106 FACULTIES 0$ BIRDS. 



against the upper mandible, a shaft or process of 

 bone, and this receives the pressure of the os quadra- 

 turn when the muscle acts ; so that, being thrust for- 

 wards like a bolt, it opens the upper mandible, which 

 moves upon the skull. Here, then, is a piece of me- 

 chanism as distinct as the lock of a gun, which is for 

 the purpose, as we have said, of giving rapidity to 

 the motions of the bill. Is it nearer the truth to con- 

 sider this as a new apparatus, suiting the necessities 

 of the creature, or an accidental result of the introduc- 

 tion of a bone, which, in its proper office, has nothing 

 to do with the jaw * ? " 



The most singular form of the bill in birds of this 

 group (Grallatores, ILLIGER) is that of the avoset 

 (Recurvirostra avocetta, GESNER), which is flexible 

 like whalebone, and, contrary to the usual direc- 

 tion of the bills of birds, is curved upwards, which 

 led Buffon, in his usual style of theorizing, to 

 suppose it to be " incapable of defence and of 

 effort, an example of one of those errors or essays 

 of nature, which, if carried a little farther, would 

 destroy itself; for if the curvature of the bill were a 

 degree increased, the bird could not procure any sort 

 of food, and the organ destined for the support of life 

 would infallibly occasion its destruction. The bill of 

 the avoset may therefore be regarded as the extreme 

 model which nature could trace, or at least preserve, 

 and for that reason it is the most distant from the 

 forms exhibited in other birds. It is even difficult, 

 he adds, to conceive how this bird feeds by help of 

 an instrument that can neither peck nor seize its 

 prey, being only fit to rake in the softest mud. It 

 seems to employ itself in searching the froth of the 

 waves for fish- spawn, which appears to be its chief 

 support f." 



*Bridgewater Treatise on the Hand, p,14L 

 f Oiseaux, Art. L'Avocette, 



