Plate P1. The modified Kofoid system (as outlined in Fensome et al., 1993b) is used in the labeling of individual plates for the gonyaulacaleans. The Kofoid system is used in the labeling of plates in the peridinialeans. The archeopyle location is denoted by diagonal lines. 1. Achilleodinium biformoides (Eisenack 1954b) Eaton 1976. Ventral view. Holotype dimension: central body diameter = 50 m. 2. Achomosphaera alcicornu (Eisenack 1954b) Davey and Williams 1966a. Dorsal view. Holotype dimensions: overall diameter = 157 m, central body diameter = 65 m x 67 m. 3. Achomosphaera andalousiensis Jan du Chne 1977. Dorsal view. Holotype dimensions: central body diameter = 35 m x 40 m, process length = 15 m. 4. Adnatosphaeridium tutulosum (Cookson and Eisenack 1960a) Morgan 1980. Holotype dimensions: overall diameter = 70 m, central body diameter = 53 m. 5. Alisocysta circumtabulata (Drugg 1967) Stover and Evitt 1978. Ventral view. Range of type material: length = 37–47 m, width = 36–47 m. 6. Alisocysta margarita (Harland 1979a) Harland 1979a. Ventral view. Holotype dimensions: length = 44 m, width = 40 m. 7. Alisocysta reticulata Damassa 1979b. Ventral view. Average range of type material: length = 55 m, width = 51 m. 8. Alisogymnium euclaense (Cookson and Eisenack 1970a) Lentin and Vozzhennikova 1990. Holotype dimensions: length = 34 m, width = 22 m. 9. Alterbidinium? distinctum (Wilson 1967a) Lentin and Williams 1985. Dorsal view. Holotype dimensions: pericyst length = 118 m, pericyst width = 61 m, endocyst diameter 58 m x 63 m. 10. Amiculosphaera umbraculum Harland 1979b. Dorsal view. Holotype dimensions: length = 80 m, width = 86 m. 11. Apectodinium augustum (Harland 1979c) Lentin and Williams 1981. Dorsal view. Holotype dimensions: pericyst length (excluding horns) = 63.75 m, pericyst width (excluding horns) = 66.25 m. 12. Apteodinium deflandrei (Clarke and Verdier 1967) Lucas-Clark 1987. Right lateral view. Holotype dimensions: overall length = 52 m, overall width = 40 m. 13, 14. Arachnodinium antarcticum Wilson and Clowes 1982. Holotype dimensions: overall length (excluding operculum) = 105 m, overall breadth = 96 m, central body length (excluding operculum) = 58 m, central body width = 48 m, antapical process length = 22 m; (13) lateral view; (14) apical view. 15. Areoligera gippingensis Jolley 1992. Ventral view. Range of type material: overall length = 32–42 m, overall width = 45–59 m, process length = 15–33 m. 16. Areosphaeridium diktyoplokum (Klumpp 1953) Eaton 1971. Ventral view. Holotype dimensions: central body diameter = 48 m. 17, 18. Areoligera semicirculata (Morgenroth 1966b) Stover and Evitt 1978. Range of type material: central body length = 45–61 m, central body width = 42–56 m, central body height = 33–40 m, process length = 5–33 m; (17) ventral view; (18) antapical view. 19, 20. Ataxiodinium confusum Versteegh and Zevenboom in Versteegh 1995. Holotype dimensions: overall diameter = 36 m, endocyst diameter = 22 m; (19) dorsal view; (20) lateral cross-section.