barred; Nevada, Ariz, and Cal. 



Crotalus tigris Kennicott Tiger Rattlesnake 

 Rostral plate higher than wide; with large, irregular cross bands, or 

 sometimes completely black; tail usually completely dark 38. 



38. Usually with a brownish mid'dorsal stripe on the anterior part of the 



body; ground color pale; Texas to Ala., and northward to 111. 



Crotalus horridus atricaudatus (Latreille) Canebrake Rattler 

 Usually with a brownish mid'dorsal stripe on the posterior part of the 

 body; ground color yellow to dark; Maine to Okla. 



Crotalus horridus horridus Linn. Timber Rattlesnake, Black 

 Rattlesnake 



39. Supraocular pitted or ragged; Inyo Co., Cal. 



Crotalus mitchellii stephensi Klauber Panamint Rattler 

 Not so 40. 



40. With one row of small scales between the upper labials and the eye; 



usually with two or three rows of small, brownish blotches along the 

 back; Ariz;. 



Crotalus triseriatus pricei (Van Denburgh) Price's Rattlesnake 



With two or more rows of small scales between the upper labials and 



the eye; with a row of large blotches along the middle of the back 41. 



41. With an upright light bar on each side of the front of the snout before 



the nostril; color greenish, with dark diamond-shaped blotches which 

 have bright yellow borders; tail greenish above, ringed with black; 

 N. C. to Fla. and Miss. 



Crotalus adamanteus Beauvois Diamond'back Rattler 

 No such light bars; color grayish, pinkish or greenish, with diamond' 

 shaped markings which have white or pale yellow borders; tail whitish, 

 ringed with black 42. 



42. Ground color greenish; light bands on tail wider than the dark bands; 



with a light line passing from the rear corner of the eye above the 

 corner of the mouth; Utah to Texas and Cal. 



Crotalus scutulatus (Kennicott) Mohave Rattlesnake 

 {Crotalus scutellatus (Kennicott) ) 

 Ground color grayish or reddish; light and dark bands on tail equal; 

 with a light line passing from the rear corner of the eye to the mouth 



43. 



43. Ground color pinkish or yellowish, with dark dots; light bands on side 



of head parallel; Ark. to Texas and Cal. 



Crotalus atrox (B. ^ G.) Western Diamond-back Rattler 

 Ground color reddish; light bands on side of head not quite parallel; 

 Cal. 



Crotalus ruber (Cope) Red Diamond-back Rattler 



44. With two, large, lengthwise plates on the front area of the chin; pupil 



of eye round; with a black and brick-red pattern on the back, the red 

 being in the form of squares or in cross bands; Family Coluhridae 

 (part) 45. 



Front area of chin with small scales; pupil of eye vertical; back brownish 

 or grayish; Family Boidae Boas 47. 



396 



