DENTINE 



2f>5 



FIG. 157. Tooth of a tertiary fossil fish (Aetobatis) showing the plici- 

 dentine in longitudinal section. From a specimen lent to the author by 

 Mr. J. Humphreys. 



FIG. 158. Longitudinal section of plicidentine from the fossil eocene fish 

 Edaphodon. From Mr. Humphrey's collection, p. Pulp cavity. 



