Orbitopsellid structure

From Foraminifera
Jump to: navigation, search
Fig. 1. The structure of Orbitopsella: a simple exoskeleton and a pillared endoskeleton in a discoidal shell: Orbitopsella dubari Hottinger, Bou Dahar, Eastern Morocco, Middle Lias. Transmitted light micrographs.A: oblique section of complete microspheric specimen; B: oblique section of microspheric specimen. The septa of the thickened margin are cut tangentially and reveal the alternating pattern in the disposition of foramina on the septal face. C: oblique tangential section of a microspheric specimen at a low angle to the equatorial plane showing a part of the disc with its exoskeleton (restricted to beams). Note the large open spaces, the lateral annular passages (arrows), that separate exoskeleton and endoskeleton. D: Oblique centered section of megalospheric specimen. Note the structured wall of the embryo, that shows it to be a sphaeroconch. E: Transverse section (parallel to the axis of coiling) of a megalospheric specimen. The septum in this tangential section reveals the alternating pattern of the apertures. F: schematic model of structure after Hottinger, 1967; not to scale; green: exoskeleton; brown: endoskeleton; a: aperture; ap: annular passage; b: beam; f: foramen; p: pillar; pr: sphaeroconch; s: septum; (Hottinger, 2006; fig. 72 [1] CC/BY-NC-SA)


Definition

  • according to Hottinger (2006):

ORBITOPSELLID STRUCTURE - arrangement of endoskeletal elements as in Orbitopsella: the arrangement of endoskeletal pillars follows the pattern of the radial stolon axes that alternate in radial position from one stolon plane to the next. Exoskeletal elements consist of beams only.





See also

References

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