WINGS OF COCKROACHES 



227 



closed collapses like a fan, and also doubles under the anterior 

 part (H) of the wing along the line a a, in Fig. 123, A, the result 

 being similar to that shown by our Fig. 124. It will be noticed 

 in Fig. 123, A, that a small tri- 

 angular area (t} exists at the tip 

 of the wing just where the fold 

 takes place, so that when the 

 wing is shut this little piece is 

 liberated, as shown in t, Fig. 124. 

 In many Blattidae, e.g. Blabera, 

 (Fig. 132), no trace of this little 

 intercalated piece can be found, 

 but in others it exists in various 

 degrees of development interme- 

 diate between what is shown in 

 Thorax porcellana (Fig. 123, A) 

 and in Anaplecta azteca (123, B), 

 so that a, b of the latter -may be 

 looked on as a greater develop- 

 ment of the condition shown in A 

 at t. It will be noticed that the 

 superadded part of the wing of 

 123, B, possesses no venation, 

 being traversed only by the line _ 



FIG. 123. Hind wings of Blattidae. A, 

 along Which it folds; but m Thorax porcellana; B, Anaplecta 



the wing of Diploptera silpha, a ^^^ ploptera silpha ' (After 

 123, C, the corresponding part 



is complexly venated. This venation, as Brunner says, 1 is not 

 an extension of the ordinary venation of the wing, but is sui 

 generis. It is curious that though all the degrees of develop- 

 ment between A and B exist in various 

 forms of the tribes Ectobiides and Oxyha- 

 loides, yet there is nothing to connect the 

 veined apex of Diploptera with the unveined 



FIG. 124. Hind wing of 7 



Biatta folded, t, Free one ot Anaplecta. 

 triangular area. (After The internal anatomy of Blattids has 



de Saussure.) . . 



been investigated in only one or two species. 

 There are no great peculiarities, but some features of minor 

 interest exist. The alimentary canal (Fig. 125) is remarkable 



1 Nouv. Syst. Blattaires, 1865, p. 265. 



