175 



ample, either dived below the water, or burrowed 

 in the earth, and that woodcocks and rails con- 

 cealed themselves in holes at the periods when 

 they were supposed to migrate. But if we re- 

 flect upon the swiftness of these birds, propelling 

 them at the rate of fifty to one hundred miles in 

 an hour if we consider that they take advan- 

 tage of favourable winds that they skirt in their 

 flight the borders of land and rest occasionally 

 their tired wings, the space travelled over by them 

 will not appear so vast and impracticable. Be- 

 sides, few migratory animals undertake, in the 

 present day, very long journeys ; we have no in- 

 terchange, at present, of American and European 

 birds by this process, and seldom any of those 

 peculiar to remote islands. 



With respect, lastly, to fishes and insects, the 

 migrations of many of these animals are hardly 

 less remarkable than those of birds, and abun- 

 dantly adequate to explain their general disper- 

 sion over the globe, even without admitting 

 which is, nevertheless, doubtless the case that 

 all tribes of these, and many other animals, are 

 liable to be conveyed, in either their perfect or 

 their embryo state, by migratory birds, from one 

 district to another. And, indeed, the journey- 

 ings of insects and fishes are not, at least in the 

 present day, very stupendous. Locusts confine 

 their migrations within comparatively limited 

 bounds ; and although some kinds of fish, as the 

 herring, traverse a vast space of a northern sea, 



