The Echinoid Directory

Contributed by Andrew Smith, November 2011

Mirechinus Nisiyama, 1966, p. 239

Diagnostic Features
  • Test small, thick and subconical; rounded on oral surface with sunken peristome.
  • Apical disc structure uncertain (only partially preserved); ocular plates not exsert in preserved part; sparsely tuberculate
  • Ambulacral zones narrow, straight; plating trigeminate with pore-pairs in more or less vertical arcs of triplets; compounding echinid-style. Single primary tubercle to each compound plate with bare median region aborally and only a few smaller secondary tubercles elsewhere.
  • Interambulacral plates rather tall. Primary tubercles form a vertical series; interradial zone naked adapically
  • Tubercles imperforate
  • Peristome rather small; buccal notches sharp and deep.
  • Spines and lantern unknown.
Distribution Upper Eocene (Lutetian), Bonin Islands, Japan.
Type Mirechinus mirabilis Nisiyama, 1966, p. 240 by original designation.
Species Included Only the type species.
Classification and/or Status Carinacea, Camarodonta

Originally placed in the family Toxopneustidae on account of its buccal notches but here treated as indeterminate to family.
Remarks Distinguished from Gagaria by its non-crenulate tubercles and deeper buccal notches. Distinguished from Tripneustes by its uniserial arrangement of pore-pairs.

Nisiyama, S. 1966. The echinoid fauna from Japan and adjacent regions. Part 1. Palaeontological Society of Japan Special Papers 11, 1-277, pls 1-18.