Cypris

Cypris, the commonest English genus of that group of "Water Fleas" known as the Ostracoda (q.v.), one of the orders of the Crustacea, Cypris abounds in fresh water, in which it swims by means of a pair of set or covered appendages at the abdominal end. The animal is protected by a small bivalved shell, composed of a horny material, and oval or kidney-shaped in form. The shells of the Cyprids accumulate in such abundance in the bottoms of the ponds in which they live that the mud is rendered quite fissile; the clays of the Wealden and parts of the Purbeck beds are thus easily broken into thin slabs. There are about 30 English living species.