48. CROTALUS 933 
Crotalus helleri Meex, Field Columbian Mus., Zool. Series, Vol. VII, 
No. 1, 1906, p. 17, pl. II (type locality, San Jose, northern Lower 
California). 
Crotalus sp., Taytor, Univ. Cal. Publ. Zool., Vol. 7, No. 10, 1912, p. 355. 
Description—Moderately large. Head broad, _flat- 
topped, varying in outline according to position of fangs, etc. 
Rostral much higher than wide, in contact with anterior 
nasal. Two nasals. Usually two (very rarely one) preocu- 
lars and four internasals. A large scale just in front of 
supraocular and occasionally large scales on prefrontal 
region. Supraocular large but not raised into a horn-like 
process, separated from its fellow by three to nine irregular 
rows of scales. Twelve to 17 (usually 14 to 16) superior 
and 14 to 19 (usually 15 to 17) inferior labials, first pair 
of latter in contact on median line in front of a single pair 
of genials. Two to four rows of scales between supralabials 
and eye. Scales in 23 to 27 rows, usually 25, keeled except 
in one to three rows of each side. Gastrosteges varying from 
158 to 189; males having from 161 to 186 (usually 169 to 
180), females from 158 to 187 (usually 175 to 182). 
Urosteges 14 to 27, a few sometimes divided, males with 
from 18 to 27 (usually 21 to 25), females with 14 to 24 
(usually 16 to 20). 
The ground color is brown, olive, gray, or dull yellow, 
marked along the back with a series of large dark brown 
blotches which become cross-bars or incomplete rings poster- 
iorly. These blotches are often paler centrally than about 
their edges, and vary greatly in shade, shape, amount of 
separation, and contrast with the ground color. Their 
number varies from 27 to 41 on the body, and three to nine 
on the tail. Smaller alternating blotches are usually present 
on the sides. Many of the scales between or around the 
dark dorsal blotches are light—yellow, gray or white. These 
colors often show between the lateral dark blotches also. 
