[Illustration:  PLATE III.  FIG. 2.—­KANGAROO RAT MOUND (DIPODOMYS DESERTI).

Den of Dipodomys deserti deserti, showing typical wide, low mound with numerous entrance holes.  This species excavates its den in soft, sandy soil.  The tree is a species of Dalea.]

DESCRIPTION.

GENERAL CHARACTERS.

Size large; ears moderate, ear from crown (taken in dry skin) 9 or 10 millimeters; eyes prominent; whiskers long and sensitive; fore feet short and weak; hind feet long and powerful, provided with four well-developed toes; tail very long, usually 30 to 40 per cent longer than the body.  Cranium triangular, the occiput forming the base and the point of the nose the apex of the triangle, much flattened, auditory and particularly mastoid bullae conspicuously inflated.

COLOR.

General color above, brownish buffy, varying in some specimens to lighter buffy tints, grizzled with black; oblique hip stripes white; tail with dark-brown or blackish stripes above and below, running into blackish about halfway between base and tip, and with two lateral side stripes of white to a point about halfway back; tail tipped with pure white for about 40 millimeters (Pl.  I).  Underparts white, hairs white to bases, with some plumbeous and buffy hairs about base of tail; fore legs and fore feet white all around; hind legs like back, brown above, hairs with gray bases, becoming blackish (fuscous-black or chaetura-black) about ankles, hairs on under side white to bases; hind feet white above, dark-brown or blackish (near fuscous) below.

Color variations in a series of 12 specimens from the type locality and points widely scattered through the range of spectabilis consist in minor modifications of the degree of coloration, length of white tip of tail, and length of white lateral tail stripes.  In general the color pattern and characters are remarkably uniform.  Young specimens, while exhibiting the color pattern and general color of adults, are conspicuously less brown, and more grayish.

There appears to be little variation in color with season.  In the series at hand, most specimens taken during the fall, winter, and spring are very slightly browner than those of summer, suggesting that the fresh pelage following the fall molt is a little brighter than is the pelage after being worn all winter and into the following summer.  But at most the difference is slight.

OIL GLAND.