More than 100 species of molluscs are listed from Nukumaruan (late Pliocene or early Pleistocene) siltstone on the summit of the first hill south of Oaro, Hundalee Hills, southern Marlborough. Most species are part of the living bathyal molluscan fauna of canyons off eastern South Island, and the siltstone evidently was deposited in 600–800 m of water.Falsilunatia, Penion benthicolusDell,P. fairfieldae(Powell),Cominella (Eucominia)alertae(Dell),C. mirabilis cantuariensis(Dell),Euthrenopsis otagoensisPowell, andVolutomitra(Latiromitra) are reported as fossils for the first time. The fauna is dominated by the buccinidsCominella nassoides otakauicaPowell, an abundant living taxon, andAeneator(Aeneator)elegans(Suter), a species only recently recognised in the living fauna. The locality is probably the type locality ofAeneator elegansand ofFalsilunatia ambigua(Suter), the latter an earlier name for the livingF. powelliDell. New species ofMesoginella(Sinugin ella),Paracomitas(Macrosinus),Splendrillia(two), andNeoguraleus(Fusiguraleus) are named.Splendrillia armataPowell,S. kingmaiMarwick,S. majorinan.sp.,S. zeobliquan.sp., andParacomitas(Macrosinus)haumurian.sp. are recorded living off eastern South Island.