474 THE OCEAN WORLD. 



Our British, mollusca are about seven hundred in number ; those 

 bearing shells are above five hundred. 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 Mediterranean. 

 But as one might expect, on close examination, the Mollusca in so 

 large an area differ so widely that we are forced to admit the existence 

 of great divisions. 



The number of species found on the coast of Madeira by Mr. 

 McAndrew was one hundred and fifty-six, of which forty-four per 

 cent, were identical with British species, and eighty-three found near 

 the Canaries. 



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 Mediter- 

 ranean, but does not contain much more than a tenth of the number 

 of its species. The number of shells found on the Spanish and Por- 

 tuguese 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, Cyprsea, and Conus. A large number of these species are 

 not found elsewhere. 



The Indo-Pacific province stretches from Australia to Japan ; the 



