ii8 



THE SNAKES OF SOUTH AFRICA. 



or 21 rows; ventrals rounded or obtusely angulate laterally. 

 Tail long ; sub-caudals in two rows. 

 Genus Thelotornis. — Maxillary teeth i6 or 17, gradually increasing 

 in length, followed after a short interspace by two or three 

 enlarged grooved teeth situated below the posterior border 

 of the eye ; anterior mandibular teeth strongly enlarged. Head 

 distinct from neck. Eye large, with horizontal pupil ; nasal 

 entire. Body cyhndrical, very slender. Scales narrow, very 

 obhque, feebly keeled, with apical pits, in 19 rows; ventrals 

 rounded. Tail long ; sub-caudals in two rows. 



I 



(Brit. Mus. Cat. Snakes.) 

 Fig. 51. — Skull of typical Back-fanged Snake. 



1. Side view showing the position of the fangs (B). 



2. Top of head and lower jaw (C). 



3. Roof of the mouth (A). Showing position of the fangs at posterior 



end of outer row of upper teeth. 

 The inner row of teeth are the palatines. 



Genus Amblyodipsas. — Maxillary very short, with 5 teeth gradually 

 increasing in size, and followed, after an interspace, by a large 

 grooved fang situated below the eye ; mandibular teeth decreas- 

 ing in size posteriorly. Head small, not distinct from neck ; 

 eye minute, with round pupil ; nostril in a single very small 

 nasal ; no internasals ; no loreal ; no preocular ; no anterior 

 temporal. Body cylindrical. Scales smooth, without pits, in 

 15 rows; ventrals rounded. Tail very short, obtuse; sub- 

 caudals in two rows. 



Genus Calamelaps. — Maxillary very short, with 3 or 4 teeth 

 gradually increasing in size and followed, after an interspace, 

 by a large grooved fang situated below the eye ; anterior mandi- 

 bular teeth enlarged. Head small, not distinct from neck ; 



