PREFACE. 
THE present work is an attempt to collect and summarize the 
existing information on the Distribution of Land Animals; 
and to explain the more remarkable and interesting of the 
facts, by means of established laws of physical and organic 
change. 
The main idea, which is here worked out in some detail for 
the whole earth, was stated sixteen years ago in the concluding 
pages of a paper on the “Zoological Geography of the Malay 
Archipelago,” which appeared in the Journal of Proceedings of 
the Linnean Society for 1860; and again, in a paper read before 
the Royal Geographical Society in 1863, it was briefly sum- 
marized in the following passage :— 
“My object has been to show the important bearing of 
researches into the natural history of every part of the world, 
upon the study of its past history. An accurate knowledge of 
any groups of birds or of insects and of their geographical dis- 
tribution, may enable us to map out the islands and continents 
of a former epoch,—the amount of difference that exists be- 
tween the animals of adjacent districts being closely related 
to preceding geological changes. By the collection of such 
minute facts, alone, can we hope to fill up a great gap in the 
