The heather voles and their relatives are primitive microtines that range through boreal North America including the higher parts of the Rocky Mountains and the cool area along the Pacific Coast. Several species are included in the genus: an arctic form (_ungava_), a lowland Pacific Coastal species (_albipes_), two tree-inhabiting species (_longicaudus_ and _silvicola_) and a mountain species (_intermedius_). Thus far only _intermedius_ has been found in Washington but further search may reveal that one or more of the arboreal species and possibly _albipes_ are also present. Heather voles are alpine animals, seldom occurring below the Hudsonian Life-zone. They are rare as compared with most microtines, and are seldom taken in traps, even by the experienced collector of small mammals. Evidence of their presence is most often found in the dense meadows of heather (_Cassiope_ and _Phyllodoce_) high on the mountains. Here their feces, runways, and old winter nests are not uncommon, and heather voles may be far more abundant than trapping records indicate. They are not restricted to the vicinity of heather, however, for one of my specimens was taken in a marshy willow thicket near Stevens Pass in King County, one in a patch of skunk-cabbage in a grassy glacial cirque near Tomyhoi Lake in Whatcom County, and one at the edge of a snowbank on a steep hillside at Deer Park, Clallam County. In each of these places, however, there were heather meadows within a thousand yards. Shaw (1924A: 12-15) also found the heather mouse on "comparatively dry hill slopes" and reports that it "rather characteristically occurs in such log-tangled areas as former fire zones." [Illustration: FIG. 110. Distribution of the heather vole in Washington. A. _Phenacomys intermedius oramontis._ B. _Phenacomys intermedius intermedius._] The winter nests of _Phenacomys intermedius_ are placed on the surface of the ground and in the season when occupied are deeply buried under the snow. They are spherical or oval in shape, six to eight inches in diameter and with a side entrance. One examined by Shaw was "formed of white heather twigs, the interstices being filled with leaves of huckleberry." It was "lined with finely shredded grass." All those examined by me were composed of grass and lichens. The principal foods of the heather vole seem to be white heather (_Cassiope mertensiana_) and huckleberry (_Vaccinium_). Red heather (_Phyllodoce empetriformis_) is not eaten. Shaw also lists beargrass (_Xerophyllum tenax_) and lousewort (_Pedicularis_) as eaten. A burrow excavated and figured by Shaw, was slightly more than a yard long and contained four young in a nest situated but a few inches from one of the three entrances. The nest was made of grass and moss. A female taken at Tye, King County, contained 4 embryos on May 28, 1939. One taken at Pass Creek Pass, Pend Oreille County, contained 3 small embryos on June 14, 1938. =Phenacomys intermedius intermedius= Merriam