166 AQUATIC BILLS. 



the action of the neck ; the plunger by a swing upon 

 the webs of the feet, the whole length of the body 

 acting as a lever. The diver, too, can make the body 

 follow the bill, as guided by the eye when under 

 water ; and the bill is compressed, or at "all events 

 narrowed and rounded at the tip, so as to make it 

 readily available in that action ; whereas the bill of 

 the dabbler, which does not dive, is probably available 

 only in the sludge, and incapable of capturing prey 

 that can move swiftly. DabbUng ducks rarely cap- 

 ture even the fry of fishes, in those shallows which 

 they frequent ; but these are the principal food of 

 many of the divers. 



The bills of birds are, however, so much in har- 

 mony with the other parts of their organisation, that 

 it is impossible by any description, however length- 

 ened, to give a clear and satisfactory notion of them, 

 even in their leading function of feeding instruments. 

 They have, in many species, other offices to perform ; 

 and though these are subordinate to the alimentary 

 function, as the functions of the mouths of all animals 

 are, yet the bill must necessarily vary with every 

 natural operation to which it is applied. 



The secondary functions of bills are chiefly preen- 

 ing the feathers, climbing, constructing nests, and 

 defensive or offensive operations not connected with 

 feeding. These functions are performed vrith so 

 apparently equal ease by bills of so different forms, 

 that it is not easy to say which answers the best ; 

 and then the comparative merits of bills, as working 

 tools, can hardly be so generalised as to convey any 

 information useful to the student of ornithology. We 

 shall therefore proceed to give some instances of 

 bills belonging to well-kno\^Ti or well-marked species, 

 as illustrative of the several orders. 



