ioo FIELD MUSEUM OF NATURAL HISTORY ZOOLOGY, VOL. XL 



GROUP 2. Length of body, without tail, (nose to root of tail) more than 8 inches 

 but less than 14 inches long. 



SECTION 1. Back marked with several distinct stripes. Back striped and 

 spotted. STRIPED GROUND SQUIRREL, STRIPED GOPHER. 



Citellus tridecemlineatus , p 138. 



SECTION 2. Back not marked with several distinct stripes. 



PART 1. General color largely gray; under parts white or whitish. 



Hairs on tail broadly tipped with white; entire length, including tail 

 vertebrae, 16 to 18 inches; usually 5 cheek teeth on each side of upper 

 jaw (2 premolars and 3 molars); front premolar very small and not 

 always present; tail vertebrae always more than 6^4 inches long. 

 Occurs within our limits only in southern Illinois. 



SOUTHERN GRAY SQUIRREL. Sciurus carolinensis, p. 115. 



Similar to preceding but slightly larger; total length, including tail verte- 

 brae, 1 8 to 20 inches; tail vertebrae always more than 6}4 inches long; 

 back clear gray, without rusty tinge in winter; usually 5 cheek teeth 

 (2 premolars and 3 molars) on each side of upper jaw, but front pre- 

 molar very small and not always present. Occurs within our limits in 

 northern Illinois and throughout Wisconsin. 



NORTHERN GRAY SQUIRREL. 

 Sciurus carolinensis leucotis, p. 116. 



PART 2. General color not gray; under parts white or whitish. 



Upper parts and tail reddish brown; en tire length, including tail vertebrae, 

 between 12 and 14 inches. RED SQUIRREL. CHICKAREE. 



Sciurus hudsonicus loquax, p. 122. 



PART 3. General color not gray; under parts not white or whitish. 



General color more or less tawny or pale rufous ; only 4 cheek teeth on each 

 side of upper jaw (i premolar and 3 molars); hairs on tail broadly 

 tipped with rufous brown; nose to root of tail, n to 13 inches; tail 

 vertebrae, 9 to 10 inches; total length, about 21 to 23 inches. 



WESTERN Fox SQUIRREL. Sciurus niger rufiventer, p. 109. 



General color grayish brown; tail gray, marked with black, the hairs 

 tipped with white; nose to root of tail, 9^2 to 10 inches; tail vertebrae, 

 5 to 5> inches, always less than 6^2 inches long; total length 

 about 15 inches. Lives in holes in the ground. 



FRANKLIN'S GROUND SQUIRREL. GRAY GOPHER. 

 Citellus franklini, p. 144. 



General color black or partly black; total length, including tail vertebrae, 



less than 20 inches; usually 5 cheek teeth on each side of upper jaw 



(2 premolars and 3 molars), but front premolar very small and not 



always present. GRAY SQUIRREL (black phase). 



Sciurus carolinensis or Sciurus carolinensis leucotis, pp. 115-116. 



General color black or partly black; total length, including tail vertebrae, 

 20 or more inches; 4 cheek teeth on each side of upper jaw (i premolar 

 and 3 molars). WESTERN Fox SQUIRREL (black phase). 



Sciurus niger rufiventer, p. 109. 



