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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 cylindrical, very slender. Scales narrow, very 

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

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



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(Brit. Mus. Cat. Snalus.) 



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). Showinp: 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. J3ody cylindrical. Scales smootli, without pits, in 

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

 caudals in two rows. 



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

 gradually increasing in size and followed, after an interspaoe, 

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

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



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