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The studied seep carbonates from Tsushima, Japan, are embedded within marine siliciclastics of the lower Miocene Taishu Group and represent the earliest evidence of hydrocarbon seepage in the Sea of Japan. In contrast to Miocene and Pliocene examples from Honshu, which are often found above anticlines, the seeps from Tsushima formed within a pull-apart basin before major anticlines had formed. The three carbonates from Fukuzaki, Kanoura and Tanohama are composed chiefly of calcite, with significant admixture of ankerite only at Kanoura. The stable carbon isotope composition of calcites (δ13C as low as −40.2 ‰ VPDB for Fukuzaki, −41.8 ‰ VPDB for Kanoura, and −52.8 ‰ VPDB for Tanohama) indicate methanogenic origin of the carbonates. Textures of these deposits, including radiaxial and yellow cements, are indicative of formation at a methane seep. The stable oxygen isotope composition of calcites (δ18O values as low as −14.4 ‰ VPDB for Fukuzaki, −14.5 ‰ VPDB for Kanoura and −13.9 ‰ VPDB for Tanohama) indicate that they were influenced by burial fluids. Burial diagenesis is also indicated by the stable isotopic compositions of ankerite (δ13C ranging from −19.1 ‰ to −7.1 ‰ VPDB, δ18O from −11.1 ‰ to −9.7 ‰ VPDB). Molecular fossils from Tanohama comprise n-alkanes with short-chain predominance, interpreted to have formed due to thermal cracking of organic matter. The carbonates yield a chemosynthesis-based community comprising vesicomyids Pleurophopsis chitanii, P. cf. hamuroi, the bathymodiolin ‘Bathymodiolus’ akanudaensis, the lucinid Lucinoma sp. and the provannid Provanna? sp., which have never been hitherto identified. ‘Bathymodiolus’ akanudaensis, Lucinoma sp. and Provanna? sp. are the oldest records of these taxa in the Sea of Japan.

Sagami Bay is among the most surveyed areas in Japan and the northwestern Pacific for marine biodiversity, partly owing to collecting efforts by the Showa Emperor, Hirohito. It was also here that the first chemosynthesis-based community was found in Japan, in the Off Hatsushima hydrocarbon seep site dominated by large vesicomyid clams. Nevertheless, new discoveries continue to be made in the deep. Here, we report observations of rare bathyal gastropods from unusual habitats. From the Off Hatsushima seep, the calliostomatid snail Otukaia kiheiziebisu was found living on tubeworm, the second record of the family from seeps. The cocculinid limpet Cocculina tenuitesta, previously only known from Suruga Bay, was found on a piece of branch-like plant debris inside the actively seeping clam field. This supports the step-wise evolutionary scenario from organic falls to hot vents recently suggested for this family. The predatory naticid snail Cryptonatica affinis represents the second record for the family at seeps, and we also show the first evidence for naticids feeding on chemosymbiotic clams—a phenomenon formerly only known from fossil seeps. We also found live individuals of Provanna stephanos, hitherto known from just two empty shells. Outside the seep area, the lepetid true limpet Sagamilepeta sagamiensis was found living on plastic debris, highlighting the function of plastic in the deep sea as settlement substrates among the muddy expanse. Our observations here have ecological and evolutionary implications, underscoring how much remains to be learned from the deep sea, even in well-studied areas like Sagami Bay.

The recent discovery and exploration of deep-sea hydrothermal vent fields in the Mid-Cayman Spreading Centre, Caribbean Sea (Beebe Vent Field, 4956–4972 m depth) and the East Scotia Ridge, Southern Ocean (E2 and E9 vent fields, 2394–2641 m depth) have yielded extensive collections of two new provannid species, Provanna beebei n. sp. and P. cooki n. sp. Morphological and molecular taxonomy (530 bp of the mitochondrial cytochrome c oxidase subunit I gene) confirm P. beebei n. sp. and P. cooki n. sp. as distinct species; these species are formally described, and details are provided of their distribution, habitat and species associations. Bayesian and maximum likelihood analyses support the placement of P. beebei n. sp. and P. cooki n. sp within the genus Provanna and show that these two new deep-sea species form a well-supported clade with the abyssal West Pacific P. cingulata. Provanna beebei n. sp. and P. cooki n. sp. represent the first records of Provanna from hydrothermal vents in the Caribbean Sea and Southern Ocean, respectively, and extend the known geographic range of the genus. For the first time, intraspecific phenotypic variation in size and sculpture has been reported for Provanna. At the East Scotia Ridge, shell-size frequency distributions and median shell size of P. cooki n. sp. varied significantly between the E2 and E9 vent fields, as well as between diffuse flow and high-temperature venting habitats within each field. The variation in shell sculpture in relation to habitat was also observed in P. cooki n. sp.

