280 FISHES OF THE FIRTH OF FORTH. 



pose of their being made to seek the rivers. Salmon gene- 

 rally delay entering fresh water in great numbers, until 

 the streams become somewhat swollen by rain, although in 

 the large rivers there may be said to be a limited daily run. 

 When the flood has fairly mingled with, and to a certain 

 extent saturated, the estuaries, the run of fish is often very 

 great, especially if there has been a continued tract of dry 

 weather. In the latter case they collect at the mouths of 

 rivers and are often taken in vast numbers ; but they do 

 not then attempt an ascent, deterred perhaps by the clear- 

 ness of the stream, or by some instinctive feeling that the 

 waters would yet be deficient to carry them ( through.*" 

 During the continuation of the floods, when the waters be- 

 come discoloured, the fish rush up with the greatest velocity, 

 and make wonderful efforts to surmount cascades and other 

 impediments, by leaping elevations of from eight to ten 

 feet, so as to gain the waters above and pursue their course. 

 The rate at which they travel is supposed to be from fifteen 

 to twenty-five miles daily, and probably at a much greater 

 speed where the waters are deeper and the interruptions 

 less frequent. Having ascended the river to a considerable 

 distance they proceed more slowly, resting for a time in 

 pools by the way, or in some chosen spot where they remain 

 until called forth by that law of nature which compels them 

 to seek the shallows to deposit their spawn. " As the spawn 

 advances the symmetry of the form is disfigured ; the fe- 

 male becomes disproportionately large, the colours lose the 

 brightness of their silvery tints, and become dull and grey. 

 The male becomes thin upon the back, the nose elongates, 

 and the under jaw turns up in a large and strong hook, 

 which enters a hollow in the nose before the inter-maxil- 

 larv bone. The colours and markings become brown and 



* Encyclopaedia Britannica. 



