J. Moll. Stud. (1989), 55, 67-78. © The Malacological Society of London 1989 A REVIEW OF POECILOGONY IN GASTROPODS

All alleged cases of poecilogony in marine gastropods, involving planktotrophic and non planktotrophic lar-val development within a single species, are reviewed. It is concluded that there is presently no known case of poecilogony in prosobranchs and shelled opis-thobranchs, although indisputable poecilogony exists in Ascoglossa and possibly nudibranchs. The multi-spiral or paucispiral form of the protoconch, which is a reflection of planktotrophic or non-planktotrophic larval development respectively, can therefore, with a very high degree of confidence, be considered a species-specific character that can be used in routine taxonomical work on both Recent and fossil material