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.