The Echinoid Directory

Cidaropsis Cotteau, 1863, p. 374

Diagnostic Features
  • Test hemispherical, flattened beneath, domed above.
  • Apical disc small, less than one-third test diameter; plating dicyclic. Genital plates large, hexagonal, G2 generally the largest. Periproct subpentagonal with smooth outer rim.
  • Ambulacra: aborally very narrow and sinuous with plating entirely simple. Plating at ambitus and adorally trigeminate, compounded in diadematid style with all three elements extending to perradius. Pore-pairs uniserial above and at ambitus, slightly expanded adorally to form weak phyllodes. Large primary tubercle on each oral and ambital plate; two subequal secondaries on adapical elements.
  • Interambulacral plates almost as tall as wide at ambitus, dominated by a large primary tubercle. Aboral plares taller than wide and with extensive secondary tuberculation. One adapical plate per zone without a primary tubercle.
  • Primary tubercles perforate and non-crenulate on aboral surface, the mamelon being so large that there is effectively no surrounding platform. On the oral surface tubercles are all imperforate. Those of the ambulacra a little smaller than those of the interambulacra in the subambital region.
  • Peristome large, more or less flush, with well defined buccal notches.
  • No sphaeridial pits and no basicoronal plate retained in adult.
  • Aboral spines stout and clavate with ornament of dense beaded ribs.
  • Lantern unknown.
Middle Jurassic (Bathonian-Callovian), Europe, North Africa
Name gender feminine
Hemicidaris minor Agassiz, in Agassiz & Desor, 1847, p. 35, by original designation.
Species Included
  • C. minor (Agassiz, in Agassiz & Desor, 1847); Bathonian-Callovian, Europe.
  • C. depressa Kier, 1972; Bathonian, Saudi Arabia.
Classification and/or Status
Carinacea, Hemicidaridae, Pseudocidarinae.
Distinguished from Pseudocidaris by its non-crenulate primary tubercles which are imperforate adorally. Pseudocidaris has crenulate and perforate tubercles.

Cotteau, G. 1861-1867. Paléontologie Française. Terrain Crétacé, Tome Septième. Échinides.  G. Masson et fils, Paris