TEETH OF POISONOUS SNAKES. 



257 



POISOX-FAXa 

 OF RATTLE- 

 SNAKE (mag- 

 nified). 



To give an idea of the structure of this 

 tooth, we may suppose a simple slender 

 tooth, like that of a boa-constrictor, to be 

 flattened, and its edges then bent towards 

 each other and soldered together so as to 

 form a tube, open at both ends, and inclosing 

 the end of the poison-duct. Such a tooth is 

 represented at Fig. 66^ where A is the oblique 

 opening penetrated by the duct, and v the 

 narrower fissure by which the venom escapes. 



The duct which conveys the poison, al- 

 though it runs through the centre of the 

 tooth, is really on the outside of the tooth. 

 The bending of the dentine about it begins 

 a little beyond the base of the tooth, where 

 the poison-duct rests in a slight groove or longitudinal 

 indentation on the convex side of the fang; as it pro- 

 ceeds, it sinks deeper into the substance 

 of the tooth, and the sides of the groove 

 meet and seem to coalesce, so that the 

 trace of the inflected fold ceases, in some 

 species, to be perceptible to the naked 

 eye ; and the fang appears, as it is com- 

 monly described, to be perforated by 

 the duct of the poison-gland. 



In the viper, the line of union may 

 be seen as marked at v, Fig. 66 ; and 

 when such a tooth is carefully divided 

 lengthwise, as in Fig. 67, the true pulp, 

 cavity in the substance of the tooth is 

 seen, as at/),|J, to terminate in a point; 

 and the poison-canal, as at u, f, to run 

 along the forepart of the singularly 



22* 



Fig. 67. 



SECTION OP A POISON- 

 FANG — RATTLESNAKE, 



