Observations on some Australian Eocene dinoflagellates

Revised descriptions and interpretations are presented for five species of Australian Eocene dinoflagellates based primarily on abundant specimens from newly collected and processed samples, and to a lesser extent on the examination of type specimens. These species, whose processes or peritabular ridges reflect a basic gonyaulacacean tabulation, were described originally as Cannosphaeropsis urnaformis Cookson, Hystrichosphaeridium floripes Deflandre & Cookson, Schematophora speciosa Deflandre & Cookson, Eisenackia ornata Cookson & Eisenack, and Aireiana verrucosa Cookson & Eisenack. For the first species, the new genus Emmetrocysta is proposed with E. urnaformis as its type species; Hystrichosphaeridium floripes is transferred to Homotrybliun Davey & Williams. The reflected tabulation and other features on Schematophora speciosa and Eisenackia ornata are analyzed and compared, and the process formula for Aireiana verrucosa is divulged.