Two young females from Chester, Iowa, nos. 2656 and 2874/2873, Coe College, have skulls larger than those of corresponding age of _primulina_ or _noveboracensis_. The color is as in spadix. The color pattern of the underparts also is as in _spadix_ or _longicauda_ except that the width of the area of light color on the belly is restricted somewhat although not so much as in _noveboracensis_ or _primulina_. Of four males from the same place, also in the collection of Coe College, no. A2874 is a white skin only and does not provide diagnostic characters. The three other males, each in summer pelage, are marked and colored as are the two females from the same place except that male no. 2861 has the color of the underparts so much attenuated on the hind legs that it barely, uninterruptedly, extends to the feet. No. 2658 is young, or perhaps barely subadult. The skull is large and referable to _spadix_. The two adults, nos. 2861 and 2657, differ cranially from typical (Elk River, Minn.) _spadix_ only in being slightly narrower across the mastoids and in having the bullae a little narrower. In these departures they show some approach to _primulina_ and to _noveboracensis_. Another male, subadult, no. 2867, Coe College, from Decorah, which has acquired half of the white winter coat, agrees with the males from Chester except that the preorbital part of the skull is shortened much as in some specimens of _primulina_. From Lansing, in extreme northeastern Iowa, a large subadult male, no. 2864, Coe College, of 453 mm. in total length and half through with acquiring the white winter coat, agrees with the males previously described from Chester except in having the palate narrower as in _noveboracensis_. The adult female available from Lansing, no. 2863/2862, Coe College, in white winter pelage except for the top of the head, although a large skin, has a skull smaller than that of any _spadix_ or _longicauda_ and of about the same size as that of no. 3838, Univ. Kansas Mus. Nat. Hist., of _primulina_, from Lawrence, Kansas, except that the skull of no. 2863/2862 is much narrower across the mastoids. This specimen, then, shows approach to _noveboracensis_ in narrowness of the mastoidal region, to _primulina_ in other respects and to _spadix_. Many of these instructive specimens from Iowa, made available to the present writer by Mr. W. F. Kubichek, were brought together at the Coe College Museum by the late B. H. Bailey. Most of them were obtained from trappers who did not supply the conventional external measurements taken in the flesh. Even though these are lacking, the specimens clearly show that actual intergradation occurs where the ranges of _M. f. longicauda_, _spadix_, _noveboracensis_ and _primulina_ meet.