BALANUS. Brug. (an Acorn; "gland de Mer." Fr.) _Order_ Sessile Cirripedes, Lam. _Fam._ Balanidea, Bl.--_Descr._ Shell composed of six valves articulated to each other side by side in a circle, by the insertion of lamina; closed at the base by a flat, cylindrical or cup-shaped valve, by which it is generally attached; and at the apex by a conical operculum, consisting of four valves in anterior and posterior pairs. Each valve of the shell is divided into a rough triangular portion pointed towards the apex, and a flat area on each side.--_Obs._ This description includes the _Acasta_ of Leach, which growing in sponges, has the base cup-shaped; _Conoplæa_ of Say, which being attached to the stems of Gorgonia and sea-weeds has the base elongated and lanceolate, and _Chirona_, Gray. Balanus is the only genus of Sessile Cirripedes the shells of which consist of six parietal valves, except _coronula_, which has no shelly base, is flatter, and has the valves of the operculum placed horizontally. The Balani are common in all seas, adhering to rocks, corals, floating timber, and to each other. The fossil species are found in the newest strata, at Bordeaux, Paris, &c. Fig. 25. B. Tintinnabulum; 26. _Acasta_ Montagui; 27. Balanus galeatus, _Conoplæa_, Say. BALANIDEA. Bl. The second family of the class Nematopoda, Bl. corresponding with Sessile Cirripedes, Lam., and consisting of Coronular Multivalves, which are fixed, and in a manner soldered to submarine substances, by the base of the shell; as distinguished from the Lepadicea, Bl., Pedunculated Cirripedes, Lam., which are attached by a fleshy stalk. The Balanidea are composed of two sets of valves, besides the shelly plate or base on which they rest. The first, called the Parietal valves, are arranged so as to surround the body of the animal; the second, called the Opercular valves, are placed horizontally, so as to cover the aperture. BALEA. Gray. _Fam._ Colimacea, Lam.--_Descr._ Spiral, turrited, concentrically striated, sinistral, and covered with a thin brown epidermis; spire composed of numerous whorls, gradually increasing in size; aperture small, sub-quadrate; peritrême entire, slightly thickened, with a very slight fold on the columella; axis perforated.--_Obs._ A genus of small land shells, found in moss at the roots of trees in Britain, not very nearly resembling any other land shells, except Clausilia, from which they differ in not having the clausium. They have been placed in Helix by De Ferrusac, and in Pupa by Draparnaud. B. fragilis, fig. 296. _Helix perversa_, Fer. _Pupa perversa_, Drap. BARBATA. Humphrey. UNIO, Lam. BARNACLES. PENTELASMIS, Auct. (fig. 34.) Called Anatifa, by Linnæus and Lamarck, from the ancient notion that they were the eggs or embryo of the Barnacle Duck. See ANATIFER.