PREFACE 



THIS volume is the outcome of the second series of " Swiney 

 Lectures " on Geology which I delivered at the Victoria and 

 Albert Museum in London in 1908. The subject chosen for 

 these lectures was the " Geological History of the American 

 Fauna." Instead of publishing the lectures, like the previous 

 ones on the " European Fauna," with little alteration, I decided 

 to amplify and rewrite them completely. In doing so I was 

 enabled to bring out more clearly certain points in the 

 geological history of the American animals which seemed 

 to me of general interest. 



It is always difficult to choose a suitable title for a work of 

 this kind. The one I have selected is brief yet comprehen- 

 sive. At the same time, it may be urged that the origin and 

 distribution of Man might reasonably be expected from the 

 title, whereas it has been omitted in the text. This omission 

 is mainly due to the fact that the literature dealing with the 

 subject, exclusive of Man, is very extensive, while the origin 

 and distribution of human races in America is treated in quite 

 a distinct set of periodicals and books. 



An important feature of my researches is the elucidation of 

 some of the problems connected with the cause and nature of 

 the " Ice Age " or " Glacial Epoch." There is a considerable 

 amount of faunistic evidence that both the Atlantic and the 

 Pacific oceans were closed simultaneously in the north, result- 

 ing in a higher temperature of these oceans and a greater 

 snowfall in the countries surrounding them in the north. 

 Similarly, if the Glacial Epoch had been due to a closing of the 

 Arctic Ocean, the higher temperature prevailing in the Arctic 



