under side of the tail brilliantly white. This latter feature is in itself unique, for it is accompanied by a most striking mannerism, that of the almost constant carriage of the stubby, flat-haired tail in an upright position, held against the back, so that the white under surface shows as a white "flag" when the animal is scurrying away, much as with the similarly advertising marks of the cottontail rabbit and antelope; only with the ground squirrel the effect in catching the eye of the observer is still further heightened by the way in which it is spasmodically twitched whether the animal be at rest or running. This flickering beam of white ever holds the attention as long as the squirrel is below the level of the horizon, and short of its burrow or the concealing tangle of prickly vegetation which it is so anxious to put between it and its pursuer.
The race called appropriately Desert Antelope Ground Squirrel (locally, Antelope "Chipmunk" because of its stripes, small size and sprightly manners) occurs broadly over the Colorado and Mohave deserts, thence north clear through the Inyo region. It shows rather wide adaptability to the varying conditions in this vast area, more so than any other desert ground squirrel, and ranges from below sea level, as on the floor of Death Valley, up regularly to 6,500 feet on the steep slopes of the desert mountains. It even "spills over" the confining rim of the Mohave Desert to the westward, locally, on to the Pacific drainage, as shown in detail in the accompanying list of specimens and on the map (fig. 24). Although notably continuous in its range over great stretches of country, it is not difficult to discover preferences, as indicated by relative abundance. Level sandy ground is, as a rule, but sparsely inhabited; and we know of some stretches of desert, such as the floor of the Coachella Valley northwest of Salton Sea, where none at all seem to exist, although the species is abundant in the foothills adjacent. The kind of ground most generally preferred seems to be hard-surfaced, gravelly wash-fans or hill slopes. Kinds of vegetation present seem to be immaterial, though clumps of squaw tea, creasote bush, cactus, or tree yucca characterize much of the territory where the Antelope Squirrels are most abundant.
Our mention of the above preferences must not give an erroneous idea as to special nature of the habitat of this species. It may be said again, for emphasis, that this animal thrives in a great variety of situations. We have seen it on the mesquite-crowned sand dunes of Death Valley, there as a companion of the Death Valley Round-tailed Ground Squirrel; on the sagebrush covered flats at the extreme head of Owens Valley, in the metropolis of the Stephens Soft-haired Ground Squirrel; on the creasote hillsides near Little Lake, one of our very few record stations for the Mohave Ground Squirrel; among the piñons and granite boulders of the northern section of the Panamint Mountains, then associated with the big Fisher Ground Squirrel; and even upon the steep rocky slopes of the White Mountains at 7,800 feet altitude, in the same rock slides with the Inyo Golden-mantled Ground Squirrel! Truly a cosmopolite is the Antelope Ground Squirrel, just so far as the dry atmosphere of the desert extends; but the coastal fog and general humidity of the Pacific drainage are almost strictly taboo.
The burrow of this rodent is in nearly all cases situated at the side of a dense brush-clump or boulder so that protection is afforded from
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