The Echinoid Directory

• Test ?discoidal, with flat oral surface and gently rounded apical surface; not larger than 50 mm diameter.
• Apical disc small. Genital plates large with multiple gonopores arranged in an arc.
• Ambulacra more or less straight with four columns of unequal plates in each zone on both upper and lower surfaces. Ambulacra about twice the width adorally and somewhat petaloid in shape, with large circular pore-pairs surrounded by a deep, well-marked peripodial area. Aboral pore pairs smaller and simpler.
• All ambulacral plates with a perforate primary tubercle.
• Interambulacral zones wide; composed of four columns of subhexagonal, imbricate plates. Adradial interambulacral plates larger and with a single, large, perforate primary tubercle; other (more interradial) plates with only secondary tuberculation.
• Peristome and lantern unknown; tooth grooved.
• Spines relatively short, stout and straight, without cortex or ornament.

Chesterian (Pella Formation), Lower Carboniferous of Iowa, USA.

Praepholidocidaris pellaensis Frest & Strimple, 1977, p. 102, by original designation. Holotype, Geology Department, University of Iowa SUI 39491.

• Only the type species.

Stem group Echinoidea; Proterocidaridae.

Monotypic; subjective junior synonym of Pholidocidaris Meek & Worthen,1869.

Frest & Strimple (1977) distinguished this taxon from the very similar Pholidocidaris on the basis of a smaller number of plate columns, the presence of at least some ambulacral plates with primary spines, and the absence of primary spines from the interradial plates on the oral surface. These differences are relatively minor.

Frest, T. J. & Strimple, H. L. 1977. Praepholidocidaris, a new echinoid from the Pella Formation (Mississippian) of Iowa. Proceedings of the Iowa Academy of Sciences 84, 98-105.