Plate P12. 1–4. Arachnodinium antarcticum Wilson and Clowes 1982; (2) upper surface (300x); (3) same specimen as 2, optical section (300x); (3) same specimen as 2, lower surface (300x). 5, 6. Areoligera gippingensis Jolley 1992; (5) ventral surface (600x); (6) oblique apical view (600x). 7, 8. Areoligera semicirculata (Morgenroth 1966b) Stover and Evitt 1978; (7) dorsal surface (450x); (8) ventral view of optical section (450x). 9, 10. Areosphaeridium diktyoplokum (Klumpp 1953) Eaton 1971; (10) dorsal surface. Both 350x. 11. Ataxiodinium choane Reid 1974. Courtesy of Dan Zevenboom. 700x. 12, 13. Ataxiodinium confusum Versteegh and Zevenboom in Versteegh 1995; (12) dorsal surface (800x); (13) ventral cross-section (800x). 14, 15. Barssidinium evangelineae Lentin et al. 1994; (14) dorsal surface (300x); (15) optical section (300x). 16. Biconidinium longissimum Islam 1983c. 400x. 17, 18. Callaiosphaeridium asymmetricum (Deflandre and Courteville 1939) Davey and Williams 1966b. Both polar views (500x). 19, 20. Cannosphaeropsis passio de Verteuil and Norris 1996a; (19) optical section (350x); (20) dorsal surface (350x).