Figure 55: An umbilical architecture dominated by funnels: Dictyokathina simplex Smout, megalospheric specimens from Qatar, Paleocene. Transmitted light micrographs.
A: subaxial section showing funnels in their longitudinal extension. B: transverse section near the axis of the shell with the positions of sections A & C-D indicated. C-E: sections more or less perpendicular to the axis of the shell showing the vast umbilical area crowded with funnels. Note the chamber arrangement in multiple spirals, The start of supplementary spirals is indicated by arrows. The material does not allow resolution of the question: is the first chamber of a supplementary spiral fed from a foramen or from a canal?
ch: chamber lumen; f: foramen; fu: funnel (vertical canal); isp: intraseptal interlocular space; ssp: spiral interlocular space; up: umbilical plate.