I02 THE COMMON FROG. [chap. 



— the stylohyoid — passes downwards on each side, 

 from a process of the base of the skull to the corni- 

 culum of the os-hyoides or tongue-bone. The 

 tongue-bone of the frog is, as we have seen, relatively 

 far greater than is that of man, and the same may be 

 said of the muscles attached to it, since we have no 

 less than four muscles descending from the skull, and 

 implanted into it, on each side. 



This fact might well be supposed to bear direct 

 relation to the size and mobility of the frog's tongue. 

 The tongue in the frog and toad is singularly different 

 from the tongues of most familiar animals, in that it 

 is not free and movable in front, but behind. These 

 Batrachians take their food by suddenly throwing 

 forwards, out of the mouth, the free hinder end of the 

 tongue. The insect or other small animal struck by 

 it, adheres to it, on account of a viscid saliva with 

 which it is coated. The prey is then suddenly drawn 

 into the mouth and swallowed. 



Fig. 66. — Head of the Frog Phyllornediisa, showing the tongue fixed in front, but 

 free posteriorly. 



Here then is the ready explanation of the develop- 

 ment of the os-hyoides and its muscles. There is a 

 difficulty, however, in that two toads already de- 

 scribed, the Pipa and the African form Dactylethra 

 (Figs. II and 12), have no tongue whatever. 



