Fig. 1. The folium and its apertures. All specimens from the Gulf of Aqaba, Red Sea, Recent. SEM graphs. A-D: Rosalina bradyi (Cushman); A: detail of dissected specimen, oblique-ventral view. The approximate position of the breakage surface (arrows A-A) is indicated by the line A-A in Fig. B. B: ventral view showing the folium at its maximum development, with anterior and posterior apertures. C-D: peripheral and dorsal views. Note the restriction of the perforation to the dorsal surface of the shell, an indication that the face extends from the umbilical side of the shell over its periphery. E-H: Asterorotalia gaimardi (d'Orbigny). E-F: dissected specimens showing details of advanced umbilical architecture covered by the folia: foraminal and coverplates. G: oblique-ventral view showing the folia that cover the ventral part of the interlocular space. H: dorsal view showing the spiral arrangement of the chambers. a: aperture; ch: chamber lumen; cp: cover plate; f: foramen; fo: folium; foa: foliar aperture; fochl: foliar chamberlet lumen; fp: foraminal plate; is: interlocular space; li: lip (of foramen); n: notch; sf: septal flap; u: umbilicus; (Hottinger, 2006; fig. 53) CC/BY-NC-SA)
- according to Hottinger (2006):
FOLIAR APERTURE - (labial aperture, pars auct.); the primary opening of a folium to the exterior in an interiomarginal anterior, posterior or umbilical (axial) position at the folium borders; it lies between the main chamber wall and the folium (foliar slit; astral fissure); or in the folium itself. A foliar aperture may be a continuation of the primary cameral aperture or separate from it, but it is never converted into an intercameral foramen. It may lead to funnels when covered by secondary lamellae.
Hottinger (2006), Illustrated glossary of terms used in foraminiferal research. Carnets de Géologie, Memoir 2, ISSN 1634-0744
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