ii METAMORPHOSIS 209 



radually disappear, the single opercular aperture closes, 

 nd thenceforth respiration is purely aerial. 



In the meantime the limbs are developed. The hind- 

 mbs appear as little rounded buds, one on either side 

 f the root of the tail (D) : they gradually elongate and 

 ivide into thigh, shank, and foot (E). The fore-limbs 

 ppear beneath the operculum and are therefore hidden 

 first (E) ; at a later stage each divides into upper 

 rm, fore-arm, and hand, and emerges from its conceal- 

 ment. As the limbs increase, the tail undergoes a 

 regressive shrinking ; its tissues become, as it were, 

 igested, and are carried off by the blood ; so that for a 

 Line the metamorphosing tadpole is nourished largely 

 y its own tail. 



The mouth widens, the horny jaws and papillae dis- 

 ppear, and teeth are formed. The suckers vanish, and 

 le intestine not only begins to grow less rapidly than 

 body, but even becomes reduced in length and loses 

 s spiral arrangement, while vegetable is exchanged 



