Plate P5. Scale bar = 10 µm. 1. Calcidiscus radiatus (Sample 189-1171C-22X-3, 15 cm) (phase-contrast light [Ph]). 2-4. Calcidiscus tropicus (Sample 189-1171C-17X-3,15 cm); (2) Ph; (3) differential-interference contrast light (DIC); (4) polarized light (XP). 5, 6. Calcidiscus leptoporus (Sample 189-1172A-10H-3, 15 cm); (5) Ph; (6) XP. 7-9. Calcidiscus premacintyrei (Sample 189-1171C-22X-4, 15 cm); (7) Ph; (8) DIC; (9) XP. 10-12. Calcidiscus macintyrei (Sample 189-1171C-16X-3, 15 cm); (10) Ph; (11) DIC; (12) XP.