108 FOSSIL INSECTS OF THE BRITISH COAL MEASURES. 



on the other half, The hinder margin of the pronotum is still hidden in the 

 matrix, and the impressions of the nnder-surfaces of the wings would need to be 

 destroyed to expose it. 



The pronotum is semicircular in outline, so far as can be determined. The 

 inner surface is marked out into two lateral areas which join in front of, and 

 behind, the central area, the latter being hollow, probably to lodge the head of the 

 insect during life. The central hollow of the pronotum is crossed in front and 

 behind by close-set parallel wrinkles, while a suture-like crack traverses the whole 

 structure in the middle line. Posteriorly to the central hollow, the lateral halves 

 have separated and become wrinkled up against each other. 



The condition of the pronotum shows that it was convex, the central hollow of 

 the inner surface marking off an area which was more convex than the sides, and 

 separated from them by grooves which bent round and joined behind the central 

 more elevated area. The central area is thinner than the sides and infolded. 



Lying behind, and partially overhung by the hind border of the pronotum, is a 

 heart-shaped structure, irregularly indented, owing its superficial appearance to 

 the overlap of the anal areas of the wings on it. On one side of this structure 

 can be seen what appears to be part of a stout segment, having a thickened anterior 

 border, and a convex surface bearing a few low tubercles. The central indented 

 structure occupies the position of the mesonotum, and the lateral stouter segment 

 may be a part of it, or of the metanotum which has been pushed forward. 



The base of the left tegmen is in actual articulation with what I suppose to be 

 the mesonotum. As the tegmina lie with their under surface uppermost, the 

 impressions on the opposite half of the nodule are also of the same surface. 



The fragment of the left tegmen is largest, and in the best condition, but not 

 more than a third of it is present. The tissue is thickly chitinous, much more so 

 than that of the pronotum. 



The costal margin is convex, and the costal area strap-shaped and wide. Sreu 

 from the underside it appears smooth, a few diagonal wrinkles alone crossing the 

 surface. We may therefore infer that the divisions of the subcosta are weakly 

 incised on the upper surface. 



The subcostal vein is more convex in direction than the margin, the costal area 

 being widest at the base. 



The radius arises close to the subcosta, and gradually diverges from it. It 

 shows no divisions in the basal portions preserved. 



The median vein arises even closer to the radius than does the latter to the sub- 

 costa, and bends inwards in a convex curve for some distance, afterwards flattening 

 and becoming parallel with the radius. 



The cubitus arises closer to the anal furrow than to the median, but bends out- 

 wards in a bold sweep away from it, becoming almost parallel with the median. 

 It gives off three inward branches in the part preserved, the first low down near 



