The Echinoid Directory

From Vadet et al. (2010)

• Test circular, in profile flattened below and above.
• Apical disc small, dicyclic with relatively large and regularly circular periproct. Apical firmly bound to corona and usually preserved.
• At the ambitus and below ambulacra polygeminate, with 5 to 6 (?) elements to a compound plate. Plate compounding appears to be of diademaoid style with all elements reaching the perradius, but united in a single perradial wedge. Pore-pairs biserial aborally and at the ambitus, expanding into moderately well developed phyllodes adorally. Adapically ambulacral plating simple.
• Ambulacral plates with single large tubercle. At the ambitus secondary tubercles present perradially. Adapically tubercles dimish in size rapidly.
• Interambulacral plates with single large tubercle; centrally placed and set in a groundmass of coarse secondary tubercles. Plates wider than tall.
• Ambulacral and interambulacral tubercles of similar size.
• No well defined aboral naked interradial zone.
• Primary tubercles weakly crenulate; some are perforate, some imperforate.
• Peristome large, almost flush; buccal notches shallow but distinct.
• Spines and lantern unknown; no primordial interambulacral plate.