MAMMALS OF THE MEXICAN BOUNDARY. 305 



numerous holes by which to make its escape; but it oftener stops and 

 chirrups saucily, stamping with its fore paws. Its curiosity is so great 

 that a few sharp chirrups with one's lips will often bring it to the 

 entrance of its burrow, or it may run directly up to within a few feet 

 of one. Then it stops, ftahips, and jerks its tail, presently beating 

 an equally precipitate retreat and diving into its burrow with a loud 

 note of alarm. Its call-note is a quick, hollow whistle; and it also 

 utters metallic chirrups and chipperings suggestive of its impulsive 

 natui'e. It verjr commonly sits up perfectly erect upon its hind 

 feet, like the prairie-dog. The perpendicular carriage of its tail, 

 when running, is characteristic. In the vicinity of Fort Verde the 

 rutting season is from the middle of January to the middle of March, 

 during which time the genitals of the male are enormously enlarged 

 and the animal very active. A female killed on March 20 contained 

 six fetuses of about the size and shape of small grapes. By the mid- 

 dle of July the young are half grown. 



It inhabits the low banks and arroyos along the Verde River. The 

 entrances of its burrows are numerous in these clay surfaces, and here 

 the ground-squirrels frequently sit sunning themselves in cold weather. 

 It is also found in the rocky slopes bordering the valley, but not so 

 plentifully as in the rich river-bottom where its food is more abun- 

 dant; but it even ascends farther, across the lower mesas to the cedar 

 forests, where its range is abruptly limited by a high cliff or rim rock, 

 bordering an elevated plateau. At the higher levels it feeds upon the 

 fruitage and seeds of the Spanish bayonet, which I have found in large 

 heaps under the stones, where it makes its home. There is snow occa- 

 sionally at this altitude, but these ground-squirrels were seen running 

 about more freely than those in the warm valley below. 



One year, when the crop of mesquite mast failed, the Harris ground- 

 squirrel migrated,from the Verde Valley in large numbers, so that the 

 species was comparatively rare for a whole year. 



This ground-squirrel is to some extent carnivorous, as is well known 

 to be the case with the prairie-dog and the large ground-squirrel { Oto- 

 spermophilus grammurus) of this region. I have poisoned it upon the 

 carcass of a cougar, whose flesh was poisoned with strychnine. 



On the Mexican Boundary the Harris ground-squirrel was not 

 observed east of the Pajaritos Mountains, but was plentiful in rocky _ 

 country, thence west to the Colorado River, grading into the sub- 

 species saxicolus West of Quitobaquita. In 1884 it was noted about the 

 San Carlos Agency. In 1885 I traced it from Fort Verde through the 

 Agua Fria Valley, the Black Canyon, Desert Well, Phoenix, Casa 

 Grande, Sweet Water, and the Santa Cruz Valley. In 1893 and 1894 

 the range of the typical form was traced through the Santa Cruz Val- 

 ley into Sonora, Mexico. In December, 1893, it was abundant in a 

 pass of the Pozo Verde Mountains, Sonora, near Monument No. 141 ; 

 30639— No. 50—07 m— 20 • 



