BRISMÆUS. Leach. _Order._ Pedunculated Cirripedes. Lam.--_Descr._ Seven plates, three pairs lateral, one dorsal; form cylindrically conical; pedicle not described. _Hab._ Holes in corals. B. Rhophodius, fig. 38.--_Obs._ This minute shell most nearly resembles Pollicipes Mitellus, fig. 37*, but the difference may be seen at once by comparing the figures. BRONTES. Montf. This generic name is given to such species of MUREX as have a very long, closed canal; with a short spire, circular aperture, and are destitute of spires and ramifications. Brontes (Murex) Haustellum, fig. 390. BUCARDIA. Schum. ISOCARDIA, Auct. BUCCINUM. Linn. _Fam._ Purpurifera, Lam. Entomostomata, Bl.--_Descr._ Subovate or oblong, covered with an epidermis; spire turrited, consisting of few whorls; aperture wide, subovate, terminating anteriorly in a very short canal, reflected over the back; outer lip simple, slightly reflected; inner lip spread over a portion of the body whorl, terminating in a thick, smooth columella; operculum horny. _Hab._ British Seas, Northern Ocean, and Coast of Africa. Most of the fossil species occur in Crag, some in upper marine formation and London clay.--_Obs._ There are considerable difficulties in keeping this genus distinct from others nearly related to it, into which many of the species run by imperceptible gradations. The genus _Nassa_ has been separated on account of the little notch, which terminates the columella. Some species of Terebra come so close upon the Buccina, that it is difficult to say where one genus ends and the other begins. T. Buccinoides, fig. 427. Buccinum Undatum, the common Whelk, fig. 421. BUFO. Montf. A generic division of the species composing Ranella, characterized as having the shell not umbilicated. _Ex._ R. ranina, fig. 394. The above character is scarcely sufficient in some cases, even as a specific distinction. BULBUS. Humph. RAPELLA, Swainson. A genus formed for the reception of PYRULA papyracea, Auct. (fig. 389), and similar species. RAPANUS, Montf. BULIMIMA. Montf. A genus of microscopic Foraminifera.