FIGURES 21–26. Figs. 21. Thalassiosira nanolineata, Fig. 21. SEM external valve view. Fig. 21a in Diatoms (Bacillariophyta) From Artificial Substrates And Sediments In The Caribbean Sea Off Yucatan, Mexico

FIGURES 21–26. Figs. 21. Thalassiosira nanolineata, Fig. 21. SEM external valve view. Fig. 21a. External opening of two central strutted processes. Fig. 21b. External tube of marginal strutted processes. Figs. 22–25. Psammodiscus nitidus, Fig. 22. SEM internal valve view, note small pore (arrow). Fig. 23. LM external valve view. Fig. 24. SEM external valve view. Fig. 24a. Details of areolae occluded by plated rotae with 2–3 spokes. Fig. 25. LM external valve view. Fig. 26. Thalassiosira eccentrica. Scale bar: figs. 21, 22, 24 = 1 μm, figs. 23, 55, 26 = 10 μm.