Vol. 1.] 



Woodworth. — Wing Veins of hisects. 



121 



Orthoptera, Heteroptera, and last of all the Coleoptera. That 

 they were not derived one from the other is quite evident, but 

 the exact source of the groups is unknown. 



The characteristic of the front wing of Heteroptera is the 

 division of the area of the wing into three regions, by the sep- 

 aration of the clavus and membrane from the rest of the wing 

 known as the corium. This division is very evidently the 

 result of the action of two distinct influences. The first is the 

 same as that which separates the anal field in the Orthoptera- 

 It is probably an adaptation to permit the flexion of the wing 

 without the excessive narrowing that exists in Coleoptera. 

 The transverse line, that marks off the membrane, is asso- 

 ciated with the overlapping of the tips of the wings. In the 

 wing of a cockroach (Fig. 51) we see an exactly similar modi- 

 fication of the front wing, such as 

 must have occurred in the first special- 

 ization of the heteropterous wing. 

 The separation of the embolium is 

 evidently produced by the line that 

 is seen in Orthoptera, just behind the 

 primary, and the cuneus may pos- 

 sibly represent a stigma. 



The venation of the front wing (Fig. 

 58) is very much obscured. The pri- 

 mary is usually at some distance from 

 the front margin, and the posterior is on the edge of the clavus. 

 Between these is a single independent, which forks at about 

 the middle of the wing; each of these forks is connected to the 

 adjacent vein by means of a cross vein. Usually these veins 

 can scarcely be made out, and it may be that in other cases, 

 where the venation is obscure, other independents may also 

 extend to the corium. 



At the edge of the membrane there is much variation. My 

 interpretation of the structures here presupposes two trans- 

 verse veins bordering the division line between the membrane 

 and the corium, one belonging to each. These may both be 

 considered as accessory veins. The inner one comes into con- 

 nection with both the primary and the independent, and in 

 some cases many become quite prominent. The membrane 

 vein runs parallel with the inner one, and usually turns out- 

 ward at both ends, but in some instances it crosses the division 



FIG. 58. Diagramatie repre- 

 sentation of an Heteropterous 

 venation. 



