lay.

[Illustration: PLATE V. FIG. 1.--CLEARING ABOUT A MOUND.

A typical clearing about a mound of _Dipodomys s. spectabilis_, showing
the autumnal denudation of the mound and surrounding areas. In this
instance about 30 feet in diameter.]

[Illustration: PLATE V. FIG. 2.--MOUND AND RUNWAYS.

A small mound of _Dipodomys s. spectabilis_ in early autumn, showing
runways radiating from the den. Evidences of activity may be noted in
and about the surface of the mound.]

[Illustration: PLATE VI. FIG. 1.--RUNWAY OF DIPODOMYS S. SPECTABILIS.

Well-traveled path leading from the main den, in the foreground, to a
subsidiary burrow (see Fig. 2, below), about 30 feet distant, at
apparent end of runway.]

[Illustration: PLATE VI. FIG. 2.--SUBSIDIARY BURROW OF DIPODOMYS S.
SPECTABILIS.

Located at the end of the 30-foot runway shown in Figure 1, above. This
has three openings, two in the foreground and the third a little to the
rear and indicated by an arrow.]

SIGNALS.

If a scratching or tapping sound be made at the mouth of a burrow, even
in the daytime, one is likely to hear a muffled tapping in response, and
this may at times be heard while one is engaged in excavating a mound.
It has a chirring or fluttering quality, described by Fisher as
resembling the noise of a quail flying. Bailey (1905, 148) is of the
opinion that it is used as a signal of alarm, call note, or challenge, a
view which the present authors believe to be correct. During the winter
of 1920-21, however, both Bailey and Vorhies discovered that this sound,
or a very similar one, is made by the rapid action of the forefeet in
digging. On one occasion in the laboratory the sound was given by one of
a pair and was responded to at once by the other, the two being in
separate but contiguous cages. This observation, however, could not be
repeated. (Vorhies MS.)

One evening, while working in the vicinity of the Burro Mountains, N.
Mex., Goldman heard a kangaroo rat near camp making this thumping noise.
Taking a lantern, he approached the den, very cautiously, until within
10 feet. The kangaroo rat was just outside the entrance of one of its
burrows, and though moving about more or less restlessly at first showed
little fear, and kept up the thumping or drumming at intervals. When
making the noise the animal was standing with the forefeet on the ground
and the tail lying extended. The noise seemed to be made with the hind
feet only, and the vibrati