30 



ISLAND LIFE. 



[part I. 



spiny Echidna, to Australia. Among birds the Struthiones or 

 ostrich tribe are almost confined to the three Southern con- 

 tinents, South America, Africa and Australia; and among 

 Amphibia the tailed Batrachia — the newts and salamanders 

 — are similarly restricted to the northern hemisphere. 



These various facts will receive their explanation in a future 

 chapter. 



