Intergradation with M. f. nevadensis and possibly with M. f. saturata is indicated by specimens from South Yolla Bolly Mountain, Trinity County. In them the external measurements and measurements of the skull are intermediate. Also the white frontal spot is much reduced in size. The white bars in front of the ears are absent in three specimens, and weakly developed in the other two. The relative proportions of the skulls as a whole are nearer those of nevadensis or saturata than munda. The skull of one of the three adult males and the skull of the adult female suggests M. f. oregonensis in certain features; for example, the dorsal outline of the skull in longitudinal axis is slightly convex as it is in oregonensis.

None of the specimens shows malformation of the frontal sinuses such as results from infestation by parasites.

Specimens examined.—Total number, 37, arranged by counties from north to south. Unless otherwise indicated specimens are in the Museum of Vertebrate Zoölogy.

California. Trinity County: S. Yolla Bolly Mt., 3[91]; 1/2 mi. S S. Yolla Bolly Mt., 1. Tehama County: 2 mi. S S. Yolla Bolly Mt., 1. Mendocino County: 6 mi. N Laytonville, 1; Mt. Sanhedrin, 1[87]; Ft. Bragg, 1; Gualala, 1; Point Arena, 5. Sonoma County: 2 mi. S and 1 mi. E Stewarts Point, 1; 3 mi. S Stewarts Point P. O., 1; Freestone, 1. Napa County: 6 mi. SSW, Napa, 1; 4 mi. N Vallejo, 1. County in question: San Pablo Bay, 1[91]. Marin County: 6 mi. W Inverness, 2; 5 mi. W Inverness, 2(1[28]); Point Reyes, 4 (2[91] 1[60], 1[75]); Nicasio, 2 (1[60], 1[75]); Kehoes Ranch, Pierce Point, 1[28]; Drakes Bay, 1[28]; Tomales Point, about 1/2 mi. SW White Gulch, 1; Point Reyes School, 3-3/4 mi. W Inverness, 1; 15 mi. (by road) N San Rafael, 1[52]; Hurley Ranch, 2 mi. W Tomales, 1. No locality more definite than California, 1[7].

Mustela frenata xanthogenys Gray

Long-tailed Weasel

Plates [21], [22], [23], [28], [30], [34], [35] and [36]

Mustela xanthogenys Gray, Ann. and Mag. Nat. Hist., 11:118, 1843.

Putorius (Gale) brasiliensis frenatus, Coues, Fur-bearing animals, p. 142, 1877 (part).

Putorius xanthogenys, Merriam, N. Amer. Fauna, 11:25, June 30, 1896; Bangs, Proc. New England Zoöl. Club, 1:56, June 9, 1899.

Mustela xanthogenys xanthogenys, Miller, U. S. Nat. Mus. Bull., 79:99, December 31, 1912.

Mustela frenata xanthogenys, Hall, Carnegie Instit. Washington Publ. 473:107, November 20, 1936.

Type.—Male, adult, skull and skin; skull no. 197a-43.6.4.55, skin no. 234a-42.11.21.4, British Museum (Nat. Hist.); from the bank of Sacramento River below mouth of Feather River, or from north shore of San Francisco Bay, California; taken in "1837 or 1838"; presented by Captain Edward Belcher.

The skull (plate [28]) lacks the occiput, the right mandible posterior to m1, and the right pterygoid; the right zygomatic arch is fractured. The teeth are not greatly worn. The skin was originally mounted for exhibition (R. I. Pocock in Litt.) but in 1937 when I saw the skin, it was prepared as a conventional study skin. The skin is in fairly good condition; some hair is missing on the hind quarters and the skin of the tail is torn at one place.

Range.—Altitudinally, less than 600 feet (Fair Oaks); Lower Sonoran and Upper Sonoran life-zones of all but southern end of the San Joaquin Valley, and probably Sacramento Valley, California. See figures [29] and [30] on pages 221 and 314.

Characters for ready recognition.—Differs from M. f. nevadensis by presence of light facial markings and Buckthorn Brown rather than near (14n to l) Brussels Brown color of upper parts; from M. f. munda by Buckthorn Brown rather than near (l) Sudan Brown, or near (l) Antique Brown color of upper parts and lesser size, in adult males basilar length less than 45 and hind foot less than 47; from M. f. nigriauris by lighter color in same way as from munda and also by having inside of ears same color as back rather than much darker than back; from M. f. pulchra in hind foot of males less than 46 and narrower skull, in males having breadth of rostrum less than 13.9 and mastoid breadth less than 26.0, see comparison of skulls in the account of pulchra.

Description.—Size.—Male: Three adults, from Fresno, Selma and Los Banos, measure, respectively as follows: Total length, 425, 417, 450; length of tail, 152, 154, 180; length of hind foot,—, 43, 44. Tail averages 61 per cent as long as head and body. Length of hind foot less than basal length.

Female: Adults from Selma, Los Banos, and 4 mi. SW Turlock, measure respectively as follows: Total length, 357, 365, 395; length of tail, 133, 132, 145; length of hind foot, 40, 38, 41. Tail averages 58 per cent as long as head and body. Length of hind foot less than basal length.

The average differences in external measurements between the two sexes, as represented by these six specimens, are: Total length, 65; length of tail, 25; length of hind foot, 3.5. One adult male weighs 274 grams and 2 adult females 182 and 214 grams.

Externals.—As described in Mustela frenata nigriauris.

Color.—Spot between eyes, band confluent with color of underparts on each side of head extending anterodorsally anterior to each ear, and posterior half to third of each upper lip white, or whitish tinged with some shade of yellowish; chin and lower lip white; dark spot posterior to each angle of mouth of varying size but uniformly present; tip of tail black; remainder of upper parts Buckthorn Brown of Ridgway or a trifle browner than tone 4 of Brown Pink of Oberthür and Dauthenay, pl. 297. Upper parts of uniform color except for slight darkening of head-markings anterior to ears. Underparts Ochraceous-Buff to Warm Buff. Color of underparts extends distally on posterior sides of forelegs over toes onto antipalmar faces of feet and wrists, on medial sides of hind limbs over antiplantar faces of toes and sometimes tarsal region. Least width of color of underparts averaging, in 9 specimens from Fresno, Selma and Los Banos, 54 (32-74) per cent of greatest width of color of upper parts. Black tip of tail in three males (one subadult and 3 adults) averages 55 (50-60) mm. long. Thus longer than hind foot and averaging 34 per cent of length of tail-vertebrae.

Skull and teeth.—Male (based on 2 adults from Fresno and one from Selma): See measurements and plates [21]-[23], [30]. As described in M. f. nigriauris except that: Weight 3.8 grams; basilar length, 43.7 (43.4-43.9); least width of palate more or less than lateral length of P4; length of tympanic bulla more than length of lower molar and premolar tooth-rows.

Female (no. 2626 W. E. Snyder, from Selma): See measurements and plates [34]-[36]. As described in M. f. nigriauris except that: Weight, 2.5 grams; basilar length, 39.4.

The skull of the female is 34 per cent lighter than the average for the three males.

Compared with skulls of nevadensis from the Sierra Nevada, those of the two adult males from Fresno differ as follows: M1 wider (transversely); tympanic bullae narrower; preorbital part of skull smaller. Comparison with pulchra is made in the account of that subspecies. Compared with skulls of adult males of nigriauris, from Santa Clara County, the two skulls from Fresno are generally smaller and in basilar length, length of tooth-rows and measurements of the teeth fall below the minimum for nigriauris. Relative proportions of the skulls are approximately the same. Comparison with munda reveals essentially the same differences as does comparison with nigriauris except that the difference in size is greater.