Fig. 1. Odd association and polar structures in Praealveolina tenuis Reichel. From Alcantara, Lisbon; Cenomanian. Transmitted light micrographs. A: microspheric specimen, axial section; B: megalospheric specimen, axial section; C-E: odd partners: C: axial section of microspheric Simplalveolina sp.; D: axial sections of megalospheric Simplalveolina sp.; E: Ovalveolina sp, axial section. F: microspheric P. tenuis, axial section, detail showing polar structure with floors and shaftsin the basement. G: model of two subsequent chambers near their polar ends where the first floors in the basement appear. H: model of the protoplasmic body filling the cavities in G. Both models schematic, not to scale, after Reichel, 1933. a: aperture: af: apertural face; bchl: basement chamberlets; bl: basal layer; chl: (main) chamberlets; fl: floor; prp: preseptal passage; rp: (incipient) residual pillar; s: septum; sa: supplementary aperture; sh: shaft; sl: septulum; sut: cameral suture; (Hottinger, 2006; fig. 70  CC/BY-NC-SA)
- according to Hottinger (2006):
BASEMENT - cavities below a main chamberlet layer, developing polewards in elongate alveolinids, delimited by floors and septula, opening into a preseptal space and connected vertically by shafts, as in Praealveolina.
Hottinger (2006), Illustrated glossary of terms used in foraminiferal research. Carnets de Géologie, Memoir 2, ISSN 1634-0744
Reichel (1933), Sur une alvéoline cénomanienne du Bassin du Beausset. Eclogae geologicae Helvetiae, Basel, vol. 26, N° 2, p. 269-280.
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