The Echinoid Directory

Suborder Clypeasterina L. Agassiz, 1835

[=Clypeasteroina Nisiyama, 1968, p. 28]


 Clypeasteroids with:

  • internal buttressing in the form of concentric walls around the periphery with or without more central pillars;
  • a pair of sunken and enclosed sphaeridia in each ambulacrum;
  • petals when well developed consisting of alternating primary plates and demiplates (N. B. apetalloid forms with simple ambulacral plating);
  • perignathic girdle of 5 pairs of ambulacral elements (auricles);
  • interambulacral plating on oral surface always disjunct.
 Late Eocene to Recent; worldwide.