||Regular echinoids with:
- test composed of 20 columns of plates; pairs of ambulacral columns alternating with pairs of interambulacral columns
- ambulacral plating simple or at most pseudocompound (i.e. every second or third element enlarged to accommodate a larger tubercle and spine, but individual elements not fused together by tubercle overgrowth)
- interambulacral plates dominated by a single large primary tubercle (except Tetracidaris which has two)
- perignathic girdle of interambulacral elements only (apophyses).
- ambulacral plates continuing as a series across the peristomial membrane
- teeth crescentic to U-shaped in cross-section; pyramids without a foramen magnum
- primary spines with external cortex (except in most primitive members)
- globiferous and tridentate pedicellariae only.
||Lower Permian to Recent; worldwide.
||Type genus Cidaris Leske, 1778, p. 74,
||There is currently only a single order in the subclass Cidaroidea. See Cidaroidea for key.
The following taxon is spine-based and probably belongs here:
Minicidaris Deraniyagala, 1961
Claus, C. F. W. 1880. Grundzuge der Zoologie. N. G. Elwertsche, Marburg & Leipzig. 1254 pp (4th edition).