240 



VIPERID^E 



raised canthus, and vertical or nearly vertical loreal 

 region. Vertical diameter of the eye equal to or a 

 little less than its distance from the mouth. The 

 raised upper border of the transversely truncate or 

 obtusely pointed extremity of the snout, coupled 

 with the downward slant of the supraocular region 

 and canthus rostralis, gives the head, seen from the 

 side, a peculiar expression ; the eye is so oblique 

 that a vertical line drawn from the posterior extremity 



of the supraocular 

 shield to the lip 

 usually passes 

 through the eye 

 or down its pos- 

 terior border; but 

 the extent to which 

 the snout is turned 

 up at the end 

 varies consider- 

 ably, some specimens approaching V. bents in this 

 respect, others V. latastii. Length of tail five and a 

 half to eight times in total length in males, seven to 

 nine times in females. 



Head-Shields. — Rostral deeper than broad, its width 

 two-thirds to seven-eighths its depth, extending to the 

 upper edge of the snout. As a rule, with the exception 

 of the large supraocular, the upper surface of the head 

 is covered with small, subimbricate scales, which are 

 smooth, very rarely feebly keeled, between the eyes 



Fig. 36 (after Sordelli) 



