ADAPTATIONS 



413 



while the latter use the beak as a probe, thrusting it far down 

 into the mud in search of worms until the prey is touched. 

 For this purpose a high degree of specialisation has become 



III. 47. — Types of Beaks 



I, Merganser. 2, Flamingo. 3, Shoveller. 4, Scissor-bill (adult). 5, Scissor- 

 bill (young). 6, Anastomus. 7, Hornbill. 8, Humming-bird, g, Avocet. 10, 

 Parrot. 11, Parrot. 12, Spoon-bill. 13, Cross-bill. 14, Nightjar. 15, Eagle. 

 16, Balaeniceps. 



necessary, and the beak has accordingly become richly sup- 

 plied with nerves ending in small pits at the tip of the beak. 

 But this is not all. As it would be impossible for such a long 



