Two new species and a new subspecies of the Astartidae (Mollusca, Bivalvia) are described from reworked shell material of beaches and estuaries in the Province of Zeeland, The Netherlands. Nomenclatural notes concerning some other species of the same family are added. Furthermore an attempt is made to demonstrate the phylogenetical development of the Astarte (Isocrassina) fusca and the A. (I.) omalii group from the younger Caenozoic (Miocene to Quaternary) of the North Sea Basin.