The ‘Shinkai Seep Field’ is a serpentinite-hosted chemosynthetic ecosystem in the Southern Mariana Forearc. In June 2015 the site was revisited and a number of rissoiform gastropods were collected. Taxonomic investigations revealed that these specimens represent a hitherto undescribed species ofProvanna(Gastropoda: Abyssochrysoidea), described herein asProvanna cingulatan. sp. This new species is characterized by numerous spiral keels, lack of significant axial sculpture, rounded and inflated whorls, and large size for the genus. With the shell height exceeding 16.5 mm (may reach 20 mm), it is the largestProvannaspecies known thus far. Phylogenetic analysis using 411 bp of the cytochrome oxidase c subunit I (COI) gene confirmed its systematic placement within the genusProvanna. This is the only gastropod from a family endemic to chemosynthetic ecosystems thus far known from the ‘Shinkai Seep Field’. Furthermore, with a collection depth of 5687 m, it represents the deepest known bathymetric range for the superfamily Abyssochrysoidea as a whole.

BackgroundGastropods of the genusProvannaare abundant and widely distributed in deep-sea chemosynthetic environments with seven extant species described in the northwestern Pacific.MethodsWe investigated the population history and connectivity of fiveProvannaspecies in the northwestern Pacific through population genetic analyses using partial sequences of the cytochromecoxidase subunit I gene.ResultsWe found thatP. subglabra, the most abundant and genetically diverse species, is genetically segregated by depth. Among the five species, the three comparatively shallower species (P. lucida, P. kuroshimensis, P. glabra) had a more constant demographic history compared to the deeper species (P. subglabra,P. clathrata).DiscussionEnvironmental differences, especially depth, appears to have a role in the segregation ofProvannasnails. The population ofP. clathratain the Irabu Knoll appears to have expanded afterP. subglabrapopulation. The remaining three species,P. lucida,P. kuroshimensis, andP. glabra, are only known from a single site each, all of which were shallower than 1,000 m. These data indicate thatProvannagastropods are vertically segregated, and that their population characteristics likely depend on hydrothermal activities.

We describe a new species, Provanna urahoroensis sp. nov. from seep carbonates of the lower Oligocene Nuibetsu Formation in eastern Hokkaido, Japan. The new species is the second fossil record of Provanna from Paleogene rocks and resembles a smooth variant of the American Paleogene species, P. antiqua Squires, in having a smooth shell with very weak spiral cords. Based on its association with Bathymodiolus (s. l.), fossil Provanna including the new species possibly grazed preferably on bacteria on the surface of Bathymodiolus (s. l.) and of exposed carbonates.

Thirteen new species of gastropods are described from the Zairov 1-2 and Biozaire 1-3 cruises to the methane seeps off the Congo River: Patellogastropoda: Paralepetopsis sasakii sp. nov. (Neolepetopsidae); Cocculiniformia: Pyropelta oluae sp. nov. and P. sibuetae sp. nov. (Pyropeltidae); Tentaoculus granulatus sp. nov. (Pseudococculinidae); Neomphalina: Leptogyra costellata sp. nov. (Family uncertain); Vetigastropoda: Puncturella similis sp. nov. (Fissurellidae); Lepetodrilus shannonae sp. nov. (Lepetodrilidae); Caenogastropoda: Provanna reticulata sp. nov. and P. chevalieri sp. nov., Cordesia provannoides gen. et sp. nov. (Provannidae); Phymorhynchus coseli sp. nov. and P. cingulata sp. nov. (Conidae); Heterobranchia: Hyalogyrina rissoella sp. nov. (Hyalogyrinidae). All species except T. granulatus (from a settlement trap) belong to groups known from cold seeps and the entire seep fauna here is new to science. Biogeographical affinity of this gastropod fauna is to the West Atlantic seeps, not to the Mediterranean seeps or Mid-Atlantic vents. Fragments of the autecology of the species are presented. The evolution of the seep gastropod fauna is briefly discussed and a continuous immigration of taxa is supported. The oldest verified occurrences of modern taxa in the seeps date back to Cenomanian (Cretaceous) time, while some taxa seem not to appear until very late Tertiary.

