A biostratigraphical analysis of the Eocene formations of the southern Aquitaine Basin, France, shows that the planktonic foraminiferal zonal scheme of Stainforth et al. (1975) and the calcareous nannoplankton zonation of Proto-Decima et al. (1975) are applicable in this area, although in a modified form. A correlation of the calcareous planktonic microfossil zonal schemes is postulated. A supraspecific phylogenetical classification of the planktonic foraminifera is proposed, based largely on test wall ultratextural studies. This classification appears to be of greater biological and stratigraphical significance than earlier typological classifications.