re being
conducted to ascertain the relation of rodents to forage. This is
typical of a large section of country occupied by _Dipodomys spectabilis
spectabilis_ and _Dipodomys merriami_. The brush is mesquite
(_Prosopis_), cat's-claw (_Acacia_), and paloverde (_Cercidium_).]

[Illustration: PLATE II. FIG. 2.--KANGAROO RAT COUNTRY FOLLOWING SUMMER
DROUGHT.

An area of the U. S. Range Reserve in the autumn of 1918, showing the
result of failure of summer rains. Such a condition is critical not only
for the stockmen but also for kangaroo rats and other desert rodents,
and results in competition between them as to which shall benefit by
what the range has to offer.]

[Illustration: PLATE III. FIG. 1.--KANGAROO RAT MOUND (DIPODOMYS S.
SPECTABILIS).

Typical _Dipodomys s. spectabilis_ mound on the Range Reserve, under
shelter of desert hackberry (_Celtis pallida_). Most dens on the reserve
are located in the shelter of brush plants, the more important being
mesquite (_Prosopis velutina_), cat's-claw (_Acacia_ spp.), and the
desert hackberry. (See also Pl. VIII Fig. 2.)]

[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 base