Burrows of pocket mice usually are at the bases of shrubs where tough roots furnish protection. They are kept closed during the day by means of a plug of fresh earth or sand. Openings may often be recognized by a fan-shaped pile of fresh sand before the hole. Burrows excavated were usually less than four feet in length and branched from two to four times. No nests were found in the burrows but one contained a few fresh stalks of desert annuals. The air in the burrows seemed warm and humid. The pouches of pocket mice from Washington often contain the fresh, green tips of desert plants, grass seeds, seeds of plants other than grasses, and plant leaves. Because of their occasional great abundance, pocket mice may be a menace to agriculture. Fortunately much of their habitat is unsuited to farming. In Washington pocket mice breed in March and April. From 4 to 8 embryos were found in pregnant females. =Perognathus parvus parvus= (Peale) _Cricetodipus parvus_ Peale, U. S. Explor. Exped., 8 (mamm. and ornith.):53, 1848. _Perognathus parvus_ Cassin, U. S. Explor. Exped., 8 (mamm. and ornith.):48, 1858. _Perognathus parvus parvus_ Miller, Bull. U. S. Nat. Mus., 128:278, April 29, 1924. [Illustration: FIG. 93. Distribution of the Great Basin pocket mouse in Washington. A. _Perognathus parvus parvus._ B. _Perognathus parvus columbianus._ C. _Perognathus parvus lordi._] _Type._--Probably obtained in the neighborhood of The Dalles, Wasco County, Oregon. _Racial characters._--Size small; upper parts brownish-buff washed with blackish or, in gray phase, ashy gray washed with blackish; sides buffy yellow; a buffy spot often present on throat; tail blackish above, olive below; facial markings usually brownish-buff but in older animals indistinct and washed with blackish. _Measurements._--Thirty-one males and 19 females from Washington average, respectively: total length 169, 164; length of tail 90, 86; hind foot 22.6, 21.8; ear 5, 5. _Distribution._--Southeastern Washington south of the Snake River, the area on the north side of the Columbia River in Klickitat County, and the Yakima Valley area as far north as the Vantage, Kittitas County (W. W. D.). Other marginal records are: Kennewick (W. W. D.), Atilla (W. W. D.) and Walla Walla (E. S. B.). _Remarks._--Dichromatism seems to be rather common in _Perognathus p. parvus_--so common that Osgood (1900: 35) recognized both a "red" and a "gray" phase. Anderson (1932: 102) found no dichromatism in _P. p. lordi_ in British Columbia. A single specimen from the Grand Coulee at Dry Falls, Grant County, does show dichromatism. It is even more red than the reddest topotypes of _parvus_ examined.