~ 
13, CROTALUS. 577 
Snout with obtuse canthus. Rostral as deep as broad or a little 
deeper than broad, in contact with the anterior nasal ; upper head- 
scales small, striated ; ; supraoculars transversely striated, as broad . 
as or slightly narrower than the space between them, which is filled 
by 3 to 10 longitudinal series of scales ; each supraocular in con- 
tact with 6 to 11 scales in addition to the pre- and postoculars ; 
three or four series of scales between the eye and the labials; 
13 to 18 upper labials. Scales striated and strongly keeled, in 
25 to 29 rows. Ventrals 168-197; anal entire ; subcaudals 17-34. 
Yellowish, greyish, or pale brown above, with a dorsal series of 
large brown or red spots, usually edged with darker and lighter 
and commonly rhomboidal or transversely elliptic in shape; a light 
streak or triangular marking across the supraocular shield; a 
more or less distinct dark, light-edged streak from the eye to the 
mouth ;- yellowish beneath, uniform or spotted with brown. 
This species may be divided into two principal varieties, which 
are not definable by any structural characters that I know of, 
viz. :—the typical form, with a dark temporal band extending to 
the commissure of the mouth; and the Texan C. atrox, in which a 
dark band descends obliquely from the eye to the mouth far in 
advance of the commissure. 
Total length 1520 millim.; tail 140. 
Western North America, from British Columbia to South 
California, eastwards to Assiniboia, Dakota, Nebraska, Kansas, and 
Western and Southern Texas; Northern Mexico. 
a. 2 Pei 25; V. 183; Duval Co., Texas, W. Taylor, Esq. [P.]. 
"6.2 
b. a skin (Se..27; Texas. Smithsonian Instit. 
V. 185 ; C. 25). 
C. é Neg 27 ; V.187; Nebraska. Smithsonian Instit. 
d, e ey 3 (Sc. 25; V. Brit. Columbia. J. K. Lord, Esq. [P. ]. 
175; C. {yao (Se. 
25, 25 ; V. 183, 175; 
C. 17, 17). 
g.3 (Se. 25; V.173; Coronado Ids., off San Prof. Eigenmann 
C. 22), Diego, California. E.}. 
h. é ire. 25; V.181; California, Christiania Mus. 
1. Her. (Se. 25; V. California. Lord Walsingham 
176; C. 18). 1 
k. 8 Le 27; V.174; California. Haslar Collection. 
. 26 
‘lm o (Se. 25; V. W.Coastof N. America. Sir E. Belcher [P.]. 
n-0o. 2 (Sc. 27; V. N. America. 
190; C. 22) & yg. 
(Se. 27; V.172; 0.25). 
p 6 Ayes 25; V. 182; ——? Zoological Society.. 
VoL, III. 2p 
