Figure 34: Cover plate and foramenal plate in Challengerella bradyi
A-B: dissected specimens in oblique ventral view. C: young specimen, ventral view. Note incipient umbilical pile against which the foliar walls are beginning to fuse, covering the spiral interlocular space. D: dorsal (spiral) view of adult megalospheric specimen. E: Detail showing foraminal and cover-plates. Colours corresponding to those used in the models. White arrow: loop-hole. F: general model showing position of plates and communications. Note position of loop-hole (red arrow). G: Detail of umbilical structures in last three chambers. Note the separation of streaming chamber plasm through successive foramina (blue arrow) and circulation in the umbilical interlocular space (black arrow) by the umbilical structures. Models schematic, not to scale, after , 2000.
a: aperture; cp: coverplate; csut: chamber (septal) suture; f: foramen; fo: folium; foa: foliar aperture; fp: foramenal plate; isp: interlocular (intrasepal) space; lh: loop-hole; n: notch; pil: umbilical plug; s: septum; sf: septal flap; suc: spiral umbilical interlocular space, transformed into spiral canal when covered by foliar extensions; u: umbilicus; ulch: ultimate chamber; vc: funnel (vertical canal); wsut: whorl (spiral) suture.