vi PREFACE 
fornia: Prof. G. Macloskie of Princeton University; Prof. W. 
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 due 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 Einfihrung; and Gustav Fischer of Jena, publisher of 
Hertwig’s Lehrbuch and Lang’s Lehrbuch. 
