962 16. CROTALIDZ 
XXIII, XXVIII, fig. 2; Srrecker, Baylor Bulletin, Vol. XVIII, 
No. 4, 1915, p- 45; STEJNEGER & Barpour, Check List N. Amer. 
Amph. Rept., 1917, p. 109; Woruies, Univ. Ariz. Agric. Exper. 
Station Bull. No. 83, 1917, p. 359. 
Description.—Size small. Head broad, flat-topped, 
with rather narrow snout. Rostral about as high as wide, in 
contact with anterior nasal. Two nasals, sometimes united. 
Two preoculars. Two or three postoculars. A large scale 
just in front of supraocular. Supraocular large, but not 
raised into a horn-like process; separated from its fellow by 
about three to five irregular rows of scales. Eleven to 14 
superior and 10 to 12 inferior labials, first pair of latter in 
contact on median line in front of single pair of genials. One 
to three rows of scales between supralabials and eye. Scales 
in 21 to 23 rows, keeled except in two or three rows on each 
side. Gastrosteges varying from 153 to 169. Anal not 
divided. Urosteges varying from 18 to 31. 
The color above is a greenish or bluish or ashy gray with 
about 17 to 19 dark brown or black blotches or cross-bands 
between the head and anus. These dark markings are sep- 
arated along the middorsal line by intervals from two to five 
times their own length along that line. They may extend 
laterally to the gastrosteges, or may be divided laterally 
into spots. Their outlines usually are irregular or serrate. 
The scales at their margins are often spotted with very dark 
brown or black, and similar spots are scattered sparsely 
through the gray intervals. The scales of the first two or 
three lateral rows may be tinted with salmon pink or orange. 
The head is of the gray ground color, minutely dotted with 
blackish brown, but without definite dark markings. The 
lower surfaces are yellowish white, more or less clouded with 
brown or gray. The tail is gray proximally, orange or sal- 
mon distally both above and below, crossed by from two to 
four brown bars or rings. 
