Habitat: Abyssinia.
II.—Viperidæ.
The African Viperidæ all belong to the Subfamily Viperinæ, of which the following are the seven principal genera:—
(a) Causus. (b) Vipera. (c) Bitis. (d) Cerastes. (e) Echis. (f) Atheris. (g) Atractaspis.
(a) Causus.
([Fig. 35].)
Head distinct from the neck, covered with symmetrical shields; nostril between two nasal shields, and the internasal; eyes moderate, with round pupils, separated from the lips by subocular shields. Body cylindrical; scales smooth or keeled, oblique on the sides, in 15-22 rows; ventral scales rounded. Tail short; subcaudals in 2 rows or single.
Four species:—
(1) C. rhombeatus.—Snout obtuse, moderately prominent. Scales in 17-21 rows; 120-155 ventrals; 15-29 subcaudals.
Colour olive or pale brown, usually with a series of V-shaped brown spots bordered with white, and a large spot in the form of a circumflex accent at the back of the head; lips bordered with black; belly yellowish or grey.