_Remarks._--This race is separated from _parvus_ by river barriers and the two do not intergrade. It differs significantly from _lordi_ only in the wider mastoid region. No barrier separates the range of _lordi_ from that of _parvus_, and the two races intergrade over a wide area (north to Moses Lake, east to Washtucna). The race _columbianus_ must have originated _in situ_ from _lordi_. The habitat of _columbianus_ seems not to differ from that of _parvus_ or _lordi_. =Dipodomys ordii columbianus= (Merriam) Ord kangaroo rat _Perodipus ordi columbianus_ Merriam, Proc. Biol. Soc. Washington, 9:115, June 21, 1894. _Dipodomys ordii columbianus_ Grinnell, Jour. Mamm., 2:96, May 2, 1921. _Type._--Obtained at Umatilla, Umatilla County, Oregon, by C. P. Streator on October 18, 1890; type in United States National Museum. _Measurements._--Fourteen males and 9 females from Walla Walla County average, respectively: total length 261.5, 248.4; length of tail 137.2, 139.1; hind foot 40.6, 40.8; ear 13.1, 13.0; weight 52.1, 49.0 grams. _Distribution._--Western Walla Walla County from the Oregon boundary north to the Snake River and on Blalock Island in the Columbia River, Benton County. [Illustration: FIG. 94. Distribution of the Ord kangaroo rat, _Dipodomys ordii columbianus_, in Washington.] _Description._--The kangaroo rat with a body about the size of that of a chipmunk has an exceptionally large head and large, black eyes. The forelegs and forefeet are tiny but the hind feet and legs are large and powerful. The hind foot is almost a third as long as the head and body. The tail is long, longer than the head and body. Kangaroo rats possess fur-lined, external cheek pouches, like those of the pocket mice. The upper parts are soft buff in color. The underparts and a stripe on each flank are white. The tail is dusky above and below, with white sides; it is tufted at the tip. Kangaroo rats are typical of the desert regions of the southwestern United States, where numerous species and subspecies are found. A single subspecies of the wide-ranging species _ordii_ occurs into southeastern Washington, where it is restricted to sandy areas in the Upper Sonoran Life-zone. In the soft, drifted sand along the Columbia River where sagebrush and other desert shrubs are low and widely spaced kangaroo rats are abundant. These rats are strictly nocturnal. When individuals are dug from their burrows in the daytime they usually hop about in a dazed manner and appear to be blinded by sunlight. Near Wallula, Walla Walla County, these rats were caught at night with a butterfly net as they stood "paralyzed" in the beam of a powerful searchlight. Such night hunting was unsuccessful on cloudy or windy nights when kangaroo rats seem not to move about.