BY R. J. TILLYARD. 



429 



hindwino-, are clearly interestino- attempts to strengthen the wino- 

 in the region of greatest curvature of the main veins. 



Beyond the level of the origin of Rs, the ci-oss-veiiis liecome 

 weaker, and are ditHciilt to make out. In the figure in Plate 

 xliv., I have indicated every possible cross-vein of which I can 

 find traces, by examination in lights of different directions and 

 intensities. 8ome of these may not be true cross-veins, while 

 tliere may be others present whicli I have missed. 



Text -fig. 1.-). 

 Ai'/'oplana nv!rahilis, n.g. et sp., (Triassic, Ipswich, Q.). Distal portion of 

 forewing beyond the transverse fracture of the rock shown in Text-fig. 



The preserved part of the forewing is very similar to the hind, 

 except for the different manner of branching of the media, 

 which has been already mentioned. Careful measurements of 

 corresponding portions of fore- and hindwings show that theii- 

 widtlis are almost the same, the forewing being slightly wider 

 than the hind, as judged by the perpendicular distance between 

 Rs and Cuj. But this may have been offset by a somewhat wider 

 anal area in the hindwing. 



The isolated distal portion of the forewing is shown in Text- 

 fig. 15. The main veins are well-preserved, yet there are few 

 indications of cross-veins. It seems probable that the cross-veins 

 became weaker and weaker towards the distal end of the win^- 

 and finally became obsolescent near the tip, so that most of them 

 are not preserved in the fossil. It will be seen that there are 



