VIPERA 241 



and on the snout ; however, an enlarged frontal 

 shield, or even a frontal and a pair of parietals, are 

 sometimes present, though rarely so large as in 

 a typical V. berus ; when present, the frontal is 

 separated from the supraocular by one or two series 

 of scales ; when the frontal is absent, four to seven 

 series of scales separate the supraoculars. Upper 

 surface of snout usually bordered by eight or nine 

 small shields — viz., two or three apicals, in contact 

 with the tip of the rostral and raised to form the 

 turned-up nose, and, on each side, two canthals and 

 the upper preocular, which separates the supra- 

 ocular from the canthals, or three canthals ; some- 

 times, however, the border is formed by six or seven 

 small shields, the second canthal being in contact 

 with the supraocular, as in V. bents. Supraocular 

 usually with very convex outer border, not extending 

 posteriorly beyond the vertical of the eye. Eight to 

 thirteen scales round the eye, usually ten to twelve ; 

 one or two vertical series of scales separate the pre- 

 oculars from the nasal, which is single or divided, 

 and often rather deeply hollowed out. As a rule 

 two series of scales (very rarely three) separate the 

 eye from the labials ; sometimes, however, there is 

 but one scale between the eye and the fourth labial, 

 the second series being incomplete. Upper labials 

 nine to thirteen, usually nine to eleven, fourth and 

 fifth, rarely fourth to sixth or fifth and sixth, below 



the eye. Temporal scales smooth or feebly keeled. 

 16 



