8 
ZOOLOGY. 
white along the edges and at the tip, with a subterminal margin of black; the hairs at the tip are white to the base, with a 
narrow central bar of black. The black bar sometimes wanting. 
A specimen of this new species was collected in the Cochetope Pass. (No. 22.) 
GEOMYS CASTANOPS, Leconte.—Chestnut-faced Gopher. 
Plate X, Fig. 2. 
Pscudostoma castanops, Baird, in Hep. Stansbury’s Exped. G. S. Lake, June, 1852, 313. (Bent’s Fort.) 
Aud. and Bach. N. Am. Quad. Ill, 1854, 304. 
Gcomys castanops, Leconte, Pr. A. N. Sc. Phil. VI, Sept., 1852, 163. 
Baird, Gen. Eep. Mammals, 1857, 384. 
Sp. Ch. —Upper incisor with a single deep groove bisecting the surface, the portions on either side similar. Fore feet shorter 
than the hinder. Second claw extending as far as the fourth. Cheek pouches small. Color, pale brownish yellow; the fore 
part of head and sides of neck yellowish chestnut, sharply defined. Pouches whitish. 
This sjtecies was found near Bent’s Fort. 
THOMOMYS RUFESCENS, Maxim.—Fort Union Gopher. 
Plate X, Fig. 1. 
Thomomys rufescens, Pr. Maximilian, Nova Acta Acad. C. L. C. XIX, i, 1839, 383. 
Baird, Pr. A. N. Sc. Phila. VII, April, 1855, 335.— Ib. Gen. Rep. Mammals, 1857, 397. 
Sp, Ch. —Cheek pouches rather small; densely furred. Tail nearly half as long as the body; thick at base. Upper incisors 
very large ; the groove very shallow and obsolete. Feet very stout and broad. Claws of hand stout; not very long; much 
curved. Third claw 4 lines long above; beneath, occupying barely two-sixths of the total length; the claw of the thumb 
reaching over two-fifths the hand. 
Color. —Above, ashy or grayish yellow brown; sides similar. Beneath, with the pouches and surrounding area, yellowish 
white. Tail whitish ; dusky above at the base. 
This species is found on the upper Missouri, as far as Fort Union. 
DIPODOMYS ORDII, Woodhouse.—Kangaroo Rat. 
Dipodomys ordii, Baird, Gen. Rep. Mammals, 1857, 410. 
Dipodomys montanus, Baird, Pr. A. N. Sc. VII, Ap. 1855, 334. 
A Dipodomys was collected near Fort Massachusetts, which was at first supposed to be distinct 
from D. ordii and characterized as D. montanus. Subsequent investigations seemed to render 
it probable that the variation from the typical characters is not of specific value. Another 
specimen from the Huerfano river is more like the typical D. ordii. 
PEROGNATI1US FLAVUS, Baird. 
Perognuthus jlavus, Baird, Pr. A. N. Sc. Phila. VII, April, 1855, 332. 
Baird, Gen. Rep. Mammals, 1857, 423. 
Sp. Ch. —Considerably less than the common mouse. Tail equal to or less than the head and body, scarcely different in color 
above and below. Hind feet short. Above, yellowish buff, with dusky tips to some of the hairs; clearer on the sides. Beneath, 
snowy white to the roots of the hairs. Fore leg white to the shoulders. Hairs on the back plumbeous only on their basal half. 
Two specimens of this species were collected on Grand White river, near Little Salt Lake, 
Utah. (6.) 
JACULUS HUDSONIUS.—Jumping Mouse. 
Dpus hudscmius, Zimmermann, Geographische Geschichte, II, 1780, 358, (based on Pennant’s long-legged mouse.) 
Merioncs hudscmius, Aud. & Bach. N. Am. Quad. II, 1851, 251; pi. lxxxv. 
Jaculus hudsonius, Baird, Gen. Rep. Mammals, 1857, 430. 
