The Rattlesnakes 



There is a dark band from beneath the centre of the eye to the 

 angle of the mouth. This is bordered both in the front and the 

 rear by a yellow stripe, the front stripe being narrow the width 

 of a single scale-row. In comparing the heads of these species 

 it will be noted that the Pacific Rattlesnake has the dark band 

 commencing behind the centre of the eye, and the forward pale 

 stripe much wider about the width of two scales. 



The eye plates are usually marked with two white or yel- 

 low lines, which run together and form a sharp point at the outer 

 margin. 



Dimensions. Total Length of an adult, female 



specimen from Wyoming 38^ inches. 



Length of Tail, ex. rattle 2'1 



Greatest Diameter \l 



Width of Head ij 



Length of Head if 



Number of "rattles" 7 uniform 

 segments. 



DistribiUion. The range is quite extensive and the writer 

 quotes the careful summing up of the distribution as given by 

 Dr. Leonhard Stejneger: * 



" Broadly speaking, the Prairie Rattlesnake occupies the 

 area bounded in the East by the ninty-sixth meridian and the 

 Upper Missouri Valley; by the main divide of the Rocky Moun- 

 tains in the West; by the thirty-third parallel in Texas and tile- 

 Mexican boundary further west in the South; and by the fiftieth 

 parallel in the North. In the Northeast its distribution appears 

 to be limited by the watershed between the Missouri and the Rei!- 

 River of the North, according to Dr. Coues (Bull. Geol. Surv. 

 Terr. IV, 1878. p. 267), who collected numerous specimens along 

 the Canadian border between this watershed and the crest of the 

 Rockies. He also slates that it is to be considered fairly com- 

 mon in the region of the Upper Missouri and Milk River and 

 some of their Northern tributaries; its range thus extending 

 some distance into the British Possessions, where Mr. James M. 

 Macoun informs me that it is most abundant from Medicine Hat, 

 on the Saskatchewan to the boundary." 



Habits. In its general demeanour toward man, this very 



* "The I'oisnnous Snakes ot' XMh America. " Report of the U. S. 

 National Museum !<>r 1X93, pp. 3.37- 4' s ; 



456 



