NUMBERS AND DISTRIBUTION. 



215 



Genus CAUSUS. 

 Two Species in South Africa. 

 KEY TO THE SPECIES. 



more or less prominent ; ventrals 

 Poison glands considerably elon- 



Snout obtuse, 



120-155. 



gated . . . . . . . . . . • . Causiis rhombeatits. 



Snout pointed, prominent, more or less turned up 



at the end ; ventrals 11 3-125 .. .. .. Causus defillippii. 



Fig. 86. — The venomous Hornsman or Horned Adder {Bitis cornuta) of the sandy 

 inland parts of South Africa. There are two species. The chief difference is 

 that the one known as Bitis cornuta has several small, erect horn-like scales 

 over the eyes, while the other_(i>!7/s caudalis) has only one erect horn-like scale. 



I. Causus rhombeatus. Night or Demon Adder ; Nacht Adder. 



Synonyms — Sepedon rhombeatus ; Distichurus maculatits ; Aspidelaps 

 rhombeatus. 



Colour — Olive or pale brown above, rarely uniform, usually with a 

 dorsal series of large rhomboidal or V-shaped dark brown spots 

 which may be edged with whitish ; usually a large dark ^-shaped 

 marking on the back of the head, the point on the frontal, and 



