248 The Bird 



them. Both mandibles of the crossbill are curved into 

 sharp hooks which cross one another, either to the right 

 or left, thus forming a unique pair of pliers, with which 

 the bird pries out the seeds shut tight behind the over- 

 lapping scales of pine-cones. 



Fig. 192.— Two extreme types of Hummingbirds' bills adapted for insertion 

 in flowers with shallow and with deep calyxes. 



The beak of a bird is always growing, and in captivity, 

 from lack of proper use, the mandibles sometimes grow 

 to a great length, and, if not trimmed, will often inter- 

 fere with the bird's feeding. 



Perhaps the most remarkably adapted beaks in the 

 world are those of the male and female Huia birds — 



