The Echinoid Directory

• Test moderately large; shape probably subglobular; plating thin and imbricate.
• Apical disc unknown.
• Ambulacra narrow and straight, plating more or less simple, biserial throughout (occasional plates may be wedge-shaped and just excluded from the adradial suture). Pore-pairs forming adradial uniserial band, but alternately offset to left and right to a greater or lesser degree. Pore-pairs small and simple.
• Two or three subequal tubercles on each ambulacral plate forming perradial row; no differentiation between oral and adapical surfaces.
• Interambulacral plates more or less uniformly hexagonal and imbricating adapically and interradially.
• 6-10 small uniform secondary tubercles on each plate: one slightly larger perforate and mamelonate primary tubercle on at least some plates.
• Peristome, lantern and spines unknown.

Lower Carboniferous, USA.

Pholidechinus brauni Jackson, 1912, p. 299, by original designation.

• Only the type species.

Stem group Echinoidea; Lepidocentridae.

Monotypic.

Like Palaeodiscus in ambulacral structure, but interambulacral plating thiner, with imbricate sutures and mamelonate secondary tubercles covering the surface. Very close to Lepidechinus, differing only in having ambulacral composed of shorter and wider plates and with incipient biseriality. Almost identical to Elliptechinus, differing from that taxon only in having less obviously offset pore-pairs in each half ambulacrum.

Jackson, R. T. 1912. Phylogeny of the Echini, with a revision of Palaeozoic species Memoirs of the Boston Society of Natural History 7, 491 pp. 76 pls.