The Echinoid Directory

• Known only from test fragments.
• Interambulacral plates wide with confluent oval areoles on ambital and adoral surfaces but separated and circular on adapical plates. Primary tubercle perforate and crenulate. Areoles incised. Scrobicular circles weakly differentiated.
• Adradial and interradial bands of heterogeneous extrascrobicular tuberculation.
• Ambulacral zones sinuous; pore zones not incised. Pore-pairs not conjugate; with relatively narrow interporal partition on adapical plates.
• Ambulacral tuberculation: perradial zone with primary marginal tubercle developed irregularly on every second or third plate; the other elements with only smaller secondary tubercles.
• Associated spines (not seen) stated to be cylindrical and thorny.

Upper Jurassic (Oxfordian), France.

Pachycidaris thieryi Collignon & Lambert, 1928, p. 262 [?=Cidaris suevica Desor, 1855], by original designation.

• Only the type species.

Cidaroida; Polycidaridae.

Subjective junior synonym of Polycidaris Quenstedt, 1858.

The material figured here comes from the Lambert collection and is probably syntype series. The material is poor and the diagnostic feature of having a primary tubercle on every third plate is seen in numerous other cidaroids. Judging from the shape of the interambulacral plates and their ornament, this material is probably part of a Polycidaris.

Thiery, P. 1928. Considerations phylogenetiques sur les Cidaridae. Archives de Zoologie experimental et general 67. Notes et Revue 4, 179-181.

Collignon, M. & Lambert, J. 1928. Especes nouvelles d'echinides fossiles etablis par Paul Thiery. Bulletin de la Societe geologique de France, Serie 4, 28, 261-272, 2 pls.