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. 
