This genus reaches the extreme northern limit of its distribution in the state of Washington, where it ranges to the Canadian border. A single subspecies occurs in Washington. The harvest mouse is a resident of the Upper Sonoran Life-zone and it is most abundant in dense growths of grass, weeds, and other vegetation. Along the Yakima River, near Ellensburg, it was abundant in thick, river-side jungle. Near Yakima many specimens were taken in a marsh of cattails and tules. In the Grand Coulee they live in thick grass. Near Moses Lake several were found in their nests in a thick growth of tumbleweed. Harvest mice occur also, although never in great numbers, in relatively open areas. At the Potholes near Moses Lake, Grant County, a few were caught on sand dunes among scattered bushes of sage. They were taken on sagebrush flats in several localities. Gray (1943: 191) estimates their numbers in the sagebrush area of the Yakima Valley at 5 per acre. Where harvest mice live in dense vegetation they make small runways and food piles similar to those of _Microtus_ but in more open areas they leave no perceptible signs. Near Yakima the nest of a harvest mouse was found among the roots of an overturned apple tree. This nest was an irregular ball composed of fine grasses and shredded bark closed above, with a side entrance and a central cavity three inches in diameter. Near Moses Lake three nests of harvest mice were discovered on the ground under cover of a dense growth of tumbleweed, and six live harvest mice were captured in the same area. These nests were cuplike, open above, and were composed of dry grasses, bits of weeds, and newspaper. The smoothly rounded inner cups measured about three inches in diameter. Embryos were found in harvest mice in Washington from March to April and numbered 3 to 6. =Peromyscus maniculatus= (Wagner) Deer mouse _Description._--The deer mouse is slightly larger than the house mouse, the head and body measuring from 3-1/2 to 4 inches. The length of the tail varies considerably in the several races, ranging from approximately 2-1/2 inches in _gambelii_ to 4 inches or more in some individuals of _oreas_. The eyes are large and protrude slightly. The ears are large, erect and naked. The tail is sparsely furred with short, posteriorly directed hairs. The color of the upper parts varies from yellowish buff in _gambelii_ to reddish brown in _oreas_ and dusky in _austerus_. Young deer mice are gray or bluish gray above. Underparts and feet are white. The tail is bicolored, being dusky above and white below. [Illustration: FIG. 106. Deer mouse (_Peromyscus maniculatus austerus_), in captivity, Seattle, Washington, September 18, 1939. (Fish and Wildlife Service photo by Victor B. Scheffer, No. 723.)]