242 MONOGRAPHS OF NORTH AMERICAN RODENTIA. 



decidedly rusty-chestnut, sometimes more rusty-orange or tawny; on the 

 head darker, tending to an intimate mixture of blackish and yellowish-brown; 

 under parts a paler but si ill strong orange rust color or tawny, brightest across 

 the belly, more dilute and whity-brown on the chin, throat, and pubes; color 

 of the back lightening insensibly into that of the belly; no stripes, spots, or 

 areas of different colors anywhere; no evident mixture even of single black 

 hairs anywhere; the coloration everywhere only on the ends of the hairs, the 

 basal portions being uniformly dark plumbeous. Feet always fuscous-brown; 

 tail dusky above, obscurely whitish below; incisors whitish or very pale yel- 

 lowish, never deep yellow or red ; whiskers both light and dark. 



Our numerous specimens, though taken at various seasons, are remark- 

 ably uniform in color; the variation is less than we should have anticipated. 

 We observe no sign of the species becoming white in winter, or of its 

 changing pelage in any way with age, sex, or season. All the differences 

 we note are in intensity of the coloration. In the most richly-colored skins, 

 the back is an intense orange-chestnut, the belly a bright rusty-orange; 

 in the palest, the upper parts are about of this latter color, the under of a 

 lighter fulvous. There is no variegation or particoloration anywhere about 

 the animal, but toward and on the head the bright color subsides into a grizzle 

 of dusky and yellowish-brown. The uniformly fuscous feet with short hairs 

 are a strong character, compared with the hoary-white feet of Cunicuhts 

 torquatus, where the longest hairs sometimes reach half an inch beyond 

 the claws. 



The American animal, as represented in our series, differs notably in 

 color from two Siberian skins, the only ones we have before us. In these, 

 the under parts are nearly white (soiled ochrey-white) below, instead of 

 intense tawny; while the upper parts are far from uniform orange-rusty, in 

 having a decided black median lengthwise stripe from the forehead over the 

 crown and nape, while here and there on the back and rump quite black 

 areas appear. The feet are broader, heavier, and more densely furry, nearly 

 white. If these differences be constant, we may readily recognize the 

 American animal as at least a variety, to be called Myodes helvolus. But 

 with only two specimens before us that may not represent average Siberian 

 skins, and certainly cannot show the variations there occurring, we are far 

 from desiring to contest von Middendorff's mature decision. 



The following table gives the measurements of our fine suite of skins, 



