618 



MONOORArnS OF NORTH AMERICAN RODENTIA. 



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of tlie upprr parts, and piiif, being not mi.xed with any dusky, and the color 

 extending to tiie roots of" the linirs. The entire nn<ler parts, including tiie 

 whole fore leg, the hind (bet, and inner side of hind leg, are snowy white, 

 tin hairs having no basal color. The tail is obscurely bicolor, white below, 

 and liot very sharply colored above to correspond with the areas of the body. 



Very young specimens, though nearly full grown and showing a sharp 

 lateral streak, are more simply colored above than the adults, being grayish, 

 with extremely faint buffy lining, instead of sharply blackish and buif. There 

 is also ol)servable, in the series before me, a tendency to exhibit two differ- 

 eit tones of coloration. Those from dry regions east of the mountains are 

 mixed grayish-brown and gruyish-buff, with the lateral pale buff stripe not 

 very conspicuous. In New Mexico, Southern Texas, and southward, the ani- 

 mal frequently assumes a ruddier shade oi the light color, mixed with much 

 less blackish ; in these, the lateral stripe is quite indistinct, because the upper 

 parts in general arc not very different. But the distinctions in these cases 

 are not strong enough to require anything further than this notice of the fact 



The following table of measurements will illustrate the size and shape 

 of the species very fairly, and to some extent expose the range of varirtion : — 





