portion of the tail, the conspicuous white side stripes, and the pure
white tip make the tail of _spectabilis_ stand in rather vivid contrast
to the pale-brown and whitish tail of _deserti_.

The dens of the two larger species of _Dipodomys_--_spectabilis_ and
_deserti_--can be distinguished at a glance from those of the two
smaller--_merriami_ and _ordii_--by the fact that the mounds of the
former are usually of considerable size and the burrow mouths are of
greater diameter. On the Range Reserve _merriami_ erects no mounds, but
excavates its burrows in the open or at the base of _Prosopis_,
_Lycium_, or other brush. The mounds of _spectabilis_ are higher than
those of _deserti_, the entrances are larger, and they are located in
harder soil (Pl. III, Fig. 1). The dens of _deserti_ are usually more
extensive in surface area than those of _spectabilis_, and have a
greater number of openings (Pl. III, Fig. 2).


[Illustration: PLATE II. FIG. 1.--WINTER VIEW OF AREA INHABITED BY
KANGAROO RATS.

A water-hole scene on the U. S. Range Reserve at the base of the Santa
Rita Mountains, Ariz., where cooperative investigations are 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.