Sixteen gastropod species from two Campanian (Upper Cretaceous) hydrocarbon seep localities in Hokkaido, Japan are described. Seven species are new: the acmaeid limpet Serradonta omagariensis; three turbinids: Homalopoma abeshinaiensis, Cantrainea yasukawensis, and C. omagariensis; the trochid Margarites sasakii; the seguenzioid Cataegis nakagawensis; and the provannid Provanna nakagawensis. The most common species in the investigated localities are acmaeid limpets (S. omagariensis), tiny turbinids (H. abeshinaiensis, C. yasukawensis, C. omagariensis), and provannids/hokkaidoconchids (P. nakagawensis and Hokkaidoconcha hikidai). The Upper Cretaceous associations described here do not resemble Lower Cretaceous associations known from other regions but are composed of species similar to gastropods from Recent hydrocarbon seeps and hydrothermal vents in the Northwestern Pacific. This strongly suggest that this region possesses a regional pool of gastropods in chemosynthesis-based communities at least since L...

A fauna of provannid and provannid-like shells is described from Upper Cretaceous seep carbonates in Hokkaido, Japan. We describe two new provannid species, Provanna tappuensis sp. nov. and Desbruyeresia kanajirisawensis sp. nov., with preserved protoconchs of unquestionable provannid type with decollate apex. This material confirms the occurrence of Provannidae as early as the Middle Cenomanian. We also describe Hokkaidoconcha gen. nov. and a new family Hokkaidoconchidae fam. nov., with two named species, H. hikidai sp. nov. and H. tanabei sp. nov. Hokkaidoconchidae are possibly related to the Provannidae, judging from a similar, but not decollate larval shell, although the juvenile teleoconch whorls differ in being of a general cerithimorph appearance and the details of the aperture are unknown. Furthermore, we review the published fossil record of Provannidae and Abyssochrysidae, and we consider that in those older than the Eocene, there is no evidence preserved that unequivocally supports a position there. The Jurassic Acanthostrophia acanthica from Italy seems to be the oldest known record of Abyssochrysidae, and the most reliable occurrence of the family, older than from the Miocene. Other fossil, pre-Miocene species that have been classified in the Abyssochryssidae are provisionally referred to Hokkaidoconchidae. © 2008 The Linnean Society of London, Zoological Journal of the Linnean Society, 2008, 154, 421–436.

Whale bones with associated molluscs have been found in a carbonate concretion in the late middle Miocene Nupinai Formation of eastern Hokkaido, Japan. The concretion contains volcaniclastic grains, pyrite and authigenic carbonate and quartz cements. Pyrite also coats and occurs within bone fragments, which are corroded and partially bored. The whale bone associated molluscs are the bivalves Vesicomya kawadai (Aoki), Vesicomya sp., Calyptogena chitanii (Kanehara), Conchocele bisecta (Conrad) and Adipicola sp., and the gastropod Provanna ? sp. These species represent a whale-fall community in the sulphophilic ecological stage. The Nupinai Formation community shares genera and species with contemporary whale-fall and cold-seep assemblages, which suggests there was a regional pool of molluscs that could utilize both seeps and whale-falls in the NW Pacific during the Miocene. It is possible that during this time sedimentation rate had a control on species composition at contemporary whale-fall sites.

