THE PRINCIPAL SPECIES OF POISONOUS SNAKES 131 
transformed into a raised horn-like process; 11—13 supralabials ; 
scales in 21 or 23 rows; dorsals feebly keeled, each scale along the 
middle of the back with a central tubercular swelling; 146 ventrals; 
17 subcaudals. 
Colour yellowish, with a dorsal series of rather indistinct brown 
blotches ; a narrow brown streak from the eye to the angle of the 
mouth. 
Total length, 250 millimetres ; tail 20. 
Habitat: Desert regions of Southern California, Nevada, 
Arizona, and Utah. 
F.—HYDROPHIINÆ (SEA-SNAKES). 
The Sea-Snakes, which are found in great numbers on the 
shores of the Indian Ocean, are common throughout the whole 
of the tropical zone of the China Sea and the Pacific. They are 
met with from the Persian Gulf to the west coast of Equatorial 
America, but are entirely absent from the east coast of the same 
continent and the west and east coasts of Africa. 
They often travel in companies. All are poisonous, and very 
savage. They never come to land, and move with difficulty if 
taken out of the water, although they are excellent swimmers. It 
is impossible to keep them in captivity in aquariums, and they die 
in two or three days. Their food consists of fishes and crustacea. 
Their tail is prehensile, and they make use of it as an anchor to 
attach themselves to coral reefs when they wish to rest. They 
generally float on the surface of the waves, but can dive to great 
depths, thanks to the extreme dilatability of their lungs, which 
enables them to store up large reserves of air. They are viviparous. 
In these snakes, the head, which is always very small, is 
scarcely distinct from the body. It is often covered with nine 
large shields. The body is laterally compressed, and the tail, 
which serves as a fin, is similarly flattened. The nostrils open 
