VI PREFACE 



fornia ; Prof. G. Macloskie of Princeton University ; Prof. \V. 

 A. Locy of Northwestern University; Prof. J. G. Needham 

 of Lake Forest University; Dr. S. H. Scudder of Cambridge, 

 Mass. ; Dr. George Dimmock of Springfield, Mass. ; Dr. 

 Howard Ayers of Cincinnati, Ohio; Dr. W. M. Wheeler of 

 the American Museum of Natural History, New York City; 

 Dr. W. L. Tower of the University of Chicago; Dr. A. *G. 

 Mayer, Director of the Marine Biological Laboratory, Tortu- 

 gas, Fla. ; James H. Emerton of Boston, Mass. ; Dr. and Mrs. 

 G. W. Peckham of Milwaukee, Wis. ; Dr. Henry C. McCook 

 of Devon, Penn. ; Dr. William Trelease, Director of the Mis- 

 souri Botanical Garden ; Dr. Henry Skinner, as editor of " En- 

 tomological News " ; the editors of " The American Natural- 

 ist " ; and W. Saville-Kent, of Wallington, England. 



Acknowledgments are further clue to the Boston Society of 

 Natural History, the American Philosophical Society and the 

 Academy of Science of St. Louis. 



Courteous permission to use certain figures was given also 

 by The Macmillan Co. ; Henry Holt & Co. ; Ginn & Co. ; Prof. 

 Carl Chun of Leipzig; F. Dummler of Berlin, publisher of 

 Kolbe's Einfuhrung; and Gustav Fischer of Jena, publisher of 

 Hertwig's Lehrbuch and Lang's Lehrbuch. 



