13. CROTAtirS. 



577 



Snout with obtuse canthus. Rostral as deep as broad or a Uttle 

 deeper than broad, in contact with the anterior nasal ; upper head- 

 seales small, striated ; supraoculars transversely striated, as broad 

 as or slightly narrower than the space between them, which is fiUed 

 by 3 to 10 longitudinal series of scales ; each supraocular in con- 

 tact with 6 to 11 Scales in addition to the prsB- 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. atroio, 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 j Northern Mexico. 



a. 5 (Sc. 25; V. 183; 

 C. 20). 



b. Ad., skin (Sc. 27 ; 

 V. 185 ; 0. 25). 



c. $ (Sc. 27 ; V. 187 ; 

 C. 21). 



d,e,f. cJ (Sc. 25; V. 



175;G.23)&2 (So. 



26,25; V. 183, 175; 



C. 17, 17). 

 g. 6 (Sc. 25; V. 173; 



C. 22). 

 h. S (Sc. 25 ; V. 181 ; 



C. 20). 

 i. Hgr. (Sc. 25 ; V. 



176; C. 18). 

 ft. 6 (Sc. 27 ; V. 174 ; 



0. 26). 

 I, m. 3 (Sc. 25; V. 



168 ; C. 20) & $ (Sc. 



25; V.?; 0.17). 

 n-o. $ (Sc. 27; V. 



190; 0. 22) & yg. 



(Sc. 27;V.172;C.25). 

 P. 2 (Sc. 25 ; V. 182 ; 



C. 24). 



TOL. ni. 



Duval Co., Texas. 



Nebraska. 

 Brit. Columbia. 



W.Taylor, Esq. [P.]. 

 Smithsonian Instit. 

 Smithsoman Instit. 

 J.K.Lord,E3q.[P.].. 



Coronado Ids., oflE San Prof. Eigenmann 



Diego, California. [E.]. 



California. Christiania Mus. 



California. 

 California. 

 W. Coast of N. America. Sir E. Belcher [P.]. 



Lord Walsingham 



[P.]. 

 Haslar Collection. 



N. America. 



Zoological Society. 



2p 



