(b) Bivalvia (= Conchae): Mya, Solen, Tellina, Cardium, Mactra, Donax, Venus, Spondylus, Chama, Arca, Ostrea, Anomia, Mytilus, Pinna.
The Senonian consists of a central facies with Micraster peini; a meridional facies with Ostrea; and a northern facies developed round Tunisia with large forms of Inoceramus and echinoids.
The Middle Eocene is characterized by the presence of Ostrea bogharensis and the Upper Eocene by highly fossiliferous sandstones and marls.
At the close of the Lower Miocene period (beds with Ostrea crassissima) great modifications in the relief and limits of the Algerian formations took place.
- Development of the Oyster, Ostrea edulis.