The Echinoid Directory

Tretechinus Tornquist, 1897, p. 784

Diagnostic Features
  • Based on single fragment showing ?aboral surface.
  • Apical disc unknown.
  • Ambulacra narrow with two columns of plates; plates imbricate; not of uniform size.
  • Interambulacra with 5-7 columns of plates in each area; small and rhomboidal; not forming regular transverse rows.
  • Some interambulacral plates with a primary tubercle that is perforate.
Lower Carboniferous, USA.
Name gender masculine
Perischodomus illinoisensis Worthen & Miller, 1883, p. 333, by original designation.
Species Included
  • Only the type species.
Classification and/or Status

Stem group Echinoidea; Proterocidaridae.

Monotypic; probably a subjective junior synonym of Perischodomus McCoy, 1844


Jackson (1912) treated this as a synonym of Perischodomus. No material has been seen.

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.

Tornquist, 1897. Abh. geol. Karte Elsass 5, p. 784.