NETTING AND SIFTING 37 



Few people, by the way, realize how a Pelican's bill 

 works ; it is not a fish-creel, but a dip-net ; when 

 the bird is fishing, the elastic branches of the lower 

 jaw expand into a great skin-floored spoon, and 

 scoop up the prey, contracting again when this is 

 captured. 



The beautiful sifting-arrangement of rows of 

 horny plates along the biUs of the typical Ducks is 

 one that can easily be seen in action, and it serves 

 for collecting not only animal but vegetable food 

 from water or mud ; in the grazing Geese and the 

 fishing Mergansers the ridges take the form of 

 teeth, since here biting rather than sifting is needed. 

 The perfection of the sifting apparatus is, as Dar- 

 win pointed out, found in the bill of the Shoveller 

 Duck, where the ridges almost equal in propor- 

 tionate length the whalebone of some of the whales ; 

 and the Shoveller seems consequently to be able to 

 extract nutriment from water in which the other 

 Ducks find " bibbling " unprofitable. 



The simplest form of the ridge-row is to be 

 found, as might be expected, in the Magpie-Goose 

 above noted, in which it is hardly more pronounced 

 than the " burring," like that of the ends of a pair 

 of forceps, to be found in the beak of the Emu. 

 Nevertheless the Magpie-Goose " bibbles " like a 

 Duck, and does so habitually, unlike the true graz- 

 ing Geese, though these will use their grazing biUs 

 in this way occasionally ; recently, in autumn, I 

 saw no less than four species of Geese, the Common, 

 Chinese, Canadian, and Bernicle, sifting in this 



