Vol. 81, pp. 143-150 April 30, 1968 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON NEW TAXA OF WESTERN ATLANTIC COLUMBELLIDAE (GASTROPODA, PROSOBRANCHIA) By George E. Radwin Smithsonian Predoctoral Intern, Division of Mollusks, United States National Museum, Washington, D.C. The Columbellidae is one of a number of piosobranch families whose classification is much in need of careful revision. The last monographic treatment of the family (Kobelt, 1897) was extensive, but was essentially a catalogue of species with no attempt to establish their possible inter-relationships. In order to establish such relationships, a taxonomic revision of the Columbellidae of the western At-lantic has been undertaken as the present author's doctoral dissertation (Radwin, mipubHshed). During the course of the above investigation, the colum-bellid components of the mollusk collections of the Academy of Natural Sciences of Philadelphia, the American Museum of Natural History, the Museum of Comparative Zoology, Harvard, and the United States National Museum have been examined. Considering the lack of attention that has been given in the past to the family in question, it is, perhaps, not too surprising that five new taxa have been uncovered. These include two new species, two new subgenera and one new genus. Rhombinella new genus Type-species: Biiccinuni laevigatum Linne, 1758 (Figs. 2, 9) Shell moderately large ( 12-20 mm ) and buccinoid, spire acute and moderately high, whorls strongly convex, and sutures impressed. Body whorl large, aperture broad, apertural lip usually unthickened and, rarely, weakly denticulate on its inner surface. Columella straight and smooth, weak anal groove present, and siphonal canal very short. Shell 17— Proc. Biol. Soc. Wash., Vol. 81, 1968 (143)
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