FEB., 1912. MAMMALS OF ILLINOIS AND WISCONSIN CORY. 43 



SECTION 1. Upper front teeth (incisors) 2. 



PART-1. Tail very broad and flat (paddle-shaped) and without hair; 

 hind toes broadly webbed; total length of adult 

 3 feet or more. 



Family CASTORID^E. Beavers, p. 158. 



PART 2. Body more or less covered with sharp, stiff quills; tail not 



flat and naked; total length of adult 

 2 feet or more. 



Family ERETHIZONTID^E. 

 American Porcupines, p. 253. 



PART 3. Tail not broad, flat and naked, and no sharp quills on body. 



A. Four or more developed grinding teeth (molars and premolars) on side 



of each jaw. 



ai. Tail thickly haired or bushy; cheek pouches (when present) open- 

 ing inside of mouth. 



Family SCIURIDiE. Squirrels, Woodchucks, etc., p. 98. 



