262 TROPICAL MEDICINE AND HYGIENE 



" Rhinghals," is known from South Africa. Sir Thomas 

 Eraser and Dr. Gunn find its venom to be like that of the 

 cobra, but less potent, and with little subsidiary action on 

 the blood. 



(c) Dendraspis. The species of this genus are known 

 as tree cobras, and are said to be extremely fierce 

 and aggressive. They have a narrow head, and a long, 

 sharpish face, and a most peculiar shape of maxilla 

 (fig. 104, b). They are usually of a greenish colour. Their 

 venom requires to be studied. 



The other African genera are Walterinnesia (one 

 species) from Egypt, Boulengeria (one species) in Central 

 Africa, Aspidelaps (two species) and Homorelaps (two 

 species) from South Africa, and Elapechis (six species) 

 from the Gaboon to the Zambesi. 



The African Viperincc belong to the following genera : 



(a) Vipera. Two species in Northern Africa, namely : 

 (i) Vipera latastii, recognized by its turned-up (sometimes 

 horn-like) snout, and (2) Vipera lebetina, distinguished by 

 the possession of a supra-nasal shield ; and Vipera super- 

 ciliaris from the Mozambique coast, which has neither 

 turned-up snout nor supra-nasal shield. 



(b) Bitis. This genus differs from Vipera (see p. 258) 

 in having above the nostril a pocket covered by a large 

 crescentic supra-nasal shield (fig. 104, h), and also in having 

 ore or several series of small scales between the nasal and 

 rostral shields. There are eight species, distributed all 

 over the southern part of the continent, from the Niger 

 to the Cape, and from the Gold Coast to the Red Sea, 

 The three best known species are the following : (i) Bitis 

 arietanSy the Puff-adder, a species that grows to a length 

 of 5 ft., and has a range co-extensive with that of the 

 genus, besides extending into Arabia : it is distinguished 

 by its nostrils, which are directed upwards (not upwards 

 and outwards), and by its colouring, which is yellowish 

 or brown with a series of dark V-shaped bands pointing 

 backwards : there is a dark patch on the crown and 

 another between the orbits, and the two are separated 



