The Echinoid Directory

• Test flattened below and domed above; circular to slighly pentagonal in outline.
• Apical disc small, dicyclic; firmly bound to corona. Genital plates large and pentagonal; ocular plates smaller and protruding a little. All plates decorated by epistroma. Periproct relatively large and subcircular.
• Ambulacra straight, expanding to ambitus; aboral pore-pairs weakly arced, a little larger than adoral pore-pairs which are more inclined; short phyllodes adorally.
• Plating in arbaciid triads throughout, with upper and lower elements as demiplates and each triad dominated by a large primary tubercle; no perradial granular zone.
• Interambulacra a little wider than ambulacra. Above ambitus plates differentiated into an interradial naked zone without tubercles, and an outer, adradial tuberculate zone. A vertical ridge marks the boundary between the two zones, and this bears small peg-like structures. In the adradial band there is a small primary tubercle on each plate, except adapically.
• Below the ambitus interambulacral plates with two primary tubercles, the adradial one distinctly smaller.
• Primary tubercles of ambulacral and interambulacral zones of similar size; imperforate and non-crenulate. The areole forms a slightly raised platform on the plate.
• Peristome subcircular or subpentagonal, large (about half test diameter). Buccal notches shallow with shallow tag.
• Single row of about eight sphaeridial pits perradially.
• Primibasal interambulacral plate present and with primary tubercle; projecting a little interradially.
• Spines unknown.

Upper Eocene - Lower Oligocene, France.

Pomel, (1883, p. 88) on setting up this genus, lists two species, C. agassizi and C. delbosi. As the name clearly refers to the latter it is type species by tautology.

• D. delbosi Desor, 1857; Lutetian to Tongrian, France.
• D. agassizi d\'Archiac, 1846; Upper Eocene, France.

Euechinoidea, Arbacioida, Arbaciidae.

Subjective junior synonym of Coelopleurus (Coelopleurus).

Pomel (1883) erected this genus based on two species, Coelopleurus agassizi and C. delbosi. He distinguished it by having zig-zag lines on its naked areas and sphaeridial pits. Neither is particularly characteristic and the type species differs little from Coelopleurus.

Pomel, A, 1883. Classification methodique et genera des echinides vivante et fossiles. Alger, Paris.