Eighteen gastropod and seven bivalve species are reported from Eocene to Oligocene cold-seep carbonates in Washington State, USA. Four species are new (Niso littlei, Turrinosyrinx hickmanae, Xanthodaphne? campbellae, and Lurifax goederti), and 16 are described in open nomenclature. Previously unknown features of protoconch or prodissoconch morphology and/or shell microstructure are provided for Retiskenea statura (Goedert and Benham), Provanna antiqua Squires, Nuculana? aff. N. grasslei Allen, and Bathy- modiolus willapaensis (Squires and Goedert). Modiolus (M.) willapaensis is placed within Bathymodiolus based on the elliptical- triangular shape of its juvenile shell, indicating that the divergence between vent/seep and whale/wood-fall inhabiting bathymodiolines took place at least 40 Ma. The first fossil species of the vent/seep genera Pyropelta (Pyropeltidae), Lurifax (family uncertain), and Catillopecten? (Propeamussidae) are reported. Niso (Eulimidae), Xanthodaphne, Turrinosyrinx, Benthomangelia (Turridae), Ledella (Nuculanidae), Tindaria? (Tindariidae), and Delectopecten (Pectinidae) are reported for the first time from fossil cold-seep assemblages. Larval developmental strategies are inferred from protoconch and prodissoconch morphologies in 14 species, which largely reflect the species' phylogenetic groups, as in modern vent and seep molluscs. The data presented here indicate that the radiation of toxoglossate turrids (Gastropoda) into deep water took place already in the Oligocene, and not in the Miocene as previously thought. Healed shell injuries and presumed naticid drill holes represent the oldest known fossil evidence of predation at cold-seeps.

Palaeogene and Neogene fossiliferous carbonates from Barbados, Trinidad and northern Venezuela are interpreted to have formed at ancient cold seep sites. The hydrocarbon seepage that fuelled these chemosymbiotic ecosystems was related to tectonic activity in the southern Caribbean region, particularly the subduction of the Caribbean Plate beneath the North Atlantic Plate. The carbonates and fossils from the Scotland District, north-eastern Barbados, are Eocene–Miocene in age and are associated with two distinct tectonic units: the Sub-Oceanic Fault Zone and a diapiric melange. The Sub-Oceanic Fault Zone is the tectonic junction between accretionary prism sediments and over-lying thrust sheets of fore-arc basin sediments. The loading of the thrust sheets caused methane-rich fluids to be expelled from the accretionary prism sediments and channelled to the sea floor via the Sub-Oceanic Fault Zone, where it supported chemosymbiotic invertebrate communities containing vesicomyid, lucinid, thyasirid, solemyid and nuculanid bivalves, a variety of gastropods and possibly vestimentiferan tube worms. The diapiric melange is considered to represent sediment that failed under pressure in the accretionary prism and was remobilised as a diapir that extruded onto the sea floor, providing a conduit for methane and other hydrocarbons that sustained a chemosynthesis-based community of vesicomyid, lucinid and nuculanid bivalves and various gastropods. The geological setting of fossiliferous carbonates known as Freeman's Bay Limestone, in southwest Trinidad, has been less fully investigated. The Freeman's Bay Limestone is a member of the Miocene Lengua Formation, which is believed to have formed in a fore-deep basin on-lapping onto an accretionary prism formed by the subduction of proto-Caribbean crust beneath the South American Plate. The carbonates and fossils of the FBL, including the bivalves Pleurophopsis unioides Van Winkle, 1919 and Thyasira adoccasa Van Winkle, 1919, lucinids, nuculanids and bathymodiolins, and provannid and other gastropods, are interpreted to have formed at palaeo-seep sites on the accretionary prism. Little is currently known about the geological setting of the fossils collected from the Miocene Huso Member of the Pozon Formation, from northern Venezuela, but a seep origin is strongly suspected based on the taxa present. Like the fossil assemblages from Barbados and Trinidad, the Venezuelan material is dominated by vesicomyid bivalves, together with lucinid, thyasirid, bathymodiolin and solemyid bivalves and various gastropods. These taxa are characteristics of modern cold seep communities. Most comparisons between the fossil Caribbean and modern seep fauna are necessarily at the generic or family level, although in some cases, individual species are found at both ancient and modern seep sites. For example, the gastropod Cataegis meroglypta is found in seep carbonate from the SOFZ of Barbados and the FBL of Trinidad as well as at modern seeps on the Barbados Prism. At the generic level, this study has revealed the first fossil occurrences of Abyssochrysos and Provanna in the Caribbean. Such temporal and spatial links further the understanding of both local and global patterns of biogeographic distribution of cold seep fauna.

