Xll PREFACE 



For thirteen years past I have been engaged in the study of 

 the great collections of fossil mammals, gathered in Patagonia by 

 the lamented Mr. Hatcher and his colleague, Mr. Peterson, now 

 of the Carnegie Museum. This work made it necessary for me 

 to visit the museums of the Argentine Republic, which I did in 

 1901, and was there received with the greatest courtesy and kind- 

 ness by Dr. F. Moreno, Director, and Dr. Santiago Roth, of the 

 La Plata Museum, and Dr. F. Ameghino, subsequently Director 

 of the National Museum at Buenos Aires. To all of these gentle- 

 men the chapters on the ancient life of South America are much 

 indebted, especially to Dr. Ameghino, whose untimely death was 

 a great loss to science. It is earnestly to be hoped that the heroic 

 story of his scientific career may soon be given to the world. 



Finally, I desire to thank Mr. Horsfall for the infinite pains 

 and care which he has expended upon the illustrations for the 

 work, to which so very large a part of its value is due. 



While the book is primarily intended for the lay reader, I can- 

 not but hope that it may also be of service to many zoologists, 

 who have been unable to keep abreast of the flood of palseonto- 

 logical discovery and yet wish to learn something of its more 

 significant results. How far I have succeeded in a most difficult 

 task must be left to the judgment of such readers. 



Princeton, N.J., 

 June 1, 1913. 



