240 



CELTICPRO VINCE. 



A local testaceous fauna, as exhibited in a list 

 of species from any part of the western coasts of 

 Europe, is the product of repeated changes of dis- 

 tribution, which have taken place there, dating 

 back into remote times. 



The Celtic or British province, whether it be 

 considered distinct, or as only a transitional one, 

 bearing the same relation to the Scandinavian that 

 the northern Lusitanian does to the southern, has 

 a good physical boundary in the breadth of the 

 English Channel. This division points clearly to 

 the distribution of the component members of its 

 fauna, to a commingling of species, by the exten- 

 sion of certain southern species northwards, mixing 

 themselves with those of a northern character, 

 which have enjoyed a longer and earlier tenure of 

 the region. This, however, does not take place 

 equally throughout the seas which surround the 

 British Islands. Certain species range both up- 

 wards and downwards along our outward western 

 coasts : they are the " Atlantic forms " of Ed. 

 Forbes. These pass, in a limited degree only, into 

 our internal seas — the Irish and English Channels, 

 and German Ocean — -just as certain West African 

 forms do into the Mediterranean, and lead to the 

 impression that these seas are of comparatively 

 recent origin, and are as yet but partially colonized ; 

 in other words, that change is still in progress. 



In like manner, Mr. Jeffreys observes, " My first 



