500 THE OCEAN WORLD. 
Our British Mollusca are about 7oo in number; those bearing 
shells are above 500. Of these about thirty are peculiar to Britain. 
The shells of the Baltic are identical with those of this province. 
The Lusitanian province stretches from Madeira and the Canaries 
to the coasts of Spain and Portugal, and includes also the Mediter- 
ranean. But, as one might expect, on close examination the Mollusca 
in such a large area differ so widely that we are forced to admit the 
existence of great subdivisions. 
The number of species found on the coast of Madeira by 
Mr. McAndrew was 156, of which forty-four per cent. were identical 
with British species, and eighty-three per cent. were common to the 
Canaries. 
The shells of the Mediterranean are 600 in number; but it is 
probable that more extensive dredging will result in great accessions 
being made to this list. Nine genera are peculiar to the Mediter- 
ranean. A very small number of species only are identical with those 
now found in the Red Sea or the West Indies ; 
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 proportion 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 400 species ; the character- 
istic genera are Terebratella, Chiton, Patella, Trochus, Fissurella, 
Cypreea, and Conus. A large number of the 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 per- 
centage of those found also in the Mediterranean being but small. 
The shells of the Persian Gulf are but little known ; one species, the 
brindled cowry (Cyprea princeps), has been sold for £50. ° 
