SNAKES OF CEYLON, 495 



does not affect the question of its being caDaliculate. The 

 line referred to is a seam which marks the spot where the 

 circumflexed walls ot the canal meet and blend. There is a 

 considerable opening at the base of this seam and a much 

 smaller one near its point, where the poison finds exit. It is 

 not generally known that it was this beautifully specialized 

 instrument in the jaws of a poisonous snake that led a medical 

 man to design the surgical instrument, used so freely in these 

 days, in the form of the hypodermic needle. 



The cobra's fang is relatively small compared with viperine 

 fangs, and is a much more solid and stronger weapon. The 

 length of my largest cobra fang is 7 mm., and was taken irom 

 a large adult. The length ot the fangs in a 15-inch Echis 

 in my collection is 5 mm., and those in a 3 feet 4 inch viper 

 (Trimeresurus anamcUlensis) are 13 mm. My largest 

 hamadryad (N, bungarus), measuring 11 feet 5 inches, had 

 fangs 10 mm. in length. 



There are usually two fully-operative fangs fixed in each 

 maxilla, but these are shed singly at intervals, and from 

 Fayrer's experiments eighteen days was the shortest period 

 that elapsed between drawing them and the fixation of a 

 new one. (Fig. 89.) 



Fig. 89- — Maxilla of Naia tripiidians. 

 Compare with Fig. 92. 



Postnodal : A solitary tooth. Palatine : 6 to 8. Pterygoid : 

 11 to 15. Mandibular : 13 to 15. 



Distribution, — (a) General : It is represented by one or 

 other of its many varieties in Ceylon and the Andamans ; 

 throughout Peninsular India to the Himalayas. In the 



