The Echinoid Directory

• Test small (less than 6 mm diameter), weakly pentagonal in outline. Test plating rigid.
• Apical disc very small, less than half diameter of peristome opening. Ocular plates enclosed within interambulacra and separated from genital plates. Genital plates not preserved; not firmly bound to corona.
• Ambulacra narrow and almost straight; composed of simple hexagonal plates throughout. Single tubercle to each element. Ambulacra not reaching apical disc opening.
• Pore-pairs small and non-conjugate; oblique; uniserial.
• Interambulacral zones wide with about 6 pentagonal plates in a column.
• Single large primary tubercle dominates each interambulacral plate; mamelon very large and perforate; no platform.
• Scrobicular circle of tubercles partially developed; interradial zone with narrow band of granules.
• Peristome large, circular; no buccal notches.
• No lantern supports around interior of peristome.

Late Triassic (Carnian); Italy.

Cidaris pentagona Munster, in Wissmann & Munster, 1841, p. 42, by monotypy. Holotype; Bayerische Staatsammlung fur Palaontologie und Historische Geologie, Munchen, Germany AS VII 392.

• Only the type species.

?Euechinoidea stem group, Triadocidaridae.

Monotypic.

Very small tests but apparently adult, since the ambulacra are separated from the apical disc opening. Parvicidaris is rather similar in appearance, but has imperforate tubercles, and the ocular plates remain in contact with the ring of genital plates.

Doderelin, L. 1887. Die japanischen Seeigel. I. Theil Familie Cidaridae und Saleniidae. 59 S. 11. Tafeln. E. Schweizerbart'sche Verlagsbuchhandlung, Stuttgart.

Kier, P. M. 1977. Triassic echinoids. Smithsonian Contributions to Paleobiology 30, 1-88.

Kier, P. M. 1984. Echinoids from the Triassic (St Cassian) of Italy, their lantern supports and a revised phylogeny of Triassic echinoids. Smithsonian Contributions to Paleobiology 56, 1-41.