272 ECONOMIC ZOOLOGY AND ENTOMOLOGY 



ducing a substance called antivenin which neutralizes the 

 effect of that particular kind of poison. In regions where 

 snake bites are of frequent occurrence the antivenin for the 

 most dangerous snakes is prepared and kept ready for use. A 

 small amount of it injected into the blood-vessels soon after a 

 snake has bitten a person usually counteracts the effects of 

 the venom. Most dangerous of all the poisonous snakes is the 

 dreaded cobra of India, Naja tripudians, a very vicious and 

 most deadly reptile. Twenty-five to 55 per cent, of cobra bites 

 prove fatal, and the annual loss of human lives in India from 

 this snake is often over 20,000. The sea-snakes, which inhabit 

 many tropical seas, attaining a length of six or eight feet, are 

 also very poisonous. The body is often compressed thus better 

 fitting them for their aquatic life. They do not leave the water 

 even to breed, but give birth to their living young while at sea. 

 The pythons, genus Python, which sometimes attain a 

 length of twenty or thirty feet, and the smaller boas or boa- 

 constrictors, Boa constrictor, are not venomous. They kill 

 their prey by coiling their body around it and crushing it. 

 These are tropical or semi-tropical snakes. 



