Mactridae, also known as trough shells or duck clams, is a family of marine bivalve clams of the order Veneroida. The shells are mostly large and ovate with a strong hinge, the teeth divided by a central spoon-shaped chondrophore. A long anterior and a similar posterior lateral in the left valve, fit between paired anterior and posterior laterals in the right valve, and, in addition, there's a small lamellate cardinal in each valve, anterior to the chondrophore. Genera Anatina Schumacher, 1817… (More on Mactridae)