850 MONOGRAPHS OP Noi.Tli AMERICAN RODENTIA. 



between Pembina and the Rocky Mountains, shows a considerable range of 

 color variation, ll is, however, mainly individual, the variation occurring at 

 the same locality, covering nearly the whole range of variation presented by 

 the whole series. The differences consist mainly in the distinctness of the 

 mottling above and in the amount: of fulvous pervading the general colora- 

 tion. In No. 1 195G. from Frenchman's River, the general color above is gray, 

 the light spots being almost white; the sides, especially posteriorly, incline 

 to brownish; the lower surface is grayish-white, with a very slight but dis- 

 tinct tinge of fulvous. Another (No. 119G3), from the same locality, is still 

 whiter below, with a rather browner cast above, wholly unvaried by spotting. 

 Still anol her (No. 1 1 954), also from the same locality as the others, is decidedly 

 reddish-brown, more varied with dusky above, while otherwise not different 

 from the last. Others differ from these in being strongly fulvous beneath, 

 with a more yellowish cast above. These can all be nearly matched by others 

 from the Milk River series, collected some two hundred miles further west. 

 The specimens most strongly suffused with tawny are from the Two Forks of 

 Milk River and the Three Buttes, these averaging more fulvous than speci- 

 mens from further eastward. Nos. 11975 (Three Buttes), 11953 (Two Forks 

 of Milk River), and 11945 (Milk River at 49°) present a strong contrast with 

 the pale phase already described, the lower surface being quite bright rusty- 

 yellow. Between these extremes there is, however, almost every conceivable 



intermediate stage. 



Var. TOWNSENDI. 



TownsencPs Spermophile. 



Varietal chars. — Smaller than var. richardsoni, with larger ears and 

 much darker coloration. Length of head and body 6 75 to 8.50; of tail to 

 end of vertebras 2.10 to 3.50; to end of hairs 3.35 to 4.60. Above, finely 

 varied with yellowish-gray and black, with generally a slight wash of dark 

 reddish-brown along the middle of the back and very indistinctly mottled; 

 below, grayish-white, tinged more or less with brownish-yellow. Top of the 

 n >se, ears, outer side of the fore and bind limbs, and buttocks reddish-brown, 

 often in striking contrast with the general coloration ; tail mostly black above, 

 edged with yellowish-white. The hairs individually, especially the lateral 

 ones, are barred successively with black, the outer bar being very broad and 

 edged with yellowish- while. 



This variety is also represented by a large suite of specimens from aeon- 



