RODENTIA MURINAE HESPEROMYS LEUCOGASTER. 



481 



anterior of these are larger, the posterior smaller in proportion than usual, the fore feet are 

 very strong, and appear quite fossorial. The fore arm is as long or even longer than the 

 hind foot from the heel, instead, as in H. leucopus, of being appreciably shorter. The fore feet 

 are not appreciably different from those of H. leucopus, except that they are much larger, the 

 toes longer, and the claws fully twice the length of the hinder ones ; the tubercles are similar. 

 The hind feet are short in proportion to the anterior ; the first claw does not reach beyond 

 the base of the adjacent toe ; there are but four tubercles, as far as I can ascertain, the two 

 posterior in Hesperomys leucopus not being represented at all. The sole is very densely hairy 

 from the heel to these tubercles, or for nearly two-thirds the length of the foot ; this hairiness 

 more extended and much more dense than in H. leucopus, the tubercles themselves appear quite 

 similar in size. 



The tail is short, about twice the length of the hind feet, and contained two and a half times 

 in the head and body. It is thick at base, quadrate, and tapers rapidly to an attenuated tip ; 

 it is very closely covered with shortish hairs, pressed flat to the surface. 



The fur is rather long and full ; it is, however, soft and fine like that of H. leucopus, or even 

 finer, and without any of the rough appearance of Arvicola and Sigmodon. The general color 

 of this species above is a grayish brown, finely lined with black ; this color predominating on 

 the back. Towards the sides there is an infusion first of reddish and then of yellowish brown, 

 until finally, on the lower part of the sides, is seen quite a distinct band of fulvous, The entire 

 under parts, the feet, and outside of the fore leg, with the lower half of the tail, are white, in 

 the alcoholic specimen, with a yellowish tinge. 



In the following table I give the measurements of some parts of this animal, (from a specimen 

 in alcohol, 2549,) compared with a large H. leucopus, (2732,) to illustrate the differences in 

 proportion : 



To show the peculiar proportions of this mouse, I need scarcely do more than to refer to the 

 preceding table. 



In external appearance this mouse bears quite a close resemblance to an Arvicola, so much 

 so, indeed, as to have been described by Prince Maximilian, several years before Audubon and 

 Bachman, as Hypudaeus leucogaster. His specimen was taken at the Mandan village, where it 

 61 L 



