226 



ORTHOPTERA 



CHAP. 



abbreviated, and 011 the whole is of subordinate importance to 

 the other three. These latter thus form four chief areas or fields, 

 viz. 1, mediastinal or marginal; 2, scapular or radial; 3, 

 median ; and 4, anal. These nervures and divisions may be 

 traced in a large number of existing and fossil Blattidae, but 

 there are forms existing at present which it is difficult to reduce 

 to the same plan. In Eutliyrliapha, found in the Pacific Islands, 



the hind wings are long and project 

 beyond the tegmina, and have a very 

 peculiar arrangement of the nervures ; 

 the species of Ifolocampsa also possess 

 abnormal alar organs, while the struc- 

 ture of these parts in Diaphana (Fig. 

 122) is so peculiar that Brunner 

 wisely refrains from attempting to 

 homologise their nervures with those 

 of the more normal Blattidae. The 

 alar organs are frequently extremely 

 different in the two sexes of the same 

 . -a -i species of Blattidae, and the hind 



FIG. 122. Ltwphanaficberi. Brazil. r ' 



A, The insect, natural size ; B, wing may differ much from the teg- 



XVru d nn C e r :f ng ' maSnifi ' men as re g ards <*<* of departure- 

 from the normal. So that it is not 



a matter for surprise that the nervures in different genera cannot 

 be satisfactorily homologised. 



But the most peculiar wings in the family are the folded 

 structures found in some forms of the groups Ectobiides and 

 Oxyhaloides [Anaplectinae and Plectopterinae of de Saussure]. 

 These have been studied by de Saussure, 1 and in Fig. 123 we 

 reproduce some of his sketches, from which it will be seen that in 

 B and C the wing is divided by an unusual cross-joint into two 

 parts, the apical portion being also longitudinally divided into 

 two pieces a and &. Such a form of wing as is here shown has 

 no exact parallel in any of the other groups of Insects, though 

 the earwigs and some of the Coleoptera make an approach to it. 

 This structure permits a very perfect folding of the wing in 

 repose. The peculiarities exhibited have been explained by de 

 Saussure somewhat as follows. In the ordinary condition of 

 Orthoptera the axillary or anal field (P) when the wings are 

 1 Ann. Sci. Nat. Zool. ser. 5, x. 1868, p. 161. 



