Plate P3. Scale bar = 10 µm. 1-4. Helicosphaera ampliaperta (Sample 189-1170A-31X-5, 60 cm); (1) phase-contrast light (Ph); (2) differential-interference contrast light (DIC); (3, 4) polarized light (XP). 5-7. Helicosphaera recta (Sample 189-1168A-47X-3, 40 cm); (5, 6) Ph; (7) XP. 8, 9. Helicosphaera elongata (Sample 189-1168A-38X-1, 15 cm); (8) Ph; (9) XP. 10-12. Helicosphaera paleocarteri, Cyclicargolithus floridanus, and Helicosphaera euphratis (Sample 1168A-38X-4, 15 cm); (10) Ph; (11) DIC; (12) XP.