96 THE BIOLOGY OF BIRDS 



tongue bears soft or horny processes which help to guide 

 the food backwards to the gullet, or guard the opening of 

 the glottis, or help in ducks to strain the mud. In some 

 fish-eating birds, like pelicans and kingfishers, which swallow 

 their prey whole, the tongue is very small ; it is better out 

 of the way. In the insectivorous woodpeckers it is very 

 long, and the branches of the hyoid bone to which its muscles 

 are attached come forwards over the top of the head as far 

 as the nostril, forming a kind of spring which makes the 

 retraction of the sticky tongue exceedingly rapid. In the 

 sap-sucking woodpeckers the tongue is comparatively short 

 and has a tip like a brush. The same brush-like termination 

 is seen in lories, and the tongue of the humming bird 

 ends in two delicate brushes, suited for nectar-sucking and 

 capturing small insects. Cockatoos have a fleshy tongue, 

 ending in a club-like knob ; in many birds, like larks, the 

 tongue is bifid as in snakes and some lizards. The tongue 

 may have spines on it as in insect-eating woodpeckers, or 

 prongs as in the chickadee, or fleshy papillae as in the 

 flamingo, and so on almost endlessly. 



One should not leave the tongue of birds without re- 

 calling the fact that this structure made its first appearance 

 in fishes, but in a non-muscular form. Fishes cannot 

 move their tongue, if they have one at all. Even in the 

 young tadpole of the frog the tongue is still non-mobile ; 

 there are muscle-fibres in it, but they are not strong enough 

 at first to move it. Perhaps their first use is to compress 

 certain glands in the tongue. But they grow in strength, 

 and the adult frog, as every one knows, has a very mobile 

 tongue. The tongue becomes the fine touch-organ of 

 snakes, the very long clubbed insect-catcher of chamaeleons, 

 the long, sticky, worm-like ant-catcher of the ant-eater, 

 the mouth-hand (we may almost call it), with which the 

 grazing cattle grip the grass, and some illustration has been 

 given of its varieties of form and use in birds. We see, then, 

 how a structure which in its earliest appearance seems to 

 be devoid of much significance is gradually improved upon 

 and reaches perfection along many different lines. 



