MORPHOLOGY OF VENOMOUS SNAKES 33 
spots rimmed with white in 3 or 4 longitudinal series; belly yellow or brown, uni- 
form or speckled. Length about 2 feet. Cape, Namaqualand, Damaraland. 
Bitis caudalis. 
The prominent keeled scales near the eyes take the form of a single horn. Color 
reddish or grayish-red, with 2 brownish series of spots; belly yellow, uniform or 
black-spotted on sides. Length about 1.5 feet. South Africa, Angola to Nama- 
qualand. 
Bitis gabonica. ‘‘ Rhinoceros Viper,” or “‘ Gabonian Viper.” 
Nostrils directed upward and outward. Between the eyes the inter-supranasal 
scales are so prolonged as to form a pair of horns, which are erect and triangular 
or sometimes even of a tricuspid form. This viper may grow about 4 feet long and 
is vicious. Color brown, with a single longitudinal vertebral series of black speckles; 
belly yellow with many small brown or black dots. Head very large and triangular. 
Body very stout with a small tail ending abruptly in a point. Nocturnal, and dur- 
ing the day appears to be very lazy and inactive. Its venom is very powerful, but 
it bites only when molested. 
Bitis nasicornis. 
The nostrils directed upward and outward. Supranasals form two triangular, 
erect horns of 3 or 4 keeled scales. Between the horns are small scales separating 
them. Color purple or red-brown above, with pale-olive or dark-brown speckles; 
the vertebral series is of brown spots rimmed white and each speckle assumes 
rhomboid shape; belly olive with black or yellow spots. Length about 4 feet. 
Western Africa, from Liberia to the Gaboon. 
Genus PSEUDOCERASTES Boulenger. 
This genus is represented by only one species, P. persicus of Persia. 
Pseudocerastes persicus. 
Head very distinct from neck, covered with small imbricate scales. Eyes 
small, vertical pupils. Upper jaw very short, and rounded off. Coloration gray 
or brown, with four series of large black speckles; the head carries two longitudinal 
black streaks behind the eyes; belly is whitish, spotted with black. Length 3 feet. 
Genus CERASTES Wagler. 
Head very distinct from neck, covered with scales, small, juxtaposed, and lightly 
imbricate. Eyes small, vertical pupils. Body cylindrical with imbricate scales 
with apical pits, in 23 to 25 rows. Tail short; subcaudals in two rows. 
Cerastes cornutus.! “‘ Horned Viper.” (Plate 12, B.) 
Upper jaw short and large. Two erect horns above the eyes. Color brown- 
yellowish or gray, with or without 4 to 6 series of brown speckles. Black bands 
run obliquely behind the eyes; belly white; end of tail black or white. Length 
2.5 feet. ‘North of Sahara, Egypt, Nubia, Arabia, and central Palestine; Asiatic 
side of Suez Canal. 
Cerastes vipera. (Plate r2, Cc.) 
Snout very short and broad. No “horns.” Color yellowish, pale brown or 
reddish, with or without black speckles; end of tail often black above and white 
beneath. Length 1 foot. North of Sahara, from Algeria to Egypt. 
Genus ECHIS Merrem. 
Head very distinct from neck, covered with small imbricate scales; eye mod- 
erate, with vertical pupil; nostrils directed upward and outward, in a single or 

1 The ‘‘ Horned Viper,” or C. vipera, is supposed to be the species which has become famous through 
the suicide of Cleopatra. In the daytime the horned viper is invisible, being buried in the 
sand with only the eyes, nostrils, and horns appearing above the surface. ‘This attracts small 
birds, which mistake the horns for insects and, approaching the viper, are themselves caught. 
