“Gen. Cyamiocardium nov.
Genotype: Cyamium denticulatum Smith 1907.
Diagnosis. Small roundish species with more or less distinct radiating sculpture. Hinge like that of Cyamiomactra Bernard; left valve with a central bifid cardinal (2) and one anterior and one posterior diverging cardinal (4a, 4b) with an oblique, narrow resilium, and a long posterior lateral-like ridge formed by the radial sculpture; right valve with a central bifid cardinal (3a, 3b) with the anterior limb slightly bifid, a long obliuqe [sic] resilium, and lateral ridges. Prodissoconch distinct.
Animal with an open mantle with papillae; two subequal adductors sitting high in the shell, foot digitiform without ventral groove, outer demibranch of gills attached to the mantle.
In this genus the nearly-related species rotundatum Thiele 1912 from Gauss may also be placed, perhaps also the Australian mactroides Tate and May 1900.”
(Soot-Ryen, 1951: 26)
