864 



MR. UOBlillT Slli;i,l'()llD OX 



though (listiiu'tly Coli'optci'oiis in jippcafiiiu'c, fall into the ciiic.y'oi'y 

 of generaiiisod beetle-niiiuics. 



Text-lio-. 42. 



Hemithyrsocera sy. 

 Wiiiji' oxp.'uuU'd {a) and folded {h). The apical triangle is shaded. 



In the genus Prosoplecta the wings ha^-e been modified in a 

 very I'emarkable manner-, and as their structure has never been 

 properly described and is of particular interest when considered 

 together with the mimetic resemblances of the genus, it is 

 necessary to go now into some details of the cockroach wing- 

 structure. The wing of a. cockroach such as Blattella germanica 

 L., is divided longitudinally into an anterior and a posterior pai-t ; 

 the anterior part is more or less rigid, being strengthened by 

 numerous longitudinal and transverse veins, while the larger 

 posteiior part is supplied only with radiating longitudinal veins. 

 When the wing is closed the postei-ior part shuts up like a fan 

 and folds undei'neath the anterior part, which remains stiff and 

 unfolded. At the apex of the line of division between the 

 anterior and posterior parts of the wing is a (juite inconspicuous 

 ar'ea which, when the wing is closed, appears as a minute fold 

 lying on the top of the anterior part. This insignificant ai-ea,, 

 which belongs neither to the anterior nor to the posterior part 

 of the wing, is the forerunner of a. part of the wing, which in 

 some genera, of Blattid;\? assumes relatively enormous proportions. 

 In the genus Hemithyrsocera (text-fig. 42) this are.i has in- 

 creased in size and is conspicuous enough to have attracted the 

 attenti,on of systematists, ever on the look out for chai-aoters 

 diagnostic of the difficult genera of the subfamily Pseudomopinse. 

 The area is now known as the triangular apical area, oi- more 



