820 BULLETIN 56, UNITED STATES NATIONAL MUSEUM. 



near Port Verde (altitude about 5,500 feet); while young no larger 



than the eastern red squirrel Were taken in the Verde River bottom, 

 2,0(11) feet lower, two months later; and a female, shot near Fort 

 Verde on dune 14, contained five small fetuses. 



The normal individual variation in color is considerable in this spe- 

 cies. This variation consists in the relative preponderance of shades 

 of gray, brown and fulvous above, and in the color of the under sur- 

 face, which varies from soiled white to brown. Examples from the 

 Verde Valley, taken early in June, had shed their coats on the front 

 half of the body, the after parts remaining lone- haired and of a dif- 

 ferent color from the front half. Their tails were very scantily haired 

 at that season. Slightly melanistic examples were occasionally seen; 

 and a perfect albino, having colorless (daws and pink eyes, was taken 

 alive at Whipple Barracks, Arizona, on September 20, 1887. The 

 latter was a young of the year and died soon after its capture. Males 

 were sometimes taken, though rarely, in which the testicles were 

 abdominal: and, in one specimen, they were wholly absent. 



On the United States and Mexican Boundary line this rock-squirrel 

 is found in rocky places in the Eastern Desert Tract. Some were seen 

 at El Paso early in November, 1892. Several were seen at the Upper 

 Corner (Monument No. 40), April and May, 1892. One was shot on 

 the actual summit of Hachita Grande, altitude 2,545 meters or 8,350 

 feet. Thence westward it was seen in abundance, except in cold 

 weather, to La Osa (Monument No. 140). It was especially abundant 

 in the oak forests of the San Luis and Patagonia mountains, and was 

 sometimes utilized as food by members of the Survey. We saw none 

 while camped at Pozo de Luis, Sonora, from December 20, 4893, to 

 January 8, 1894, but "squirrels" were seen farther west, at Nariz 

 Mountain, by several members of the party, which may have been this 

 species or Ammospermophihos harrisii. 



In the Dog Mountains one was shot on Emory Peak, and the skin 

 was made into a purse by " Bob," an Apache Indian trailer. Although 

 this species was abundant, no form of Euta/mias or Ammosperrncphihis 

 was found to inhabit the Dog - Mountains. 



It was common from the lower timber line to the summit (2,498 

 meters or 8,196 feet) of the San Luis Range, where it often climbed 

 the tallest oaks for acorns, upon which it loves to feed. A female con- 

 tained T small fetuses, .June 23, 1892, and young, from half to two- 

 thirds grown, were taken at the end of September; quite young ones, 

 duly 18. 



I found it exceedingly numerous on the upper forks of Cajon Bonito 

 Creek in September, 1893. It uttered a startling succession of loudly 

 whistled notes in descending scale and single loud whistles. It was 

 unusually active after rain. It was feeding on mallow, walnut, and 

 oak mast. It often burrowed into the enormous piles of driftage 



