Vol. 1.] 



Woodworth. — Wing Veins of Insects. 



83 



out the developing of folds. The extreme specialization in 

 this direction is seen in the Orthoptera, where the number of 

 posteriors has become very large. 



The process of decrease appears to follow two lines: The 

 posteriors may fade out and disappear from the hind angle for- 

 ward, in the reverse order to their production. The other 

 method is seen in the cases where the bases of the veins have 

 been modified into an arch-like structure to hold the base of 

 the wing flat when lying at rest upon the body. In this case 

 the tips of the veins fuse together, and this fusion extends 

 more and more toward the base till the two veins ultimately 



entirely coa- 

 lesce. In the 

 front wings of 

 Lepidoptera the 

 posteriors very 

 commonly show 

 evidence of this 

 fusion. In sev- 

 eral families of 

 Diptera the first 

 stages in the 

 process can 

 often be seen all 

 around the outer 

 edge of the wing, 

 and the method of the fusion of the marginal to the primary 

 is the same process. 



In contrast with these evidences of the independence of areas, 

 we may find abundant examples of modifications of one area 

 which greatly change the size and venation. We will call atten- 

 tion to only one of the most striking cases of this kind. In the 

 accompanying illustration of the front wing of a male cricket 

 (Fig. 25) we may note the great expansion of the posterior 

 area for the production of the stridulating organ, which so 

 impinges upon the space usually occupied by the principal 

 series of independents that the area has practically disap- 

 peared, except at the extreme tip. Modifications of this kind 

 are evidently not for flight, and need not be considered in 

 detail. 



FIG. 25. Front wing of male cricket (Grylius), showing 

 expansion of posterior region to form a sounding-board for 

 stridulating organ. 



