296 



THE WINGS OF DERMA PTERA 



are easily recognized, as they occupy exactly similar positions. The two 

 remaining branches, those that arise near the base of the wing, are doubt- 

 less the tracheae that precede the second and third anal veins respectively. 



The costo-radial group of trachese is represented by a single trachea ; this 

 I believe to be the radial trachea. It is surely not the costal trachea, as the 

 vein that it precedes is far from the margin of the wing of the adult; and 

 of the other three veins of the costo-radial group of veins, the radius is the 

 more persistent one in other orders of insects. 



In the adult wing the preanal area is divided into two parts by the nodal 

 furrow (Fig. 305, nf), a basal part and an apical part. 



Fig. 306. — Tracheation of the hind wing of an earwig. 



The radius extends about one-half the length of the basal part of the 

 preanal area ; it is connected with the cubitus by a cross-vein or a branch 

 near the tips of the two veins. 



The cubitus arises from the first anal vein and extends transversely 

 until it nearly reaches the radius and then extends longitudinally a little 

 more than half the. length of the basal part of the preanal area. It is 

 forked near its end, and the posterior fork is connected with the anal vein 

 by a vestige of a vein, which may be the remnant of vein Cu-i. 



A striking feature of the adult wing is a series of intercalary veins 

 alternating with the branches of the first anal vein. There is no indication 

 of the presence of these veins in the wing of the nymph. Neither is there in 

 the wing of the nymph any indication of the series of cross-veins that 

 extends parallel with the margin of the wing and connects the alternating 

 branches of the first anal vein and the intercalary veins. 



