The Echinoid Directory

• Test circular in outline and probably depressed in profile.
• Apical disc monocyclic; less than half the test diameter.
• Ambulacra weakly sinuous and narrow; biserial. Plating simple with slightly elongate pore-pair on each plate. Single primary tubercle on narrow perradial portion.
• Adradial margins of ambulacral plates bevelled strongly beneath interambulacral plates. The inner surface of ambulacral plates without perradially directed flanges; the radial water vessel lay entirely beneath the ambulacral plates.
• Interambulacral zones wide; composed of four columns of large, hexagonal plates. Plates imbricate with small flanges; adradial margin of adradial series denticulate.
• All interambulacral plates bear a single imperforate and non-crenulate primary tubercle surrounded by a large and depressed areole. This is surrounded by a circle of scrobicular tubercles. There is no granulation or tuberculation outside the scrobicular circle.
• Lantern large and well developed. Pyramids with shallow formamen magnum; teeth broad and U-shaped.
• Spines long, hollow and lacking a cortex; smooth in type species.

Carboniferous, North America.

Archaeocidaris wortheni Hall, 1858, p. 744, by original designation.

• Lambert & Thiery (1910) used this genus for all archaeocidarids with four columns of interambulacral plates in each zone and thus included many species.

Stem group Echinoida; Archaeocidaridae.

Subjective junior synonym of Archaeocidaris McCoy, 1844.

Distinguished from Archaeocidaris by its smooth spines (as opposed to thored spines).  Jackson aand all later workers have synonymized this taxon with Archaeocidaris. 

Jackson, R. T. 1896 Studies of Palaechinoidea. Bulletins of the Geological Society of America 7, 171-254, pls 2-9.

Jackson, R. T. 1912. Phylogeny of the Echini, with a revision of Paleozoic species. Memoirs of the Boston Natural History Society 7, 443 pp, 76 pls.

Kier, P. M. 1958. New American Paleozoic echinoids. Smithsonian Miscellaneous Collections 135(9), 26 pp, 8 pls.

Pomel, A. 1883. Classification méthodique et genera des Échinides vivante et fossiles. Thèses présentées a la Faculté des Sciences de Paris pour obtenir le Grade de Docteur ès Sciences Naturelles, 503, 131 pp. Aldolphe Jourdan, Alger.