87 



" From what I have stated, it Mould appear that the two 

 points on the west coast of Britain, where the greatest change 

 takes place in the species and genera of molusca, are — the 

 parallel of our most southern shores and that of the Clyde. 

 Respecting the east coast I cannot speak from personal obser- 

 vation, my researches having been limited to the most 

 northern shores of it. 



" At the time of that important and comparatively recent 

 geological change, when were elevated into dry land those 

 deposits of what has been called the glacial epoch, which we 

 see largely developed in the Clyde basin, the shores of the 

 Irish Sea, including the north portion of the Isle of Man, and 

 of which we have a near example in the river bank at 

 Egremont ; several northern forms of molusca, previously dis- 

 tributed throughout our seas, became either quite extinct in 

 them, or confined to particular localities, which were probably 

 less affected by the general disturbance. These tracts, where 

 survive — though somewhat degenerated in certain instances — 

 the representatives of a more ancient fauna of our seas, are 

 situated principally among the lochs and islands on the west 

 of Scotland ; but there is one, a district of considerable extent, 

 off the south coast of Ireland, including what is called the 

 ]S T ymph Bank, where we find crania norwegica and lottia fulva 

 actual inhabitants of the Scandinavian seas, as also arctic 

 forms of buccinum and fusus, associated with the most southern 

 species of molusca that reach our coasts. 



" The examination of these tracts, the last remaining strong- 

 holds (if I may so express myself) in our latitudes of species 

 which abound in a fossil state in the crag and drift formations, 

 furnish evidence that a change is now actually taking place 

 in the fauna of these seas ; some species having very recently 

 become extinct, while others are dying out, and promise to 

 disappear entirely at no distant period. 



" Cemoria flemingii, a common fossil of the Clyde basin, 

 still ilourishcs abundantly in Hie adjoining sea, though il is 



