Citellus spilosoma (Bennett) Spotted Sand Squirrel 

 Tail included about four times in total length; northwestern U. S. 



Citellus washingtoni Howell Washington Ground Squirrel 



48. Tail included about three times in total length 49. 

 Tail included about four times in total length 51. 



49. Back uniformly colored, e.xcept for the white tips to the hairs; adults 



about ten inches in total length; hair coarse and stiff; Ariz, to Cal. 

 CiteUiis tereticaudiis (Baird) Round-tailed Ground Squirrel 

 Back grizzled or dark spotted; adults about fourteen to fifteen inches in 

 total length 50. 



50. Limbs rusty-yellow; tail included slightly more than three times in total 



length; northwestern U. S. 



Citellus columbidnus (Ord) Columbian Ground Squirrel 

 Limbs grayish; tail included slightly less than three times in total length; 

 northern plains area; introduced into N. J. 



Citellus fran\linii (Sabine) Franklin's Ground Squirrel 



5L Upper parts grayish; hair very soft; Wash, to Nev. and Utah 



Citellus toiimsendu (Bachman) Townscnd's Ground Squirrel 

 (Includes C. mollis (Kennicott) ) 

 Upper parts brownish 52. 



52. Tail yellowish beneath; Mont, to Wyo. and Nevada 



Citellus richardsonn (Sabine) Richardson's Ground Squirrel, 

 Flickertail 

 Tail reddish beneath; Great Basin, Oregon and Idaho to Nev. and Cal. 

 Citellus heldingi (Merriam) Belding's Ground Squirrel 



53. Hairs on sides of tail not much longer than those above or below; back 



often blotched or dappled; not living in trees; southwestern U. S. and 

 Pacific states (Subgenus Otospermophilus) Rock Squirrels 54. 



Hairs much longer on sides of tail than above or below; back evenly col- 

 ored; arboreal; generally distributed 55. 



54. With a central dark patch on the neck and shoulders; Pacific states 



Citellus heecheyi (Richardson) California Rock Squirrel 

 Not so; Colo, to Texas and Cal. 



Citellus variegatus grammurus (Say) Arizona Rock Squirrel 



55. With four grinding teeth in each side of upper jaw; color variable, but 



usually rusty to blackish; hairs of tail tipped with yellow, not white; 



total length of adult twenty to twenty-seven inches Fox Squirrels 56. 



With five grinders in each side of upper jaw, the first quite small or 



sometimes absent; reddish or gray; large or small 57. 



56. With several color phases, even in the same subspecies, from pale gray, 



through rusty-red (the most common phase) to black; eastern and 

 central states 



Sciurus niger Linn. Fox Squirrel 

 Color mixed black and white, often appearing gray; with yellowish- 

 brown dorsal stripe evident in winter but indistinct in summer pelage; 

 Ariz, and N. M. 



Saurus arizonensis Coues Arizona Gray Squirrel 



509 



