CLASSIFICATION OF SNAKES 227 



and when scales are present they are minute, and are 

 deeply embedded in the skin. Eels, even if they have 

 scales and have not fins of any kind, always have at least 

 one external gill-opening. 



The habits of Snakes, in so far as one may desire to 

 study them with a view to avoiding the dangerous species, 

 will be dealt with at the end of this article. 



Classification of Snakes. About 1,700 species of snakes 

 are known, of which rather more than 300 have efficient 

 poison-fangs, and so must be classed as " venomous," 

 while 300 more possess grooved teeth of a sort, and so, 

 though not commonly regarded as venomous, can instil 

 saliva into their bite, and can thus inflict' a wound that 

 must be regarded with suspicion or even with dread. 



These 1,700 species are distributed in nine families, and 

 though only two of the families include venomous and 

 " suspicious" species, it is just as well, for many reasons, 

 not to ignore completely those forms which, though 

 harmless, may come to the notice of a medical officer 

 in the Tropics. 



(A) The snakes of the following seven families are, so 

 far as their bite is concerned, innocuous : 



(i) Typhlopidce (Blindworm Snakes). These are 

 burrowing snakes that live underground, and feed 

 chiefly on earthworms and grubs. They are found all 

 round the globe in tropical and warmer temperate lati- 

 tudes, one of the hundred and odd species known ranging 

 into South-eastern Europe. The smaller species are not 

 much bigger than an earthworm, and the largest does not 

 attain a length of 30 inches. They can be recognized by 

 their cylindrical body; by their hard, shiny, cycloid 

 scales ; by their minute eyes, which lie beneath the 

 shields of the head ; and by the fact that the scales of 

 the belly are quite like those covering the rest of the 

 body i.e., by the absence of enlarged ventral shields. 

 Their chief skeletal peculiarities are the possession of a 

 vestigial pelvis, the presence of a coronoid bone in the 

 mandible, and the absence of squamosal and transpalatine 



