Great Black Cockatoo. 



451 



ways in its bill and keeping it firm by a pressure of the 

 tongue, it cuts a transverse notch by a lateral sawing motion 

 of the sharp-edged lower mandible. This done, it takes hold 

 of the nut with its foot, and, biting off a piece of leaf, retains 



HEAD OF BLACK COCKATOO. 



it in the deep notch of the upper mandible, and again seizing 

 the nut, which is prevented from slipping by the elastic tis- 

 sue of the leaf, fixes the edge of the lower mandible in the 

 notch, and by a powerful nip breaks off a piece of the shell. 



