238 



MA BINE PROVINCES. 



including the two magnificent Conch-shells Triton 

 nodiferus and T. cutaceus, which, though common, 

 are amongst the largest and most striking of Medi- 

 terranean forms. 



Mr. M'Andrew has compared the results of his 

 dredgings on the north coasts of Spain, including 

 Vigo Bay, with those on the south. The British 

 Testacea common to the north coast are 246 species 

 in 406, or 61 per cent. ; whilst the southern species 

 are as 227 in 406, or 56 per cent. ; and he further 

 notices that, of the Scandinavian Testacea, which 

 reach as low down as Spain, as many as 19 stop 

 short, or do not pass south, of Cape St. Vincent. 

 South of the same point, the character of the marine 

 fauna becomes most obviously Lusitanian, so that, 

 if it is thought desirable to reduce the number of 

 independent provinces to two, it may, at the same 

 time, be convenient to subdivide these ; the North- 

 ern Lusitanian, in such a consideration as this, 

 would extend from Cape St. Vincent to the Channel 

 Islands. 



When a marine fauna becomes specifically more 

 numerous, as it always does (and always did) in a 

 direction from cold to warmer temperatures, the rate 

 of appearance and disappearance of forms in any 

 direction is unequal. Of 212 species collected by 

 Mr. M'Andrew on the north of Spain, only 29 did 

 not extend to the south of Cape St. Vincent ; out of 

 352 species obtained on the coasts of Portugal and 



