Preface ix 



Needham regarding the venation of the anal area. In the course of this 

 investigation the wings of more than six hundred species of insects, repre- 

 senting eight orders were examined. 



Nearly all of the figures illustrating this work are reproductions of 

 photographs of wings. In preparing these figures blue prints were made 

 from the negatives and the lines in the prints were inked with waterproof 

 India ink; then the blue was bleached from the figures by the use of a 

 solution consisting of one ounce of potassiimi oxalate dissolved in six ounces 

 of water. This results in producing figures suitable for reproduction by 

 photo-engraving. By this method very accurate figures can be made 

 easily, even of complicated wings like those of the Odonata. 



John Henry CoiMstock. 

 Entomological Laboratory. 

 Cornell University, 

 November, 191 7. 



