916 16. CROTALIDA 
Description.—Large. Head broad, flat-topped, varying 
in outline according to position of fangs. Rostral usually 
higher than wide, in contact with anterior nasal. Two nasals. 
Usually two preoculars and two to four internasals. A 
large scale just in front of supraocular. Supraocular large 
but not raised into a horn-like process; separated from its 
fellow by from three to six irregular rows of scales. About 
13 to 17 superior and 14 to 18 inferior labials; first pair 
of latter usually meeting on median line in front of a single 
pair of genials, but rarely divided. About three to five rows 
of scales between supralabials and eye. Scales in 25 to 27 
rows, of which one or two on each side are smooth. Gas- 
trosteges varying from 179 to 191. Urosteges 17 to 27. 
The general color is yellowish or grayish brown, with a 
series of large, darker brown blotches along the back. These 
blotches often are not well defined, usually are not com- 
pletely enclosed in light borders, and show much of the 
punctulate or pepper-and-salt style of coloration. The sides 
are more or less indefinitely spotted or blotched with dark 
brown in the same punctulate manner, and sometimes show 
pinkish shades. The head is nearly unicolor above or 
mottled with darker. A yellowish or whitish stripe runs 
across the side of the face from the preocular plates to the 
mouth. The scales behind and above this light stripe are 
darker than the ground color and are set off posteriorly by 
a light streak which runs down and back from the corner of 
the eye and strikes the supralabials in front of the corner of 
the mouth. The tail is whitish or grayish with about four 
to six black cross bands or rings. The lower surfaces are 
yellowish white. 
Ikength to anus.22- = 840 870 975 1000 1060 1280 
Length of tail to base 
Of rattle ane te 55 65 65 83 82 102 
