X 
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, (Woodhouse,) Lec. Pr A. N. Sc. Phila. VI, Jan. 1853, 224. 
Woodhouse, 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. 
Sp. 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 vertebras 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, hut 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 along 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 among Captain Beckwith’s collections a 
large Dipodomys , differing materially in certain respects, I described it as new, under the name 
