(2) N. flava.—Same arrangement of scales. Neck dilatable. 200-227 ventrals; 50-67 subcaudals.
Colour very variable, yellowish, reddish, brown, or black, uniform or with light spots; sometimes a black transverse band on the neck.
Total length, 1,470 millimetres; tail 230.
Habitat: South Africa.
(3) N. melanoleuca.—Coloration very variable. Sides of the head yellow or whitish; labial shields tinged with black on the posterior edge.
Total length, 2,400 millimetres; tail 400.
Habitat: Tropical Africa.
(4) N. nigricollis.—Third supralabial shield the deepest, sixth and seventh not in contact with the postoculars; 183-228 ventral scales; 55-68 subcaudals.
Coloration very variable; lower surface of the neck with a black transverse bar.
Total length, 2,000 millimetres; tail 300.