Cruickshank, A. R. I.2014-09-222014-09-2219680078-8554http://hdl.handle.net/10539/15573The structure of the large laniary teeth of the Lower Carboniferous rhipidistian fish Rhizodu hibberti Ag. is interpreted in terms of a new theory of tooth development. The structure of these teeth is found to correspond almost exactly to that of the synchronomorial scale as defined by Orvig (1951) and Stensio (1961; 1962). These labyrinthodont teeth are thus shown to be composed of many tooth primordia, and are not a single unit of dentine. Some isolated Rhizodus teeth are described in which the entire labyrinthodont structure is missing, leaving an empty space inside the tooth. From this, a non-mechanical tooth removal mechanism is postulated.enArticle