598 AVES BIRDS. 



as yet but very imperfectly developed ; and their tongue, instead 

 of being soft and flexible, as in the Mammalia, is supported 

 by one or two bony pieces, derived from the os hyoides (Jig. 271), 

 and covered with a horny sheath, obviously ill adapted to gus- 

 tation, but simply assisting in the deglutition of food. We 



Fig. 271. 



must not, therefore, be at all surprised if even in birds the 

 tongue is convertible into various instruments assisting in the 

 apprehension or preparation of nourishment : thus, in the Parrot 

 it is a thumb opposable to the upper mandible, and eminently 

 serviceable in holding and turning nuts or morsels of fruit: 

 in the honey-eating tribes the tongue is armed at its extremity with 

 a tuft of horny filaments, resembling a camel-hair pencil, which, be- 

 ing plunged into the bell of a flower, sucks up the nectar from the 

 bottom ; and in the Woodpecker it is absolutely converted into a 

 harpoon, whereby the insect is speared in its lurking-place, and 

 dragged into the mouth. 



(666.) In most birds, in consequence of the very small size of the 

 cavity of the stomach, or gizzard as it is generally called, some other 

 receptacle for the aliment becomes indispensable ; and accordingly 

 various provisions have been made for lodging food in sufficient 

 quantities in situations where it may be retained until the gizzard is 

 ready to receive it. In birds that catch insects on the wing, this is 

 most conveniently effected by dilating the fauces and upper part of 

 the throat into a capacious chamber, wherein the insects as they are 

 seized accumulate : this is remarkably the case in the Swifts. In 

 the Pelican a very peculiar plan is adopted ; the beak is amazingly 

 prolonged, and beneath the lower jaw is suspended a wide pouch, 

 formed by the skin of the throat, wherein large quantities of fish may 

 be contained and carried about. In other fishing birds the whole 

 esophagus is extraordinarily capacious, and will hold a considerable 

 supply ; but the most usual arrangement in birds requiring such a 



