is known in Oklahoma only from
the Panhandle, thence southward through the Panhandle and Trans-Pecos
areas of Texas to southern Mexico, westward across the mountains in New
Mexico to the Pacific Coast, and northward to the west of the Rockies to
southern British Columbia.

Hoffmeister and Warnock (1955) studied western harvest mice from
Illinois, Iowa, northeastern Kansas, Minnesota and Wisconsin, concluded
that one subspecific name (_Reithrodontomys megalotis dychei_ J. A.
Allen, 1895, with type locality at Lawrence, Douglas Co., Kansas)
applied to all, and relegated _Reithrodontomys megalotis pectoralis_
Hanson, 1944 (type locality at Westpoint, Columbia Co., Wisconsin) to
synonymy under _dychei_. Our study, based upon an examination of 1350
specimens, concerns the area west of the Missouri River from Kansas and
Nebraska westward to Montana, Wyoming, Colorado and northern New Mexico.
Our objectives were to study variation in _R. megalotis_ in the region
indicated and to decide what subspecific names properly apply to
populations of the species that occur there.

Aside from the name _R. m. dychei_, currently applied to western harvest
mice from a large part of the region here under study, three other
subspecific names need consideration:

"_Reithrodontomys aztecus_" J. A. Allen, 1893 (type locality, La
Plata, San Juan Co., New Mexico), currently applied to specimens
from northern New Mexico and southern Colorado (and adjacent parts
of Arizona and Utah) east to southwestern Kansas and the Oklahoma
Panhandle;

"_Reithrodontomys megalotis caryi_" A. H. Howell, 1935 (type
locality, Medano Ranch, 15 mi. NE Mosca, Alamosa Co., Colorado),
proposed for, and currently applied to, harvest mice from the San
Luis Valley, Colorado, but possibly a synonym of _aztecus_ according
to Hooper (1952:218); and

"_Reithrodontomys dychei nebrascensis_" J. A. Allen, 1895 (type
locality, Kennedy, Cherry Co., Nebraska), proposed for harvest mice
from western Nebraska and adjacent areas, but regarded as a synonym
of _dychei_ by A. H. Howell (1914:30-31).

Our comments concerning the taxonomic status of these several names
appear beyond.

We are grateful to Dr. W. Frank Blair, University of Texas, for the
loan of a specimen from the Texas Panhandle (TU), and to Dr. Richard
H. Manville, U.S. Fish and Wildlife Service, for the loan of
specimens of _R. m. caryi_ from th