210 University of California Publications in Zoology I VoL - 10 



servations be made and specimens acquired from the base of the 

 mountains bordering the pass, and four camps were therefore 

 established in this region, at Cabezon, Snow Creek, Whitewater 

 and Banning. These were all on the desert slope. The San 

 Diegan fauna and flora extend over the summit of the divide 

 well down towards the desert, and it was the region of blending 

 with the desert fauna that we wished especially to explore. 



The first camp was at Cabezon. The railroad station of this 

 name, about twelve miles from Beaumont at the divide, lies 

 aboul midway between the summit of the pass and the floor of 

 the desert, ('amp was established in the foothills, a mile and a 

 half south of the railroad, a1 an elevation of about 1700 feet. 

 The precipitous slopes at I his end of the mountains are clothed 

 to their bases with the dense Upper Sonoran chaparral charac- 

 terisl ic of the Pacific side of the range, while the canons are steep 

 and narrow, containing comparatively few trees. This associa- 

 tion carries with it many of the birds and mammals of the 

 Pacific slope, these in must eases extending cpiite to the base of 

 the hills, but not out upon the floor of the valley below. This 

 latter area, also densely covered with brush and cactus, but of 

 Lower Sonoran forms, is inhabited by a few desert species of 

 animals though many of the most typical do not ascend this high 

 in the pass. The vegetation here is of the character of the 

 Lower Sonoran washes of the San Diegan district rather than 

 that of the Colorado Desert, but some desert plants, such as 

 the mesquite, were also found in small quantity. 



Field work was prosecuted at Cabezon from May 1 to 25. 



Snow Creek 

 Snow Creek is an extremely precipitous canon extending due 

 north from the rocky summit of San Jacinto Peak and empty- 

 ing onto the floor of the desert near Whitewater, about seven 

 miles east of Cabezon. Camp was established at the mouth of 

 the canon, at about 1500 feet elevation. San Jacinto Peak, 

 toweling above, at an altitude of 10,805 feet, was in an air line 

 less than five miles distant, the mountain sides here being little 

 less than a series of precipices. A narrow line of trees bordered 

 the creek, mostly alder, with an occasional cottonwood. Away 



