_Range._--Transition and Canadian life-zones along coast of northern California and southern Oregon from Humboldt County, California, north through Curry County, Oregon, thence inland, west of the Cascades, north to the Columbia River. See figures 29 and 30 on pages 221 and 314. _Characters for ready recognition._--Differs from _M. f. altifrontalis_ in presence of frontonasal white patch, lighter color above (tone 2 to 3 of Raw Umber, pl. 301, rather than tone 4 of Brownish Drab, pl. 302, Oberthür and Dauthenay), wider extent of light color of underparts which is extended distally beyond knee, and in females, longer tooth-row which amounts to more than 38 per cent of basilar length; from _M. f. munda_ in shorter hind foot of males which is less than 50, and in both sexes, smaller, less rugose skull (see measurements and plates); from _M. f. saturata_ in presence of frontonasal white patch, in having color of underparts extended uninterruptedly over ankle onto foot; from _M. f. nevadensis_ in presence of frontonasal white patch, lack of light color of underparts on ventral face of tail, and longer skull, which relative to its length in males, is shallower through braincase; from _M. f. effera_ in presence of frontonasal white patch, lack of light color of underparts on ventral face of tail, and larger skull with basilar length averaging more than 41.7 in males; from _M. f. washingtoni_ in presence of frontonasal white patch, shorter skull in males, which in percentage of basilar length has, on the average, orbitonasal length amounting to less than 35, mastoid breadth more than 55, and zygomatic breadth more than 63; and in females larger skull with least width of palate more than length of P4, upper tooth-rows more than 38-1/2 per cent of basilar length, bullae larger and averaging more than 13.4 long. _Description._--_Size._--Male: Five males (3 adults and 2 subadults from Eureka, Ferndale, and Carlotta, California) yield average and extreme measurements as follows: Total length, 392 (347-430); length of tail, 138 (110-160); length of hind foot, 46 (43-50). Tail averages 54 (46-61) per cent as long as head and body. Length of hind foot more or less than basal length. The type specimen, and an adult from Goldbeach measure, respectively, as follows: Total length, 412, 386; length of tail, 155, 137; length of hind foot, 44, 46.