Figure 33: Countersepta.
A-D: Amphistegina tuberculata , Dominican Republic, Upper Miocene, SEM stereographs showing the split halves of a megalospheric shell. A: dorsal side in ventral view, B: ventral side in dorsal view, with details in C and D. E-G: Amphistegina lopeztrigoi , thin slides in transmitted light micrographs, Eocene, Florida. Generic and specific name are unclear and need revision. E: centered section perpendicular to the coiling axis; F: section perpendicular to the coiling axis located below the megalosphere; G: poorly centered axial section.
cs: counterseptum; egh: eggholder; f: main foramen; pust: pustules covering successive faces; s: septum of main chambers; stc: stellar chamberlets.