16. CROTALIDJE 



Amer. Amph. Rept., 1917, p. no; Vorhies, Univ. Ariz. Agric. 

 Exper. Station Bull. No. 83, 1917, p. 359. 

 Crolalus willardi Vorhies, Univ. Ariz. Agric. Exper. Station Bull., 

 No. 83, 1917, p. 361. 



Description. — Size small. Head subtriangular, with 

 flattened top. Rostral nearly as broad as high, in contact 

 with anterior nasal plate. Two nasals. Two preoculars. 

 Usually one loreal, sometimes two. Internasals proportion- 

 ally rather large. A large scale just in front of supraocular. 

 Supraocular large but not raised into a horn-like process, sep- 

 arated from its fellow by from one to three scales. Superior 

 labials nine to 11 , separated from eye by one row of scales. 

 Inferior labials nine to 11 , first pair in contact on median 

 line. Scales in 21 or 23 rows, keeled except in parts of the 

 first and second rows. Gastrosteges varying from 151 to 

 162. Anal entire. Urosteges 19 to 27, the first and from 

 two to nine posterior usually divided. Rattle very slender 

 and delicate. 



The general ground color is olive gray so thickly covered 

 with minute brown dots as to give a decidedly brownish 

 hue. A narrow dark brown band of uniform width runs 

 back and down from the eye, just touching the upper angles 

 of the eighth and ninth labials without involving them. 

 The scales below this band are vinaceous cream. There are 

 two small seal brown spots on the occiput. The genials and 

 gulars are yellow, tinged with vinaceous laterally. The rest 

 of the head is unicolor. Along each side of the back is a 

 series of from 54 to 60 small brown blotches. Anteriorly 

 these have a tendency to alternate, but posteriorly they unite 

 with one another to form cross-bars. There are seven simi- 

 lar brown bars on the tail. The dorsal blotches are seal 

 brown, palest centrally, and are edged with very pale brown 

 or white. They are about one and one-half scales long, and 

 from t^o to three rows of scales wide,- They are separated 



