PREFACE ix 



Dr. L. O. Howard, Dr. F. H. Chittenden, Dr. Charles W. 

 Richmond, Miss Mary J. Rathbun, Mr. Nathan Banks, and 

 Professor L. H. Merrill ; 



For generously giving permission to copy certain figures, 

 to the Open Court Publishing Company, Macmillan & Com- 

 pany, D. Appleton & Company, Edward Arnold, Bradlee 

 Whidden, Swan Sonnenschein & Company, Smith, Elder & 

 Company, Charles Scribner's Sons, E. P. Dutton Company, 

 The Crowell Publishing Company, to Professor August 

 Weismann, Professor E. B. Poulton, Dr. and Mrs. G. W. 

 Peckham, Rev. Dr. H. C. McCook, Mr. A. R. Dugmore, Dr. 

 F. M. Chapman, President D. S. Jordan, Professor Vernon 

 L. Kellogg, and Hon. Addison Brown ; 



For kindly selling the right to use certain figures, to 

 Doubleday, Page & Company, A. & C. Black, the Autotype 

 Company, and A. G. Wallihan ; 



For assistance in revising certain paragraphs, to Dr. C. 

 Hart Merriam and Professor W. B. Clark ; 



For assistance in revising proof of all of the illustrations, 

 to Mr. Max Broedel. 



