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The Echinoid Directory

Polyechinus Mortensen, 1942, p. 231

Diagnostic Features
  • Test hemispherical; height ca. 50-60% diameter.
  • Apical disc dicyclic.
  • Ambulacra polygeminate, with mostly four pore-pairs to a plate (some with three or five); pore-pairs forming oblique lines; not expanded adorally.
  • Primary tubercle to each ambulacral plate; tubercles imperforate and non-crenulate.
  • Interambulacral plates with prominent primary tubercle and scattered and much smaller secondary tubercles. Granules generally rather sparse so that plates appear naked.
  • Peristome relatively small; less than one-third test diameter.
  • Globiferous pedicellariae with tubular blade and several lateral paired teeth.
Distribution
Recent; South Africa.
Name gender masculine
Type
Paracentrotus agulhensis Doderlein, 1905, p. 623, by original designation.
Species Included
Only the type species.
Classification and/or Status

Camarodonta; Echinoida; Echinidae.

Monotypic.
Remarks

Distinguished from Echinus and Parechinus by its polygeminate ambulacral plating. Distinguished from Paracentrotus by the prominence of its primary tubercles and the number of pore-pairs to a compound ambulacral plate.

Mortensen, T. 1943. A monograph of the Echinoidea Part III, 3. Camarodonta II. C. A. Retzel, Copenhagen.