HYPERMEGETHES NORTHUMBRLE. 33 



5 in., and the whole insect a span of wing of nearly 11 in. The wing-fragment 

 shows the basal portions of the costa, subcosta, radius, radial sector, median, and 

 cubitus, and possibly a trace of an anal vein. 



Much of the finer detail of the wing is not seen until the fossil is immersed in 

 water — a mode of treatment suggested to me by Dr. F. A. Bather, F.R.S., who had 

 previously photographed the wing in this manner, and brought out details of 

 which, by ordinary methods, I could not find a trace. 



The costa is moderately convex from its base to a distance of about 30 mm., 

 beyond which it becomes straight. Separated from the outer or costal border by 

 a wide area basally is the subcosta, an extremely feeble and hardly distinguishable 

 vein. It passes straight to the outer margin some distance beyond the middle of 

 the wing. The radius arises close to the subcosta, and is parallel with it. It gives 

 off two branches posteriorly, the proximal branch passing obliquely towards the 

 inner side of the wing-apex, while the second or distal branch arises from the 

 radius a little further out, and keeps parallel with it. 



T had formerly considered the proximal branch of the radius to be the radial 

 sector, and the distal a branch of the radius ; but as the interstitial neuration now 

 shows the specimen to be closely related to Hypermegethes schucherti, the proximal 

 branching vein must be regarded as the main stem of the median which has entered 

 into union with the radius, and the distal branch as the radial sector. 



Regarding the proximal offshoot of the radius as the median vein, it diverges 

 widely from the radius, giving off a forward twig parallel with the radial sector, 

 and then continues inwards and unites with the next vein, separating again a little 

 further out on the inner side. A comparison of this assumed median vein with 

 that of H. schucherti, Handl., is instructive. In the latter species the branching 

 of the main stem of the median arises nearer the base of the wing than does the 

 branching off of the radial sector. It is therefore somewhat in the position of 

 the starting-point of the median vein as a free structure in the present wing. The 

 median vein of 11. schucherti, Handl., has, however, no union with the radius, the 

 main stem running out towards the wing-apex parallel with the inner branch of 

 the radius, giving off a backward branch of the cubitus, which passes obliquely 

 inwards and unites with the anterior branch. In the middle of its length it gives 

 origin to a twig running parallel with the main stem, and midway between 

 that vein and the cubitus. The course of the median vein in the specimen 

 here described is exactly similar to that of the branch of the median vein in 

 77. schucherti, Handl., except that the inner branch not only unites with the 

 cubitus, but crosses it. 



The condition may be summarised by saying that, in II. schucherti, Handl., the 



median vein is entirely free and gives off an inner branch dividing into two twigs, 



of which the inner unites with the cubitus. In the specimen here described the 



median is united with the radius for some little distance, becoming free before the 



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