GENERAL CLASSIFICATION OF POISONOUS SNAKES 



11 



They are oval in shape, and may, in Naja tripudians for example, 

 attain the size of a large almond (fig. 8). 



Their structure is the same as that of the salivary glands of the 

 larger animals. The poison that they secrete accumulates in their 

 acini and m the efferent duct that opens at the base of the corre- 

 sponding fang. 



Each gland is surrounded by a capsule, to which are partly 

 attached the fibres of the masseter muscle, which violently com- 

 presses it and drives 

 the poison, just as 

 the piston of a 

 syringe would do, in- 

 to the canalicule or 

 groove of the fang. 



In a few venom- 

 ous snakes the gland 

 is developed to such 

 an extent that it ex- 

 tends as far as the 

 first ribs. 



The species, on 

 the contrary, that 

 have the poison- 



FiG. 8. — Poison-gland and Fangs of a Venomous 

 Snake (Naja tripudians, Colubridcis). (Natural size.) 



L,, Lobe of the gland ; d, poison-duct ; f, fang attached 

 to the maxillary bone ; G G, gland ; m, capsule of mucous 

 membrane surrounding the fangs ; r, reserve fangs ; 

 A A, muscular fascia covering the gland. 



(After Sir Joseph Fayrer. ) 



teeth placed in the 



hinder part of the mouth {Opisthoglyplia) have glands but little 



developed. 



Muscular Apparatus of the Head. — Figs. 9 and 10, 11 and 12 

 show the arrangement of the principal muscles that work the jaws 

 and glandular organs in Vipera russellii and Naja tripudians, which 

 respectively represent the most formidable types of ViperidcB and 

 venomous ColiihridcB. 



It is not necessary to give a detailed description of each of these 

 muscles. Let it suffice to point out that all contribute in giving 

 the greatest elasticity to the jaws, and at the same time strength 



