574 TIPEKID^. 



Crotalus horridus, part., Qray, Cat. p. 20 (1849). 



molossus, Baird ^ Oir. Cat. N. Am. Rept. p. 10 (1853), and 



Mep. U.8. Mex. Bound. Surv., ii. Rept. pi. ii. (1869) ; Oarm. Bull. 



JEssex Instit. xix. 1888, p. 123 ; Cope, Proc. U.8. Nat. Mus. xiv. 



1892, p. 688 ; Stejneger, Rep. U.S. Nat. Mus.f. 1893, p. 424 (1895). 

 ornatus, Hallow. Proc. Ac. Philad. 1854, p. 192, and Rep. U.S. 



Surv. JR. R. X., Parke's Rep. p. 23, pi. ii. (1859). 

 durissiis (non L.), Cope, Proc. Ac. Philad. 1859, p. 337 ; Garm. 



N. Am. Rept. p. Ill (1883) ; Cope, Proc. U.S. Nat. Mus. xiv. 



1892, p. 688. 

 Caudisona ba.silisca, Cope, Proc. Ac. Philad. 1864, p. 166, and 1866, 



p. 308. 



■ durissa, Cope, Proc. Ac. Philad. 1866, p. 308. 



molossus. Cope, I. c. 



Crotalus rhombifer (non Latr.), Dugis, Naturaleza, iv. 1877, p. 22. 



basiliscus. Cape, Proc. Amer. Philos. Soc. xxii. 1885, p. 180 ; 



JDvges, Naturaleza, (2) i. 1888, p. 133; Cope, Proc. U.S. Nat. 

 Mus. xiv. 1892, p. 688. 



terrificus, Cope, Proc. U.S. Nat. Mus. xiv. 1892, p. 688. 



horridus, var. unicolor, v. Lidth de Jeude,' Notes Leyd. Mus. 



ix. 1887, p. 133. 



Snout very short, with, obtuse canthus. Eostral as deep as 

 broad or a little deeper than broad, in contact with the anterior 

 nasal ; upper surface of snout covered by a pair of internasals and 

 a pair of praefrontals, rarely with one or two small shields between 

 them ; scales between the supraoculars often more or less enlarged 

 or shield-like, in two to live longitudinal series ; three or four series 

 of scales between the eye and the upper labials ; latter, 12 to 17. 

 Scales in 253 to 31 rows, dorsals very strongly keeled. Ventrals 

 160-199 ; anal entire ; subcaudals 18-30. Brown above, with a 

 series of darker, light-edged rhombs, often lighter in the centre, in 

 contact with one another or narrowly separated, or with decussating 

 yellow lines ; occiput and neck with or without two more or less 

 distinct dark parallel stripes ; a dark streak from the eye to the 

 angle of the mouth, and often another from the loreal pit to below 

 the eye or beyond ; the markings sometimes indistinct ; yellowish 

 white beneath, uniform or spotted with brown ; tail usually brown 

 or blackish. 



Total length 1320 millim. ; tail 130. 



Arizona, New Mexico, and Texas to Southern Brazil and 

 Northern Argentina. 



A. Stripes on the neck absent or ill-defined. 



a-h. Hgr. (Sc. 27, 27 ; Presidio, W. Mexico. Hr. A. Forrer [CI. ; 



V. 188, 191 ; C. 24, F. D. Godman, 



30). Esq. [P.], 



c, d. d' (Sc. 27, 23 ; V. City of Mexico. Mr. Doorman [C.]. 



173, 170 ; 0. 24, 26). 

 e. Hgr. (Sc. 29 ; V. Mezquital del Oro, Zaca- Dr. A. C. Bidler [0.1. 



182 ; 0. 27). tecas. 



f-h. d (Sc. 25 ; V. 170 ; S. Mexico. F. D. Godman, Esq. 



C.24)&hgr. (Sc.25, [P.J. 



25; V. 173, 174; 0. 



18, 18). 



