GENERAL ANALOGIES. 235 



element, and lose the grand characteristic of birds, 

 the wings, though they retain the general structure 

 and habits. The feathery covering is never w^anting ; 

 but in the extreme of ground bird upon land it has 

 much of the loose character of fur, while in the 

 extreme of the divers at sea, it is so close and com- 

 pact, that it has the appearance of one unbroken 

 covering', in which the individual feathers cannot be 

 distinguished. 



In the second place, those sea-birds, from the 

 marsh-breeding-gulls, or rather from the skuas, to the 

 terns, which bear a resemblance to the omnivora 

 among land-birds, are all, like these, good walkers, 

 quite as much at home upon the shores as they are 

 in the water or on the wing. This coincidence is 

 the more worthy of being borne in mind, that the 

 omnivorous birds are the only land ones which have 

 the two motions of walking and flying nearl}^ equal 

 throughout the group ; and the corresponding group 

 of sea birds are the only ones which possess all the 

 three in equal perfection. 



Those birds which are the most general in their 

 feeding, are thus, also, the best fitted for reaching 

 their food in all sorts of places ; and not only this, 

 but they are the most generally distributed over the 

 globe, and resemble each other the most in all lati- 

 tudes. They are not the most numerous at particular 

 spots, though many of them assemble in great num- 

 bers at their breeding places. 



Between the air-feeding birds of the sea and the 

 land, there is not the same perfect correspondence, 

 because there are among sea-birds no literal preyers 

 on the wing. There cannot be, for there is no food for 

 them, as the sea sends up into the air nothing upon 

 which a bird can subsist. The level of the waters is 



