-Arizona "I 
Exp. Sta. / 
LIFE HISTORY OF THE KANGAROO RAT. 
7 
dusty sand, they soon recover their normal sleek appearance. Ap- 
parently the former condition is due to an excess of oil, the latter 
to the absorption of the excess in a dust bath. The oil is doubtless 
an important adjunct to the preservation of the skin and hair am id 
the dusty surroundings in which the animal lives. 
MEASUREMENTS AND WEIGHTS. 
External measurements include: Total length, from tip of nose 
to tip of tail without hairs, measured before skinning; tail vt rtebra , 
length of tail from point in angle when tail is bent at right angles 
to body to tip of tail without hairs; and hmd foot, from heel to tip 
of longest claw. 
The following are measurements of a series from the U. S. Range 
Reserve : 
Averages for 17 adult females: Total length, 326.4 millimeters 
Total length, 326.2 millimeters (349-310) ; tail vertebrae, 188.4 (208- 
180) ; hind foot, 49.5 (51-47) ; the average weight of 29 adult speci- 
mens of both sexes was 114.5 grams (131.9-98.0). 
Averages for 17 adult females: Total length, 326.4 millimeters 
(349-310) ; tail vertebrae, 188.8 (208-179) ; weight (16 individuals), 
113.7 (131.9-98.0) ; excluding pregnant females, 13 individuals 
averaged 112.9 grams (131.9-98.0). 
Averages for 13 adult males : Total length, 326 millimeters (345- 
311) ; tail vertebrae, 187.8 (202-168) : weight, 116.8 grams (129-100). 
There appears to be no significant difference in the measurements 
and weights of males and females, with the possible exception of the 
comparison of adult males and adult nonpregnant females. 
OCCURRENCE. 
GENERAL DISTRIBUTION. 
Dipodomys spectabilis spectabilis is found in southeastern Ari- 
zona, in northwestern, central, and southern New Mexico, in ex- 
treme western Texas, in northern Sonora, and in northern and 
central Chihuahua (Fig. 1). A subspecies, D. s. cratodon Merriam, 
has been described from Chicalote, Aguas Calientes, Mexico, the 
geographic range of which lies in central Mexico in portions of the 
States of Zacatecas, San Luis Potosi, and Aguas Calientes. 
habitat. 
In the Tucson region spectabilis is typically a resident of the Lower 
Sonoran Zone. This is perhaps the principal zone inhabited over 
its entire range, but the animal is often found in the Upper Sonoran 
also, and in the Gallina Mountains of Xew Mexico Hollister found it 
