MECYNOPTERA TITBERCULATA. 39 



sented by two undivided elements which are directed obliquely to the margin. 

 The inner margin of the wing is more curved than the outer, and merges into the 

 apex. The interstitial nenration is remarkable. Between the costa, snbcosta and 

 radius it consists of short stout nervures crossing the areas somewhat obliquely, 

 and in some cases arranged in V-shape. The area between the radius and radial 

 sector is crossed by a numerous S-shaped series of nervures, which are joined up 

 into a meshwork in the outer or radial half of the area. The area itself is very 

 wide, and only equalled by that separating the two branches of the median. 



The radial sector and the median occupy the greater part of the wing- 

 surface. 



The remaining areas are crossed by transverse nervures near the junction of 

 branches with the principal veins, and further out by nervures which are joined up 

 by zig-zag longitudinal branches which occasionally enclose polygonal cells. The 

 interstitial nenration is very well developed, and must have added materially to 

 the strength of the win<> - s. 



to to 



Affinities. — The close approximation of the costa, snbcosta and radius, and the 

 coriaceous thickening and tuberculations of the principal veins, are characters 

 which may rank as of generic importance. Less distinctive, but also characteristic, 

 is the interstitial nenration of the transverse nervures and meshwork, with its 

 minute monilation. 



The characters of the genus Mecynoptera are in closest agreement with those 

 of this insect. There is the same approximation of the costa, snbcosta and radius, 

 the radial sector is widely spaced from the latter, and the interstitial nenration 

 consists of transverse nervures near the junctions of the principal veins and their 

 branches, and of a meshwork further out. The general outline of the wing is also 

 the same. 



M. splendida, Handlirsch, throws light on one point which had proved a 

 difficulty in the determination of the wings. It has the radial sector of large 

 size and much branched, the divisions occupying all the inner half of the apex of 

 the wing, and extending out on the inner margin into the area usually occupied by 

 the outer branches of the median. Prior to noting this feature in M. splendida, 

 I had formed the opinion that the first division of the radial sector was the median, 

 which had united with the radial sector and the radius. 



The broken condition of the Rochdale wings prevents absolute determination 

 of this point, but by analogy I conclude that the whole vein which branches off 

 from the radius basally is the radial sector, and the next vein the median. This 

 conclusion also removes the insect from the neighbourhood of ^Enigmatodes danielsi,, 

 Handlirsch, a wing discovered in the Coal Measures of Mazon Creek, near Morris, 

 Illinois, U.S.A., which possesses the same character of interstitial nenration, but 

 with the divisions of the median vein stretching out to the wing-apex, and the 

 costa, snbcosta and radius more widely separated. 



