98 



REPTILES AND BATRACHIANS 



of snakes are venomous, the reverse is in reality the case, 

 for of the couple of thousand or so different species, 

 barely one-third are endowed v^ith poison glands, and of 

 these the bite of certainly not more than one hundred and 

 fifty could possibly produce death in man. 



Poisonous snakes are classified into the following three 

 divisions — 



Fig, 6. — Poison-gland and Fangs of Cobra. 



L. Lobe of the gland. 

 D. Poison-duct. 



F, Fang attached to maxillary bone. 



G. Gland. 



M. Capsule of mucous membrane surrounding the fangs. 

 R. Reserve fangs. 



{After Fayrer.) 



I. The Opisthoglyphs, in which the poison fangs are 



fixed to the posterior extremity of the bone of the 



upper jaw. 

 II. The Proteroglyphs, in which the fangs are situated 



in front. 

 III. The Vipers, in which the large fangs are attached to 

 a much shortened vertically movable maxillary 

 bone. 



The poisonous properties of the Opisthoglyphs are, with 

 one or two exceptions, not nearly so highly developed as 



