Comments on some mediterranean rock dwelling helicids

(Presidential Address, delivered 11 March 1981)

Species have been defined as ‘groups of actually (or potentially) interbreeding natural populations which are reproductively isolated from other such groups’. If this is adopted, it is suggested that many generally accepted named species with widely differing shell characters are not species but ‘forms’, ‘local races’ or ‘varieties’.
      The more conspicuous divergent but interbreeding mediterranean forms are considered, with early and modern authors’ comments thereon and the efforts of some of them to adapt the nomenclatural system so as to indicate the close relationship between such forms.