TYPE SPECIES: Here designated Voluta mammilla Sowerby, 1844; Recent, Australia. DISTRIBUTION: The two living species in this genus inhabit Australian waters off the coasts of southern Queensland, New South Wales, Victoria, and the state of South Australia. They have a bathymetric range of 25 to 100 fathoms. Both species are uncommon. DIAGNOSIS: Shells are oval or ovate-fusiform, light in weight or solid, with a moderately low to a very low spire. Protoconch is large to extremely large, mammillary, and smooth; the nucleus and part of the first whorl are situated laterally. Teleoconch is with or without axial ribbing. Spiral striae are present in varying degrees of strength. Aperture is very wide, flaring upward and outward posteriorly. Siphonal notch is present; fasciole indistinct or absent. Operculum is absent. Radula is uniserial with tricuspid teeth. REMARKS: In 1957 Iredale described Livonia quisqualis, pointing out that this species appeared to be a hybrid exhibiting a large mammillary protoconch approaching in size that of Livonia mammilla (Sowerby 1, 1844) and having the strong axial and transverse surface sculpture typical of Livonia roadnightae (McCoy, 1881). The genus Pterospira Harris, 1897 was based on the fossil Voluta hannafordi McCoy, 1874. A study by Iredale of a number of specimens of hannafordi showed there was considerable variation in protoconch size. According to him, this variation suggests that the genus Pterospira is not worthy of recognition. He refers roadnightae to the genus Livonia Gray, 1855. For the reasons just listed, we agree with Iredale's generic decision, but we have placed the hybrid quisqualis in the synonymy of roadnightae.

The genus Livonia Iredale, 1934 differs from all other genera by its deciduous protoconch. Only a few specimens of L.nodiplicata with an intact protoconch are known : one of these has been figured by the late F.Abbottsmith in La Conchiglia (1982). This author also observed the explosion of a protoconch just after a shell was brought above the surface level on board of a ship. The difference of pressure between the biotope and the sea level may explain this explosion. No information is available as on what fills the protoconch : a liquid, a gas or a mixture of these. It is certain that the protoconch is deciduous : most shells, even the young ones, lost it already during their lifetime. They formed a septum to close off their shell. It is unknown if the septum is formed before or after that the protoconch breaks off.