Figure 3. 



The under surface of the head of a typical snake to show 

 head shields. 



= mental. 



anterior sub-lingual or chin-shield. 

 " posterior do. do. 



first, second, etc., infra-labials. 



mental groove. 



M 

 A 

 P 



1, 2, 3, 4, 5, 6, 7 =. 

 a to b - 



