The white, winter skin is only moderately well stuffed but in a good state of preservation. The spring coat is appearing along the back. This coat is visible at only two places unless the hair be parted when the new brown pelage, which is coming in, can be seen all along the midline of the back. _Range._--Kodiak Island, Alaska. See figure 25 on page 95. _Characters for ready recognition._--Differs from _M. e. arctica_ in hind foot less than 33 in females and in zygomatic breadth amounting to less, instead of more, than distance between last upper molar and jugular foramen irrespective of sex. _Description._--_Size._--Male: One adult and 3 subadults yield average and extreme measurements as follows: Total length, 341 (318-360); length of tail, 93 (86-102); length of hind foot, 47 (44-49). Female: An adult measures: Total length, 258; length of tail, 70; length of hind foot, 31. _Color._--As described in _M. e. arctica_, except that least width of color of underparts averaging 54 (40-83) per cent of greatest width of color of upper parts. Black tip of tail in 3 males in summer pelage averaging 80 (70-90) mm. which is 85 (69-96) per cent of length of tail-vertebrae. _Skull._--Male (based on 2 adults): See measurements and plates 2-4. As described in _Mustela erminea richardsonii_ except that: Weight 3.1 grams; basilar length, 42.6 (42.1-43.2); length of tooth-rows more than length of tympanic bulla; breadth of rostrum measured across lacrimal processes averaging more than a third of basilar length; interorbital breadth more than distance between glenoid fossa and posterior border of external auditory meatus. Female (based on one adult, no. 98042): See measurements and plates 9-11. As described in _Mustela erminea richardsonii_ except that: Weight, 1.2 grams; basilar length, 33.0; length of tooth-rows more than length of tympanic bulla. 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_.