COSBLIA PALMIFORMIS. 83 



of the intercostal area has l)een already described ; that between the subcosta 

 and radius, between the radius and radial sector, and between the radial sector 

 and the median, consists of a few irregular cross-nervures, one or two of which 

 unite. In the median -cubital area the cross-nervures are joined up by longitudinal 

 branches following a zig-zag course. A similar neuration is seen between the 

 inner branches of the cubitus, while the anal area is crossed by irregular 

 cross-nervures occasionally uniting, as in the fore-part of the wing. 



Affinities. — The general characters agree most closely with those of the 

 Cacurgidae, a family of insects which Handlirsch has described from ironstone 

 nodules found in and around Mazon Creek, Illinois, U.S.A. It comprises insects 

 which possess well-marked characters, but which, as a whole, Handlirsch is 

 unable to assign with certainty to the Protorthoptera, or to the Protoblattoidea 

 (Handlirsch, 'Amer. Journ. Sci.' [4], vol. xxxi, 1911, p. 323). 



The wing of Cacurgus spilopterus, Handlirsch, has the same wide costal area'; 

 the radial sector arises far out, and the median gives off a commissural vein 

 to the cubitus. The central portions of the median and cubital areas are also 

 very wide, and the anal veins have the same strong inward curve. 



The interstitial neuration is much similar, but the formation of a meshwork 

 has not proceeded so far in the British specimen as in Cacurgus spilopterus, where 

 it is present between all the main veins, except the costal and subcostal. In the 

 British specimen the meshwork is chiefly developed in the median and cubital 

 areas. Areolae are present in the wings of both species 



The differences between the wings of the two species are, hoAvever, important. 

 In Cacurgus spilopterus, the first branch of the median does not unite with the 

 radial sector, nor does it approach it very closel}-, whereas in the British wing, 

 the first outer branch must have united with the radial sector. The median 

 also branches again further out, the median in C. spilopterus having one outer 

 branch only. Lithosialis brong?iiarti (Mantell) shows less affinity to the wing, 

 but possesses the wide costal area, the same irregular and ramified interstitial 

 neuration, but a more complex median and simpler cubitus. The commissural 

 vein is also wanting. 



One other form with which a comparison needs to be made is Omalia 

 macroptera, Van Beneden and Coemans. This species was obtained from the 

 Westphalian (Middle Upper Coal Measures) of Hainault, Belgium. In its wing 

 the costal area is wide, and crossed by oblique branches from the subcosta; the 

 median sends an outer branch to join the radial sector, but there is no union 

 of the median and cubitus. The interstitial neuration is not mesh-like. 



These wings are so similar that there seems no doubt they are closely 

 related, but the relationship of the British specimen is closest with the genus 

 Cacurgus. 



