140 CITELLUS. 
Body rather slender; tail either long, moderate, or short, varying 
greatly in its length among the different species; ears large to rudi- 
mentary, not tufted; cheek pouches large; skull variable, short and 
broad like Scturus, or long and narrow; postorbita] processes strong, 
with a downward direction; antorbital foramen circular, with a well- 
developed tubercle on outer lower border. 
KEY TO THE SUBGENERA. 
A. Coronoid process of mandible broad and heavy. 
a. Nasals equal in length to the premaxille 
salon (FRSA SNS es ih bak ath Say hace he Satna cated Be Ammos permo philus 
b. Nasals not so long as the premaxille. ...\erospermophilus 
B. Coronoid process of mandible long and slender. 
a. Nasals longer than the premaxille. 
Be) PAIIOROD ES, - TUB ye ckstateneehin aate< testes Callos permo philus 
b.’ sDaillong anime busiit. Sit, ora. coc Otospermo plhilus 
KEY TO THE SPECIES AND SUBSPECIES: 
A. Size small; tail short, narrow. 
a. Upper parts not spotted. 
a.’ Tail beneath white on central portion, 
a.” Above grizzled grayish brown and vina- 
CROWS Ait ce de ake Ween ene eat pta oo. Ghar 
b.’’ Above pale yellowish brown and white. C. h. saxicola 
c.” Above grizzled orev. Wk wee a ... C, leucurus 
Go A bOVe ITGR Ona, Ae earns ee sees C. Ll. peninsulke 
e.” Above grizzled gray and vinaceous ....C. interpres 
b.’ Tail not white beneath. 
a.’ Above grizzled gray and _ yellowish 
Dro wits si. orate Can ase eee Nile a eee C. tereticaudus 
b.” Above ‘tawn, colori eure a C. t. sonortensts 
c.”’ Above grizzled yellowish brown and 
hE Nol Se ee eo te ere id een C. perotensts 
b. Upper parts spotted. 
a.’ Above reddish-browm..3 7 seen an tie C. spilosoma 
b.’ Above russet brown, white spots bordered 
with: dusky.c::<.% iy Gate .. .C..s, microspilotus 
ce.’ Above dark reddish or yellowish brown. . ..C. mextcanus 
d.’ Above pale reddish brown............ C. m. parvidens 
B. Size large, tail long, bushy. 
a. Tail not over one-fourth total length....... C. madrensis 
b. Tail less than half total length. 
a.’ Tail not annulated. 
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