220 CALIFORNIA ACADEMY OF SCIENCES. 



the corner of the mouth. Another narrow light streak 

 crosses the side of the face below the dark one, and is 

 bordered in front by dark brown on the side of the 

 snout. The tail is provided with brown and light rings 

 or cross-bars, a few of the former, near the tip of the 

 tail, being sometimes blackish. The lower surfaces are 

 dull yellow or white, sometimes clouded with brown. 



" The color varies greatly, being sometimes duller, 

 sometimes brighter, lighter or darker, depending upon 

 age, season, condition of skin, climate, and the pre- 

 dominating color of surroundings."^ 



Length to auus 595 



Length of tail to rattle 37 



Distribution. — "Broadly speaking, the Prairie Rattle- 

 snake occupies the area bounded in the East by the 

 ninety-sixth meridian and the Upper Missouri Valley; 

 by the main divide of the Rocky Mountains in the West; 

 by the thirty-third parallel in Texas and the Mexican 

 boundary further west in the South; and by the fiftieth 

 parallel in the north. * ^ * Although the main 

 divide of the Rocky Mountains in this northern region 

 seems to be the limit of its extension to the west, yet in 

 at least one place where there is no high crest to ob- 

 struct its passage across, it has been found on the west- 

 ern slope, viz.: at Lemhi, Idaho."! It has not been 

 taken in Nevada, nor in any of the Pacific States. 



74. — Crotalus tigris Kennicott. Tiger Rattlesnake. 



Croialus injris, Kenn., U. S. Mex. Bound. Surv., II, Eept., 1859, 

 p. 14, pi. IV (type locality Sierra Verde and Poso Verde); 

 Stejneger, N. a. Fauna No. 7, 1893, p. 214; Stejneger, Eeport 

 U. S. Nat. Mus., 1893, 1895, p. 449; Boulenger, Cat. Snakes, 

 Brit. Mus. Ill, 1896, p. 580 (part). 



♦Stejneger. Report D. S. Nat. Mus. for 1893. 

 t Stejneger. Report U. S. Nat. Mus. for 1893. 



