12 



STORY OP "^E AMPHIBIANS 



usually a sticky substance on its end. In the tailed 

 amphibians, the tongue is variable, and quite helpful 

 in describing groups. In some it is a mere wrinkling 

 of a membrane on the floor of the mouth. It is so in 



: the giant salamanders. 



^"^"^f^^ ] In no case is it ever 



split, nor is it thread- 

 like and capable of 

 being thrust fap- out 

 while the mouth is 

 closed, as it is in some 

 reptiles. Legless' am- 

 phibians inay always 

 be thus known from 

 legless reptiles. 



In the tailed am- 

 phibians, the tongue 

 is not free behind and 

 tied in front only, as in frogs, but in a few sala- 

 manders it is free all around and tied in the cen- 

 ter. This freedom may be so great that there is 

 left only a central stem (or pedestal), and the whole 

 becomes mushroom-shaped. In a few cases this ped- 

 estal is capable of stretching, so that the cap may 

 perhaps be thrust out of the mouth. But since above 

 this kind of tongues there is usually a quantity of 

 teeth on the roof of the mouth, it is not unlikely that 

 the tongue is used to grind the food against these. 

 In other salamanders, the tongue is free at the sides, 

 but only so in a limited degree behind. In the sirens, 

 which have no teeth, it is free in front to a slight ex- 



FiG. 8. — Head of frog, showing 

 tongue fixed in front but free 

 behind. 



