CHAPTER IV. 
GEOGRAPHICAL DISTRIBUTION OF VENOMOUS SNAKES. 
New Zealand is entirely free from snakes. Australia and its adjacent islands 
are free from the Viperidee—containing neither the Viperine nor the Crotal- 
ine. ‘The American continents are noted for the absence of the true viperine 
forms, whereas the Crotalinz, another representative of the Viperide family, 
is fully established throughout temperate and tropical America. ‘The famous 
rattlesnakes are the most specialized of all the venomous snakes and are 
exclusively confined to the New World. The total absence of the poisonous 
Colubridz from Europe is another remarkable geographical feature, and it 
is highly interesting to note that the only venomous snakes here belong to 
the Viperine, of which but one genus is represented. In Africa the repre- 
sentatives of the Viperinee are most numerous, but there are none of the 
Crotaline; of the Colubride no Hydrophiinz are found, while the Elapinz 
are fairly numerous. 
Asia contains almost every genus of poisonous serpents, except Croéalus. 
The Elapinz are well represented by Naja, Bungarus, Hemibungarus, Cal- 
lophis, and Doliophis, while the Hydrophiine are most abundant along the 
coasts of the tropical regions of Asia. ‘The true vipers are not unknown 
here, as the Viperinz are represented by four genera. The crotalines are 
abundantly represented in Asia, as far as its western neighboring continent 
Africa, both by Ancistrodon and by Lachesis, better known as Trimeresurus, 
but, as was stated above, no Crotalus or rattlesnake. Thus Asia may be 
looked upon as a region where the evolutional balance of various venomous 
snakes is comparatively well preserved. 
One of the most extraordinary facts is that Australia is an exclusive home 
of venomous Colubride, of which no less than 16 elapine and g marine 
genera are enumerated; but, as pointed out previously, there is no representa- 
tive here of the Viperide. 
Returning to the American continents, the conditions are found to be quite 
contrary. Here peculiar relations exist between the Crotaline and the 
Colubride —both Elapinee and Hydrophiine on one hand, and Crotalinz 
and Viperinz on the other. The prevailing venomous snakes of America 
belong chiefly to Crotaline, and the colubrine and the viperine snakes are 
thrown into the background. Especially no true vipers exist on this continent. 
Of the colubrine snakes only one genus is represented, Hlaps,! which, although 
it includes more than 20 species, is in a state of more or less general degra- 
dation, as may be judged from its diminutive size and its tendency to burrow. 
1 Another genus was described, Micropechis, with only one species, elapoides. 
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