28 INTRODUCTION 



7. Snout not turned up at the end ; supra- 

 ocular narrow or broken up into several 

 small shields ; upper surface of head 

 with small, usually keeled scales ; two or 

 three series of scales between the eye and 

 the upper labials ; scales in 23 to 27 rows, 

 usually 25 ; ventrals : S 151-177, ? 153- 



180 Vipera lebetina. 



b. A pit between the nostril and the eye ; 

 upper surface of head with 9 large shields ; 

 nasal in contact with the rostral ; third 

 upper labial entering the eye; scales in 

 23 rows ; ventrals 149-174 ; subcaudals 

 3 1-44 A ncistrodon halys. 