Whale bones have been found in two large concretions in the uppermost part of the lower middle Miocene Chikubetsu Formation, northwestern Hokkaido, Japan. The bone surfaces are coated in pyrite, and some of the most exterior bone portions and associated bone chips are extensively bored by an unknown organism, possibly microbial. Closely associated with the whale bones is a fossil mollusc assemblage including the mytilid Adipicola chikubetsuensis (Amano), Solemya sp., Vesicomya ? sp. and Calyptogena sp. and the gastropod Provanna sp. These molluscs represent a chemosynthetic community dependent on the decaying whale bone-lipids for nutrition, and the mytilids, vesicomyids and solemyids almost certainly had symbiotic chemoautotrophic bacteria. Since the Oligocene, small mussels, such as Adipicola or Idas, and vesicomyid bivalves have been common elements of whale-fall communities in the Pacific; Provanna similarly since at least the Miocene. However, there are some important differences between modern and fossil whale-fall communities, not least that there appear to be no shared species.

The genomic DNA of two Provanna sp. individuals was extracted, sequenced using an Illumina HiSeq1500, and the mitogenome was assembled. The nearly complete metogenome was 16,183 bp in length, consisting of 37 typical metazoan mitochondrial genes with the typical caenogastropod mitochondrial gene order. All mitochondrial genes were encoded on the heavy strand with the exception of eight transfer RNA genes. To reconstruct the phylogenetic position of the deep-sea Provannidae, we used amino acid sequences of all the 13 mitochondrial protein-coding genes in Bayesian inference, maximum likelihood, and maximum parsimony analyses with sequences of selected gastropods. The resultant phylogenetic trees supported the placement of Provannidae in the superfamily Abyssochrysoidea of the clade Littorinimorpha of Gastropoda, providing new data for understanding the phylogeny of these deep-sea snails.

A limited fauna of relatively simple, thin-walled, hexactinellid sponges, including moderately coarse-textured, funnellike Hexactinella(?) conica new species, fine-textured, tubular to branched Hexactinella(?) tubula new species, fragments of delicate Eurete goederti(?) Rigby and Jenkins, 1983, and Farrea(?) species, has been found in the Oligocene Lincoln Creek Formation on Canyon River, in the southcentral part of the Olympic Peninsula, Washington. These sponges dominate a chemosynthetic invertebrate assemblage that included the gastropod Provanna antigua Squires, 1995; the polyplacophoran Leptochiton alveolus (Lovén, 1846), and radiolarians. Most of the sponges are preserved as silica in a localized cherty and botryoidal, calcareous cement-filled limestone formed at bathyal depths by bacterial oxidation of methane at a cold seep. This is the third known report of sponges from ancient chemosynthetic deposits.

We describe three Miocene species of Provanna from Japan, two new and one in open nomenclature, that represent the only known fossil examples from whale-falls and a considerable increase in the Miocene diversity of the genus. Provanna hirokoae sp. nov. comes from the latest Middle Miocene Kuroiwa seep site in central Honshu. The shells of this species are mostly recrystallized, but contain relict crossed lamellar microstructures. Provanna alexi sp. nov. is from the early Middle Miocene Shosanbetsu whale-fall site in northwestern Hokkaido, and has well preserved shells comprising an outer simple prismatic layer and an inner crossed lamellar layer. The two Provanna specimens from the Middle Miocene Rekifune whale-fall site, in eastern Hokkaido, are preserved as external moulds only, so are left in open nomenclature. Based on current knowledge, the presence of an outer prismatic layer and an underlying crossed lamellar layer seems to be a common feature in the shells of Provanna, as well as in other genera belonging to the family Provannidae and the superfamily Abyssochrysoidea. Although the oldest occurrence of Provanna was in the Late Cretaceous, the genus did not spread geographically and ecologically until the Miocene (with four, or possibly five species), a date concordant with some molecular estimates. However, this could be an artefact of the fossil record because the known pre-Miocene seep and whale-falls are more geographically restricted than those from the Miocene.

