Note: Do not rely on this information. It is very old.
Hippuritidse
Hippuritidse, an extinct family of Lamellibranchiata (q.v.), which flourished during the Cretaceous period. They were allied to the Chamas or Clams; they had a high, almost tubular, right valve, which was attached to rocks, the sea floor, or other shells; they lived in colonies. The left or upper valve is a thin flat plate. Though very abundant in the chalk of France and the south of Europe, the type genus Hippurites has not yet been found in England.