FEB., 1912. MAMMALS OF ILLINOIS AND WISCONSIN CORY. 99 



habits, varying from the arboreal and semi-aerial little Flying Squirrel 

 to the terrestrial and burrowing Woodchuck or "Groundhog." In 

 all the species the lower leg bones are separate and the skull shows 

 well marked post -orbital processes. The tail is always more or less 

 bushy (never bare or scaly). Generally there are two premolars on 

 each side of the upper jaw, but the first is always small and often absent. 

 The molars are tuberculate and rooted. Some species hibernate in 

 this latitude and some do not. Squirrels' hair is used in the manu- 

 facture of the so-called "Camel's hair" brushes. 



KEY TO THE GENERA 

 IN ILLINOIS AND WISCONSIN. 



GROUP 1. Length of body, without tail, (nose to root of tail) more than 14 inches; 



tail less than % total length of body and tail. Genus MARMOTA, p. 150. 



GROUP 2. Length of body, without tail, less than 14 inches; tail X. or more, total 



length of body and tail. 

 SECTION 1. Back with several distinct stripes. 



Back with four pale stripes and several black ones; no rows of round pale 



spots. Genus EUTAMIAS, p. 135. 



Back with two pale stripes and several black ones; no rows of round pale 



spots. Genus TAMIAS, p. 128. 



Back with rows of pale, rounded spots down middle of each dark stripe. 



Genus CITELLUS, p. 137. 

 SECTION 2. Back without several distinct stripes; front and hind legs not 



joined together by a thickly furred expansion of loose skin. 

 PART 1. General color largely gray or grayish. 



Hairs distinctly vermiculated with black; tail vertebrae always less than 



6 l /2 inches long. Genus CITELLUS, p. 137. 



Hairs not distinctly vermiculated with black; tail vertebrae more than 



6^ inches long. Genus SCIURUS, p. 108. 



PART 2. General color largely red brown, tawny or yellowish. 



Genus SCIURUS, p. 108. 



SECTION 3. Back without distinct stripes; front and hind legs joined together 

 by an expansion of loose skin extending laterally from side of body. 



Genus SCIUROPTERUS, p. 102. 



KEY TO THE SPECIES. 



GROUP 1. Length of body, without tail, (nose to root of tail) more than 14 inches 



long. 



General color grizzly brown; feet brownish black; about size of Domestic Cat 

 or larger. Occurs in Illinois and Wisconsin. 



WOODCHUCK, GROUND HOG. Marmota monax, p. 150. 



Similar but smaller, and under parts more rusty brown. Occurs in extreme 

 northern Wisconsin. CANADA WOODCHUCK. 



Marmota monax canadensis, p. 157. 



