TWO YOUNG NATURALISTS. 



9' 



"Much less than you suppose/' said Uncle Bob. 

 " Each kind of fish, like the terrestrial animals, has its 

 area of distribution, beyond which it cannot pass. In 

 the case of many species the great currents of the 

 ocean form an impassable barrier. Here is an instance 

 of it. Formerly the shoals of. herring came by way 



TUBBOT (Plcitronectes maxinmn, Burbo.). 



of the North Sea, along the coasts as far as the mouth 

 of the Seine, but at present they scarcely come 

 beyond Etretat. Some imperceptible change in the 

 condition of the bottom, in the composition of the 

 water, or perhaps in the direction of the currents, and 

 these innumerable hosts at once quit their old habits 

 and change their route." 



