Part 72

The average differences in external measurements of the two sexes as shown by the six males from San Diego and the four females from San Diego County are: Total length, 73; length of tail, 19; length of hind foot, 8. Corresponding differences shown by the eight males and three females from Los Angeles are: 54, 23, 3.

Externals.--Longest facial vibrissae brownish, like dark color of head and extending beyond ear; carpal vibrissae mostly color of underparts and extending to apical pad of fifth digit; hairiness of foot-soles slightly more than shown in figure 20.

Color.--Spot between eyes, band confluent with color of underparts on each side of head extending anterodorsally anterior to ear, and posterior third of each upper lip tinged with color of underparts or, less often, white; chin and lower lips white; remainder of sides and top of head posteriorly to near line connecting posterior margins of ears, blackish; inside of pinna of ear, and sometimes outside of pinna, blackish; dark spot posterior to each angle of mouth present on each side in three-fourths of specimens; tip of tail black; remainder of upper parts near (l) Antique Brown, and with more yellow than tone 3 of Raw Umber of Oberthür and Dauthenay, pl. 301. Underparts Ochraceous-Buff to Warm Buff and in some specimens from Los Angeles and Ventura counties Ochraceous-Orange, especially in young and juveniles. Color of underparts extends distally on posterior sides of forelegs over toes onto antipalmar faces of feet and wrists and on medial sides of hind limbs over antiplantar faces of toes. Least width of color of underparts averaging, in 15 adult and subadult males from San Diego County, 54 (35-75) per cent of greatest width of color of upper parts. Black tip of tail in same series of males averaging 54.5 (46-60) mm. long. Thus averaging longer than hind foot and 35 per cent of length of tail-vertebrae.

Skull and teeth.--Male (based on 6 adults from San Diego County). See measurements and plates 22-24. As described in M. f. nigriauris except that: Weight (4 specimens), 3.9 (3.8-4.0) grams; basilar length 43.8 (41.9-47.0); postorbital breadth more than width of basioccipital measured from medial margin of one foramen lacerum posterior to its opposite; interorbital breadth not less than distance between foramen opticum and anterior margin of tympanic bulla; anterior margin of tympanic bulla as far posterior to foramen ovale as width of 2 to 2-1/2 (including I3) upper incisors; length of tympanic bulla more than length of lower molar and premolar tooth-row and longer than rostrum; anterior margin of masseteric fossa below m2.

Female (based on 4 adults from San Diego County): See measurements. As described in M. f. nigriauris except that: Weight, 2.6 (2.2-2.8) grams; basilar length, 40.0 and 40.1; postorbital breadth more than width of basioccipital measured from medial margin of one foramen lacerum posterior to its opposite; length of tympanic bulla more than length of rostrum.

The skull of the female averages 34 per cent lighter than that of the average male.

The skull of the male of latirostra, compared with that of nigriauris, is by weight, more than one-fourth lighter, has a lesser basilar length, a lesser mastoid breadth, a lesser zygomatic breadth and a narrower M1. In these features no overlap has been observed between adults from the general vicinities of the type localities of the two forms. In adult males of latirostra the postorbital breadth, with one exception, is more than the combined length of P4 and P3 whereas the reverse is true in adult males of nigriauris. Both males and females of latirostra have a generally smaller skull with relatively broader interorbital and postorbital parts and the tympanic bullae are relatively larger, rounder and more inflated.

Compared with the skull of the male of pulchra that of latirostra is, by weight, more than one-fourth lighter, has a lesser basilar and orbitonasal length, lesser zygomatic and mastoid breadth and a more nearly flat braincase. In these features no overlap has been observed between adults from the general vicinities of the type localities of the two subspecies. Also, in latirostra the tympanic bulla is longer than the rostrum whereas the opposite is true in pulchra. The skull of latirostra is generally smaller and relatively, on the average, has the preorbital part of the skull deeper and broader with longer tooth-rows, although with shorter rostrum, while the zygomatic and mastoid breadths are less. Study of skulls of subadult females of pulchra indicate that females of latirostra and pulchra differ in the same fashion as do males.

