Chap. IV.] 



TEETH OF REPTILES. 



the bones of the skull are loosely connected with one 

 another, and so allow of the enlargement of the cavity 

 of the mouth ; others, finally, kill their prey by biting 

 and simultaneously injecting poison into the wound. 

 In these last (the venomous snakes) there may be 

 several not very long teeth in the maxillary bone, or 

 there may be 



/ 



but one maxil- 

 lary tooth, which 

 in such cases is 

 long and mov- 

 able. In the 

 former the fangs 

 are distinctly 

 grooved along 

 some part of 

 their length, but 

 the sides of this 

 groove are suffi- 

 ciently close to 

 form a service- 

 able canal, along 

 which the poison 

 from the poison 

 gland may make 

 its way into the 

 wound. In the 

 latter the single 

 large maxillary 

 tooth appears, 

 from the outside, to be solid and ungrooved ; the real 

 fact is, however, that the two edges of the groove have 

 completely united to form a closed canal, the existence 

 of which becomes apparent in a transverse section of 

 the tooth ; the opening of the canal is not placed quite 

 at the tip of the sharp fang, but, just as in a subcu- 

 taneous injection syringe, the orifice is a little behind 



Fig. 65. Transverse Section of the Poison Fang 

 and Eeserve Set of a Viper. 



1, Tooth in use; 2, the tooth which will succeed it ; 3 to 

 10, tooth-sacs numbered in the order of their succes- 

 sion. (After C. S. Tomes.) 



