The Echinoid Directory

• Test very small; flattened below, gently domed above to flat apical disc.
• Apical disc thick forming raised platform; dicyclic; plates firmly bound to corona. Genital plates pentagonal and projecting interradially; inner edge sunken forming a periproctal ledge. Ocular plates smaller and projecting. Perianal tubercle developed on the inner edge of genital plates and sunken. Periproct relatively small and subpentagonal.
• Ambulacra straight; pore-pairs small, uniserial; ambulacra expanded orally into weak phyllodes.
• Ambulacral plating in triads throughout, but style of compounding not discernible.
• Interambulacral plates a little wider than tall; with a large primary tubercle on each; secondary tubercles and miliary granulation minimal. Primary tubercles largest just above the ambitus.
• Tubercles imperforate and non-crenulate, with rather large mamelon.
• Peristome large, subcircular; buccal notches sharp with raised rim; no tag.

Goniopygus pilleti Cotteau, 1883, p. 570, by original designation.

Arbacioida, Acropeltidae.

Subjective junior synonym of Goniopygus Agassiz, 1838.

Valette (1906) established this taxon to accomodate forms of Goniopygus with quadrigeminate plating, basing this on the illustrations in Cotteau (1883). Unfortunately, the drawings are inaccurate in this respect and the type species has regular trigeminate plate as all other Goniopygus.

Cotteau, G. 1883, in 1880-1885. Paleontologie francaise. Terrain Jurassique X(2). Echinides regulier. G. Masson, Paris.

Valette, D. A. 1906. Etude sur la formule porifere d'un certain nombre d'Echinides reguliers. Bulletin de la Societe Scientifique d'Histoire Naturelle de l'Yonne 59, 1-41.