Remarks.--This subspecies long has gone by the name M. xanthogenys and the type locality was generally supposed to be in the vicinity of San Diego. This supposition seems to have originated with Merriam's (1896:25) statement that the type locality was "Southern California, probably vicinity of San Diego." Nevertheless, as set forth in the account of M. f. xanthogenys the type specimen concerned now is thought to have come from much farther north.

Although 76 Recent specimens are available from southern California, additional adults are needed to understand the geographic variation there. M. f. latirostra may be a composite--made up of more than one geographic race. Specimens from San Diego County differ so much in relative length of the tail that at one stage in the present study it was thought that a difference in this respect existed between the coastal animals and those from farther inland. Material received later did not wholly substantiate this view and because of the uniformly small size of all of the skulls from that county, the animals were later regarded as of the same subspecies. Eventually, even this supposed common feature proved to be inconstant for an adult male from Jamacha, no. 7098, of the San Diego Society of Natural History, and another adult male from San Marcos, no. 8869, collection of Ralph Ellis, were later examined and found to have skulls as large as those of average-sized, adult males of nigriauris.

Despite these puzzling local variations, it is established that the long-tailed weasels of southern California are smaller than those from farther north. Also, the southern animal averages smaller in weight and size of skull, and the skull is differently proportioned. Specimens in series from Los Angeles County definitely are intermediate in size and shape of skull between latirostra from San Diego County and nigriauris from, say, Santa Clara County, but definitely more closely resemble latirostra from San Diego County than they do nigriauris. A skull of a young animal, not here identified to subspecies, from Potholes, in the Colorado River Valley, 10 miles northeast of Bard, Imperial County, California, may have closest relationship to M. f. latirostra. Additional comment on this specimen is offered in the account of M. f. neomexicana.

From the asphalt pits of Rancho La Brea, in Los Angeles County, a total of 57 skulls have been examined, more than half of which are reasonably complete. I have been unable to learn whether these came from pits regarded by students of the deposit as wholly Recent, from pits regarded as of Pleistocene age, or from both. Suffice to say that only two specimens were found which could be distinguished from skulls of the subspecies of weasel living in that area today.

These two specimens, lent to me by Professor Chester Stock, were with other skulls received from the Los Angeles Museum of History, Art and Science and bore identifying numbers as follows: 16/20-27, the anterior part of the skull of an adult, and 16, the skull posterior to the cribiform plate of a subadult or possibly young individual. The latter has a mastoid breadth of 28.0 millimeters, a tympanic bulla 16.1 long and other measurements in proportion. It is larger than any specimen of weasel, of any subspecies, seen from California and in the subgenus Mustela seems to be exceeded in size only by certain individuals of M. f. texensis. M. f. neomexicana attains relatively large size and comparisons were made with individuals of that subspecies. However, the young specimen from Rancho La Brea differs from neomexicana in that the tympanic bullae rise less steeply on the medial sides and the inferior lip of the external auditory meatus is less developed laterally. Age considered, the sagittal crest is less developed and the mastoid processes project more abruptly from the skull. The anterior part of the skull of the adult, no. 16/20-27 is larger than any specimen seen of M. f. latirostra or adjoining subspecies, and among California-taken specimens is equaled in size only by the largest males of M. f. munda from the northwest coastal district in Mendocino County. This adult from Rancho La Brea differs from neomexicana, sex and age taken into account, in greater postorbital breadth, lesser rostral width in comparison with the interorbital breadth, and in having the temporal ridges at the anterior end of the sagittal crest spread out into a Y-shaped, rather than a T-shaped, pattern. All these differences from neomexicana are features of agreement with the California bridled weasels of the subspecies latirostra, nigriauris, and munda. The same is true of the characters which set apart the young specimen from neomexicana. In summary: of 57 weasel skulls examined from the asphalt pits at Rancho La Brea, Los Angeles County, all but two are indistinguishable from the skulls of the Recent weasel living in that region today. These two skulls agree in qualitative characters with animals of the California coastal subspecies now living from Los Angeles northward to Humboldt County, but are larger. For the time being these two may be thought of as giants of the same type of animal inhabiting the Los Angeles region today.

Only one of 41 adult and subadult skulls examined for malformation of the frontal sinuses shows infestation by parasites.

Specimens examined.--Total number, 142, listed by counties from north to south. Unless otherwise indicated specimens are in the Museum of Vertebrate Zoölogy.

