BILL OF THE COCKATOO. 213 



wing, the bill is generally larger in proportion as the 

 food is smaller. The ground parrots, which are better 

 walkers than the rest, have the bill large, but the food 

 appears to be, in part at least, taken by the tongue, 



Cockatoo, 



which is more slender than that of the others, but 

 capable of being protruded, and armed at the tip with 

 a horny portion cleft in two. The above figure will 

 show the general form of the bill. 



BILLS OF THE COLUMBAD^. 



We have already mentioned some of the reasons 

 why the dove or pigeon family should be separated 

 from the poultry; but as both are chiefly ground 

 feeders, and as some of both perch on trees, and others 

 sit or squat on the ground or on rocks, we may expect 

 some correspondence in the form of their bills. The 

 pigeons are, however, more vegetable in their feeding ; 

 and though they are by no means elaborate nest- 

 builders, some of them at least do much more in that 

 way than the gallinaceous birds. , " 



