. A history of birds . yand becomes pointed. It is used for the purpose of capturingsmall Crustacea which lurk under stones at low tide. Using thebeak as a lever the bird raises, and finally overturns the stone,seizing whatever may have been in hiding before escape is pos-sible—hence the name Turnstone . In the closely alliedand larger Oyster-catcher {Ostralegus) the beak has increasedenormously both in length and density, and is now used forbreaking open the shells of the larger molluscs, such as mussels{Mytilus). Yet other long-billed Plovers are the Curlews and former, like the I
. A history of birds . yand becomes pointed. It is used for the purpose of capturingsmall Crustacea which lurk under stones at low tide. Using thebeak as a lever the bird raises, and finally overturns the stone,seizing whatever may have been in hiding before escape is pos-sible—hence the name Turnstone . In the closely alliedand larger Oyster-catcher {Ostralegus) the beak has increasedenormously both in length and density, and is now used forbreaking open the shells of the larger molluscs, such as mussels{Mytilus). Yet other long-billed Plovers are the Curlews and former, like the Ibises—birds belonging to the Stork family,and not even distantly related to the Plovers—have down-wardly curved beaks which are used as forceps to drag outsmall Crustacea, molluscs, and so on, from their hiding-places ; ADAPTATIONS 413 while the latter use the beak as a probe, thrusting it far downinto the mud in search of worms until the prey is 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, , Balaeniceps. necessary, and the beak has accordingly become richly sup-plied with nerves ending in small pits at the tip of the this is not all. As it would be impossible for such a long 414 A HISTORY OF BIRDS and elastic organ to move away the mass of soil surroundingthe whole beak, a mechanism has been evolved whereby thetips only of the jaws are opened sufficiently wide to allow ofthe worm being grasped. The mechanism in question is simple,and may be briefly described as follows : The beak of theSnipe is formed by the elongation of the premaxilla and theextension forwards of the narial fossa to within a short distanceof the tip of the beak. Thus is formed an upper and a lowerpair of lateral rods of g
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbirds, bookyear1910
