THE REPTILE BOOK 



PLATE CXX 



HEAD OF RATTLESNAKE 



When the jaws are closed the fangs fold back against the roof of the mouth. They 

 are exactly like the hypodermic needle having an elongated orifice at their tip for 

 the ejection of venom. The opening near the front of the lower jaw shows the location 

 of the tongue-sheath. Thus it should be understood that the forked tongue is not a 

 sting or in any way connected with the poison apparatus 



SKULL OF A PIT VIPER, SHOWING DEVELOPING FANGS 



The illustration shows how fangs are constantly developing to take the place of the functional pair 



