Note: Do not rely on this information. It is very old.
PalaeechinoideaPalaeechinoidea, a sub-class of Echinoidea, or Sea-Urchins, including all the Palaeozoic and some Triassic species. The only character by which it differs from the other sub-class, or Euechinoidea, is that the plates are not arranged in twenty zones. It includes four orders - the Bothriocidaroidea, Perischoechinoidea, Plesiocidaroidea, and Cystocidaroidea. Palaeechinus is the best-known genus.
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