PREFACE . 
Vll 
To the authorities of Cornell University the authors of 
this book are under deep obligation for aid and encourage¬ 
ment. The preparation of the work would not have been 
possible but for the liberal grants which they have made for 
the purchase of specimens and books. 
John Henry Comstock. 
Entomological Laboratory, 
Cornell University, 
December, 1894. 
