Family CRICETIDAE 163 



. Distribution. — The white-footed mouse is abundant through- 

 out Illinois. The subspecies in northern and central Illinois is 

 Peromyscus lencopus noveboracensis (Fischer) ; that in southern 

 Illinois is probably P. 1. leucopus (Rafinesque). The range of 

 the species extends from southern Maine to southern Alberta 

 and southward to southern ^lexico. Its western limits are 

 marked by northeastern Wyoming, northwestern Kansas, and 

 south-central Arizona. The range does not include the extreme 

 southeastern United States. 



PEROMYSCUS GOSSYPINUS (LeConte) 

 Cotton Mouse 



Description. — The adult of the cotton mouse is dark reddish 

 brown on the upper parts and white on the under parts. An 

 immature may be gray or grayish brown on the upper parts. 

 The adult closely resembles the white-footed mouse but usually 

 can be distinguished from it by the longer body and hind feet and 

 the larger skull. 



Length measurements: head and body 4-4l4 inches (100-107 

 mm.); tail 3-3]/2 inches (78-88 mm.); over-all 7-7^ inches 

 (178-195 mm.) ; hind foot about 1 inch (23-26 mm.) ; ear from 

 notch ^ inch (15-16 mm.) in dry study skins. 



The skull is 28-30 mm. (about l]4, inches) long. The upper 

 molar tooth row is 3.6-4.0 mm. (about ]/8 inch) long. Dental 

 formula: I 1/1, C 0/0, Pm 0/0, M 3/3. 



Life History. — The cotton mouse lives in swamps and bot- 

 tomlands, and in forests adjacent to them, fig. 3. Apparently 

 it picks the driest spot beneath a fallen log or stump to place 

 its nest. 



Little is known about the cotton mouse in Illinois. Probably 

 its breeding habits are similar to those of the white-footed 

 mause. Both species may occupy the same swampy woodlands. 



It is not clear how the common name for this mouse was 

 derived; in southern states where it is abundant it usually is 

 found in areas not far removed from cotton fields. 



Signs. — Tracks and nests of the cotton mouse are like those 

 of the white-footed mouse. 



Distribution. — The cotton mouse is uncommon in Illinois and 

 is known in the state only in the southern tip south of the Ozark 

 Plateau and the Shawnee Hills. The subspecies in this state is 



