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. 
Fic, 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— 
