Intergradation with the two subspecies whose geographic ranges adjoin that of _arizonensis_ is indicated by specimens at hand. One of these is the adult male from 25 miles southeast of Flagstaff, which shows decided approach to _neomexicana_, in color and in possessing white facial markings less well developed than in _neomexicana_. Even better developed white facial markings, with intervening blackish coloration, are displayed by no. 148271, U. S. Nat. Mus., from 8500 feet altitude on Willow Creek, New Mexico. This subadult female shows approach to _neomexicana_ also in larger size of the skull and entire animal. The great inflation of the posterior part of each of its bullae and the dark color of the upper parts are characters of _arizonensis_. The color of the underparts stops at the ankles leaving the hind feet dark colored, in which respect the specimen is unlike either _neomexicana_ or _arizonensis_. If additional specimens showing the same characters as this one be found at other nearby localities they probably should be given recognition as a separate subspecies. For the present it seems best to regard the specimen merely as an intergrade. Although it might, with almost equal propriety, be referred to either _neomexicana_ or _arizonensis_, the specimen is here placed with the latter. The subadult male from Springerville, Arizona, is of larger size than the topotypical male of _arizonensis_ and in this respect shows slight approach to _nevadensis_. The narrower mastoidal breadth and slightly less inflated tympanic bullae of the male from the Kaibab Plateau may reflect merely individual variation or may represent intergradation in these features with _nevadensis_. The statement made by Merriam (1896:22) that, "The type specimen . . . is an immature female and is of unusually small size. A male obtained by him [Mearns] near the same place is of the normal size, as is another male in the Department collection from Springerville, Ariz., collected by E. W. Nelson," needs correction. The female is not immature. The specimen obtained by Mearns near the same place probably refers to Amer. Mus. No. 2489, from Quaking Asp Settlement, which lacks both the skull and external measurements. As stuffed it is of small size for a male. The male from Springerville, as shown by the external and cranial measurements, is not of normal (_i. e._ average) size, but is smaller than the average for the other populations of similarly colored weasels referred to by Merriam (_op. cit._) as _arizonensis_ but here described under the name _nevadensis_. None of the skulls shows signs of infestation of the frontal sinuses by parasites. _Specimens examined._--Total number, 17, arranged alphabetically by states and from north to south by counties in each state. Unless otherwise indicated specimens are in the collection of the United States National Museum.