It will be admitted that every stream draining a forest-covered country carries on its waters, especially at times of high flood, some of the animal-life whose habitat is the ground. Almost the whole of our land Mollusca shelter under fallen timber and amongst the leaves and decaying debris. An exceptionally torrential rainfall would scour hillsides and gullies, and carry to the main stream very considerable quantities of loam and debris, together with the animals inhabiting it. We have only to view some of the large rivers, such as the Wanganui when in high flood, to gain a clear conception of the vast toll gathered from the forest lands: its surface is strewn with huge logs, freshly uprooted trees, and masses of debris, the water charged to its maximum carrying-capacity with loam and sandy clay. This continues for hours, and in a lesser degree for several days: on entering the sea it forms a great fan of discoloured water extending to the horizon. In such a flood immense numbers of the land-snails must have shared the fate of not a few of the higher animals, yet they leave little record on the beach. A careful search may reward the collector with a few specimens only.

Almost the whole of our land-shells are very fragile, and no doubt the pounding they receive in the surf is sufficient to destroy them. This, however, does not appear to be the sole cause of their non-preservation: there are large streams flowing into well-sheltered bays and harbours, and each deposits its quota of land-shells in the protected waters. During Tertiary and Cretaceous periods, we may reasonably assume, innumerable similarly situated streams must have existed, but, so far, little record of the land molluscan fauna has been found in the rocks. The shells as a whole are constructed of a very thin calcareous deposit, and when the epidermal conchin is destroyed they are in a condition readily to disintegrate. A brief period of immersion in water is sufficient with most of our species to destroy the epidermal coating.

The conditions that obtained when the Akatoa bed was deposited must have been unusually favourable. Its position above the high-tide level would appear to indicate a strong banking of the sea on the coast, that it held the storm-water and silt from the land close on the shore-line, and that it was not subjected to a heavy surf. No doubt the bed extended considerably along the shore and only a fragment is preserved.

We are informed by a resident who occupies land several miles nearer to the Taieri River that a similar bed occurs on the coast opposite to his farm. We have had no opportunity of examining the deposit, and it may or may not be of a similar nature. Should it, however, prove to contain a land fauna, then its source is more than likely to be the Taieri River. The fact that this is the first record of a land fauna in a sea-beach deposit goes far to prove that they must be of rare occurrence, and it is much to be desired that a careful investigation of the coast-line be made between the Taieri River and the Akatoa Creek.

List of Land Mollusca.

• Aeschrodomus barbatula (Reeve)

• Allodiscus planulatus (Hutt.)

• Charopa (“Cavellia”) biconcava var. minor Sut.

• Charopa (“Fectola”) otagoensis Sut.

• Charopa (“Fectola”) tapirina (Hutt.)

• Phrixgnathus celia Hutt.

• Phrixgnathus pumila (Hutt.)

• Ptychodon suteri Murdoch and Finlay.

• Thalassohelix igniflua (Reeve)

• Therasia thaisa Hutt.