Cynomys ludovicianus (Ord, 1815) . In Guthrie, New Geogr., Hist. Coml. Grammar, Philadelphia, 2nd ed., 2:292.

TYPE LOCALITY: "vicinity of the Missouri." Restricted by Hollister (1916a:14) to "Upper Missouri River."

DISTRIBUTION: Saskatchewan (Canada); Montana to E Nebraska, W Texas, New Mexico, and SE Arizona (USA); NE Sonora, and N Chihuahua (Mexico).

SYNONYMS: arizonensis Mearns, 1890; cinereus Richardson, 1829; grisea Rafinesque, 1817; latrans (Harlan, 1815); missouriensis (Warden, 1819); pyrrotrichus Elliot, 1905; socialis Rafinesque, 1817 .

COMMENTS: Subgenus Cynomys . Intraspecific variation reviewed by Chesser (1983).