192: MESOZOIC INSKCTS OF QUEENSLAND, i., 



total length of the fragment is 30 mm., its greatest breadth 

 14 mm. It represents the mould of a right j'orewing . 



The method of determining what wing a given specimen repre- 

 sents may be briefly stated as follows. In the Panorpoid wing, 

 there are two strong and highly convex veins, viz., R and Cuj. 

 If such a wing became fossilised, and a cleavage of rock later on 

 reveals it, there should be a cast of the wing showing R and 

 Cuj as high convex ridges, and a mould showing them as concave 

 furrows. In the mould, also, all the veins will be concave 

 grooves 111 themselves; whereas, in the cast, thev will be convex 

 rods, quite apart from whether they stand high up on ridges of 

 the wing (as R and Cui do), or not. Now in 106a, R and 

 Cuj lie upon high ridges, and all the veins are convex rods: 

 hence it must be a cast; and, as the apex lies to the left, it must 

 be a left wing. In No. 120a, R and Cu^ lie at the bottom of 

 furrows, and all the veins are conclave grooves; hence it must be 

 a mould; and, as the apex lies to the left, it must have been 

 formed by a right wing turned over, so that its underside lay 

 uppermost. 



Further, the fore- and hindwings of all Panorpids, though 

 closely similar, differ in the following points : 



(1) So always extends further towards the apex in the fore- 

 wing than in the hindwing. 



(2) In the hindwing, M tends to become fused basally with 

 Cuj, but this tendency is not so much in evidence in the 

 forewing. 



(3) In the forewing, Cu, ends up on the posterior margin of the 

 wing somewhat beyond half-way. In the hindwing, it reaches 

 only about half-way, or less. 



Now, if we compare Nos.lOGa and 120^, we see at once that 

 Sc ends up much further from the apex in 106« than it does in 

 120a. Further, although only a small remnant of Cuj is left in 

 No. 120a, yet the slant of this vein to the wing-axis is measur- 

 ably less than in 106a. The measurements, carefully deter 

 mined, give an angle of 23^ for No. 120a, 31° for No. 106a. 

 Measurements made to determine the obliquity of corresponding 

 portions of Cuj in Panorpa confusa give 22° for the forewing. 



