Transparent and sparkling rivers, from which it is delightful to drink as they flow. Macaulay.

River chub (Zoöl.), the hornyhead and allied species of fresh-water fishes. -- River crab (Zoöl.), any species of fresh-water crabs of the genus Thelphusa, as T. depressa of Southern Europe. -- River dragon, a crocodile; -- applied by Milton to the king of Egypt. -- River driver, a lumberman who drives or conducts logs down rivers. Bartlett. -- River duck (Zoöl.), any species of duck belonging to Anas, Spatula, and allied genera, in which the hind toe is destitute of a membranous lobe, as in the mallard and pintail; -- opposed to sea duck. -- River god, a deity supposed to preside over a river as its tutelary divinity. -- River herring (Zoöl.), an alewife. -- River hog. (Zoöl.) (a) Any species of African wild hogs of the genus Potamochœrus. They frequent wet places along the rivers. (b) The capybara. -- River horse (Zoöl.), the hippopotamus. -- River jack (Zoöl.), an African puff adder (Clotho nasicornis) having a spine on the nose. -- River limpet (Zoöl.), a fresh-water, air-breathing mollusk of the genus Ancylus, having a limpet-shaped shell. -- River pirate (Zoöl.), the pike. -- River snail (Zoöl.), any species of fresh-water gastropods of Paludina, Melontho, and allied genera. See Pond snail, under Pond. -- River tortoise (Zoöl.), any one of numerous fresh-water tortoises inhabiting rivers, especially those of the genus Trionyx and allied genera. See Trionyx.