
The Pteriida are an order of large and medium-sized marine bivalve mollusks. It includes five families, among them the Pteriidae.

Isognomon is a genus of marine bivalve mollusks which is related to the pearl oysters.

Isognomon alatus, the flat tree oyster, is a species of bivalve mollusc in the family Isognomonidae. It can be found along the Atlantic coast of North America, ranging from southern Florida to Brazil and Bermuda.

Isognomon californicum, the black purse shell or nahawele, is a species of Hawaiian bivalve in the family Isognomonidae. It was first formally named in 1837 by Timothy Abbott Conrad as Perla californica.

Isognomon radiatus, the radial purse oyster or Lister's tree oyster, is a species of bivalve mollusc in the family Isognomonidae. It can be found along the Atlantic coast of North America, ranging from southern Florida to Brazil and Bermuda.

Isognomonidae is a family of medium-sized to large saltwater clams. They are pearl oysters, marine bivalve molluscs in the superfamily Pterioidea

Naiadites is an extinct genus of thin-shelled non-marine bivalve from the Upper Carboniferous coal-measures of Nova Scotia in Canada.
The Pinnidae are a taxonomic family of large saltwater clams sometimes known as pen shells. They are marine bivalve molluscs in the order Pteriida.