ii6 



photograph is labeled with the name of the genus it repre- 

 sents. 



Spread out the photographs before you and study the 

 costal area of the wings ; the costal area is the area between 

 the costa and the subcosta ; it corresponds to cell C of the 

 few-veined insects. Observe the varying degrees of com- 

 plexity of the cross-veins ; observe also the stiffening of the 

 area opposite the point where veins Sc and R coalesce, and 

 compare it with the stigma in the Hymenoptera. 



Study the radial area of all of the wings, determine the 

 homologies of the branches of the radius in each, letter 

 them, and number the accessory veins. Also indicate with 

 pencil marks the way in which the suppression of the dichot- 

 omous branching has been brought about. 



That part of the wing of these insects lying caudad of the 

 radius presents difficulties that could hardly be solved by a 

 study of adults alone. A study of the development of the 

 wings of an ant-lion has shown that the second of the two 

 principal branches of the media and vein C//, coalesce. 

 Study the fore wings, which are less modified than the hind 

 wings, and observe that the media appears to be a simple 

 vein for the greater part of its length, and that the cubitus 

 exhibits a well-marked fork before the middle of the wing. 

 This fork is the point of separation of veins Cu^ and Cu^. 

 Observe that near this forking of the cubitus there is what 

 appears to be an oblique cross-vein extending from the media 

 to the cubitus ; this is not a cross-vein, but is the beginning 

 of vein M^^^, which coalesces with vein Cu^ for the greater 

 part of its length. Letter the branches of the media and or 

 the cubitus on each photograph. After this work has been 

 criticised, trace the course of media with red ink and tne 

 courses of radius and cubitus with black ink, omitting tne 

 accessory veins. 



