Gryphaeidae

thumb|Praeexogyra hebridica from the Frome Clay (Bathonian, Middle Jurassic) of Langton Herring, Dorset, England. thumb|Liostrea strigilecula from the Carmel Formation (Middle Jurassic) of southwestern Utah.

thumb|350x350px|Silicified Gryphaea sp. from the Lower Jurassic. Le Liquier, Aveyron, France. Max Rouger collection. Gryphaea, one of the genera known as '''devil's toenails''', is a genus of extinct oysters, marine bivalve mollusks in the family Gryphaeidae.

Exogyra is an extinct genus of marine oysters that belongs to the family Gryphaeidae (honeycomb oysters). These bivalves were cemented by the more cupped left valve. The right valve is flatter, and the beak is curved to one side. Exogyra lived on solid substrates in warm seas during the Jurassic and Cretaceous periods.

Hyotissa is a genus of large saltwater oysters, marine bivalve mollusks in the family Gryphaeidae.

species of mollusc

species of mollusc

species of mollusc

species of mollusc (fossil)

Pycnodonte is a genus of extinct oysters, fossil marine bivalve mollusks in the family Gryphaeidae, the foam oysters or honeycomb oysters. Shells of species in this genus are found around the world in fossil shell beds from the Valanginian (140.2 Ma) to the Early Pleistocene (0.781 Ma). They are a commonly found fossil in Cretaceous shellbeds of the Navesink Formation in New Jersey.