64 



MANXJAl OP THE MOtLUSCA. 



•weed bank, so as to include Madeira, tlie Azores, and Canary 

 Islands.* 



In the Atlantic portion of the proTince occur the following 

 genera, not met with in the Celtic and Boreal seas, although 

 two of them, Mitra and Mesalia, occur on the coast of Green- 

 land : — 



Spain and Portugal. 



The coast of Spain and Portugal is less known than any other 

 part of the province, but the facilities for exploration are in 

 some respects greater than in the Mediterranean, on account of 

 the tides. Shell-fish are more in demand as an article of food 

 here than with us, and the Lisbon market afi'orded to Mr. 

 M 'Andrew the first indication that the genus Cymba ranged so 

 far north. 



On the coasts of the Asturias and Gallicia, especially in Yigo 

 Bay, Mr. M'Andrew obtained, by dredging, 212 species, of a 



* In tlie northern part of the Lusitanian province are the Pilchard fisheries ; in the 

 Mediterranean, tlie Tunny, Coral, and Sponge fisheries. 



Tlie Gulf- -weed banks (represented in the map) extend from 19' to 47' in the 

 middle of the North Atlantic, covering a space almost seven times greater than the 

 area of France. Columbus, •who first met with the sargasso about one hundred miles 

 west of the Azores, was apprehensive that his ships would run upon a shoal. {Hum' 

 boldt.) The banks are supposed by Professor E. Forbes to indicate an ancient coast- 

 line of the Lusitanian land-province, on which the weed originated. Dr. Harvey states 

 that species of Sargaesum abound along the shores of tropical countries, but none 

 exactly correspond with the Gulf- weed {S. bacciferum). It never produces fructifica- 

 tion — the " berries " being air-vesicles, not fruit — but yet continues to grow and 

 flourish in its present situation, being propagated by breakage. It may be an abnormal 

 condition of S. vulgare, similar to the varieties of Fncus nodosits (Mackaji) and 

 F. vesicidosus which often occur in immense strata ; the one on muddy sea-shorea, the 

 other in salt marshes, in which situations they have never been found in fractificatioa, 

 {Afanual of British Algcc, Mr. 16, 17.) 



