178 
THE POISONOUS SNAKES OF THE ANGLO-EGYPTTAN SUDAN 
True Vipers 
This species likewise attains a length of two metres (tail, 300 mm.), but no specimen 
of such dimensions has been found hitherto in the Egyptian Sudan. It possesses the same 
ferocious habits as the preceding, and is, undoubtedly, the snake which deserves first rank 
as a spitting snake, as the majority of the observations ahotit this curious habit are 
referred to it. 
The distribution of this snake is still more extensive than that of the preceding one, 
for we have records of it from nearly the whole of Tropical Africa — from Senegambia to 
the Sudan, and even to Upper Egypt, and from Angola to the Transvaal. In the Nile 
valley it is known fi'om Assuan (Anderson, Werner) to Clondokoro (Werner), has been 
recorded from Khartoum by L. O. Anderson, and collected at the Sobat, near Taufikia, 
by Dr. Wenyon. 
A third species of Naja, A*, mehmoleuca, Hallowell, has been found in Uganda by 
Mr. Baxter, and may eventually be met with in the Sudan. It agrees with N. hajie in 
having the sixth upper labial largest and in contact with the lower postocular, but differs 
in having the third and fourth upper labial entering the eye, and the rostral considerably 
broader than deep. Sides of head yellowish or whitish ; some or all of the lalhals with 
posterior black edge ; head and body black above, uniform or (in the young) with white 
dots or edges to the dorsal scales; the white mostly disposed in cross-bars ; anterior 
ventral region with yellowish cross-bars alternating with black ones. Total length 
(according to Boulenger), 2'400 metres ; tail, 700 mm. Bather common in West Africa 
from the Niger to the Gaboon, especially in the Cameroons ; apparently rare in East Africa. 
II. True Vipers 
Upper jaw very short, erectile and supporting a i)air of very large poison-fangs 
without external longitudinal gi'oove, but with inner canal ; no teeth on the upper jaw 
behind these fangs. 
Genus: Causus, Wagler 
Head covered with large symmetrical shields, as is noi'inally the case wdth the 
Colubrine snakes; teeth in the lower jaw well developed ; eye moderate, with round 
pupil, separated from the eye by suhocular scales; loreal shields present. Body, 
cylindrical, scales smooth or keeled, oblique on the sides, min. 15-22 rows; ventrals 
rounded; tail short, subcaudals in two rows or single. Poison-gland very elongate, 
situated at the side of neck, between the skin and the body-muscles (see Plate XIX, r). 
Tropical and South Africa. 
(jd-Hsiis rhomheatns, Lichtenstein (Plate XVII., fig. 3) 
Boulenger, l.c., p. 407 
(Figured in Sehlegel, Kssui stir la I'hysioi/nomie des Serpens, II., 1837, p. 483, 
Plate XVII., figs. 12 and 13) 
Snout obtuse, not turned up at the end. Scales in 17-21 rows, dorsals more or less 
distinctly keeled; ventrals 120-155; subcaudals 15-29, all or greater part in pairs. 
Coloration olive or pale brown above, rarely uniform, usually with a dorsal series of 
large rhomboidal or V-shaped dark brown spots, in many edged with black, usually a 
large dark V-shaped marking on the back of the head, the point of the frontal, and an 
oblique dark streak behind the eye (missing in the only known specimen from the Sudan) ; 
labials usually dark edged (not in the Sudan specimen) ; lower parts yellowish-white, 
uniform, or the shields edged with black. 
Total length, 700 mm.; tail, 75 mm. 
Tropical and South Africa. 
