Figure 25: Calyces in arborescent Miniacina miniacea (
A: Fragment broken perpendicularly with respect to the axis of the branch, showing an exterior view of the broken funnel walls of the calyces. SEM graph. B: External view of a branch tip showing calyces and apertures at the limiting suture of the expanse chamber that covers previously formed tubular peristomes. SEM graph. C: Fragment broken in the axial plane of branch. SEM graph. D: Thin section perpendicular to the stem axis of the shell. Transmitted light micrograph. Calyces cut obliquely produced characteristic undulating intersections.
a: apertures in marginal position, to be transformed into stolons when overgrown by a subseqent expanse chamber; cy: calyx; per: tubular peristome either terminal or overgrown by subsequent expanse chambers; pr: proloculus; s: marginal suture of expanse chamber; st: stolon.