4. Bins. 493 



deep pit or pocket above, closed by a valvular, crescentic supra- 

 nasal. Postfrontal bone very large, in contact with the ecto- 

 pterygoid, which has an outer, hook-shaped process. Scales keeled, 

 with apical pits, in 22-41 rows ; lateral scales in some species 

 slightly oblique ; ventrals rounded. Tail very short ; subcaudals in 

 two rows. 

 Africa. 



Synopsis of the Species. 



I. Nostrils directed upwards ; no nasal or palpebral raised scales ; 



one or two series of scales between the nasal and the rostral ; 

 scales in 29-41 rows 1. arietans, p. 493. 



II. Nostrils directed upwards and outwards. 



A. No enlarged raised scales between the supranasals ; two or 



three series of scales between the nasal aud the rostral ; 

 scales in 22-31 rows. 



1. Supraocular region not raised ; no horn-like scales ; sub- 



caudals well developed and smooth in both sexes. 



Outer row of scales smooth 2. peringueyi, p. 495. 



Outer row of scales keeled 3. atropos, p. 495. 



2. Supraorbital region raised, but without horn-like scales ; 



subcaudals well developed and smooth in both sexes. 



4. inornaia, p. 496. 



3. Supraorbital " horns " usually present ; subcaudals, in 



females, small and scale-like, more or less distinctly 

 keeled. 



Several supraorbital " horns " 5. cornuta, p. 497. 



Supraorbital " horn," if present, single . . 6. caudalis, p. 498. 



B. Enlarged, more or less raised or horn-like scales between the 



supranasals ; four or five series of scales between the nasal 

 and the rostral ; scales in 33-41 rows. 



A single enlarged scale above the supra- 

 nasal, in contact with its fellow 7. gabonica, p. 499. 



Two or three enlarged scales above the 

 supranasal, usually with small scales 

 between them and their fellows 8. nasicomis, p. 500. 



' 1. Bitis arietans. 



Seba, Thes. ii. pis. xxx. fig. 1, liv. fig. 4, & xciv. fig. 2 (1735). 



? Cobra clotho, I^ur. Syn. Eept. p. 104 (1768). 



Cobra lachesis, Law. I. c. 



Coluber lachesis, Omel S. N. i. p. 1085 (1788). 



? Coluber clotho, Omel. I. c. p. 1086. 



? Coluber bitin, Bonnat. Encycl. MUh., Ophiol. p. 22 (1789). 



