94-8 16. CROTALlD.m 



Rept., 1917, p. no; VoRHiES, Univ. Ariz. Agric. Exper. Station 

 Bull. No. 83, p. 360; Van Denburgh & Slevin, Proc. Cal. Acad. 

 Sci., Ser. 4, Vol. XI, 1921, p. 29. 

 Caudisona tigris Cope, in Mitchell's Res. Venom Rattlesn., 1861, p. 122; 

 Cope, Proc. Acad. Nat. Sci. Phila., 1866, p. 309; Coues, Surv. 

 W. looth Merid., Vol. V, 1875, p. 608. 



Description. — Of moderate size. Head rather small, 

 flat-topped varying in outline according to position of fangs, 

 etc. Rostral wider than high, in contact with anterior nasal. 

 Two nasals. Usually two preoculars and four internasals. 

 Supraocular large but not raised into a horn-like process; 

 separated from its fellow by five to seven irregular rows of 

 scales. About 14 to 16 superior and 1 3 to 1 6 inferior labials; 

 first pair of latter meeting in front of single pair of genials. 

 Three rows of scales between labials and eye. Scales in 21 

 to 25 rows, dorsals strongly keeled. Gastrosteges varying 

 at least from 165 to 183. Urosteges 18 to 26. 



The ground color is yellowish ash, varying from whitish 

 to tawny, marked along the back with a series of rather small 

 and indistinct brown blotches which become cross-bars or 

 stripes posteriorly, and number about 31 to 37 on the body 

 and three to six on the tail. These blotches are paler centrally 

 than about their edges, and sometimes are nearly obsolete. 

 Smaller alternating blotches are present on the sides. The 

 head markings are rather indistinct, especially the postocular 

 stripe, which is often lost in the dense sprinkling of minute 

 black dots covering the sides of the head. The lower sur- 

 faces are yellow or white, sometimes faintly clouded with 

 brown. 



Length to anus - 515 582 625 688 708 750 



Length of tail to rattle 35 43 46 48 56 58 



Distribution. — The Tiger Rattlesnake "was formerly 



