38. Upper parts with many dark and light stripes, each dark stripe with a 



central row of light spots; central states 



Citellus tndecemlineatus (Mitchill) Thirteen-striped Ground 

 Squirrel 

 With one light stripe on each side, with or without darker stripes above 

 or below it 39. 



39. Upper incisors slender and almost straight; crown, sides of neck and 



shoulders chestnut, contrasting with the rest of the dark upper parts 



Subgenus Callospermophilus Merriam 40. 



Upper incisors heavy and recurved; no light mantle Subgenus AmmO' 



spermophilus Merriam 41. 



40. With a well developed dark stripe above the white stripe; Oregon and 



Cal. 



Citellus chrysodeirus (Merriam) Golden Mantled Ground 

 Squirrel 



(Now considered to be a subspecies of the following) 

 Dark stripe above the light stripe poorly developed or absent; Rocky 

 Mountain and Pacific states 



Citellus lateralis (Say) Say's Mantled Ground Squirrel 



41. Tail grayish or mixed black and white below; southwestern states 



Citellus harrisii (Audubon 6? Bachman) 

 Gray-tailed Antelope Ground Squirrel 

 Tail white below 42. 



42. Hairs of tail with one black band; southwestern states to Idaho and 



Oregon 



Citellus leucurus (Merriam) White-tailed Antelope Ground 

 Squirrel 

 Hairs of tail with two black bands; in southern California 



Citellus nelsoni (Merriam) Nelson's Antelope Ground 

 Squirrel 



43. Front and hind legs on each side joined together by a wide fold of skin 



extending from the side of the body Flying Squirrels 44. 



Not so 45. 



44. Under parts white to roots of hairs; total length usually less than ten 



inches; eastern and central states 



Glaucomys volans (Linn.) Eastern Flying Squirrel 

 Under parts with hairs dark at base; usually larger; northern and western 

 states 



Glaucomys sahrinus (Shaw) Northern or Western Flying 

 Squirrel 



(Many subspecies) 



45. Length of tail (not including hair) about one-third of total length; 



tail not bushy 46. 



Tail almost or about one-half total length; tail bushy 53. 



46. Back with light spots or blotches 47. 

 Not so 48. 



47. Tail included about three times in total length; Mexican border north- 



ward to Neb. 



508 



I 



