Plate P1. Illustrations of taxa, sample, and slide number. Scale bar = ~20 µm unless stated otherwise. Scanning electron microscope (SEM) photographs have varying scale bars. 1. Adnatosphaeridium multispinosum (Sample 189-1172D-15R-3, 40-42cm) (1). 2. Aio

Plate P1 (continued). 13. Alterbidinium acutulum (Sample 189-1172D-24R-5, 130-133 cm) (1); scale bar = ~15 µm. 14. Alterbidinium distinctum (Sample 189-1172A-39X-4, 85-87 cm) (2). 15-17. Arachnodinium antarcticum (Sample 189-1172A-48-3, 85-87 cm) (1). 18, 19. Batiacasphaera cassicula (Sample 189-1172D-10R-1, 40-42 cm) (1). 20-22. Brigantedinium? sp. (Sample 189-1172A-39X-3, 128-130 cm) (2); scale bar = ~15 µm. Note periphragm delineating long slender antapical horns. 23. Brigantedinium spp. (Sample 189-1172A-6H-4, 85-87 cm) (2); scale bar = ~15 µm. Specimen from the Quaternary; compare with Brigantedinium? sp. 24. Cerebrocysta bartonensis (Sample 189-1172A-49X-4, 85-87 cm) (1); scale bar = ~15 µm.