8 BULLETIN 1091, U. S. DEPARTMENT OF AGRICULTURE. { BuR 1 No^l, 
invading the yellow pine Transition where the soil was dry and sanely 
and the pine woods of open character. The same observer found it 
common in grassy and weed-grown parks among the large junipers, 
pinyons, and scattering yellow pines of the Bear Spring Mountains. 
N. Mex. Bailey calls attention to the fact that the animal apparently 
does not inhabit the lower half of the Lower Sonoran Zone, as it ex- 
tends neither into the Rio Grande Valley of Texas nor the Gila 
Valley of Arizona. In extreme western Texas it is common at the 
upper edge of the arid Lower Sonoran Zone, and in this region does 
not enter the Upper Sonoran to any extent. 
In July* 1914, Goldman found this kangaroo rat common on the 
plain at 4.600 feet altitude, near Bonita, Graham County, Ariz., and 
noted a few as high as 5,000 feet altitude on the warm southwestern 
slopes of the Graham Mountains, near Fort Grant. Apparently 
spectabilis reaches its upper altitude limit in the Burro Mountains. 
N. Mex., where Bailey has found it sparingly on warm slopes up to 
5,700 feet, and at the western base of the Sandia Mountains, east of 
Albuquerque. X. Mex.. where dens occur at approximately 6,000 
feet. 
About Tucson it is undoubtedly more common in the somewhat 
higher portions of the Lower Sonoran Zone, above the Covillea asso- 
ciation, than elsewhere (PI. IV. Figs. 1 and 2). A few scattered 
dens are to be seen in the Covillea belt, but as one rises to altitudes 
of 3,500 to 4,000 feet, and the Covillea is replaced by the cat's-claws 
(Acacia sp. and Mimosa sp.) and scattered mesquite (Prosopis) . with 
the Opuntia becoming less abundant, kangaroo rat mounds come more 
and more in evidence. Here is to be found the principal grass growth 
supporting the grazing industry, and the presence of a more luxuriant 
grass flora is probably an important factor in the greater abundance 
of kangaroo rats, both spectabilis and meniami. In this generally 
preferred environment the desert hackberry (Celtis pallida) is one of 
the most conspicuous shrubs; clumps of this species are commonly 
accompanied by kangaroo rat mounds. 
In order to ascertain whether the banner-tailed kangaroo rat has 
any marked preference for building its mounds under ( 'eltis or some 
other particular plant, all the observable mounds were counted in a 
strip about 20 rods wide and approximately 4 miles long, an area 
of approximately 160 acres, particular note being taken of the kind 
of shrub under which each mound was located. Of 300 mounds in 
this area, 96 were under Prosopis, 95 under Acaeia, 65 under Celtis, 
11 under Lycium, 31 in the open, 1 about a " cholla " cactus (O punt ia 
spinosior) , and 1 about a prickly pear (Opuntia sp.). There is ap- 
parently no strong^ marked preference for any single species of 
plant. While both desert hackberry and the cat's-claws afford n better 
