Family CRICETIDAE 179 



lands and orchards. These burrows may be just beneath a thick 

 carpet of leaves or deeper in the soil. They vary in diameter 

 from somewhat less than \]/z inches to as much as 2 inches. 

 Some of them may surface beneath well-rotted logs. In orchards 

 they may lead to fallen apples, on which the vole may feed from 

 beneath. Pine vole burrows are often appropriated by shrews. 

 Distribution. — The pine vole is state-wide but sporadic in 

 occurrence and usually uncommon. There are two subspecies 

 in Illinois, Pitymys pinetorum auricularis (Bailey) in the south- 

 ern third of the state and P. p. scalopsoides (Audubon & Bach- 

 man) elsewhere. The species occurs from Massachusetts and 

 Vermont to central Wisconsin and south to central "Texas and 

 northern Florida. 



ONDATRA ZIBETHICUS (Linnaeus) 

 Muskrat 



Description. — The muskrat, fig. 98, is a large vole, nearly 

 the size of a cottontail rabbit, that is adapted to a life in and 

 near water. Its body is a dark or chocolate brown, darkest on 

 the back where long glistening guard hairs are thickest. The 

 eyes and ears are small. The hind feet are large and webbed. 

 The blackish, nearly naked tail is laterally flattened, long, and 

 scaly. 



Length measurements: head and body 11-12^4 inches (280- 

 325 mm.) ; tail 8j4-lG>4 inches (210-275 mm.) ; over-all 19i. r 

 2Si _> inches (490-600 mm.); hind foot 2^-3^ inches (73-85 

 mm.). Weight: about 2\A pounds. 



The skull is more than bO mm. (2> x inches) long; the grind- 

 ing or cheek teeth, fig. 40r, are long and flat surfaced, each con- 

 sisting of a series of upright prisms or columns; the incisors are 

 not grooved. Dental formula: II 1, C 0/0, Pm 0/0, M ?>/i. 



Life History. — The muskrat lives along or in the many 

 rivers, streams, drainage ditches, marshes, lakes, ponds, and 

 water-filled strip mine areas of Illinois. Usable habitat for the 

 muskrat has been increased by construction of drainage ditches 

 and strip mine areas and by protection of stream and ditch- 

 banks from overgrazing and erosion. 



The muskrat is at home in water, on land, and below the sur- 

 face of the ground. Muskrats that live in marshes, ponds, and 

 strip mine areas usually build houses, figs. 3 and 11. some for 



