Figure 32: Columellas. Transmitted light micrographs.
A-D: Kurnubia palastiniensis Henson. Upper Jurassic, Northeastern Morocco. A: transverse section near and almost parallel to the axis of coiling; B: axial section; C-D: oblique sections. Position of sections relative to the axial section marked by red lines. E: Borelis schlumbergeri (Reichel), axial section. Gulf of Aqaba. Recent. Note double columella in planispiral-fusiform shells.
b: beam; bl: basal layer; col: columella; f: foramina; prp: preseptal passage; r: rafter; s: septum; sl: septulum; t: tunnel; wsut: whorl suture.