The influence of bone cells on the formation, and mineralization, of bone matrix.

C A L C I U M P H O S P H A T E S Rhynchobatus ancylostmu ; Guitar fish (ray). The teeth of fish show great variety of form and structure. In sharks and rays there is a succession of teeth; new ones form on the buccal surface of the jaws and, as they migrate outwards, they increase in size and thickness. Finally, they are cast off and replaced by succeeding teeth. The teeth in this specimen are used for crushing prey. Cementin, enamel and dentine may all be constituents of fish teeth. Of these, dentine, in all its different varieties, is the most important. It is a calcium hydroxy phosphate.