The shells of the Mediterranean are six hundred in number, but it is probable that more extensive dredging will result in great accessions being made to this list. A very small number of species only are identical with those now found in the West Indies.
Nine genera are peculiar to the Mediterranean.
In the character of its shells, the Black Sea resembles the Mediterranean, but does not contain much more than a tenth of the number of its species. The number of shells found on the Spanish and Portuguese coasts is much smaller than one would expect, and can only be attributed to the scanty explorations that have been made. As we might expect, the number of species identical with those of Northern Europe is much greater on the Atlantic than on the Mediterranean coast of Spain.
The sea of Aral, and the Caspian, contain a few peculiar species; but they have been so little explored, that it is premature, we think, to form them into a province. The proportions of salt contained in these seas is much less than in the ocean.
The west of Africa affords a considerable number of fine shells; the species most numerous being those of Murex, Conus, and Clavatula.
The south African province contains four hundred species; the characteristic genera are Terebratella, Chiton, Patella, Trochus, Fissurella, Cypræa, and Conus. A large number of these species are not found elsewhere.
The Indo-Pacific province stretches from Australia to Japan; the greater part of the east coast of Africa; the Red Sea; Persian Gulf; the Asiatic coast, and the islands of the Indian Archipelago.
The molluscs of the Red Sea remind us of those of India; the percentage of those found also in the Mediterranean being much less. The shells of the Persian Gulf are but little known; one species, the brindled cowry (Cypræa princeps), has been sold for fifty pounds.
The seas of New Zealand and Australia have been formed into a province. As might be anticipated, their mollusca have little in common with those of the rest of the globe.
The Japonic province includes the coast of Japan and the Corea.