Abstract: Australian Mesozoic freshwater and estuarine bivalves belonging to the Hyriidae, Glauconomidae and Sphaeriidae have been described from only a few localities in Queensland, New South Wales and South Australia, revealing a low-diversity fauna. The hyriids Megalovirgus flemingi McMichael, 1956, and Megalovirgus stirlingi sp. nov. are among the first Cretaceous freshwater bivalves to be described from Victoria and were recovered from upper Strezlecki Group (lower Aptian) strata, ca 4km southwest of Inverloch, Gippsland Basin. These strata represent major fluvial flood deposits that accumulated in the Australia-Antarctica rift during the Early Cretaceous breakup of eastern Gondwana. The distribution of Megalovirgus flemingi in the Cretaceous of both New Zealand and Victoria indicates close links in the freshwater faunas between Zealandia and southeastern Australia during the Early Cretaceous.