Pectinida

Pectinida is a taxonomic order of large and medium-sized saltwater clams, marine bivalve molluscs, commonly known as scallops and their allies. It is believed that they began evolutionarily in the late Middle Ordovician epoch; many species, of course, are still extant.

The Pectinoidea are a superfamily of marine bivalve molluscs, including the scallops and spiny oysters.

Cyclochlamydidae is a family of bivalves belonging to the order Pectinida.

The Anomioidea are a superfamily of marine bivalve molluscs that include two families, the Anomiidae and the Placunidae, the jingle shells and saddle shells. They are mainly sessile bivalves that superficially resemble true oysters (partially in that they cement themselves to a substrate). Though they are pleurothetic, however, the Anomioidea attach via their right valve rather than the usual left. Their irregular shells are inequilateral, are round to oval, with a large byssal notch. The byssus itself is usually short and plug-like. The left valve is convex, and the hinge is considered edentu