754 



STUDIES IN AUSTRALIAN NEUROPTERA, vi., 



The most stiiking specialisation in tlie venation of the Psych- 

 ojysidce, apart from the great enlargement (jf the costal area, is 

 the manner in which the three parallel main veins, 8c, R, and 

 Rs, have become strengthened, for from two-thirds to three- 

 quarters of their lengths, to form a kind of midrib, from which 

 the rest of the wing, apart from the much reduced median, 

 cubital and anal areas, is supplied with numerous, delicate, 

 radiating veins. I propose to term this strengthened portion of 

 these three veins the vena trip/ lea; its distal end is already known 

 as the anastomosis. In order to understand this structure, we 

 must consult the precedent tracheation. There (Text-fig. 3, A) we 



Text-fig. 3. 

 P.^f/cJiopsIs ehf/ans (Guerin). The radial anastomosis in the forewing. A, 

 pupal tracheation; E, imaginal venation; .Vj, .I'a, the two cross-veins 

 which join the distal ends of the vena triplica. 



shall find that the trachete run normally through the anastomosis, 

 without any thickening basad to it, and without any true anasto- 

 mosing between them. The strengthening of these veins, from 

 the base to the anastomosis, to form the vena triplica, their ap- 

 parent unions at the anastomosis, and the strong differentiation 

 of their distal portions so as to appear exactly the same as the 

 branch-veins above and below them, are purely imaginal special- 

 isations, peculiar to this family, and not found elsewhere in the 

 Planipennia. The development of the irregular series of cross- 



