Genus Mactra Linnaeus, 1767

[=Trigonella Da Costa, 1778, subsequent designation by Winckworth (1929); Deikea Mayer, 1872; Colorimactra Iredale, 1929; Telemactra Iredale, 1929]

Type species: Cardium stultorum Linnaeus, 1758 [subsequent designation by Fleming (1818: 309)]

Diagnosis. Shell trigonal to oval, subequilateral, inflated; lunule and escutcheon well developed. External ligament separated from internal portion by a ridge. Pallial sinus short and oval; lateral teeth elongated, similar in shape and size.

Distribution. Worldwide, Atlantic and Pacific coasts of America, Mediterranean Sea, coast of Great Britain, Atlantic and Indian coasts of Africa, and coasts of Australia and New Zealand.