14 



The Five 

 Forms of 

 Dentition. 



helps to lubricate the system, and plays an import- 

 ant part in assisting the liver and other organs in 

 their work of digestion. The Ovaries lie in front 

 of the intestine, and resemble transparent sacks, 

 which sometimes extend nearly half way up the 

 body of the snake. 



The Dentition of Snakes is of five kinds : — 

 (i) Solid teeth (all harmless snakes). 



(2) Grooved and immovable fangs, situ- 

 ated in the back of the upper jaws, behind 

 the solid maxillary teeth, and which may be 

 provided with a slight amount of poison 

 (Dipsadinse, Homalopsinse). 



(3) Fangs grooved and immovable, situ- 

 ated in front of the other maxillary teeth and 

 supplied with virulent poison (Hydropiinse). 



(4) Poison fangs in a better stage of 

 development, supplied with virulent poison, 

 and situated in front of the other maxillary 

 teeth, with well-marked poison canals down 

 their centres. These fangs can be slightly 

 erected and depressed (Elapidae of India and 

 Ceylon). 



(5) The whole poison apparatus in its 

 best stage of development. Fangs much en- 

 larged, caniculate, and capable of being en- 

 tirely erected and depressed (Viperidae). 

 The erection and depression of the fang is 



found in its most perfect form among the Viperidae, 

 and is accomplished in the following manner : — 



The maxillary bone is a bone situated behind 

 and below the snout, where it moves in a socket 



Bones of the ^o^^^d by the " snout bones" (prae-frontal). 



skull and Welded to the lower end of the maxillary bone 

 is the fang, while the centre of the maxillary bone 

 is itself hinged on to another bone (the ectopteri- 

 goid), which can be protruded and retracted by 

 muscles, thus raising and depressing the fang. 



Mobility of 

 the fang. 



jaws. 



