216 THE SNAKES OF SOUTH AFRICA. 
an oblique dark streak behind the eye; labials usually dark- 
edged; lower parts yellowish white or grey, uniform, or the 
shields edged with black. 
Average length—2z feet. 
Distribution—All over South Africa; North to Tropical Africa. 
2. CAUSUS DEFIILIPPII. Snouted Night Adder. Snoet Nacht Adder. 
(Gesnoet Nacht Adder.) 
Synonyms—Heterodon defillippii ; Causus rostratus. 
Colour—Grey or brown above, vertebral region darker, with a series 
of large rhomboidal or V-shaped dark brown spots; a large 
A-shaped dark brown marking on the occiput, the point on the 
frontal; an oblique dark streak behind the eye; upper labials 
dark edged; yellowish white beneath, uniform, or with small 
greyish-brown spots. 
Average length—1z foot 6 inches. 
Distribution—Griqualand; Natal; Zululand; Transvaal; Southern 
Rhodesia ; East and Central Africa. 
Fic. 86.—Head and neck of the poisonous Night or Demon Adder 
(Causus rhombeatus). 
Note the triangular blackish mark on its head. 
Genus BITIS. 
Six Species in South Africa. 
KEY TO. THE SPECIES: 
Nostrils directed upwards ; scales in 31 to 41 rows .._ Bitis arietans. 
Nostrils directed upwards and outwards; scales in 21 
to 31 rows. Supraocular region not raised, with- 
out horn-like scales ; sub-caudals well developed 
and smooth in both sexes. Outer row of scales 
smooth .. ihe: 5% a Be .. Bitis peringueyi. 
Same as the former except that outer row of scales are 
keeled .. ay itiie Bitis atropos. 
Supraocular region raised, without horn-like scales ; 
sub-caudals well developed and smooth in both 
sexes .. ae ss ae ta “te ..  Bitis inornata, 
