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The Echinoid Directory

Family Stomechinidae Pomel, 1883, p. 81

Diagnosis

 Stem group Echinacea with:

  • apical disc relatively small; hemicyclic to dicyclic. Periproct subcircular with smooth rim;
  • ambulacra trigeminate, with simple diadematid style compounding; central element largest and upper and lower elements in each compound plate expanded and generally extending from adradial to perradial suture and bearing primary tubercle; other elements demiplates;
  • Pore-pairs offset throughout, forming a wide adradial band; expanded adorally to form phyllodes;
  • primary tubercles small, imperforate and non-crenulate; those of ambulacral and interambulacral zones similar in size.
Range
Jurassic (Pliensbachian) to Cretaceous, Europe, North America, Middle East, North Africa.
Classification and/or Status Euechinoidea, Acroechinoidea, Echinacea
Remarks Distinguished from arbacioids by their diadematid-style ambulacral plate compounding. Distinguished from pedinopsids and Pseudodiadematidae by their imperforate, non-crenulate tubercles.

Pomel, A. 1883. Classification méthodique et Genera des Échinides vivante et fossiles. Thèses présentées a la Faculté des Sciences de Paris pour obtenir le Grade de Docteur ès Sciences Naturelles 503, Aldolphe Jourdan, Alger, 131 pp.