CHAPTER XX. 



VI FERINE FANGS. 



THOUGH the ensuing chapter will be devoted more 

 exclusively to the CrotalidcB or rattlesnakes, it were 

 well to repeat here that the two families VipcridcB and 

 Crotalidce comprise the sub-order oi Ophidia ' ViPERINA,' — 

 those that have the isolated, moveable fangs, the term 

 isolated having reference to the functional fang only. It 

 may appear incongruous to present the illustration of a 

 viperine jaw with a whole cluster of fangs, while affirming 

 that there is the one pair only ; but the pair in use are 

 'solitary,' because the jaw bears no simple teeth, as in those 

 with fixed or permanently erect fangs. 



The first observation of the mobility of the viperine fang 

 and its peculiar structure is ascribed to Felix Fontana,^ 

 an eminent naturalist and Professor of Philosophy at Pisa, 

 in the eighteenth century. He formed the cabinet of 

 Natural History at Florence, and died 1805, in his 75th year. 

 But the mobility or action of rattlesnake fangs was known 



^ Ricerche Jisiche sopra il vcl no delta vipera. Lucca, 1767. 



S6S 



