144 RODENTS OF IOWA 



Genus Tamias Illiger. 



Back conspicuously striped ; tail short, not bushy ; cheek pouches 

 large; postorbital processes slender, pointed, directed obliquely 

 backward and downward; infraorbital foramen oval, confined to 

 lower part of maxilla. 



Dental formula I, 1/1 ; Pm. 1/1. M. 3/3=20. 

 Key to Species of Tamias. 



Back with two whitish stripes, and five black ones; chestnut 

 rufous on rump; total length, about 9.60 inches. 



Chipmunk. 

 Tamias striatus striatus, p. 26 



Similar to above, but grayer and larger ; rump -cinnamon brown; 

 total length, about 10.25 inches. 



Gray Chipmunk. 

 Tarsias strMus griseus. p. 27 



Subfamily MARMOTIN/E. 

 Genus Citellus Oken. 



Body rather slender; tail variable in length, but not bushy; 

 ears variable, but not tufted; cheek pouches large; front feet 

 with four well developed toes, the thumb rudimentary; hind feet 

 with five toes; postorbital processes slender and spinelike; ante- 

 orbital foramen circular, a tubercle on lower outer edge; two 

 upper premolars, the first much smaller than the second. 



Dental formula I. 1/1; Pm. 2/1; M. 3/322. 

 Key to Species of Citellus. 



Color grayish brown, not striped; total length, about 15.00 

 inches. 



Franklin's Spermophile. 



Citellus franklini. p. 36 



Back with seven yellowish white lines, which alternate with 

 six rows of rounded, yellowish white spots in a brown background ; 

 total length, 10.50 inches. 



Thirteen-lined Spermophile. 

 Citellus tridecemlineatus tridecemlineatus. p. 29 



