NOTES ON THE GEOGRAPHICAL DISTRIBUTION OF ANIMALS. 269 
in South America is less certainly known ; but Africa is now 
the only region which is sufficiently rich in the higher forms of 
life to lead us to suppose that it in any degree adequately re- 
presents the zoology of former times ; and it appears to have 
been exposed in a less degree than other countries to the agencies 
which have destroyed animal life to so great an extent else- 
where. 
In concluding this somewhat desultory article, we may re- 
mark that, contrary to the general idea, extreme heat seems to 
have a tendency to reduce the size of animals. The largest 
known animals are, or were, natives of cold countries ; and 
most insects common to Europe or Japan, and India, are 
•considerably smaller in the latter country. Even the tropical 
representatives of widely distributed genera are nearly always 
inferior in size and beauty to temperate forms. 
