THE PRINCIPAL SPECIES OF POISONOUS SNAKES 79 



the middle of the dentary bone. Head small, not distinct from the 

 neck, covered with large symmetrical shields ; nostril between 

 two nasal shields ; eyes minute, with round pupils ; postfrontal 

 bone absent. Body cylindrical; scales smooth, in 17—37 row's ; 

 ventrals rounded. Tail short ; subcaudals in 1 or '2 rows. 



(1) A. liildebrandtii. — Six supralabials ; no praeocular shields; 

 frontal shorter than the parietals ; scales on the body in 17 rows ; 

 ventrals 167—174. 



Colour uniform 

 dark brown. 



Total length, 450 

 millimetres ; tail 53. 



Habitat : East 

 Africa. 



(2) A. congica. — 

 Five supralabials, of 

 which the fourth is 

 the larger ; postocu- 

 lar in contact with a 

 large temporal ; one 

 praeocular ; frontal 

 as long as or slightly 

 shorter than the 

 parietals. Scales on 

 the body in 19—21 

 rows ; 209 — 230 ven- 

 trals ; 19 — 23 sub-caudals. 



Colour uniform dark brown or black. 

 Total length, 450 millimetres ; tail 35. 

 Habitat : Congo, Angola. 



(3) A. irregularis. — Characters as before, but scales on the 

 body in 2.5 — 27 rows ; 220—257 ventrals , subcaudals 22 — 28 pairs. 



Colour uniform black or dark brown. 

 Total length, 560 millimetres; tail 35. 



Fig. 42. — Skull of Atractcnpis aterrbm (African 

 Yiperine). (After G. A. Boulenger, op. cit.) 



