The northern coast of Australia, from Shark's Bay in Western Australia, along the north coast and down the east coast of Queensland, has been named the Solanderian Region, and includes two sub-regions, the Dampierian (the north-western part) and the Banksian (the Great Barrier Reef). The south-eastern coast from south Queensland to south Tasmania has been named the Peronian Region, with eastern Tasmania and southern Victoria forming a sub-region, the Maugean. Southern Australia, reaching from western Victoria into Western Australia as far as Geraldton, has been named the Flindersian Region. These regions do not have precise boundaries, as the Mollusca are mobile animals which often overlap from one region to another, but the general outline has proven to be generally applicable. It may be stated that, as a rule, the species predominant in one region are not common in any other region. In many cases, genera are restricted to one or other of the regions.
The State of New South Wales almost, but not quite, coincides with the Peronian Region (minus the Maugean Sub-Region) but many species characteristic of the Solanderian Region are found as stragglers in the north of the State, and vagrants from the Flindersian Region may reach to southern New South Wales. It should also be noted that, while the littoral and shallow water Mollusca agree well with the zoo-geographical scheme here outlined, the deepwater Mollusca transgress the boundaries altogether, though they are still very inadequately known.