934 16. CROTALIDE 
Young specimens show a light transverse streak on the supra- 
ocular, usually not present in adults. A dark streak runs 
from the eye to the corner of the mouth, the line of its 
lower edge striking the eye about under the pupil, although 
a narrow forward continuation may be present. This dark 
streak is bordered above by a light streak which is wider than 
the width of one scale and passes above the corner of the 
mouth. Another light streak crosses the side of the face 
below the dark one and usually is bordered in front by a 
dark brown patch on the side of the snout. Sometimes these 
markings are more or less completely obscured. The tail 
is provided with brown and light rings, a few of the former, 
near the tip of the tail, being occasionally blackish. The 
lower surfaces are white or yellow, more or less spotted or 
clouded with brown. 
Some specimens are nearly black, and one from Utah is 
pure white without any markings. 
dkenpth \towantsie sees es 253 540 740 810 810 960 
Length of tail to base of rattle 22 35 43 64 85 77 
Distribution —The Pacific or Black Rattlesnake occupies 
all parts of California except the Colorado and Mohave 
deserts. It ranges south into northern Lower California and 
north across Oregon and Washington to British Columbia. 
Farther east, it occurs in Idaho along the Snake River, and 
has been taken in many parts of Nevada, in Utah, and in 
Arizona. Throughout the northern part of this territory it 
is the only rattlesnake, but in the southern regions is found 
with other species. 
In California, it ranges from sea level up at least to an 
altitude of 8,600 feet in the Sierra Nevada. Specimens have 
been taken in San Diego (De Luz, Bonsall, San Diego, 12 
miles northwest from San Diego, Julian, Dulzura, Cuyama- 
ca Mountains, Orcutt, Witch Creek, Santa Ysabel, Campo, 
