Fig. 9. 



Side View of the Head op the Timsa oe Nile Crocodile 



{Crocodilus niloticus). 



X Fourth lower tooth. 



(Photographed from a specimen in the Museum.) 



Fig. 10. 



Side View of the Head of""the N. American Alligator 

 (.-■1 lligator mississippiensis) . 



(Photographed from a specimen in the Museum.) 



[To face page 10. 



