MARINE PROVINCES. 15t 



9, Australo-Zealandie ; 10, Japmiic ; 11, Aleutian ; 12, Califor- 

 niau ; 13, Panamic ; 14, Peruvian; 15, Magellanic ; 16, Pata- 

 gonian ; 17, Caribbean ; 18, Transatlantic. 



I. Arctic Province. 



The North Polar Seas contain but one assemblage of Mollusca, 

 whose Southern limit is formed by tlie Aleutian Islands in the 

 Pacific, but in the North Atlantic is determined chiefly by the 

 boundary of floating ice, descending as low as Newfoundland 

 on the West, and thence rising rapidly to Iceland and the North 

 Cape. The existence of the same marine animals in the Kam- 

 tchatka Sea and Baffin's Bay was long since held to prove at 

 least a former Northwest passage ; but the occurrence of recent 

 sea-shells in banks far inland rendered it probable that even 

 recent elevation of the land in Arctic America might have much 

 reduced the passage. During the " Glacial period," this Arctic 

 Sea, with the same fauna, extended over Britain ; over Northern 

 Europe, as far as the Alps and Carpathians ; and over Siberia, 

 and a considerable part of North America. The shells now 

 living in the Arctic Seas, are found fossil in the deposits of 

 " Northern Drift," over all these countries ; and a few of the 

 species yet linger within the bounds of the two next provinces, 

 especially in tracts of unusual depth. The Arctic shells have 

 often a thick epidermis and but little color ; they occur in very 

 great abundance, and are remarkably subject to variation of form ; 

 a circumstance attributed by Professor E. Forbes to the influence 

 of the mixture of fresh water produced by the melting of great 

 bodies of snow and ice. 



II. Boreal Province. 



The Boreal Province extends across the Atlantic from Nova 

 Scotia and Massachusetts to Iceland, the Faroe and Shetland 

 Islands, and along the coast of Norway from North Cape to the 

 Naze ; it includes Iceland except its northern coast. Its Southern 

 American boundary is Cape Cod. 



Of 289 Scandinavian shells catalogued by Dr. Loven, 21t, or 

 15 per cent, are common to Britain, and 137 range as far as the 

 North coast of Spain. 



The boreal shells of America are catalogued by Dr. Gould ; 

 from whose lists it appears that out of 270 sea-shells found on 

 the coast of Massachusetts north of Cape Cod, more than half 

 are common to Northern Europe. 



Many of the species, it is believed, could only have extended 

 their range so distantly by means of continuous lines of con- 

 necting coast, now no longer in existence. 



This province is very poorly defined : a large portion of the 



