Plate P25. 1, 2. Spongodinium delitiense (Ehrenberg 1838) Deflandre 1936b; (1) ventral surface (300x); (2) dorsal surface (350x). 3, 4. Stephodinium coronatum Deflandre 1936a; (3) scanning electron micrograph (SEM), dorsal surface (500x), courtesy of E.J. Kidson; (4) apical surface (500x). 5–10. Stoveracysta ornata (Cookson and Eisenack 1965a) Clowes 1985; (5) dorsal surface (350x); (6) specimen with operculum in place (350x); (7) dorsal surface (350x); (8) same specimen as 7, ventral surface (350x); (9) dorsal surface (350x); (10) same specimen as 9, ventral surface (350x). 11. Sumatradinium druggii Lentin et al. 1994. 275x. 12–14. Sumatradinium soucouyantiae de Verteuil and Norris 1992; (14) dorsal surface. All 350x. 15–17. Surculosphaeridium? longifurcatum (Firtion 1952) Davey et al. 1966. All 500x. 18–20. Thalassiphora delicata Williams and Downie 1966c. All 400x.

Plate P25. 1, 2. Spongodinium delitiense (Ehrenberg 1838) Deflandre 1936b; (1) ventral surface (300x); (2) dorsal surface (350x). 3, 4. Stephodinium coronatum Deflandre 1936a; (3) scanning electron micrograph (SEM), dorsal surface (500x), courtesy of E.J. Kidson; (4) apical surface (500x). 5–10. Stoveracysta ornata (Cookson and Eisenack 1965a) Clowes 1985; (5) dorsal surface (350x); (6) specimen with operculum in place (350x); (7) dorsal surface (350x); (8) same specimen as 7, ventral surface (350x); (9) dorsal surface (350x); (10) same specimen as 9, ventral surface (350x). 11. Sumatradinium druggii Lentin et al. 1994. 275x. 12–14. Sumatradinium soucouyantiae de Verteuil and Norris 1992; (14) dorsal surface. All 350x. 15–17. Surculosphaeridium? longifurcatum (Firtion 1952) Davey et al. 1966. All 500x. 18–20. Thalassiphora delicata Williams and Downie 1966c. All 400x.