Males seem to be a little larger than females, on an average, with proportionally longer tails. We are unable to find anything in our material to indicate variation in measurements with either altitude or latitude within the state of California.
Weights.—Average and extreme weights, in grams, of twenty adult specimens from Inyo County are as follows: Ten males, 104.4 (94.5–120.7); ten females, 104 (83.6–115.0). Average in ounces, for both males and females, about 3⅔.
Type locality.—San Gorgonio Pass, below [east of] Banning, Riverside County, California (Merriam, 1889, p. 20; Stephens, 1906, p. 75).
Distribution area.—In general, the southeastern desert region (see fig. 24). Life-zone chiefly Lower Sonoran, but extends locally up through Upper Sonoran and even into Transition (see fig. 23). More specifically, the Colorado and Mohave Deserts (not, however, in some of the sandier or low-lying parts) from the Mexican line on the western rim of the Imperial Valley and the vicinity of Picacho on the lower Colorado River, north to the extreme head of Owens Valley in the vicinity of Benton, Mono County (Mus. Vert. Zool.).
Along the western edge of the area inhaabited by this squirrel, it extends well up onto the sides of the confining mountains and often far through the passes, as far as arid conditions prevail; for example, in San Gorgonio Pass, Riverside County, above Cabezon, and over Walker and Kelso passes, in Kern County, down the valley of the South Fork of the Kern River to as far at least as Weldon (Mus. Vert. Zool.), thus well over the rim of the San Joaquin basin. There are in southern California at least two outlying colonies on the Pacific side of the desert divides; namely, in San Jacinto Valley, Riverside County (Grinnell and Swarth, 1913, p. 326), and in Lytle Creek wash within six miles northwest of San Bernardino, in San Bernardino County (Mus. Vert. Zool.).
Altitudinally, the species ranges from below sea-level, as at Furnace Creek Ranch, -178 feet, in Death Valley, up regularly to 6,000 feet on most of the desert mountains which reach that height, and in some instances to 7,500 feet, as at the north base of Sugarloaf in the San Bernardino Mountains (Grinnell, 1908, p. 141), and even to 8,500 feet, as near the head of Mazourka Canyon, in the Inyo Mountains (Swarth, MS).
Specimens examined.—A total of 271, from the following localities in California. Mono County: Benton, and two miles south of Benton Station, 11. Inyo County: Laws, 6; Silver Canyon, White Mts., 9; Mazourka Canyon, Inyo Mts., 5; Independence, and two miles north of Independence, 19; west base Kearsarge Pass, Sierra Nevada, 4; Lone Pine Creek, 4,500 ft., 10; Carroll Creek, 5,500 ft., and Hockett Trail, 6,500 ft., near Carroll Creek, 4; Keeler, 31; Olancha, 2; Darwin (fifteen miles, and two miles, north of), 7; Panamint Mts. (Emigrant, Wild Rose, Hanaupah, and Johnson canyons), 17; Furnace Creek Ranch, and Triangle Spring, in Death Valley, 13; Shoshone, 2; Little Lake, 2. Kern County: Weldon, Onyx, and west slope Walker Pass, 16; one mile east of Warren Station, 1; Mohave, 12. Los Angeles County: Fairmont, 8. San Bernardino County: one mile northeast of Barstow, 1; Oro Grande, 2; mountains on west side of Colorado River, lat. 35°, 1; Blythe Junction, 1; five miles below Needles, 1; opposite The Needles, 5; Chemehuevis Valley, 2; Victorville, 14; San Bernardino Mts. (Cushenbury Springs, Cactus Flat, Doble, north base of Sugarloaf), 17; Cajon (Lytle Creek) Wash near San Bernardino, 1. Riverside County: base of San Jacinto Mts., near Cabezon, 7; Snow Creek, near Whitewater, 5; Vallevista, San Jacinto Valley, 4; Palm Springs, 7; Carrizo Creek and Dos Palmos Springs, Santa Rosa Mts., 5; Palm Canyon, San Jacinto Mts., 1; Riverside Mt., near Colorado River, 1. San Diego County: San Felipe Valley, 2; Grapevine Spring, 1; La Puerta, 2; Vallecito, 2; Jacumba, 1; Mountain Spring, 1. Imperial County: Colorado River, opposite Cibola, 2; twenty miles north of Picacho, 4; eight miles east of Picacho, 2.
The Antelope Ground Squirrels constitute a group distinct in many ways from all our other species. They are hardly less inhabitants of the ground, as compared with the tree squirrels and true chipmunks, but in manner they are more vivacious than any of the other ground squirrels; they run at a much faster clip and hence can forage at greater distances from safety refuges. Their coloration is distinctive, too, gray, with one white stripe along each side of the back, and with the
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