Feb., 1912. Mammals of Illinois and Wisconsin — Cory. 209 



of the hairs on the under parts are dark plumbeous and the tips 

 white or buffy white, the dark parts being nearly or quite concealed, 

 but occasionally the under fur shows through, giving a gray tinge 

 to the under parts; adults often have a patch of pale, sometimes 

 whitish, fur surrounding the gland on the flank. 



Dark phase: Occasionally specimens representing a dichromatic 

 or dark phase of pelage are taken ; the reddish brown back is replaced 

 by dusky and the general coloration is darker and grayer. In the 

 large number of specimens examined I have seen only one in this 

 pelage from Wisconsin. 



Measurements — (12 adult specimens from northern Wisconsin.) 

 Total length, 5.10 to 6 in. (130 to 154 mm.); tail vertebree, about 

 1.37 in. (30 to 41 mm.) ; hind foot, about .73 in. (18 to 20 mm.). 



Remarks — The Museum series contains 25 apparently not fully adult 

 specimens which are small, several having a total length of 118 to 

 125 mm., and are very similar in size and coloration to specimens 

 of E. g. loringi from Dakota. Other specimens from the same 

 locality, however, are of normal size. There is considerable varia- 

 tion in size of the adults of this species, as will be seen by the follow- 

 ing measurements of 12 selected specimens from different localities 

 in northern Wisconsin. 



Total Length. Tail Vertebrae. Hind Foot. 



Spread Eagle, Florence Co d" 147 mm. 41mm. 19 mm. 



Spread Eagle, Florence Co. .. . 6" 144 " 39 " I9 



Conover, Vilas Co cT 152 " 38 " 19 



Conover, Vilas Co cf 130 " 32 " 18.5 



Conover, Vilas Co 9 139" 32 " 18.5 



Lac Vieux Desert, Vilas Co. . . & 154 " 38 " 20 

 Lac Vieux Desert, Vilas Co. . . d" I35 " 32 " 18 

 Lac Vieux Desert, Vilas Co.. . 9 I53 " 39 " 19" 

 Lac Vieux Desert, Vilas Co. . . 9 142 " 34 " 18 " 

 Lac Vieux Desert, Vilas Co.. . 9 I34 " 3° " 18 " 

 Upper St. Croix Lake, Doug- 

 las Co cf 137 " 32 " 18 



Upper St. Croix Lake, Doug- 

 las Co 9 149 " 38 " 18.5 



The Red-backed Mouse is a woodland species, frequenting low 

 ground in heavy timber, sphagnum bogs and banks of streams, although 

 like many other species of similar habitat, it occasionally resorts to 

 fields and pastures bordering the woods. It is more diurnal in its 

 habits than others of our Mice and is not uncommonly to be seen run- 

 ning about in the day time. 



It is found in favorable localities throughout the greater part of 

 Wisconsin except, perhaps, in some of the extreme southern and south- 



