than in our more eastern mouse and 
the line of demarkation is more distinct, there being none of 
the gray on the hips usually seen in the latter, and the sides and 
lower parts are beautifully white. The brown portion of the 
tail is a narrow stripe and the back is not so conspicuously 
marked with black hairs as in /Jewcopus. Besides these differ 
ences in the whole anterior portion, the pelage is sifted over 
with whitish so as to give it a grayish tinge, while only on the 
rump is found the bright reddish brown of our familiar species. 
Should the color not prove distinctive the marked difference in 
size is sufficiently conspicuous. 
The following table fairly represents the limits of normal 
variation and in one case (No. 100) a specimen to some extent 
resembling the deer mouse. 








MON Aer nal etl ee eeatleg coetona | toon | Baie ||" Bex: Date. 
Bela) |eae ee | ORGS MONOON PONG it els ccc tel slantelces « Dec 4, 1883. 
89 | 3.62 | 2.25 | 0.90 | 0.50 | 0.72 | 0.388 | 0.50 | female | July 1, 1885. 
90: | 3.38 | 2.40 | 0.75 | 0.45 | 0.71 | 0.35 | 0.50 | female by 
91 | 3 60 | 2 25 | 1.00 | 0.50 | 0.70 | 0.35 | 0.51 | male a 
OSHIP B00- |2ce5--|) OF 95, 0850) 105770 1.0. 35A lee. os female a 
OO ose aOOn | Oroo eOeDON Os TO cil. cevelic ase > male ue 
TOO perso OOF) LOO eOnay PORSO: "0. 35. lio. ccc male a 
IONE rarcoll 2: 360i O05) O.50) FO alee... &. 0.55 | male a 
TOG OE COL mene s OOS | OLSO IO G2r oy. cents orvesss female | July 4, 1885. 
NOR oeaom aero Os9se | Cea Gr Os Ol. cece looee oe female 
