n, therefore, we
feel that the kangaroo rat should be let alone, unless its presence
threatens infestation of valuable agricultural or grazing lands.

SUMMARY.

(1) Kangaroo rats may be separated with ease from all other mammals; the
long tail and short and weak fore feet separate them from the pocket
gophers; the white hip-stripe distinguishes them from the pocket mice.
The decidedly larger size and the white-tipped tail separate _Dipodomys
spectabilis spectabilis_ and _D. deserti_ from _D._ _merriami_ and _D.
ordii_. The darker color and vividly contrasted black-and-white tail of
_spectabilis_ distinguish it from _deserti_.

(2) _Dipodomys s. spectabilis_ occurs in the open arid country of
portions of the Lower and Upper Sonoran Zones of Arizona, New Mexico,
Texas, Sonora, and Chihuahua. It lives in harder soil than does
_deserti_, and builds more conspicuous mounds.

(3) There is no evidence of intergradation or hybridization between
_spectabilis_ and _deserti_.

(4) _Dipodomys s. spectabilis_ is nocturnal; it is gentle, and does not
offer to bite when taken in the hand; is silent for the most part;
active; somewhat sociable with its fellows, but fights in defense of its
food stores; progresses chiefly by leaping; signals by a drumming or
tapping on the ground with its hind feet.

(5) The breeding season of _spectabilis_ begins in January and continues
into August. Whether more than one litter is raised in a single season
is unknown. The number of young in each litter varies from 1 to 3,
averaging 2.

(6) _Dipodomys s. spectabilis_ does not hibernate, but provides food
stores, mostly seeds, for use during seasons when food would be
otherwise unavailable. Storage in each den varies in quantity from 5
grams (about 1/6 ounce) to 5,750 grams (12.67 pounds). Materials stored
include several important forage plants; for example, various species of
_Bouteloua_ and _Aristida_, with _B. rothrockii_ (crowfoot grama) the
most important. Accessibility and abundance of different plants have
much to do with the kinds of storage found.

(7) The dens of _spectabilis_ are the most notable of all kangaroo rat
dwelling places. They range from 6 inches to 4 feet in vertical height,
and from 5 to 15 feet in diameter. Here the kangaroo rat has its home,
shelter, and food-storage chambers. Within the den is found a tortuous
network of burrows, with many storage and some nest chambers, the whole
arranged so as to be two to