In Mescal Wash on the desert slope of the San Gabriels, this mouse was
one of the most abundant mammals and was the only rodent other than
_Peromyscus maniculatus_ regularly trapped in the barren channels of
washes. In Mescal Wash, at an altitude of 4000 feet, _eremicus_ occurred
along with the chaparral-inhabiting _Peromyscus boylii_ and _Peromyscus
californicus_. The two species last mentioned were associated with the
occasional large patches of manzanita, antelope brush, and other brush
of the wash, whereas _eremicus_ was trapped in the rocky and sandy
channels among scattered bushes of scale-broom. No specimens of
_eremicus_ were taken on the juniper-clad benches adjacent to the wash.
_Specimens examined._--Los Angeles County: Mescal Wash, 4000
ft., 10 (4 PC).
=Peromyscus eremicus fraterculus= (Miller)