PREFACE vii 



Professor H. S. Pratt has kindly read over the manuscript and also 

 the proofs of the portion on embryology and metamorphoses, and 

 the author is happy to acknowledge the essential service he has 

 rendered. 



The bibliographical lists are arranged by dates, so as to give an 

 idea of the historical development of each subject. The aim has 

 been to make these lists tolerably complete and to include the 

 earliest, almost forgotten works and articles as well as the most 

 recent. 



Much care has been taken to give due credit either to the original 

 sources from which the illustrations are copied, or to the artist ; 

 about ninety of the simpler figures were drawn by the author, many 

 of them for this work. For the use of certain figures acknowledg- 

 ments are due to the Boston Society of Natural History, to the 

 Division of Entomology, U. S. Department of Agriculture, through 

 the kind offices of Mr. L. 0. Howard, and to the Illinois State 

 Laboratory of Natural History, through Professor S. A. Forbes and 

 Mr. C. A. Hart. Professor W. M. Wheeler, of the University of 

 Chicago, has kindly loaned for reproduction several of his original 

 drawings published in the Journal of Morphology. A number are 

 reproduced from figures in the reports of the United States Ento- 

 mological Commission. 



PROVIDENCE, R.I., 



March 4, 1898. 



