New gastropods from East Pacific hydrothermal vents

The following new prosobranch species are described: Cyuthermia (gen.n.) naticoides, Lucunoidc (gen.n.) exquisitus (Neomphalidae); Peltospira Iamellifera, Pachydermia (gen.n.) laevis, Depressigyra (gen. n.) g1obulus. D. plunispira, Solutigyra (gen. n.) reticulata, Lirapex (gen. n.) humata, L. granularis (Peltospiridae); Bathymargarites (gen.n.) symplector (Trochidae) and Provanna mucleani (Littorinoidea). Shells and soft parts of the species are described and figured. One species each of Sinezona (Scissurellidae), Moel1rriopsis (Seguenzoidea) and Phymorrhynchus (Turridae) is recorded from East Pacific hydrothermal vents, but not identified to species. Information about feeding biology and type of larval development is given for most of these species. The systematic position of the new species of Neomphalidae and Peltospiridae is considered uncertain, but further anatomical investigations are in progress. The gastropod fauna of East Pacific sulphide-rich environments is summarized and composition, endemism, age. dispersal, predation, adaptations and feeding biology are discussed.