An account is presented of a restudy of type material of 13 species of dinoflagellate cysts and one species of acritarch from Upper Cretaceous flints of Belgium and Germany. The new combinations Amphorosphaeridium major (Lejeune-Carpentier), Hystrichokolpoma? crassipes (Reade) and Deflandrea damasii (Lejeune-Carpentier) are proposed. The former Exochosphaeridium spinosum var. deflandrei is elevated to specific status, as Fibrocysta? deflandrei (Lejeune-Carpentier). The former Hystrichosphaeridium cruciatum is shown to be an acritarch ; the new combination Veryhachium? cruciatum (0. Wetzel) is proposed. Emended diagnoses are presented for these five species and for the following: Gonyaulacysta wetzeli (Lejeune-Carpentier), Gonyaulacysta? obscura (Lejeune-Carpentier), Cribroperidinium ventriosum (0. Wetzel), Leptodinium porosum (Lejeune-Carpentier), Deflandrea galeata (Lejeune-Carpentier) and Lejeunecysta tricuspis (0. Wetzel). Full synonymies are presented for the species Oligosphaeridium complex (White) and Areoligera senonensis Lejeune-Carpentier ; their stratigraphical and geographical distribution is discussed. The taxonomic problems presented by Palaeoperidinium? subconicoides are considered. Photographs of all species are presented, in most cases for the first time ; and interpretative drawings, most of them redrawn versions of the first author's original figures, supplement the text.