Of the 37 skulls of subadults and a few adults, 11 had the frontal sinuses malformed as a result of infestation by parasites. _Specimens examined._--Total number, 56, arranged within each state by localities from north to south. Unless otherwise indicated specimens are in the collection of the United States National Museum. =Oregon.= Mt. Jefferson, Permilia Lake, 1. =Washington.= _Pierce County_: 5500 ft., Spray Park, Mt. Rainier, 1; Spray Park, 1[74]; 5935 ft., Glacier Basin, Mt. Rainier, 5 (1[10]); 5051 to 5100 ft., Owyhigh Lakes, Mt. Rainier, 7 (1[10]), Tahoma Creek, 1[72]; Nisqually entrance, 1[72]; Longmire, 1[72]; Mt. Rainier Nat'l Park, 2[72]. _Klickitat County_: Trout Lake, S Base Mt. Adams, 35; 3500 ft., Gotchen Creek, Mt. Adams, 1. =Mustela frenata saturata= (Merriam) Long-tailed Weasel Plates 19, 20, 21 and 30 _Putorius saturatus_ Merriam, N. Amer. Fauna, 11:21, June 30, 1896. _Mustela saturata_, Miller, U. S. Nat. Mus. Bull., 79:98, December 31, 1912. _Mustela arizonensis saturata_, Grinnell, Univ. California Publ. Zoöl., 40:102, September 26, 1933. _Mustela frenata saturata_, Hall, Carnegie Instit. Washington Publ. 473:106, November 20, 1936. _Type._--Male, adult, skull and skin; no. 65930, U. S. Nat. Mus., Biol. Surv. Coll.; Siskiyou, Jackson County, Oregon; June 6, 1894; obtained by C. P. Streator; original no. 3905. The skull (plates 19-21, 30) lacks the middle part of each zygomatic arch. The teeth all are present although much worn, probably from gnawing at the trap which captured the animal. The skin, in fresh summer pelage, is fairly well made. _Range._--Transition and Boreal life-zones of Siskiyou and Trinity mountains in southern Oregon and northwestern California. See figures 29 and 30 on pages 221 and 314. _Characters for ready recognition._--Differs from _M. f. nevadensis_ in lacking light color of underparts on tail and ankle and in greater average breadth across mastoid processes of skull (see measurements); from _M. f. oregonensis_ in lacking white nasofrontal spot, in having color of underparts interrupted at ankle; from _M. f. munda_ in lacking white nasofrontal spot, in smaller and relatively deeper skull of males and smaller skull of the female. _Description._--_Size._--Male: Four adult males (the type, 1 from Mt. Ashland and 2 from Jackson Lake) yield average and extreme measurements as follows: Total length, 414 (402-437); length of tail, 150 (136-160); length of hind foot, 46 (43-50). Tail averages 57 (49-62) per cent as long as head and body. Length of hind foot more or less than basal length.