The Echinoid Directory

Isechinus Lambert, 1903, p. 476

[?=Psammechinus Agassiz & Desor, 1846, p. 368, type species Echinus miliaris Muller, 1771 ]

Diagnostic Features
  • Apical disc structure unknown.
  • Ambulacral plating trigeminate, with pore-pairs in oblique arcs of three forming a distinct adradial band. The inner pore series somewhat distinct.
  • Two subequal tubercles on ambital ambulacral plates.
  • Pore-zones uniform throughout; no phyllode expansion adorally.
  • Interambulacral plates with slightly larger central primary tubercle flanked by one or two secondary tubercles, almost as large as the primary.
  • Peristome decagonal with small, poorly defined buccal notches.
Miocene of Patagonia.
Name gender masculine
Toxopneustes praecursor Ortmann, 1904, p. 53, by subsequent designation of Lambert & Thiery, 1914, p. 241.
Species Included
Only the type species.
Classification and/or Status

Camarodonta; Echinoida; ?Echinidae or Parechindae.


Fell & Pawson (1966) placed this genus in the family Echinidae, which it resembles in interambulacral tuberculation. It comes closest to Psammechinus in appearance, differing from that taxon in having two subequal ambulacral tubercles on ambital ambulacral plates.

Lambert, J. 1903. Bulletin de la Societe geologique de France, serie 4, 3, p. 476.