246 
HAROLD’S DISCUSSIONS. 
wings on account of the strong, continuous winds 
that blow upon the island. Mr. Wallace describes 
the peculiar insect life of some of the isolated trop¬ 
ical islands, which he so thoroughly explored. He 
mentions butterflies of striking color and habits, and 
other insects which seem to belong to former geolog¬ 
ical times. Each isolated island seems to have its 
own peculiar fauna. 
Australia still contains both animal and plant life 
that belonged to former ages. Among these we may 
mention the tree-ferns, the “ grass-tree ” ; and among 
animals, the kangaroo, the emu, and others. The 
dodo has become extinct in historic times. 
The Galapagos islands lie about five hundred 
miles west of Ecuador. They are so far isolated from 
other countries that the land animals can have no 
communication with the animals of other regions. 
The sea-birds and the fish of these islands, being able 
to cross the intervening waters, are like those of the 
American coast. But while the land-birds, reptiles, 
insects, and animals closely resemble those of South 
America in color, habits, and tone of voice, yet they 
are so different in structure that scientists classify 
them as different species. These islands lie in a calm 
sea, have an equable climate, and abundance of food, 
so that the struggle for existence is reduced to a mini¬ 
mum. Its animal life, and plant life too, possesses 
less vigor, so that whenever they have been introduced 
into the new conditions of the continent they have 
not been able to maintain themselves against their 
better-schooled rivals. 
