GEOGRAPHICAL DISTRIBUTION 255 



'Head with large symmetrical shields (fig. 104, g) Ancistrodon. 



(Asia and America.) 

 2 \ Head with small scales alone, or with small 



scales and some small shields Lachesis. 



(Asia and America.) 



THE THANATOPHIDIA OF EUROPE all belong to the 

 one genus, Vipera ; five European species are known, 

 of which only two are peculiar to Europe. Most of the 

 species are speckled and have a dark V-shaped mark on 

 the crown, a dark oblique bar behind the eye, a zigzag 

 or wavy stripe along the back, and a series of dark lateral 

 spots. In some of the species the tip of the snout is 

 turned up, and may form a sort of horn". Vipers as a 

 rule prefer dry, sandy, or rocky country, where they can 

 bask in the sun ; but they may be found anywhere, even 

 in marsh-land, and they will take to water. The common 

 viper (V. berus) is responsible for a good many bites, a 

 small percentage of which are fatal. The action of the 

 venom is said to be, both locally and generally, like that 

 of rattlesnake venom, but not so severe. 



THE THANATOPHIDIA OF ASIA are peculiar in including 

 numerous examples of all four sub-families. The number 

 of species, exclusive of sea-snakes, is more than sixty. 



The Asiatic Elapince belong to the following genera : 



(a) Naja. In this genus, which is also represented in 

 Africa, the eye is of fair size, the scales are smooth and 

 are disposed obliquely ; and in all the Asiatic species the 

 neck can be dilated under excitement to form a " hood." 

 (i) Naja tripudians, the common Asiatic cobra, is a 

 familiar snake all over Southern Asia. Its colour varies 

 from dingy yellow to black, uniform or banded, and on 

 the hood there is often a " pair of spectacles," or a large 

 " eye," or a U-shaped mark. It may grow to a length of 

 6 ft. It is very commonly met with in houses and gar- 

 dens and among neglected buildings, and is proverbially 

 a fatal snake. (2) Naja bungarus, the "king cobra," 

 or hamadryad, is distinguished by its superior size, and 

 by the possession of a pair of large occipital shields 



