Female: Three adults (2 from Fortuna and 1 from Carlotta, California) yield average and extreme measurements as follows: Total length, 367 (360-374); length of tail, 130 (123-134); length of hind foot, 40 (39-40). Tail averages 55 (52-57) per cent as long as head and body. Length of hind foot less than basal length. A subadult from Goldbeach, an adult from 13 mi. SW Grants Pass, and an adult from Medford, measure, respectively, as follows: Total length, 316, 344, 294; length of tail, 114, 120, 122; length of hind foot, 36, 40, 38. The average differences in external measurements of the two sexes in the vicinity of Carlotta, are: Total length, 25; length of tail, 8; length of hind foot, 6. Corresponding differences, at Goldbeach, are: 70, 23, 10. Probably the females at Fortuna reflect the large size of _munda_ more than do the males at Carlotta and the differences between the measurements of the two sexes probably, therefore, are actually more than are indicated by the figures above. _Externals._--Longest facial vibrissae black, brown or white (often all three colors in same specimen) and extending beyond ear; carpal vibrissae same color as underparts and extending to apical pad of fifth digit; hairiness of foot-soles, in summer pelage, as shown in figure 20. _Color._--Upper parts, in summer, near (16 _l_) Brussels Brown or tone 2 of Raw Umber of Oberthür and Dauthenay, pl. 301, to slightly darker than tone 3 of same plate. Darker on nose and top of head, usually with frontonasal white patch but lacking white bar in front of each ear, except in the type and 2 specimens from Salem. Chin, lower lips, angle of mouth, and usually posterior seventh of upper lip white. Remainder of underparts Pale Orange-Yellow. In winter usually lighter above with underparts Warm Buff to Straw Yellow. Tip of tail at all times black. Color of underparts extends distally on posterior sides of forelegs over toes onto antipalmar faces of feet and wrists, on medial side of hind leg, typically over ankle in extremely narrow line which widens out over distal phalanges of antiplantar faces of toes but sometimes interrupted at ankle. Least width of color of underparts averaging, in twenty available specimens, 39 (27-54) per cent of greatest width of color of upper parts. Black tip of tail in five adults averaging 50 (43-60) mm. long; thus averaging longer than hind foot and 33 per cent of length of tail-vertebrae. _Skull and teeth._--Male (based on 4 adults and subadults from Eureka, Requa, Goldbeach, and Grant Pass): See measurements and plates 19-21, 30. As described in _Mustela frenata nevadensis_ except that: Weight, 3.5 (3.5-4.1) grams; basilar length, 42.9 (41.8-44.0); least width of palate more or less than medial length of P4.