502 Annals of the SoutJi African Museum. 



Anal entii'e ; loreal separated from the eye by the prasocular ; 



maxillary teeth increasing in size posteriorly Leptixlira. 



Anal entire ; loreal entering the eye Ch(ima'tortit:<. 



h. Pupil round. 



a. Scales smooth (or feebly keeled on the posterior 

 part of the back) in 13 to 17 rows. 



Eostral moderate ; nostril in a single, semidivided nasal liiiplorJiinu^t. 



Eostral moderate ; nostril between two nasals and the internasal ; 



maxillary teeth subequal TrimcrorJiiintx 



Eostral large, projecting, snout pointed BJidDipJiioijIiit. 



Eostral moderate ; nostril between the nasals ; one or two middle 



maxillary teeth much enlarged P.iniinnophis. 



/3. Scales keeled, in 19 or 21 rows; eye very large Diajiholidux. 

 c. Pupil horizontal ; eye large ; scales in 19 rows ; 



body very slender Thelotornu. 



B. Eye small or very small ; head not distinct from neck. 



1. Subcaudals in pairs; no prseocular. 



Scales in 15 rows ; no internasals Aiiihlijodipxan. 



Scales in 17 or 19 rows ; internasals present Calamelaps. 



2. Subcaudals single. 



Scales in 23 to 27 rows ; no prseocular Macrelaps. 



Scales in 15 rows ; nasal in contact with a praeocular -ipdrallactuit. 



III. Proteroiilyplun, with grooved fangs at the anterior end of the 

 upper jaw. — Poisonous. 



A. Tail compressed, oar-shaped ; head narrow and elon- 

 gate ; no distinctly enlarged ventrals (Sea-snakes) . . . . Hijdrus. 



B. Tail cylindrical, ending in a point. 



1. Head short. 



a. Scales in 17 rows or more ; internasal bordering the 

 nostril. 



Eostral moderate ; scales smooth Xaia. 



Eostral moderate ; scales strongly keeled Sepedon. 



Eostral very large, detached on the sides ; scales smooth or 



keeled on posterior part of body Ai^pidclaps. 



h. Scales in 13 or 15 rows. 

 Nostril between two nasals ; scales in 18 rows ; eye small . . . . Elapechiit. 

 Nostril in a single nasal ; scales in 15 rows ; eye very small . . Hoinorelaps. 



2. Head narrow, elongate; scales very oblique, in 19 to 



25 rows ; body slender Dendras])ii<. 



1. TROPIDONOTUS. 

 Kiibl, Bull. Sc. Nat. ii., 1824, p. 81 ; Boiileng. Cat. Sn. i. p. 192. 



Tioo Species in South Africa. 



Ventrals 162-180 ; anal entire T. laviasimm 



Ventrals 131-149 ; anal divided T. olivaceus. 



