REPTILES OF THE PACIFIC COAST. 



223 



feebly keeled except in one to three lower rows on sides 

 where smooth; those near middle of back with central 

 tubercular swellings. Gastrosteges varying at least from 

 one hundred and thirty-four to one hundred and forty- 

 six. Urosteges sixteen to twenty-one, a few sometimes 

 divided. 



The general color above is gray, often with a yellow- 

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

 indefinite blotches of gray- 

 ish or yellowish brown. 

 Smaller blotches or spots 

 are usually present on the 

 sides and on the tips of 

 the gastrosteges. The su- 

 praocular shows an indis- 

 tinct transverse streak. A brown streak runs from the 

 eye to the corner 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 yellow- 

 ish white, sometimes faintly clouded with brown or 

 gray. 



Length to anus 415 440 450 



Length of tail to rattle ,38 42 31 



Distribution. — The Sidewinder occupies the lower lev- 

 els of the Colorado and Mojave Deserts, where the Tiger 

 Rattler occurs in the mountainous districts, and ranges 

 thence across western Arizona and southern Nevada to 

 ** southwestern Utah." In California it has been taken 

 near Salton, in the Colorado Desert; at Lone Pine, in 

 Owen's Valley; in Panamint Valley; at Borax Flat; at 

 Bennett Wells, Death Valley; and at Pilot Knob. It is 

 known to occur in Nevada in Pahrump, Vegas, and In- 

 dian Spring Valleys, at Sarcobatus Flat, in the Amar- 

 gosa Desert, and in the valleys of the Virgin and Lower 

 Muddy. 



