BILLS OF DIVING BIRDS. 227 



pies of this in the razor-bill and the puffin, which 

 though they can fly, do not habitually perform that 

 operation ; and still more in the great auk and the 

 penguins, which have very powerful trenchant bills. 

 With these one set of the sea birds may be said to 

 terminate ; and they bear nearly the same relation 

 to the water that the ostrich and apteryx bear to the 

 land it is their principal, and almost their exclusive 

 element. 



In the rapid sketch which we have taken of them, 

 we have traced the birds in their regular gradation, 

 from those that feed on foot upon the land, to those 

 that feed by swimming and diving in the water. But 

 the birds bring us out to sea on another element 

 the air ; and there are tribes which take up the con- 

 nexion from the heron and the kingfisher, which fish 

 in the fresh waters only, and the succession continues 

 till we come to races which are as discursive over 

 the sea as the swallows and swifts are over the land. 



But as all these nestle on the shores (for there is 

 no bird that breeds in the water), and as none of 

 them can be insect feeders on the wing over the sea, 

 there being no insects there, there is not the same 

 diversity of habit among them as there is among the 

 air-feeding birds of the land. The living produce of 

 the shoreward parts of the sea, the waste and refuse 

 which the sea casts up, and the waste which floats 

 on its surface, are the three principal classes of the 

 food of marine birds. 



There are none of these birds which prey directly 

 upon other birds, as the accipitres do upon land ; 

 and therefore there are none of them which have 

 crooked talons or beaks like these. It is true that 

 several of the eagles fish, and, though none of them 

 refuse land prey when they can obtain it, there are 

 Q2 



