THE EUROPEAN SEAS. 



229 



would affect the composition of the water. To 

 what extent it does so, whether the degree of salt- 

 ness of the Mediterranean waters is greater than 

 that of the Atlantic, is yet an unsettled question. 

 There is no doubt but that there is a difference be- 

 tween the waters of parts of the Eastern Mediter- 

 ranean and the Western, owing to the influx from 

 the Black Sea, sufficient, as has been shown, to pro- 

 duce a marked influence in the fauna ; but the 

 latest authorities find no difference between the 

 degree of saltness of the Western Mediterranean 

 and of the external Atlantic Ocean. 



Along the outline of all our seas, wherever there 

 are deep indents into the land into which rivers 

 discharge, or where the set of tides or other causes 

 have run out banks of sand and shingle in advance 

 of shelving coast-lines, the composition of the in- 

 cluded waters undergoes variable amounts of change : 

 in some regions brine-lakes are produced ; in others 

 brackish-water estuaries and lagoons. These last 

 are the favourite resort of the keener sportsmen 

 of all countries; fishes abound, as do water-birds, 

 from the land side and the sea. They have their 

 peculiar testaceans, whilst purely-marine species 

 pass in and exhibit the power which certain forms 

 possess of adapting themselves to altered conditions, 

 to how great an extent they can change their habits, 

 and what curious modifications their external forms 

 can experience. 



