Figure 12: Single and multiple areal apertures.
A-B: Monalysium acicularis (Batch); C-D: Peneroplis planatus (Fichtel et Moll), both from the Gulf of Aqaba, Red Sea, Recent. SEM graphs. Note the presence of pits in the porcelaneous wall and the umbilical bowl characterizing P. planatus.
a: areal aperture(s); pst: peristomal rims; ub: (delimitation of) umbilical bowl; ws: whorl suture. Note the absence of interiomarginal apertures.