XII 



PHYLUM CHORDATA 



429 



shrinking. The mouth widens, the intestine undergoes a 

 relative diminution in length, and vegetable is exchanged 

 for animal diet. The little tailed Frog can now leave the 

 water and hop about upon land ; its tail is soon completely 

 absorbed, and the metamorphosis is complete. 



The Frogs and Toads are all closely allied as regards 

 the main features of their structure the chief differences 

 between the many genera and species being in such super- 



FIG. 243. Salamandra maculosa. (After Cuvier.) 



ficial characteristics as colouration and proportions. In 

 some teeth are altogether absent; in others the webs between 

 the toes are not developed : in some Tree-Frogs (Hyla and 

 allied genera) the toes terminate in sucking discs. A less 

 superficial point of divergence from the structure of the 

 common English Frogs is to be observed in some members 

 of the group such as the Tree-Frogs and Toads (ffyta, Bufo 

 and others) in which the two halves of the shoulder-girdle, 

 instead of being firmly united together in the middle line, 

 overlap one another. In one small group the tongue is 



