=Alaska.= Prince of Wales Island: Craig, 18 (10 in Mus. Vert. Zoöl., and 8 in Los Angeles Mus. Hist. Art and Sci.); Kasaan Bay, 2; no locality more definite than the Island itself, 3; Dall Island, Otter Harbor, 1 (Los Angeles Mus. Hist. Art and Sci.). Long Island, Howkan, 1 (Field Mus. Nat. Hist.). =Mustela erminea seclusa= Hall Ermine Plates 5, 6 and 7 _Mustela erminea seclusa_ Hall, Proc. Biol. Soc. Washington, 57:39, June 28, 1944; Hall, Journ. Mamm., 26:181, July 19, 1945. _Type._--Male, adult, skull alone; no. 31232, Mus. Vert. Zoöl.; Port Santa Cruz, Suemez Island, Alaska; March 24, 1920; obtained by George Willett. The skull (plates 5-7) is complete and unbroken. Of the upper incisors only right I3 is present. Otherwise the teeth are present and unbroken. _Range._--Known only from the type locality. See figures 25, 26 on pages 95, 134. _Characters for ready recognition_ (only the male known).--Differs from _M. e. celenda_ in basilar length less than 38.2, from _M. e. salva_, _initis_ and _haidarum_ in zygomatic breadth more than distance between last upper molar and jugular foramen. _Description.--Size_ and _Color._--No external measurements or skins available. Skull.--Male: See measurements and plates 5-7. As described in _Mustela erminea richardsonii_ except that: Weight, 1.8 grams; basilar length, 34.3; length of tooth-rows about the same as length of tympanic bulla; breadth of rostrum measured across lacrimal processes more than a third of basilar length; interorbital breadth more than distance between glenoid fossa and posterior margin of external auditory meatus; zygomatic breadth more than distance between last upper molar and jugular foramen. Female.--Skull not available. From _alascensis_ and _salva_, _seclusa_ differs in larger teeth, shorter skull, much larger preorbital and interorbital regions, actually as well as in relation to basilar length. Excepting the teeth, which are of about the same size, the same general differences obtain in comparison with _initis_ which, however, is 29 per cent heavier. From _celenda_, _seclusa_ differs in smaller skull in all parts measured, being 22 per cent lighter. The teeth are about the same size. In relation to its length the skull of _seclusa_ is much broader and deeper. From _haidarum_, _seclusa_ differs in: teeth larger; skull shorter and more convex in dorsal outline along median longitudinal axis; in relation to basilar length, skull broader, deeper and braincase relatively shorter. _Remarks._--The characters shown in the one available skull are far outside the limits of individual variation for other known subspecies. Other specimens are much to be desired to ascertain what the "average" individual is like and to learn the characters of the female. _Specimen examined._--One, the holotype.