Light (A, C) and scanning electron (B, D-I) micrographs of Assulina seminulum. (A-C) View of many specimens to illustrate variability in shape and size of the shell. (D) Broad lateral view showing general shape and regular arrangement of shell-plates. (E) Narrow lateral view. (F) Apertural view. (G) Close up view of aperture to illustrate shape of aperture, arrangement of apertural-plates and thin border of organic cement. (H) Lateral view of apertural region (I) Detail of shell surface to show overlapping, oval shell-plates.