This rat is common in the Joshua tree and juniper belts, and locally penetrates the pinyon belt at about 5000 feet elevation. It occurs regularly along the entire desert slope of the San Gabriel Mountains. The upper limit of the range of this species roughly coincides with the upper limit of the juniper belt, and within this range it was found to inhabit areas having widely different soil types. It occurred on the sandy ground of desert washes, the gravelly soil of the juniper-clad benches, and the mixed sandy and rocky ground of washes in canyons. A preference is shown by _panamintinus_ for fairly level ground. Rough terrain or steep slopes are generally avoided, whereas rather large colonies of these kangaroo rats are found in small flats of the desert foothills. Below about 4500 elevation on the interior slope this species was the most numerous rodent, and seemed to reach maximum abundance in the Joshua tree association. About 500 trap-nights in the juniper belt near Graham Canyon yielded 31 specimens, whereas about 300 trap-nights in Joshua tree flats took 34 individuals. The cheek pouches of many specimens taken in early winter contained green shoots of grass and little dry material. On many occasions rat traps set next to wood rat nests beneath large junipers produced _panamintinus_, and many of these animals had their cheek pouches crammed full of juniper berries. In December, 1948, _panamintinus_ was trapped consistently on nights when the temperature dropped to below 20° F. On December 27, 1948, after a three inch snowfall, tracks of this species were noted in the snow at the mouth of Mescal Canyon. Parts of the skulls of this species were found in many coyote feces from the desert slope. _Specimens examined._--Total, 11, distributed as follows: Los Angeles County: Mescal Wash, 4000 ft., 8 (6 PC); 2 mi. E Valyermo, 4600 ft., 3. =Dipodomys merriami merriami= Mearns Merriam Kangaroo Rat This kangaroo rat barely enters the area under consideration and is almost restricted to the Joshua tree association, for only a few individuals were taken at the lower edge of the juniper benches. This species inhabits the Joshua tree belt all along the desert base of the San Gabriels. As mentioned in the description of the Joshua tree association, the relative numbers of _Dipodomys merriami_ and _D. panamintinus_ shifted from 1948 to 1951, possibly concurrent with the seasons of low rainfall in this period. Whereas in 1948 _merriami_ was decidedly less abundant than _panamintinus_ in the Joshua tree belt, in 1951 the numbers were reversed. In December, 1951, it was found by tending the traps in the early evening that _merriami_ foraged fairly early before the ground had frozen solidly. _Specimens examined._--Los Angeles County: 2 mi. NW mouth of Graham Canyon, 3500 ft., 5 (PC). =Dipodomys merriami parvus= Rhoads San Bernardino Kangaroo Rat