Reithrodontomys montanus (Baird, 1855) . Proc. Acad. Nat. Sci. Philadelphia, 7:335.

TYPE LOCALITY: USA, Colorado, Saguache Co., upper part of the San Luis Valley (as restricted by Allen, 1895a:125). See Armstrong's (1972:190) lucid summary of the contradictory references to the type locality .

DISTRIBUTION: High Plains of C USA, from W South Dakota and E Wyoming to EC Texas and extreme SE Arizona; NE Sonora and Chihuahua to N Durango, Mexico.

SYNONYMS: albescens, griseus .

COMMENTS: Subgenus Reithrodontomys, megalotis species group. See Wilkins (1986, Mammalian Species, 257).