The Echinoid Directory

• Test rather flattened in profile and thick-plated.
• Apical disc hemicyclic; posterior oculars generally insert.
• Ambulacra polygeminate with pore-pairs in arcs of four, tending to form distinct vertical series. Each ambulacral plate with a primary tubercle.
• Ambulacral pore zones uniform; not expanding as phyllodes but narrowing towards the peristome.
• Interambulacral plates with a primary tubercle and two or three slightly smaller secondary tubercles forming a distinct horizontal series. No adapical naked zone interradially.
• Spines short (less than 1/4 test diameter).
• Globiferous pedicellariae with muscular neck and no lateral teeth.
• Buccal notches small and indistinct.

Recent; Japan and China; 0-45 m.

Psammechinus pulcherrimus A. Agassiz, 1863, by original designation.

• Only the type species.

Camarodonta; Echinoida; Strongylocentrotidae.

Monotypic.

A well characterized genus.