The Echinoid Directory

 Stem group atelostomates with:

• disjunct apical disc, the posterior oculars separated from the remainder of the disc by plates of interambulacra 1 and 4 meeting along the aboral midline
• ocular plates II and IV meeting behind the anterior genital plates so that the apical disc is elongate
• posterior oculars in direct contact with the margin of the periproct.

Lower Jurassic (?Pliensbachian, Toarcian) to Lower Cretaceous (Valanginian); Europe, North Africa, India.

A paraphyletic grade of forms basal to the Collyritidae and Disasteridae.

Jesionek-Szymanska, W. 1961. Echinides irreguliers du Dogger de Pologne. Acta Geologica Polonica