406 STUDIES IN AUSTRALIAN MECOPTERA, ii., 



Tlie Radius {R) is a strong convex vein branching at the 

 radial fork {rf) into Rj and Rs. The main stem, Rj, reaches 

 the wing-margin well before the apex. Around its distal end is 

 formed the pierostigma {'pt), a hardened membranous area 

 bounded by the costal margin above and the pApvostuimatic furrow 

 {ptf) beneath. Within this area are sometimes developed one 

 or more ptpvostiy mafic vpinhfs, which are also parts of the 

 original venation, not cross-veins, but true branches of Rj, since 

 they carry macrotrichia. The Radial St^cfor (Rs) has the typical 

 dichotomous branching seen in the Trichoptera, giving rise, in 

 each wing, to four branches, R.,, R3, R4, and R., respectively. 

 The separation of R., from R;. takes place far distad, under the 

 pterostigma; that of R^ from R5 much further basad, not far 

 from the first forking of Rs into R2-1-3 and R4_|^5. All these 

 branches are connected and strengthened b}' a number of cross- 

 veins, whose position varies greatly in different individuals. 



The .]ffidia (M) resembles the radial sector in the manner of 

 its branching, as in Trichoptera; except that, in the forewing of 

 Chorista, the most posterior of its four branches, M^, divides 

 into two parts, M.^^ and Mj,^. The cross-vein connecting M^ near 

 its base with Cuj carries no macrotrichia. and must, therefore, 

 be regarded as a true cross-vein, and not a branchlet from Cu^ . 

 Hence there is no evidence for the existence of the two branches 

 of Cuj, which I have called Cuj^ and Cun,, and which are to be 

 found in the most archaic Lepidoptera and in the Planipennia, 

 but not in the Trichoptera. 



The Cubitus (Cu) is two-branched, as in Trichoptera. The 

 anterior branch, Cuj, arches upwards to connect with M, and 

 then continues the line of M to the wing-margin as a strong, 

 convex vein. The posterior branch, Cua, in the forewing, simply 

 continues the line of the main stem of Cu. In the hindwing, 

 however, it fuses for some distance with lA, and then separates 

 from it, and runs beneath Cu, to the wing-margin, at about half- 

 way along the wing. 



Three Anal Veins are developed in each wing. These remain 



