The 100 µm scale bar applies to figs. 3a and 4a;
all other figs. have their own scale bar.
Figs. 1-4. Rhizosphaera arcadophora. Figs. 2 and 3b: Details of microspheres. Note how radial spines arise from the periphery, and how most are slightly twisted along their axes (fig. 2) and irregularly spaced barbs on spines (fig. 3b, upper half). Fig. 4b: detail, illustrating how the radial spines transverse the wall of the cortical shell. BSS 28B(IX/1180, VIII/790, IX/1295 and 1272).