More than 100 species of gastropods from vent and seep localities around the world are reviewed, based on literature information and new material. The following new taxa are described (localities with parentheses, systematic position within brackets): Cantrainea macleani sp.n. (Louisiana Slope) [Turbinidae]; Fucaria striata gen. et sp.n. (Juan de Fuca Ridge area), Vetuloniaphalcata sp.n. (North Fiji Basin) [both Trochidae]; Protolira valvatoides gen. et sp.n. (Mid-Atlantic Ridge) [Skeneidae]; Ventsia tricarinata gen. et sp.n. (Lau Basin), Bruceiella globulus gen. et sp.n. (Lau Basin) [both tentatively in Skeneidae]; Melanodrymia brightae sp.n. (Juan de Fuca Ridge area), Pachydermia sculpta sp.n. (Lau Basin), Planorbidella gen.n., P. depressa sp.n. (Lau Basin), Ctenopelta porifera gen. et sp.n. (EPR 13°N)[Peltospiridae]; Helicrenion reticulatum gen. et sp.n. (Lau Basin), Lepfogyra inflata sp.n. (Lau Basin) [families unknown]; Desbruyeresia spinosa gen. et sp.n. (Lau Basin), D. cancellata sp.n.(Lau Basin), D. melanioides sp.n. (Lau Basin), Provanna buccinoides sp.n. (Lau Basin) [Provannidae]; Hyalogyra vitrinelloides sp.n. (Lau Basin), Hyalogyrina grasslei s p a (Guaymas Basin)[Hyalogyrinidae fam. n.], Xylodiscula major sp.n. (North Fiji Basin) [Xylodisculidae]. The external morphology of the soft parts [for Ifremeria and Alviniconcha (Provannidae) also the anatomy] is described for most of the taxa involved. Some features in the biology and distribution of the gastropod fauna are discussed. About half the fauna consists of species belonging to families or superfamilies endemic to this environment. One-fifth of the remaining species belong to taxa normally associated with biogenic substrates in the deep sea. Alviniconcha hessleri has previously been shown to harbour chemosynthetic bacteria in the gill; Ifremeria nautilei is here confirmed to do the same. Ctenopelta porifera, and Hirtopelta hirta are suspected to have such bacteria because of reduction of the alimentary system.

Provanna marshalli sp. nov. is described from Early to Middle Miocene-age fossil hydrocarbon seep localities in the East Coast Basin, North Island, New Zealand, adding to 18 modern and three fossil species of the genus described. Modern species are well represented at hydrothermal vent sites as well as at hydrocarbon seeps and on other organic substrates in the deep-sea, including sunken wood and whale falls. All described fossil Provanna species are restricted to hydrocarbon seep deposits, with a few reports of suspected fossil specimens of the genus from other chemosynthetic environments such as plesiosaurid carcasses, and the oldest occurrences are dated to the Middle Cenomanian (early Late Cretaceous). The New Zealand fossil species is the most variable species of the genus described to date, and may be conspecific with, or antecedent to, a poorly sampled, undescribed modern species found at seep sites off the East Coast of North Island. The microstructure of a fossil Provanna species is reported here for the first time, and found to be comparable to some modern specimens of the genus.

The anatomy of the hydrothermal vent gastropod Provanna is described. It is shown to be a primitive neotaenioglossan with mainly plesiomorphic features in all systems, including open pallial gonoducts, epiathroid nervous system with accessory pedal ganglia and a circulatory system where a considerable portion of the venous blood from the coelomic spaces enters the pallial skirt. Apomorphic features include the possession of an anterior notch, or short canal in the shell (and mantle edge), an annulated sensory pallial tentacle, paraspermatozoa modificd as nurse cells. multiple seminal receptacles, a posterior bursa copulatrix, and a renal oviduct with three distinct regions. the middle one expanded. Comparisons are madc with Abyssochrysos, a genus assumed to be a relict member of the Loxonematoidea, which appears to be the closest known relative. A new family. Provannidae fam.n., is created and tentatively included in the Loxonematoidea. The following new specics are described: Provanna segonzaci sp.n. (from hydrothermal vents at the Fiji Back Arc), P. laevis sp.n. (from hydrothermal seeps in the Gulf of California), P. sculpta sp.n. and P. admetoides sp.n. (from hydrocarbon seeps in the Gulf of Mexico). New records are added for previously described species of Provanna.

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.