_Description._--_Size._--Male: Seven adults and subadults from Prince of Wales Island, yield average and extreme measurements as follows: Total length, 286 (277-304); length of tail, 77 (74-85); length of hind foot, 36 (35.5-40.5). Female: No specimen available. _Color._--As described in _Mustela erminea richardsonii_ except that upper parts about tone 3 of dark Chocolate Brown of Oberthür and Dauthenay, pl. 342; lower throat and chest covered by a large patch of same color as upper parts; color of underparts extending to toes but in interrupted fashion on both fore-and hind-feet; least width of color of underparts averaging, in four males from Prince of Wales Island, 41 (38-49) per cent of greatest width of color of upper parts. Black tip of tail averaging, in 8 males in winter pelage, 65 (59-78) mm. which is 84 (69-92) per cent of length of tail-vertebrae. From its geographic neighbors _alascensis_ and _initis_, _celenda_ differs in darker color of upper parts, presence rather than absence of patch of dark color on lower throat and chest, and longer black tip on tail. From _haidarum_, _celenda_ differs in darker color of upper parts, presence rather than absence of patch of dark color on lower throat and chest, narrower light-colored under parts, black tip of tail averaging less rather than more than nine-tenths of length of tail-vertebrae and ventral face of tail colored like upper parts rather than like underparts. _Skull._--Male (illustrated by 5 adults): See measurements and plates 5-7. As described in _Mustela erminea richardsonii_ except that: Weight, 2.3 (2.2-2.5) grams; basilar length, 39.5 (38.9-40.7) mm.; length of tooth-rows more than 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 border of external auditory meatus; zygomatic breadth more or less than (about equal to) distance between last upper molar and jugular foramen. Female.--Complete skull of adult unavailable.