410 U. S. P. R. R. EXP. AND SURVEYS ZOOLOGY GENERAL REPORT. 



as the Platte, on one side of the Rocky Mountains, and to the Columbia river on the other ; 

 thence west to the Pacific. 



DIPODOMYS ORDII, Woodhouse. 



Kangaroo Rat. 



Dipodomys ordii, (WooDHotrsE,) LEC. Pr A. N. Sc. Phila. VI, Jan. 1853, 224. 



WOODHOCSE, Pr. A. N. Sc. Phila. VI, Jan. 1853, 235. IB. Sitgreaves' Report Expl. Zufii, 1853, 



50; pi. iv, Mammals. 



AUD. & BACH. N. Am. Quad. Ill, 1854, 317. 

 ? Dipodomys montanus, BAIRD, Pr. A. N. Sc. Phila. VII, April, 1855, 334. 



g p . CH. Above, yellowish brown, the back little darker. Tail about as long as the body, with an erect crest of long hairs 

 towards the end. A dusky stripe on the upper part of the tail to the tip, where, however, the hairs are white at the base, A 

 dark stripe beneath the tail, which runs out on the terminal fourth, leaving the rest white. The antitragus low. 



Varies in darker color, white tip to tail, &c. 



Head very broad and snout acute. Ears broad and large ; antitragus low, narrow. Whis 

 kers much longer than the head. Thumb with a short curved claw; the other claws very long ; 

 the third longest ; fourth scarcely shorter ; the second longer than the fifth ; palms smooth. 

 The rudimentary first toe provided with a short claw ; the third and fourth longest ; the second 

 a little shorter ; the claw of the fifth not reaching to that of the fourth ; all the claws nearly 

 straight and shorter than those on the fore feet. The under surface of hind feet, from heel to 

 claws, is densely furred, so as to conceal the skin, even on the toes. Tail vertebrae about equal 

 to the head and body, or about one-fourth longer, and unusually thick. The hairs of the tail 

 somewhat close pressed towards the base, but elongating gradually to the tip on the upper 

 surface ; not materially so on the lower ; this lengthening beginning at about the middle of the 

 tail, and the hairs standing up like a compressed crest. 



The prevailing color of the upper parts and sides is of a clear light yellowish brown, with a 

 little intermixture of dark grayish on the back. This is owing in great part to the effect of the 

 lead colored bases of the hairs, the bases of those on the sides being white. The tip and sides 

 of the snout, a patch above the orbit and behind the ears, the entire under parts, lower half of 

 the sides, and the limbs, have the hairs snowy white to the base, except a distinct line down the 

 centre of the soles, which is of a grayish lead color. There is also a white line across the thighs 

 to the base of the tail. The space above, occupied by the yellowish brown described, has the 

 hairs bright metallic lead color at the base, except on the middle of the sides, where they are 

 white. 



The tail is white, with a broad distinct stripe of grayish lead color above, which extends from 

 near the base to the tip. The hairs, however, are white at the base, except sometimes towards the 

 more brush-like tip, where they are uniform in color. On the lower side of the tail is a corres 

 ponding strip extending over nearly two-thirds of the total length, when it runs out to a point 

 and disappears ; the sides of the tail between these stripes is pure white, and the terminal third 

 also, except on the upper side and extreme tip for about half an inch. 



There is not much variation with different specimens of this species ; in one or two (533) the 

 dark band beneath the tail extends further alon towards the tip. 



In the preceding paragraph I have described a typical specimen of Dipodomys ordii, agreeing 

 very well with the animal of Woodhouse. Finding an^ng Captain Beckwith's collections a 

 large Dipodomys, differing materially in certain respects, I detT orited it; as new > under the name 



