BRODIA PBISCOTINCTA. 61 



margin, for while the interval between it and the stem of the median is much 

 wider than any other in the fore-part of the wing, the interval between the cubitus 

 and the next vein is nearly twice as wide. There is, in fact, a progressive 

 widening between the veins as they are traced from the apex to the base of the 

 Aving, the areas between the median and its branches being wider than those 

 enclosed by the branches of the radial sector. 



Two somewhat dissimilar anal veins are present. The first has a wide curve 

 to a point far out on the margin, sometimes giving off a short branch, while the 

 second vein is much shorter and joins the margin at an acute angle. In some 

 specimens this vein is seen to give off two, or even three, short oblique branches. 



The shape of the wings is very similar to that of the wings of mosquitoes 

 (Anopheles), and they bear evidence of having been folded in a plicate or fan-like 

 fashion along their length. The first two folds are united at the wing-base, and 

 pass out along the radius and the first outward branch of the median. The third 

 fold lies along the line of the cubitus vein. The degree of plication which a wing 

 retained when silted up modifies considerably the apparent distance between the 

 several veins and their branches, and at times hides important junctions. In one 

 example (Brit. Mus., no. In. 184ol) the wing was well flattened out before being 

 buried, and the origin of the veins and their true position can now easily be 

 determined. This specimen shows that the radial sector arises much nearer the 

 wing-base than the first outward branch of the median — a feature not usually 

 shown in the remaining specimens. 



The general build of the wing is such that the bases of the costal and subcostal 

 veins on the outer margin, and those of the anal veins on the inner, must have 

 served as the main support to the distal two-thirds of the wing, the latter consisting 

 mainly of the radial sector and its branches, the median, and the distal half of the 

 cubitus. Flight must have been mainly maintained by the action of this more 

 distal expanded area, while the strain of movement would fall across the narrow 

 neck-like base of the wing, and may ultimately have led to fracture and the loss of 

 the wings. It is quite possible, also, that these insects were capable of finding 

 food among the decaying vegetation of the coal forests, and thus prolonging life 

 for a considerable period after the wings were lost. Such a presumptive sequence 

 of events would account for the total absence of any trace of the bodies or legs, 

 although the wings of this species are more numerous than any others in the Coal 

 Measures and preserved in good condition. 



Colour Bands. — Scudder mentions this species as the most striking instance 

 among Palasozoic insects of the preservation of " colour bands," and as he states, 

 some wings show three broad irregular belts of dull umber-brown colour across 

 the wings. Close examination of these " colour bands " in the type-specimen, and 

 in other examples, leads us to doubt the correctness of his view. In all cases 

 where the " colour bands " do not show on the wings, the areas appear to be 



