The Echinoid Directory

Family Calymnidae Mortensen, 1907

Diagnosis

 Segasterine holasteroids with:

  • thin test;
  • periproct marginal to inframarginal;
  • ambulacral plates tall and polygonal aborally; similar in size to interambulacral plates;
  • plastron orthosternous;
  • small circular peristome close to anterior and associated with shallow furrow;
  • marginal fasciole present.
Range
Upper Cretaceous (Campanian) to Recent; worldwide.