236 FOSSIL INSECT WING, OHDER PARAMECOPTEKA, 



cannot be removed without serious risk of damaging the speci- 

 men. The rock has also broken away obliquely at the opposite 

 end of the wing, so that an apical portion carrying the distal 

 ends of all the branches of R and Rs is missing. Besides this, 

 Mr. Mitchell informs me that, in trying to clear the base of the 

 wing, he unfortunately broke the rock in two, transversely across 

 the middle of the wing; the two parts have, however, been care- 

 fully glued together, so that the break is barely noticeable. This 

 break is indicated by the line xy in Text-fig. 1. 



Total length of preserved portion of wing, 16 mm.; greatest 

 breadth, 5-5 mm. Approximate total length of complete wing, 

 20 mm. The impression is that of a forewing, and is the mould, 

 not the cast; this is proved by the fact that the strongly convex 

 veins R and Cuj appear as deep grooves instead of raised ridges. 

 Consequently, although the apex of the wing lies to the left in 

 the fossil, the wing itself was the right forewing. 



The venational characters have all been included in the generic 

 definition given above. Besides these, it may be added that the 

 main veins mostly show, under a good oblique light, the bases 

 of macrotrichia; but these cannot be seen on the cross-veins. 

 The membrane was evidently very thin, as usual also in Tricho- 

 ptera and many Lepidoptera, and shows the peculiar oblique 

 rucking and stretching usual in fossils of these Orders and also 

 in the Diptera. A very careful examination reveals slight traces 

 of an archedictyon in places, apparently with some rather small 

 macrotrichia upon it; but these indications are scarcely more 

 than would be seen if the mesh work were in the last stage of 

 aphantoneurism. 



In Text-fig. 1, the base of the wing is represented as cut off in 

 the conventional manner; but as a matter of fact the wing dis- 

 appears along the basal break underneath a portion of rock some 

 1| mm. higher than the level of the wing itself. 



T y p e in Mr. John Mitchell's Collection. Label, " No. 40, 

 Wing. Loc. Belmont. Coll. J. Mitchell," on back. 



Locality, Belmont Beds, Upper Coal-Measures, near New- 

 castle, N.S.W. (Upper Permian). 



