(Popofsky)
One latticed cortical shell and one medullary shell represented by an irregular formation of anastomosing centripetal bars arising from the cortical shell (may be missing in poorly preserved materials; not focused in specimen illustrated). Pores on outer shell irregular in shape and size, generally subcircular. Surface rough or thorny. Diameter of cortical shell: 150-270 µm.
Ref.: Benson (1966).