Genus Conchocele Gabb, 1866

Type species. Conchocele disjuncta Gabb, 1866, = C. bisecta (Conrad, 1849) after Kamenev et al. 2001.

Type locality. C. disjuncta: Pliocene, Dead Man's Island, San Pedro, California ; C. bisecta: Miocene, Astoria, Oregon.

Species included. C. bisecta (Conrad, 1849), C. novaeguinensis Okutani, 2002,

Tertiary fossil taxa in Krishtofovitch (Kamchatka), Thyasira conradi Rosenkrantz, 1942 (Svalbard) .

Diagnosis. Medium to very large shells. Equivalve. Inequilateral, prosogyrous beaks close to anterior, outline obliquely oval. Anterior margin sloping steeply, almost straight; anterior area defined by a distinct keel; lunule weakly impressed approximately half the length of the anterior area. Posterior margin broadly rounded and indented by a single sinus; posterior sulcus deep, distinctly angulated; escutcheon weakly defined; no distinct marginal sulcus. Anterior adductor muscle scar greatly elongate. Hinge teeth lacking. Ligament partially sunken.

Anterior adductor muscle much longer than posterior; mantle unfused except for a small exhalant aperture; foot vermiform; ctenidia of two fully reflected demibranchs, filaments highly modified with the abfrontal zone divided into a tubular framework and a laminar zone with regular inter-lamellar junctions; tubes lined with bacteriocytes; lateral body pouches densely arborescent.