The Echinoid Directory

 Micrasterine spatangoids with:

• ethmolytic apical disc; four gonopores
• petals flush, long and subparallel and open distally with or without occluded plates. Perradial zone separating pore-pair columns wider than pore-pairs
• anterior petals with both columns equally developed except very close to the apex
• antero-lateral ambulacra not pinched between phyllodes and ambitus
• labral plate elongate and wedge-shaped; extending to third or fourth ambulacral plate or beyond
• sternal plates short and triangular
• episternal plates opposite and strongly indented to rear; ambulacral plate 6 laterally elongate and indenting posterior interambulacrum
• first pair of post-episternal plates also paired and opposite

Miocene to Recent; Indo-Pacific

 Distinguished from Spatangidae and Echinocardiidae by their long, wedge-shaped labral plate and short triangular sternum. Resembling Loveniidae in plastron structure but with more strongly indented episternal plates, a shield-shaped subanal fasciole and usually with occluded plates at the ends of the posterior petals.