Figure 37: Chamber arrangement and apertural face. Schematic, not to scale. In part after
1: planispiral-spiroliniform. 2: planispiral-evolute and flaring, peneropliform. 3: planispiral-evolute, approaching reniform, 4: annular-concentric, with thickened and folded margins, as in Marginopora vertebralis. 5: planispiral-involute, as in Archaias. 6: biserial – textulariid. 7: biserial-cuneiform. 8: uniserial-conical. 9: uniserial-conical with marginal apertures. 10: streptospiral-involute as in Pseudonummuloculina. Coiling axis rotating with each chamber. 11: streptospiral with planispiral-involute adult stage, as in Helenalveolina. 12: planispiral involute. Coiling axis fixed throughout ontogeny. 13: planispiral-fusiform: A: axial section, E: equatorial section. Black arrow: direction of growth; white arrow: direction of movement. 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. 18: low-trochospiral, as in Rotorbinella. 19: high-trochospiral, as in Sakesaria.
a: aperture; af: apertural face; apax: apertural axis; col: columella; fol: folium; ma: marginal aperture; n: notch; per: periphery; potort: polar totion; pst: peristome; spax: coiling axis.