198 MESOZOIC INSKCTS OF QUEENSLAND, i., 



panorpa divides into Rsa and Rsb, and each of these again 

 divides* before reaching the wing-border. 



(4) The area enclosed between R4 and R 5 would be, in Tri- 

 choptera, the second apical fork (Af.2 in Text-figs. 2-4). In 

 Mecoptera, this area is often subdivided by a cross- vein (Text- 

 fig. 6). In Archipanorpa, both R4 and Rg divide into two again 

 before reaching the wing-border. Thus Rs, wliich in Trichoptera 

 sends four veins to the apical wing-border, and in Mecoptera 

 five, sends no less than nine such veins to the border in the 

 hindwing of Archipanorpa, eight in the forewing. 



(5) Turning next to the media (M), we see that the thyridium 

 (t), or median fork, is clearly preserved in both wings, lying just 

 below the first forking of Rs. As this is its position also in the 

 two Trichopterous wings already dealt with, we are probably 

 right in assuming that it is the archaic condition, and that a 

 shifting of the thyridium to a level distad from the level of the 

 first forking of the radius (as in Panorpa, Text-fig. 7; and in 

 many recent Gaddis-flies) is a caenogenetic character. The cell 

 below t is the thyridial cell (tc), and is only partially preserved 

 in both wings. At t, M forks into M^+o above and M3+4 below, 

 and the two branches enclose between them the median cell (mc). 

 Ml +2 then divides into Mj and Mo, and M.-^^^ into M3 and M4; 

 and the forks thus made are sessile upon mc, as in the two fossil 

 Trichopterous wings already studied, and in recent Mecoptera 

 (Text-tig.7). 



(6) The area enclosed between Mj and M.^ would be, in all Tri. 

 choptera and true Mecoptera, the third apical fork (Af.3, in 

 Text-figs. 2-4). In Archipa^iorpa, both Mj and Mo fork again; 

 in the hindwing, the two middle branches fuse together, so that 

 only three separate veins reach the wing-border, instead of four 

 as in the forewing. This difference offsets the difference in the 

 behaviour of Ro in the two wings (see above), and makes the 

 total number of apical end- veins the same in both wings (viz., 

 seventeen between R and CuJ. 



(7) The area enclosed between M.^ and M^ would be, in all 

 Trichoptera and true Mecoptera, the fourth apical fork (Af.4 

 in Text-tigs. 2-4). The archaic condition of this fork is that it is 



* In the hindwing; in the forewing, only the lower fork divides. 



