244 The Bird 



latter birds are fused together, to yield a firmer support 

 for the muscles of the neck. 



Chimney Swifts and hummingbirds both feed upon 

 insects and are rather closely related to each other, but 

 here again the most decided difference is to be found in 

 their bills. The broad, flattened mandibles of the swifts 



Fig. 188. — Bill of Toucan; cut open to show its light, spongy structure. 



open wide, as the birds dash through the air, engulfing 

 gnats and flies with wonderful skill; while the humming- 

 birds, as we all know, probe the deepest calyxes. Could 

 tw^o bills more unlike be imagined? In very young hum- 

 mingbirds the bill is short and broad, very like the swift 

 tj'pe, and later its long and slender shape is acquired 



