Fig. 1. Milioline coiling. Schematic, not to scale. Note the coiling mode: only two chambers per whorl. Chamber lumina green, coiling axes black. Foramina aligned in the apertural axis (red). A: quinqueloculine mode of coiling: for each new chamber the coiling axis rotates 72° around the apertural axis. B: triloculine mode of coiling: for each new chamber the coiling axis rotates 120°. C: biloculine mode of coiling: the coiling axis does not rotate; a: aperture; cax: coiling axis; chs: chamber suture; mt: miliolid tooth; (Hottinger, 2006; fig. 68  CC/BY-NC-SA)
Fig. 2. Chamber arrangement and apertural face. Schematic, not to scale. In part after Hottinger, 2000. 14: miliolid (-quinquelocular, -trilocular), with fixed apertural axis and with coiling axis rotating in perpendicular position in respect to apertural axis. 15: miliolid-bilocular with fixed apertural and coiling axes. 16: unilocular-concentric, with discoidal trematophore, as in Lacazina elongata. 17: unilocular-concentric with annular trematophore, as in Lacazina compressa; apax: apertural axis; spax: coiling axis; (Hottinger, 2006; fig. 37  CC/BY-NC-SA)
- according to Hottinger (2006):
MILIOLINE COILING is in porcelaneous foraminifera: bilocular coils where all terminal apertures are positioned on one common axis (apertural axis). The axis of coiling is normal to the apertural axis and is rotated so that several descrete angles exist between the median planes of consecutive chambers: these are 72° (quinqueloculine), 120° (triloculine) or 180° (spiroloculine or biloculine). If the chambers are positioned so that in a section normal to the apertural axis they form an S-shaped curve, their arrangement is called sigmoiline.
Hottinger (2006), Illustrated glossary of terms used in foraminiferal research. Carnets de Géologie, Memoir 2, ISSN 1634-0744.
Hottinger (2000), Functional morphology of benthic foraminiferal shells, envelopes of cells beyond measure, In: Lee J.J. & Hallock P. (eds.), Advances in biology of Foraminifera, Micropaleontology, New York, vol. 46, suppl. 1, p. 57-86.
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