SCAL^OPTERA RECTA. 89 



than half that separating the subcosta and the margin. It lies also on a ridge 

 which increases in strength distally. The radius and snbcosta are parallel. The 

 actual point of origin of the radial sector is not shown, but can be determined 

 within narrow limits. It arises almost in the basal fourth of the wing, and so far 

 as its course can be traced, diverges from the radius. 



The median diverges along its whole course from the radius, and gives off 

 on its outer side two branches, which remain undivided to the broken edge of 

 the nodule. The first branch arises in line with the origin of the radial sector, 

 and at an acute angle which soon enlarges, so that the interval separating it from 

 the radial sector is less than half that separating them at their origin. 



The cubitus divides into two nearly equal branches very low down in the base 

 of the wing, the second branch sending off a short division against the broken 

 edge of the nodule. 



The stem of the median, and the two branches of the cubitus, have a parallel 

 course, like the outer margin, subcosta and radius, the widening interval between 

 the two groups of veins being occupied by the radial sector, and the two outer 

 branches of the median. The direction of the subcosta, radius, radial sector, and 

 first branch of the median, indicates that they traversed almost the whole length 

 of the wing and ended on the wing-apex. The main stem of the median and 

 the branches of the cubitus would reach the distal half of the inner margin. 

 There are no traces of anal veins. 



Affinities. The extreme width of the intercostal area, the marked divergence 

 of the costa, subcosta and radius from the median and cubitus, are features not 

 readily recognisable among other known fossil insects. The few widely-spaced 

 cross-nervures are not wholly peculiar to the specimen. Similarly, the spinulose 

 principal veins are paralleled by those of Brodia priscotincta and Archxoptihis 

 ingens. I have not seen so marked a coriaceous texture in any British fossil 

 insect. The length of the wing-fragment before branching of the principal veins 

 occurs, implies a long and relatively narrow wing. Such a wing-form is seen in 

 the Pala?odictyoptera and in the Protorthoptera. The wing differs from that of 

 Brodia priscotincta in its much greater size, in the presence of a well-developed 

 series of cross-nervures, and in the coriaceous surface of the wing-membrane. 

 The direction of the radial sector and the divisions of the median vein are unlike 

 those in Brodia, where these veins curve steadily from their points of origin 

 inwards to the wing-margin. 



Two groups of insects described by Handlirsch ('Amer. Journ. Sci.' [4], 

 vol. xxxi, 1911), from the Pennsylvanian Series of the Carboniferous of Mazon 

 Creek, 111., under the family names of Spanioderida3 and Geraridae, appear to 

 resemble most nearly the wings we are considering. The wings in these families 

 are long and narrow, and obtusely rounded at the apex, and the principal veins, 

 especially in the Spanioderidse, pass straight out for the whole, or the greater 

 12 



