Outer lamella

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Fig. 1. The pore and its organic constituents. A: a pore in an inner chamber covered by an outer whorl, according to Leutenegger (1977), schematic, not to scale.; (Hottinger, 2006; fig. 20)[1] CC/BY-NC-SA)
Fig. 2. Enveloping canals produced by folded outer lamellas. A-D: Lamellae in the peripheral portion of three successive chambers. Stereograph, schematic, not to scale. A: ultimate and penultimate chamber: red: inner lamella; green: outer lamella of ultimate chamber, white: outer lamella of penultimate chamber. B: addition of the next chamber with an inner lamella in red and an outer lamella in blue. C: addition of an other chamber with its outer lamella in yellow. D: superposition of lamellas B and C over the then final chamber A after two additional growth steps. E: SEM micrograph of the complete test of Calcarina defrancii d'Orbigny, ventral view, showing distribution of canal orifices over all the test including the canaliferous spines. F: SEM micrograph of an epoxy resin cast of the shell cavities in Calcarina gaudichaudii d'Orbigny cut in a direction perpendicular to the axis of the spiral shell, ventral view; G: detailed SEM micrograph of the ventral shell surface of C. gaudichaudii. Calcarinas from Keij Island, Indonesia. Recent. After Hottinger and Leutenegger, 1980. apil: axial pile of lamellae; ch: chamber and chamber lumen; co: canal orifice; csp: canaliferous spine; envc: enveloping canal; isc: intraseptal space or canal; il: inner lamella; lh: loop-hole; ol: outer lamella; p: pore; paf: perforate part of apertural face; ssk: supplemental skeleton; st: stolon; uc: umbilical canal network; uch: ultimate chamber suture, chamber walls broken off; (Hottinger, 2006; fig. 43)[2] CC/BY-NC-SA)


Definition

  • according to Hottinger (2006):

OUTER LAMELLA - the mineralized layer of the primary wall in bilamellar foraminifera, on the outer side of the primary organic sheet. At its contact with the primary organic sheet is the outer array of distinctly larger paired crystals (included by some authors in the so-called median layer) succeeded by the stacks of calcite platelets or pseudohexagonal aragonite prisms that form the major part of the outer lamella, and is completed by the outermost thin layer of blocky columnar crystals that comprise the veneer.



See also


References

Hottinger (2006), Illustrated glossary of terms used in foraminiferal research. Carnets de Géologie, Memoir 2, ISSN 1634-0744

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