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.