H. spiralis.—Olive above, yellowish beneath, with black rings; head black above, with a horse-shoe-shaped yellow mark, the convexity of which rests on the præfrontal shields; end of tail black.
Total length, 400 millimetres. Grows to 1,800 millimetres.
Habitat: Coasts of India, and the Malay Archipelago.
H. cærulescens.—Grey above, with black cross-bands, which form complete rings, or are interrupted on the belly; head uniform black.
Total length, 665 millimetres; tail 75.
Habitat: Bombay Coast, Bay of Bengal, Straits of Malacca.
H. nigrocinctus.—Pale olive on the back, yellowish on the belly, with black annuli, which are broader on the back.
Total length, 1,000 millimetres; tail 100.
Habitat: Bay of Bengal and Straits of Malacca.
