472 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



been supposed that in the cobra these small lobules are 

 mucus glands. Thus in the Ophidia are to be found the 

 only animals in which an admixture of mucus is present 

 in the parotid saliva. 



Before reaching its termination the duct doubles on 

 itself, and opens upon a small papilla on the anterior wall 

 of the mucous sheath surrounding the base of the tooth. 



The fang is attached to the maxilla, is tubular and 

 slightly curved. The canal for the poison is really on the 

 outside of the tooth, being formed by the longitudinal 

 reflection of the margins of a fang, which has, as it were, 

 been flattened out transversely. 



It has two openings. The basal one, near the papilla of 

 the duct, is on the anterior surface ; the other opening is 

 on the same surface of the tooth within a short distance of 

 the point. 



In the largest specimens of the cobra, the fang does not 

 often exceed Jin. In the viper it is much longer and 

 beautifully curved, but never exceeds ^in. in length. 



In the vipers the fang is so long that it cannot, as in the 

 cobra, be received into a pit in ihe lower lip. Complete 

 depression, when the mouth is closed, is therefore brought 

 about by a slip of the ecto-pterygoid muscle which passes 

 to the mucous sheath surrounding the fang. 



When the snake opens its mouth the fangs are erected. 

 This takes place to a greater or less extent in different 

 snakes. The sheath of the fang is drawn tightly over the 

 anterior surface, and the aperture of the poison duct and 

 the opening at the base of the fang are brought into 

 apposition. 



The muscles acting in the closing of the jaws are the 

 masseters and internal pterygoids. The masseters have 

 some of their fibres inserted into the tough fibrous capsule 

 of the poison gland, and when contraction of the muscle 



