Semelidae

The Semelidae are a family of saltwater clams, marine bivalve molluscs in the order Cardiida.

==Description== Members of this family have rounded or oval, elongated shells, much flattened. The two valves are connected by an internal ligament in contrast to the closely related family Tellinidae where the ligament is external. The two separate siphons are very long, sometimes several times the length of the shell. These siphons have a characteristic cruciform muscle at their base.