DENTTTTOX OF LOWER VERTEBRATES 



35 



The very fact that we have chosen fish in this first illustra- 

 tion indicates that the occurrence of teeth is by no means con- 

 fined to the higher animals. Analogous structures have indeed 

 been found in some Invertebrates but it would not help our 

 present purpose to consider these. We must note however that 

 teeth of a simple pattern exist far down in the vertebrate 

 scale. 



Fig. 4. — Jaws of Pickerel to show the occurrence of teeth upon the palate. (After 

 Dewey-Thompson.) Teeth are not confined to the jaws themselves. 



Another point to notice is that whereas the teeth upon the 

 jaws of the Pike are firmly united to the underlying bone those 

 of the palate are hinged so that they can be made to lie flat 

 against the buccal lining, their tips pointing toward the throat, 

 by small fish as prey passing through the mouth. If however 



