Mactridae

Mactridae, common name the trough shells or duck clams, is a family of saltwater clams, marine bivalve mollusks in the order Venerida.

Description
These clams have two short siphons, each with a horny sheath. The shell is shaped like a rounded-cornered equilateral triangle and there is a slight gape at the posterior. Each valve bears two cardinal teeth with four lateral teeth on the right valve and two on the left. The foot is white and wedge-shaped. They mostly inhabit the neritic zone.

Ecology
Trough shells burrow in sand or fine gravel and never in muddy substrates.

Genera


According to the World Register of Marine Species (2012), this family contains 37 genera:
 * Anatina Schumacher, 1817
 * Austromactra Iredale, 1930
 * Barymactra Cossmann in Cossmann & Peyrot, 1909
 * Coelomactra Dall, 1895
 * Crassula Marwick, 1948
 * Cyclomactra Dall, 1895
 * Darina Gray, 1853
 * Diaphoromactra Iredale, 1930
 * Eastonia Gray, 1853
 * Harvella Gray, 1853
 * Heterocardia Deshayes, 1855
 * Huberimactra Cosel & Gofas, 2018
 * Leptospisula Dall, 1895
 * Lutraria Lamarck, 1799
 * Mactra Linnaeus, 1767
 * Mactrellona Marks, 1915
 * Mactrinula Gray, 1853
 * Mactromeris Conrad, 1868
 * Mactrotoma Dall, 1894
 * Maorimactra Finlay, 1928
 * Meropesta Iredale, 1929
 * Mulinia Gray, 1837
 * Oxyperas Mörch, 1853
 * Pseudocardium Gabb, 1866
 * Raeta Gray, 1853
 * Rangia Desmoulins, 1832
 * Resania Gray, 1853
 * Scalpomactra Finlay [in Marwick], 1928
 * Scissodesma Gray, 1837
 * Simomactra Dall, 1894
 * Spisula Gray, 1837
 * Standella Gray, 1853
 * Tanysiphon Benson, 1858
 * Tresus Gray, 1853
 * Trinitasia Maury, 1928
 * Tumbeziconcha Pilsbry & Olsson, 1935
 * Zenatia Gray, 1853
 * Zenatina Gill & Darragh, 1963