Mud bass (Zoöl.), a fresh-water fish (Acantharchum pomotis) of the Eastern United States. It produces a deep grunting note. -- Mud bath, an immersion of the body, or some part of it, in mud charged with medicinal agents, as a remedy for disease. -- Mud boat, a large flatboat used in dredging. -- Mud cat. See Catfish. -- Mud crab (Zoöl.), any one of several American marine crabs of the genus Panopeus. -- Mud dab (Zoöl.), the winter flounder. See Flounder, and Dab. -- Mud dauber (Zoöl.), a mud wasp. -- Mud devil (Zoöl.), the fellbender. -- Mud drum (Steam Boilers), a drum beneath a boiler, into which sediment and mud in the water can settle for removal. -- Mud eel (Zoöl.), a long, slender, aquatic amphibian (Siren lacertina), found in the Southern United States. It has persistent external gills and only the anterior pair of legs. See Siren. -- Mud frog (Zoöl.), a European frog (Pelobates fuscus). -- Mud hen. (Zoöl.) (a) The American coot (Fulica Americana). (b) The clapper rail. - - Mud lark, a person who cleans sewers, or delves in mud. [Slang] -- Mud minnow (Zoöl.), any small American fresh-water fish of the genus Umbra, as U. limi. The genus is allied to the pickerels. -- Mud plug, a plug for stopping the mudhole of a boiler. -- Mud puppy (Zoöl.), the menobranchus. -- Mud scow, a heavy scow, used in dredging; a mud boat. [U.S.] -- Mud turtle, Mud tortoise (Zoöl.), any one of numerous species of fresh-water tortoises of the United States. -- Mud wasp (Zoöl.), any one of numerous species of hymenopterous insects belonging to Pepæus, and allied genera, which construct groups of mud cells, attached, side by side, to stones or to the woodwork of buildings, etc. The female places an egg in each cell, together with spiders or other insects, paralyzed by a sting, to serve as food for the larva. Called also mud dauber.