Intergradation between _nevadensis_ and _munda_ is indicated by specimens from South Yolla Bolly Mountain, Trinity County, which are commented on at greater length in the account of _M. f. munda_. _M. f. inyoensis_ is so closely related to _nevadensis_ as to leave no doubt that specimens from suitable localities will show actual intergradation. That intergradation occurs directly with the bridled weasel of the interior valleys of California, _M. f. xanthogenys_, is shown by specimens from along the west-facing flank of the southern part of the Sierra Nevada. Probably intergradation occurs all along the Sierra Nevada on the western slope but specimens are lacking to show this. Weasels are known to occur in the foothill territory and the lesser attention given to this region by mammal collectors than to the higher parts of the mountains may explain the lack of preserved specimens. Individual specimens, here referred to _nevadensis_, but, showing varying degrees of approach to _xanthogenys_ are as follows: A female from Hume; a male and a female from 8000 feet elevation, Monache Meadows; a male from 9800 feet elevation on the east fork of the Kaweah River; and 7 specimens, probably one family, from one-half mile south of Mineral King, 7850 feet. Of the specimens from 7850 feet, the adult male has no light facial markings and the head is only slightly darker than the back. The adult female has much restricted, light facial markings and the intervening areas are darker than in the male. The five juveniles trapped in the same burrow as the female, each has more extensive light facial markings than the adult female although the area of this varies from only slightly more than in the female to as much as in typical specimens of _xanthogenys_. Also, the dark color of the head in these five specimens averages darker than in _nevadensis_ and more as in weasels to the southwestward especially _latirostra_. One of the five juveniles is lighter colored over all of the upper parts than _nevadensis_ and is suggestive of _xanthogenys_ in this respect. Finally, the adult male has on the underparts small spots of ochraceous orange suggestive of _latirostra_ and some individuals of _pulchra_. No. 30655/42628, U. S. Nat. Mus., taken on Mount Whitney, also shows white facial markings and some other features of the valley-inhabiting _xanthogenys_. A suggestion of intergradation with _arizonensis_ is furnished by specimens, referred to that race, from Springerville and the Kaibab Plateau. No specimens happen to be available from the region in which intergradation would be expected between _nevadensis_ and _neomexicana_. Since _neomexicana_ and _arizonensis_ intergrade it is probable that _nevadensis_ also will be found to intergrade with _neomexicana_. In summary, _nevadensis_ is judged to intergrade with each of the subspecies of _Mustela frenata_ whose range adjoins that of _nevadensis_.