=California.= Santa Barbara County: Rincon Point, 1. Ventura County: Cuyama Valley, 2200 ft., 1; Nordhoff, 3; Santa Paula, 1; Ventura, 7. Los Angeles County: near Owensmouth, 1; Cahuenga, 1; Llano, 10 mi. E Littlerock, 1; Flint Ridge, Pasadena, 1; Pasadena, 3; Lankershim, 1; 1 mi. S Lankershim, 1; Duarte, 1; Covina, 1; Claremont, 1; El Monte, 4 (2, 1); Montebello, 1; Alhambra, 6 (5, 1); El Nogal, 2; Gardena, 1; Palos Verdes Estate, 3; Rancho La Brea asphalt deposits, 57^{ and }. San Bernardino County: San Bernardino Valley, 1; San Bernardino, 4 (2, 1); Redlands, 2 (1); Bluff Lake, 2 (1, 1). Riverside County: West Riverside, 1; Arlington, 800 ft., 1; 3-1/2 mi. E and 1/2 mi. N Beaumont, 2600 ft., 1; Banning, 1; Cabazon, 1; San Jacinto Plain, 1; Tahquitz Valley, 8000 ft., 1; Elsinore, 1. San Diego County: Twin Oaks, 1; San Marcos, 2 (1, 1); Escondido, 1; Witch Creek, 1; Ballena, 1; Santa Ysabel, 3 (2, 1); Julián, 1; La Jolla, 1; Lakeside, 1; El Cajon, 1; El Vido (not found on map), 1; San Diego, 9 (1, 1, 1, 1); Jamacha, 2; Chula Vista, 1.

=Mustela frenata pulchra= Hall

Long-tailed Weasel

Plates 22, 23 and 24

Mustela frenata pulchra Hall, Carnegie Instit. Washington Publ. 473:98, November 20, 1936.

Type.--Male, adult, skeleton and skin; no. 16668, Mus. Vert. Zoöl.; Buttonwillow, Kern County, California; April 30, 1912; obtained by J. Grinnell; original no. 1953.

The skull (plates 22-24) is complete and unbroken (a fracture in the right jugal has healed). All teeth are present and entire. The skeleton lacks the os penis, left fibula, shaft of left tibia and the distal three or four caudal vertebrae. Some of the bones of the feet distal to the radius and tibia are with the skeleton, and the remainder probably are in the skin. The skin is fairly well made and in good condition, except for the left hind leg which was torn when the animal was captured. A well-developed scrotal pouch shows the specimen to have been a male.

Range.--Altitudinally around 300 feet in San Joaquin Valley to 2500 feet at Isabella; Upper Sonoran and Lower Sonoran life-zones of southern end of San Joaquin Valley and in mountains at southern end of Valley, California. See figures 29 and 30 on pages 221 and 314.

Characters for ready recognition.--Differs from M. f. nevadensis in presence of light facial markings, and from M. f. nevadensis and M. f. inyoensis in near (16 j) Buckthorn Brown to near (h) Yellow Ocher rather than near (14 n to l) Brussels Brown color of upper parts, and greater size with hind foot more than 40 in females and basilar length averaging more than 46.0 in males; from M. f. latirostra in having rostrum (orbitonasal length) longer than tympanic bulla and from M. f. latirostra and M. f. nigriauris by color of upper parts as stated above rather than near (l) Antique Brown, and by having inside of ears same color as back rather than much darker than back; from M. f. xanthogenys in hind foot of males more than 46 and broader skull which in males has breadth of rostrum more than 13.9 and mastoid breadth more than 26.0.

Description.--Size.--Male: The type specimen and five other adults yield average and extreme measurements as follows: Total length, 454 (428-477); length of tail, 178 (153-184); length of hind foot, 50 (47-55). Tail averages 65 per cent as long as head and body. Length of hind foot approximately equal to basal length. The type specimen measures, 460, 184, 49.

Female: Three subadult topotypes yield average and extreme measurements as follows: Total length, 399 (383-411); length of tail, 154 (140-161); length of hind foot, 42 (41-42). Tail averages 63 per cent as long as head and body. Length of hind foot less than basal length.

The average differences in external measurements of the two sexes are: Total length, 55; length of tail, 24; length of hind foot, 8.

Externals.--As described in Mustela frenata nigriauris.