THE WINGS OF A CICADA 



3<f A 



Fig. 273. — The base of a fore wing of an 

 adult cicada (After C. & N.). 



ontogeny of the cicada indicates the course by which this speciaHzation has 

 been reached. 



From a study of the two nymph wings (Fig. 270 and 272), it is an easy 



matter to trace the homologies of 

 the veins and cells of the fore wing 

 of the adult ; these are indicated 

 by the lettering in Figure 269; in 

 those cases where the veins are 

 not niunbered, these homologies 

 are indicated by the ntmibering 

 of the cells behind them. 



The more difficult features of 

 the \'enation of the fore wing are 

 elucidated by Figure 273, which 

 represents the base of the fore 

 wing of an adult, and Figure 274, 

 which represents the region of the 

 nodal furrow of the same wing. 

 These figures are based on a study 

 of the wings of an adult which was killed at the moment of emergence from 

 the nymph skin, and in which the wing-tracheae were distinctly visible 

 within their corresponding wing-veins. 



These figures show^ well the coalescence of sub-costa and radius from the 

 base of the wing to a point near the nodal furrow ; this is a feature which 

 occurs in a large proportion of the families of the Homoptera and Heterop- 

 tera. 



The changes that have taken place in the hind wings of Cicada are much 

 greater than those of the fore wings, and it would be exceedingly difRcult to 

 understand them without an examination of the tracheation of immature 

 wings. Figure 271 represents the tracheation of the hind wing of a young 

 nymph and Figure 275 that of the 



base of the hind wing of an adult. 



By comparing Figures 2 70 and 

 271, it will be observed that the 

 forking of trachea R takes place 

 much nearer the hinge line (a-6) 

 in the hind wing than it does in 

 the fore wing. Upon this fact 

 depends the most striking differ- 

 ences in the venation of the fore 

 and hind wings of the adult. 



In the fore wing the subcosta and radius coalesce to a point near the 

 nodal furrow (Fig. 269). But in the hind wing it is only vein Ro+.s that 



Fig. 274. — The nodal furrow of a fore wing 

 of an adult cicada (After C. & N.). 



