Comparison with _arctica_ has been made in the account of that subspecies. Although _richardsonii_ and _kadiacensis_ are described as having the zygomatic breadth less than the distance between the last upper molar and jugular foramen, the zygomatic breadth is considerably more in _kadiacensis_ than in _richardsonii_; consequently the two dimensions are more nearly equal than in _richardsonii_. Except for being slightly narrower, the skull of _kadiacensis_ is only a slightly smaller edition of that of _arctica_.
_Remarks._--When naming the weasel from the mainland of Alaska as new, under the name _Putorius arcticus_, Merriam (1896:16) wrote: "A small form of _arcticus_ occurs on Kadiak Island. . . . It is probably worthy of recognition as subspecies _kadiacensis_." The informality of this description possibly was in part due to the describer's recognition of the fact that the degree of difference between _arcticus_ and the insular _kadiacensis_ was slight. Specimens collected after Merriam proposed the name for the weasel of Kodiak Island show the animal there to be less different from _arctica_ of the adjacent mainland than he thought; small size is the most pronounced distinction of _kadiacensis_ and Merriam's male type specimen is smaller than any of the five additional males saved from Kodiak Island since that time. Even so the differences fully warrant subspecific recognition, in my opinion, although _kadiacensis_ is not a strongly differentiated race. More adult females are needed to ascertain the norm of form and size for that sex. If the one female known is typical, the difference from _arctica_ is more pronounced in females than in males. The lesser size of _kadiacensis_ can hardly be credited entirely to the effect of insularity, for animals from the southern part of the mainland, on Kenai Peninsula for example, are smaller than those from central and northern Alaska and provide evidence of intergradation of a sort between _kadiacensis_ and _arctica_.
_Specimens examined._--Total number, 9, all from Kodiak Island, Alaska, and unless otherwise indicated in the U. S. National Museum.
Karluk, 1 (Stanford Univ.); Kodiak, 7; Kodiak Island, 1 (Field Mus. Nat. Hist.).