93 



TWE DISTINGUISHING CHARACTERISTICS BETWEEN 



POISONOUS AND NON-POISONOUS SNAKES. 



By Capt. F. Wall, I.M.S. 



W^iTH Plates A, B, C & D. 



{Read before the Bombay JSatural History Society on 11th Dec^ 1900.) 



Perhaps no sectiou of the study of snakes is of suoh universal 

 interest to those who have to reside in tropical countries as that 

 which deals with the distinctions between the poisonous and non- 

 poisonous varieties. Many who do not care to enter the subject of 

 ophiology deeply nevertheless show keen enough interest in this 

 particular direction, and I have been led to believe that some easy and 

 reliable guide, by which even those ignorant of the subject might 

 with certainty discover for themselves the poisonous nature or other- 

 wise of any snake, would be welcomed, and I have endeavoured in 

 this paper to supply this guide. 



There have been at least 270 varieties of snakes hitherto described 

 as inhabiting India (with which is included Assam, Burmah and 

 Ceylon), and of these no fewer than 81 are poisonous, aud this fact 

 alone must convey to any thinking individual the complexity of the 

 question, and serve to dispel a somewhat common belief that the 

 matter is an easy one which can easily be settled by a single- hard and 

 fast rule. 



The methods adopted by many are full of fallacies, and 1 will point 

 out some of these. 



1. Perhaps one of the commonest guides in use and one con- 

 sidered by many an absolutely certain one is the presence or absence 

 of a fang. This test in the case of some of the larger vipers may be 

 a fairly easy point to determine, as the fangs are particularly large in 

 this class of snakes. 



Fallacies. — (a) In many poisonous snakes with less developed fangs, 

 aud especially in the Kraits (Bungarus) in which fangs are prover- 

 bially small, it is extrem.ely easy to overlook them concealed as they 

 usually are to a more or less extent in folds of mucous membrane. 

 (&) In all the small varieties of the poisonous kinds with which I may 

 include the young of the larger species it is often a difficult matter 

 to see, much less investigate accurately, the characters of a supposed 

 fang, (c) It must not be lost sight of, too, that fangs may be broken off 



