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CHAPTER III. 



DESCRIPTION OF THE PRINCIPAL SPECIES OF 

 POISONOUS SNAKES. THEIR GEOGRAPHICAL 

 DISTRIBUTION. 



Poisonous snakes are especially cpmmon in the tropical zones 

 of the Old and New Worlds. The species found in Europe are 

 but of small size and not very formidable. In hot countries, on 

 the other hand, they attain large dimensions, their venom is much 

 more active, and, although they hardly ever attack man, and in 

 most cases avoid him, they cause a considerable number of fatal 

 accidents. 



It is sometimes a rather difficult matter to recognise from the 

 mere appearance of a snake whether it is poisonous or not. Natu- 

 ralists themselves are occasionally deceived. It is therefore useful 

 to learn to distinguish the most dangerous species by their external 

 characters, and to know in what countries there is a risk of their 

 being encountered. 



A.— EUROPE. 



Of the continents of the Old World, the poorest in poisonous 

 snakes is Europe. The only species found there are a CffiLOPELTis 

 (belonging to the Sub-family Dipsadoviorpliinm of the Opistho- 

 glyplia), and certain ViPBRiNiE, which rarely exceed 75 centimetres 

 in length. 



CcELOPELTis, the cranial skeleton and head of which are repre- 

 sented in fig. 20, is characterised by a narrow, concave frontal shield. 



