Fresh-water oyster (Zoöl.), any species of the genus Etheria, and allied genera, found in rivers of Africa and South America. They are irregular in form, and attach themselves to rocks like oysters, but they have a pearly interior, and are allied to the fresh-water mussels. -- Oyster bed, a breeding place for oysters; a place in a tidal river or other water on or near the seashore, where oysters are deposited to grow and fatten for market. See 1st Scalp, n. -- Oyster catcher (Zoöl.), any one of several species of wading birds of the genus Hæmatopus, which frequent seashores and feed upon shellfish. The European species (H. ostralegus), the common American species (H. palliatus), and the California, or black, oyster catcher (H. Bachmani) are the best known. -- Oyster crab (Zoöl.) a small crab (Pinnotheres ostreum) which lives as a commensal in the gill cavity of the oyster. -- Oyster dredge, a rake or small dragnet of bringing up oyster from the bottom of the sea. -- Oyster fish. (Zoöl.) (a) The tautog. (b) The toadfish. -- Oyster plant. (Bot.) (a) A plant of the genus Tragopogon (T. porrifolius), the root of which, when cooked, somewhat resembles the oyster in taste; salsify; -- called also vegetable oyster. (b) A plant found on the seacoast of Northern Europe, America and Asia (Mertensia maritima), the fresh leaves of which have a strong flavor of oysters. -- Oyster plover. (Zoöl.) Same as Oyster catcher, above. -- Oyster shell (Zoöl.), the shell of an oyster. -- Oyster wench, Oyster wife, Oyster women, a women who deals in oysters. -- Pearl oyster. (Zoöl.) See under Pearl. -- Thorny oyster (Zoöl.), any spiny marine shell of the genus Spondylus.