The Echinoid Directory

• Test rounded in profile with height about half of diameter; up to 38 mm in diameter.
• Apical disc large, presumed monocyclic, but plates lost in all specimens.
• Ambulacra with all elements reaching the midline. Pore-pairs in arcs of three from the ambitus adorally.
• Primary tubercle overlapping two or three elements to form compound plates at ambitus and below; plating simple adapically.
• Interambulacral plates carrying a single large primary tubercle; wider than tall at ambitus, but becoming taller adapically. Areoles confluent. Secondary granules confined to the adradial and interradial margins of the plate.
• Tubercles with large boss, small perforate mamelon and distinct crenulation.
• Peristome large with very large, U-shaped, buccal notches.
• Spines unknown.

Jurassic (Pleinsbachian to Oxfordian) of western Europe.

Pseudodiadema varusense Cotteau, 1881, p. 231, by subsequent designation of Pawson & Fell, 1966, p. U 387.

• G. jessoni (Gregory, 1896, p. 465); ?Middle Jurassic (late Callovian), Upper Jurassic (Oxfordian) of France and England [= Eosalenia miranda Lambert in Lambert & Savin, 1905, p. 311; = G. kuhni Hess, 1971; Callovian, Switzerland].
• G. varusense (Cotteau, 1881); Lower Jurassic (Pliensbachian) of Plan d'Aup, Var, France; Callovian of Sarthe, France.
• G. dumortieri (Cotteau, 18 ); Middle Jurassic (Bajocian) of Saint-Rambert, Ain, France.
• G. sarthacensis Cotteau, 1856; Bathonian, France.
• ?G. lepidum (de Loriol, 1890); Callovian, Portugal.

Acroechinoidea, Aspidodiadematoida, Aspidodiadematidae.

Very similar in test form to the extant Plesiodiadema, differing from that taxon in having rudimentary tubercles adapically in interambulacral zones. It co-occurs with the echinoid Disaster in late Jurassic basinal mud facies, living well-below active wave base.

Distinguished from Culozoma by its narrower and taller interambulacral plating, proportionally larger interambulacral tubercles, and by its ambulacra which are never more than acrosaleniid-style in compounding (i.e. 2+1 pattern) and which have strictly uniserially arranged pore-pairs throughout.

Hess, H. 1971. Uber einige Echiniden aus Dogger und Malm des Schweizer Juras. Eclogae geologica Helvetica 64, 611-633.

Vadet, A. & Slowik, D. 2001. Les oursins du Bajocien de Liocourt. Memoires de la Societe Academique du Boulonnais. Serie Histoire Naturelle 22, 1-48.