126 THE WINGS OF ORTHOPTERA 



homologies of the wing-veins of adults. The principal veins are easily 

 recognized except the costa, which is either greatly reduced or is entirely 

 lacking. But the general appearance of the wings of recent cockroaches is 



Fig. 1 1 8. — Right fore wing of Phyllodroma germanica. 



very different from that of the hypothetical primitive type. In fact, 

 although cockroaches are in many respects very generalized insects, the 

 stiiicture of their wings has been greatly modified in the course of the 

 evolution of the family. There has been an extensive development of 

 accessory veins, a great reduction of the radial sector, and a modification of 

 the branching of the media, or the reduction of this vein to an unbranched 

 condition. 



The venation of the wings of certain modern cockroaches does not differ 

 so much from the hypothetical primitive type as does that of the wings 

 figured above. For example, the fore wings of Phyllodroma germanica, 

 commonly known in the United States as the croton bug, present a much 

 more generalized condition. Figures ii8 and 119 represent the venation 

 of the two tegmina of the same individual. 



The radial sector in the right tegmen of this insect (Fig. 118) is nearly 

 typical; veins R2 and R3 coalesce nearly to the margin of the wing, but 



Fig. 119. — Left fore wing of Phyllodroma germanica. 



their tips are still distinct; veins R4 and R5 coalesce throughout. In the 

 left tegmen (Fig. 119), the radial sector is reduced to an unbranched 

 condition. 



The media is four branched in the right tegmen (Fig. 118), but the 

 branching is not quite typical. Spuler ('92) figures the right wings of this 



