13. OBOIALUS. 583 



light-edged cross-bands narrowing on the sides ; two dark spots or 

 a V- or heart-shaped black marking on the nape ; a dark streak 

 behind the eye present or absent ; beneath dirty white spotted with 

 brown. 



In C. palmeri, Garm., which appears to be based on a colour 

 variation 6i this species, the markings are much effaced on the 

 body and altogether absent on the head. 



Total length 350 millim. ; tail 60. 



Western Texas, New Mexico, Arizona, North Mexico. 



a. cJ (Sc. 23 ; V. 169 ; C. 31). Milpas, Durango. Hr. A. Forrer [C.]. 



11. Crotalus cerastes. 



Orotalus cerastes, Hallow. Proc. Ac. Philad. 1854, p. 95, and Rep. 



U.S. Surv. JR. B. x., Williamson's Sep. p. 17, pi. iv. fig. 1 (1859) ; 



Kennicott, Sep. JI.S. Mex. Bound. Surv. ii. Sept. p. 14, pi. iii. 



(1859) ; Cope, Proc. Ac. Philad. 1859, p. 337 ; Jan, Icon. G4n. 46, 



pi. iii. fig. 5 (1874) ; Garm. N. Am. Sept. p. 116 (1883) ; Cope, 



Proc. U.S. Nat. Mm. xiv. 1892, p. 689 ; Stejneger, N. Am. Fawn. 



no. 7, p. 216 (1893), and Rep. U.S. Nat. Mus. f. 1893, p. 450, 



flgs. (1895). 

 Oaudisona cerastes, Cope, Proc. Ac, Philad. 1866, p. 309, and 1867, 



p. 85. 

 (^chmophrys) cerastes, Coues, Wheeler's Surv. W. 100th 



Mer. V. p. 609 (1875). 



Canthus rostralis rounded. Eostral as broad as deep or a little 

 broader than deep, in contact with the nasal, which is single ; snout 

 and vertex covered with small scales ; supraocular produced into a 

 raised horn-like process ; two or three series of scales between the 

 eye and the labials ; 11 to 13 upper labials. Scales in 21 or 23 

 rows, dorsals feebly keeled, each scale along the middle of the back 

 with a central tubercular swelling. Ventrals 146 ; anal entire ; 

 Buboaudals 17. Yellowish above, with a dorsal series of rather 

 indistinct brown blotches ; a narrow brown streak from the eye to 

 the angle of the mouth. 



Total length 250 millim. ; tail 20. 



Desert regions of Southern California, Nevada, Arizona, and Utah. 



