The Echinoid Directory

Aspidodiadematoida with:

• test subglobular; coronal plating entirely rigid
• apical disc large; genital plates subquadrate, not pointed interradially; disc plates membrane embedded, not attached to corona
• ambulacral plating trigeminate, either with three simple elements reaching the perradius, one of which bears the primary tubercle, or with an enlarged element and two smaller demiplates
• pore-pairs arranged as simple arcs; no pore-crowding adorally
• sphaeridial pit close to every third pore-pair from peristome to apex
• tubercles perforate and crenulate
• peristome large; buccal notches shallow and rounded
• spines with central lumen crossed by partitions and fine needle-like pillars.

Early Jurassic (Pleinsbachian) to Recent; worldwide.