38 FOSSIL INSECTS OF THE BRITISH COAL MEASURES. 



When complete, the wings must have had a length of <>o — 70 mm. They were 

 originally identified with those of Stenodictya lobata, Brongniart, and are quoted as 

 such in the faunal lists of the Sparth Bottoms deposits, but with no detailed 

 description or figures. 



When the specimens were first examined they presented an apparently anoma- 

 lous union or suppression of certain of the principal veins. Careful development 

 has since shown that what was formerly considered to be the onter or costal 

 margin of the wings was really the thickened and tuberculated radius vein, and 

 that the outer margin, with the costa and subcosta, had been hidden under the 

 matrix. A little of the outer marginal costa and the subcosta are now uncovered, 

 and the wing-structure is therefore proved to be of a normal type. 



The three wings in the larger, more nearly complete specimen are superposed 



and fragmentary. The uppermost fore-wing is represented by two portions, one 



having a little of the outer or costal margin, the subcosta, and the greater part of 



the radius and radial sector. The second part consists of the median, and a 



portion of the cubitus. The second fragment is displaced backwards, allowing 



the radius and radial sector of the second fore-wine: to be seen. The median- 

 ts 



cubital area of the hind-wing is very thin and closely pressed on the rest, but the 

 course of the veins is clearly discernible, and by their sharp inward turn indicates 

 that the hind-wings were much broader than the fore-wings. 



Although the wings are thus broken up, displaced, and superposed, the parts 

 missing in the one wing are present in the other, and it is possible to reconstruct 

 their general character. The outer margin is almost straight, gently rounded into 

 the base, and into the wing-apex. The subcosta is weak, and lies in a deep sulcus, 

 extending into the apex of the wing. The radius is a little elevated, thickened, 

 tuberculated in the basal third, and in close proximity to the subcostal vein. The 

 radius is a strong vein, raised above the level of the rest of the outer margin of 

 the wing, so that when the latter was hidden, it naturally appeared to be the outer 

 marginal costal vein. It is much thickened in its basal third, tuberculated, and 

 remains parallel with the subcosta in the apex of the wing. 



The wing-space taken up by these three veins is very small, and their close 

 approximation and the coriaceous thickening of the costa and radius serve to give a 

 considerable degree of strength and rigidity to the outer margin of the wing. The 

 radial sector passes straight outwards to the apex of the wing, giving off three inner 

 branches in one wing and two in the other, the first branch only forking. The first 

 branch soon forks, the outer fork dividing into two twigs, and the inner into three 

 upon the distal inner half of the wing-apex. The median is a large vein, occupying 

 the greater part of the inner half of the wing. It divides at its point of origin into 

 an outer undivided branch which traverses the middle of the wing, and an inner 

 branch which is widely separated from its fellow, and gives off three twigs to the 

 wing-margin, the first forking in the middle of its length. Cubital veins are repre- 



