;j64 



MR. ROBERT SHELFORD OX 



though distinctly Coleopterous in appearance, fall into the category 

 of generalised beetle-mimics. 



//< mithyrsocera sp. 

 Wing expanded (a) and folded (b). The apical triangle is shaded. 



In t the genus Prosoplecta the wings have been modified in a 

 very remarkable 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 cockirach wing- 

 structure. The wing of a cockroach such as Blattella germanica 

 L.. is di\ ided longil udinally into an .-interior and a posterior part : 

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

 numerous longitudinal and transverse veins, while the larger 

 posterior pari is supplied only with radiating longitudinal veins. 

 When the wing is closed the posterior part shuts up like a fan 

 and folds underneath the anterior part, which remain,- still' and 

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



anterior and posterior parts of the wing i^ a quite inconspicuous 

 area which, when the winy is closed, appears as a. minute fold 

 lying on the top of the anterior part. This insignificant area, 

 which belongs neither to the anterior nor to the posterior pari 

 of the winy, is the forerunner of a pari of the wing, which in 

 some genera of Blattidse assumes relatn ely enormous proporl ions. 

 In the genus Hemitht/rsocera (text-fig. 42) this area has in- 

 creased in size and is conspicuous enough to have attracted the 

 attention of systematists, ever on the look out for characters 

 diagnosl ic of t he difficult genera of the subfamily Pseudomopinse. 

 The area is now known as the triangular apical area, or more 



