The Permian gastropod fauna of New South Wales is revised and 7 new genera and 16 new species are described and figured.
For the purposes of correlation gastropods have proved to be an unsatisfactory group. This is because they appear to be very susceptible to environmental changes and many species develop within a sequence to a marked extent in comparatively narrow limits both horizontally and vertically. Some species, however, form valuable "marker" or "index" fossils for certain horizons of limited extent.
In this paper a correlation of the Permian horizons in New South Wales is made, so far as is possible, from a study of the gastropod fauna. Special attention is directed towards the uncertain correlations of the "rock unit subdivisions" of the South Coast with those of the Hunter River Valley.
The study of the Permian gastropods has led to certain interesting correlations, but attempts made to correlate the complete sequence of Permian rocks of the South Coast with those of the Hunter River Valley have been impossible.