The Echinoid Directory

Cassiduloids with:

• ovate to subquadrate outline, with flat adoral surface and subanal heel in side view;
• apical disc anterior, monobasal;
• petals modestly developed; bowed and open distally; terminating abruptly;
• peristome with vertical walled vestibule and feeble bourrelets; basicoronal plates short, specialized perioral spines and tubercles present, but confined to vertical-walled entrance to peristome;
• phyllodes widened, single pored, with an outer and inner series (inner series sometimes highly reduced);
• periproct supramarginal to marginal, transversely elongate, associated with a shallow subanal ledge or short anal groove;
• broad naked and pitted sternal area both in front and to the rear of the peristome.

Lower Cretaceous (Albian) to Recent.

Distinguished from nucleolitids by having single pores below the petals. Distinguished from Echinolampadidae, which have a similar oral area, by their supra-ambital periproct position.