48. CROTALUS 955 



or vinaceous tinge, with a series of rather small and indefinite 

 blotches of grayish or yellowish brown. There usually are 

 from 31 to 33 of these blotches between the head and anus, 

 and from three to nine on the tail. Smaller blotches or 

 spots usually are present on the sides and on the tips of the 

 gastrosteges. The supraocular shows an indistinct trans- 

 verse streak. A brown streak runs from the eye to the cor- 

 ner of the mouth. The tail is ash-color with half rings of 

 brown, which are much darker near its tip than anteriorly. 

 The lower surfaces are yellowish white, sometimes faintly 

 clouded with brown or gray. 



Length to anus 4-04 415 428 440 450 592 



Length of tail to rattle.... 30 38 42 42 31 38 



Distribution. The Sidewinder occupies the lower levels 

 of the Colorado and Mohave Deserts in California, where 

 the Tiger Rattler occurs in the mountainous districts, and 

 ranges thence across Arizona and southern Nevada to "south- 

 western Utah." 



It is known to occur in southern Nevada in Pahrump, 

 Vegas and Indian Spring Valleys, at Sarcobatus Flat, in the 

 Amargosa Desert, and in the valleys of the Virgin and 

 Lower Muddy, and in Cotton wood Canyon. 



In Arizona, it has been found at Yuma and Chrystoval, 

 Yuma County; Salado Valley near Tempe, Maricopa Coun- 

 ty; Fort Buchanan, Santa Cruz County; and at Vulture. 



It is said to be common in northeastern Lower California, 

 where it is confined to the lower gulf strip, and has been 

 secured at San Felipe. 



In California, it has been taken at Chalput, Mono Coun- 

 ty; Keeler and Lone Pine in Owen's Valley, Borax Flat, 

 Panamint Valley, Mesquite Valley, Ballarat, Echo Canyon 

 in the Funeral Mountains, Furnace Creek Ranch and Ben- 

 nett Wells in Death Valley, Inyo County; Barstow, Daggett, 



