Plate P4. Scale bar = 10 µm. 1A-AC. Chiasmolithus oamaruensis (Sample 183-1138A-37R-1, 25-26 cm); (1A) crossed polarizers, (1B) differential interference contrast light (DIC), (1C) transmitted light. 2A-2C. Isthmolithus recurvus (Sample 183-1138A-37R-1, 25-26 cm); (2A) crossed polarizers, (2B) DIC, (2C) transmitted light. 3A, 3B. Isthmolithus recurvus (side view) (Sample 183-1138A-37R-1, 25-26 cm); (3A) crossed polarizers, (3B) DIC. 4. Reticulofenestra umbilica (Sample 183-1138A-37R-1, 25-26; crossed polarizers). 5A-5C. Reticulofenestra bisecta (Sample 183-1138A-37R-1, 25-26 cm); (5A) crossed polarizers, (5B) DIC, (5C) transmitted light.

Plate P4. Scale bar = 10 µm. 1A-AC. Chiasmolithus oamaruensis (Sample 183-1138A-37R-1, 25-26 cm); (1A) crossed polarizers, (1B) differential interference contrast light (DIC), (1C) transmitted light. 2A-2C. Isthmolithus recurvus (Sample 183-1138A-37R-1, 25-26 cm); (2A) crossed polarizers, (2B) DIC, (2C) transmitted light. 3A, 3B. Isthmolithus recurvus (side view) (Sample 183-1138A-37R-1, 25-26 cm); (3A) crossed polarizers, (3B) DIC. 4. Reticulofenestra umbilica (Sample 183-1138A-37R-1, 25-26; crossed polarizers). 5A-5C. Reticulofenestra bisecta (Sample 183-1138A-37R-1, 25-26 cm); (5A) crossed polarizers, (5B) DIC, (5C) transmitted light.