THE EUROPEAN SEAS. 



267 



in space, will be found to have a history like that of 

 the species which have been here taken as an illus- 

 tration. The sum of these gives to a local fauna 

 its character ; sectional portions of a fauna acquire 

 distinctive features, according to the number of spe- 

 cific forms which attain their numerical maximum, 

 and development there. 



The peculiarities of the marine fauna of the 

 Channel Islands' group must have often puzzled 

 the working naturalist : not only are things he 

 there meets with wanting, in a great measure, on 

 our own south-western coasts, but, so far as we 

 know, they are also wanting for a broad band in 

 latitude along the western coasts of France, and even 

 to the south of Spain ; so that if, as has been seen, 

 the fauna of Vigo Bay is less Lusitanian than it 

 ought to be from its position, that of the Channel 

 Islands, on the other hand, is much more so ; and 

 the more we know of this local fauna, the more 

 strongly does this peculiarity come out.* 



The explanation of peculiar local assemblages 

 has to be sought far back in time ; and this is just 

 one of those cases of geographical distribution in 

 which it is necessary to call in the aid of geology. 

 The area of this peculiar fauna is the coast of the 

 Department of Finisterre (p. 90), forming the 

 advancing foreland of France on the west, the coast 



* See, particularly, " Gleanings in British Conchology," 

 by M. Gwyn Jeffreys.— Annals of Nat. Hist., 1858-9. 



