26 INTRODUCTION 



Frontal i\ to ij times as long as broad, much 

 shorter than the parietals ; loreal entering the 

 eye; scales oblique, in 19 or 21 rows; ventrals 



186-222; anal divided ; subcaudals 48-73 



Tarbophis fallax. 



Frontal ij to i| times as long as broad, nearly 



as long as the parietals ; loreal entering the eye ; 



scales oblique, in 19 or 21 rows ; ventrals 203-235 ; 



anal entire ; subcaudals 54-70 ... Tarbophis iberus. 



2. Scales keeled, with two apical pits ; anal 



shield entire. 



a. No pit between the nostril and the eye ; 

 upper head-shields small, if present ; nasal 

 separated from the rostral by a naso- 

 rostral ; eye separated from the upper 

 labials by suboculars. 



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

 ocular usually extending posteriorly 

 beyond the vertical of the posterior border 

 of the eye; frontal and parietal shields 

 usually well developed ; usually a single 

 series of scales between the eye and the 

 upper labials. 

 Snout obtusely pointed, flat above, or with the 

 canthus slightly raised ; rostral usually in contact 

 with a single apical shield, rarely with two ; 6 to 9 

 upper labials, usually 7 or 8 ; scales in 19 rows, 



rarely 21 ; ventrals: S 120-135, ? 125-142 



Vipcva ursinii. 



