Plate P3. Thalassiosira praeoestrupii Dumont, Baldauf, and Barron. 1. Whole valve showing rimoportula (R) and central fultoportula (CF) (Sample 186-1150B-6R-CC); light microscope (LM). 2. Whole valve showing R and CF (Sample 186-1150B-5R-CC); LM. 3. External view of whole valve showing openings of R and CF (Sample 186-1151A-54R-CC); scanning electron microscope (SEM). 4, 5. Sample 186-1150B-9R-CC; SEM; (4) internal view of whole valve showing broken R, broken processes of marginal fultoportulae (MF), and internal process of CF; (5) internal process of CF with three operculate structures (OP) and three trifultate structures (T). 6, 7. Sample 186-1151A-54R-CC; SEM; (6) internal view of whole valve showing broken R, internal processes of MF and CF; (7) internal process of MF.

Plate P3. Thalassiosira praeoestrupii Dumont, Baldauf, and Barron. 1. Whole valve showing rimoportula (R) and central fultoportula (CF) (Sample 186-1150B-6R-CC); light microscope (LM). 2. Whole valve showing R and CF (Sample 186-1150B-5R-CC); LM. 3. External view of whole valve showing openings of R and CF (Sample 186-1151A-54R-CC); scanning electron microscope (SEM). 4, 5. Sample 186-1150B-9R-CC; SEM; (4) internal view of whole valve showing broken R, broken processes of marginal fultoportulae (MF), and internal process of CF; (5) internal process of CF with three operculate structures (OP) and three trifultate structures (T). 6, 7. Sample 186-1151A-54R-CC; SEM; (6) internal view of whole valve showing broken R, internal processes of MF and CF; (7) internal process of MF.