PREFACE 
Vll 
general illustration of my views. I have felt that although I 
am open to criticism, my views will be more easily understood, 
and we shall eventually make more rapid progress in arriving 
at the correct conclusions as to the alterations in the configura¬ 
tion of the oceans and continents that actually occurred in 
the past than if such maps were altogether omitted. 
The immense advance that has been made in the United 
States in the study of zoology has greatly facilitated my work. 
And everywhere in America I found willing helpers ready to 
impart information. My thanks are particularly due in this 
respect to Prof. H. F. Osborn, Dr. Matthew and Dr. Hornaday 
of New York, to Prof. Morse and Mr. John Ritchie of Boston, 
to Dr. Henry B. Bigelow and Mr. T. Barbour of Harvard 
University, to the late Dr. A. E. Brown and Mr. Witmer Stone 
of Philadelphia, to Dr. Dali, Dr. T. W. Vaughan, Dr. Stejneger 
and Miss Richardson of Washington, to the late Prof. Packard 
of Providence, to Dr. Ortmann of Pittsburg, to Dr. Van Den- 
burgh of San Francisco and to Dr. Ruthven of Ann Arbor. 
Several of my European friends also aided me in many ways. 
Among them particularly the following members of the staff 
of the British Museum : Dr. Smith Woodward, who was good 
enough to look through the proofs and to draw my attention 
to several errors, Dr. Andrews, Dr. Boulenger, Mr. Regan, 
Mr. Pycraft and Mr. B. B. Woodward. Prof. Hull, Dr. Bruce 
and Dr. Stapf kindly pointed out to me various valuable 
sources of information. My most grateful acknowledgment, 
moreover, is due to the guardians of the Great Libraries, with¬ 
out whose ready assistance I should never have succeeded in 
accomplishing this work. The most generous facilities for 
study were given me by my friends Mr. Lyster of the 
National Library of Ireland, Mr. Praeger of the Royal Irish 
Academy Library and Dr. Foord of the Royal Dublin Society’s 
Library. I am indebted, too, for many services to Mr. Kappel, 
the Librarian of the Linnean Society, to Mr. Jones, Librarian 
of the Geological Society, Mr. Waterhouse of the Zoological 
Society of London, and Mr. Hinch of the National Library of 
Ireland. 
I am under a great obligation to Messrs. Meiklejohn & Son 
