This paper continues previous ecological studies (Dakin, Bennett, and Pope 1948) of the intertidal zone of south-eastern Australia. The environmental factors and the zonation of the animals and plants on the exposed rocky coasts of Victoria are described. As a result of this survey a rearrangement of the biogeographical provinces of the Australian littoral is made, and a new Cool-temperate fauna and flora are recognized on the coast of Victoria.

The environmental factors and the zonation of the plants and animals on the exposed rocky coasts of Tasmania are described, and the findings of the present survey are compared with those of other workers both in Tasmania and in southeast Australia generally. A distinct biota, traces of which were first noticed in Victoria by the present authors (1963), is evident on Tasmanian shores, and the validity of the authors' cool temperate Maugean Province is reaffirmed. This paper concludes the series of ecological studies (Dakin, Bennett, and Pope 1948; Bennett and Pope 1953) on the intertidal zone of south-eastern Australia.

The marine fauna of Low Isles was surveyed by the Great Barrier Reef Expedition of 1928-9. A cyclone in 1950 caused damage to the island's coral, and an expedition visited Low Isles in 1954 with the prime objectives of assessing the extent of this damage, and of ascertaining the extent and nature of changes undergone by the island and its fauna and flora since 1929. It was found that the cyclone had caused great destruction to branching corals but that massive corals had, in most cases, survived. A heavy swell accompanying the cyclone had struck what is normally the lee side of the island, where a dense growth of fragile corals occurred. It is believed that the mechanical force exerted by breaking waves was the chief factor causing the destruction of corals. Coral rubble resulting from this destruction was being rolled about by waves on the seaward slopes of the island, and was hampering recolonization by hard corals. Soft corals, which appeared to have been unaffected by the cyclone, had spread, and appeared to be competing with hard corals for the available substratum. Alterations in the topography of habitats investigated by the 1928-9 expedition were observed. Some of the shingle ramparts had increased in size, and shingle was encroaching on many of the moats. The mangrove area had increased in extent. No marked changes in the faunistic composition of the fauna generally had occurred since 1929. However, direct comparison of the results of the 1928-9 expedition with those of the present survey proved difficult. In order to provide a basis for future surveys of the fauna, attempts were made to separate a large number of distinctive habitats, and to list the species found within each of these habitats. The relative abundance of each species found in each habitat was noted, and the general ecology and biogeography of the commoner animals investigated.

Nudibranchs Glaucus and Glaucilla store and utilize for their own defense the nematocysts of the venomous siphonophore Physalia.

Glaucilla Bergh, 1868 is positively recorded for the first time from eastern Australia, together with Glaucur Forster, 1777. The former is allocated to G. mrginuta Bergh, 1868 and the latter to G. atlanticuc Forster, 1777. Glaucilla has multiseriate ceratal clusters (uniseriate in Glaucus), an unarmed penis (armed with a chitinous spine in Glaucas) and several anatomical peculiarities. Glaucid nudibranchs feed upon species of Velella, Physalia and Porpita; nematocysts of Physalia are subsequently employed for defence. Both Glaucus and Glaucilla are potentially harmful to man.