VII. Upon the structure and development of the enamel of elasmobranch fishes

Abstract

Considerable interest has always attached to the teeth of Plagiostome fish, there being in them a plain ocular demonstration that the teeth are merely modified dermal spines, so that they exemplify the first appearance of true teeth amongst the vertebrates, while the modification and enlargement which has taken place in the adaptation of dermal spines to serve as teeth is but slight in some, whilst in others it is considerable. But although they have been investigated and described with care, the literature of the subject is not at all copious, perhaps because the classical paper of Hertwig (1) upon the structure and development of placoid scales has seemed to cover the ground pretty completely.