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Family Cyprinidae

SHELL regular, equivalve, oval, valves solid; epidermis thick, dark; ligament prominent, outside; hinge with four large interlocking teeth; umbones oblique; muscle scars two, oval, polished; joined by pallial line; mantle united posteriorly to form two short ciliated siphons, elsewhere free; foot thick, tongue-like; gills unequal, two on each side. A small family of chiefly fossil species.

Genus CYPRINA, Lam.

Characters of the family.

The Iceland Cyprina (C. Islandica, Linn.) is our sole living representative of a family containing fossils of several genera and over one hundred species. It is found as a fossil in Sicily and Piedmont; living it ranges from the coasts of Norway and England to Labrador and south to Massachusetts. When alive the clam wears a shaggy coat of brown or black epidermis. It is like the quahog in general form, or a giant Astrate. It is found after storms on New England beaches. Length, 3 to 4 inches.

Another genus is represented by one of the handsomest of bivalve shells, Isocardia vulgaris, Rve., remarkable for the spiral development of its beaks.

Habitat.-China.