248 VIPERIDiE 



pair of parietals, may sometimes be distinguished ; 

 four to seven longitudinal series of scales between 

 the supraoculars, which are large, and do not as a 

 rule extend posteriorly beyond the vertical of the 

 eye. Five or six (rarely three) scales on the posterior 

 aspect of the raised part of the snout ; two canthal 

 scales on each side, the second in contact with the 

 supraocular, or separated from it by the uppermost 

 preocular. Eight to thirteen (usually nine to twelve) 

 scales round the eye; two or three series of scales 

 between the eye and the labials. Nasal hollowed 

 out, entire, separated from the preoculars by one or 

 two vertical series of scales ; naso-rostral sometimes 

 divided into two in North African specimens. 

 Temporal scales smooth or feebly keeled. Upper 

 labials nine to eleven (rarely eight), fourth and fifth 

 (rarely third and fourth) below the eye. Four or five 

 lower labials in contact with the single pair of chin- 

 shields. 



Scales in twenty-one rows, with two apical pits, 

 strongly keeled, outer row smooth or feebly keeled. 

 Ventral shields 125 to 146 in males, 135 to 147 in 

 females ; anal entire ; subcaudals 35 to 45 in males, 

 32 to 38 in females. 



Coloration. — Grey or brown above, the back often 

 paler than the sides, with a broad darker, usually 

 black-edged, wavy or zigzag band along the spine, and 

 a lateral series of spots (Plate XIII.) ; the band some- 

 times replaced by large rhombic or transversely oval 



