60 FOSSIL INSECTS OF THE BRITISH COAL MEASURES. 



to be beyond the mark in estimating the total span of the insect as about !:><> mm.. 

 or over 5 inches. 



The outer or costal margin is straight, or feebly convex at most, over the greater 

 part of its length, curving distally into the wing-apex. Close to the base it swells 

 out into a slight hump-like elevation which is seen in all cases where the wing has 

 been broken off close to the body. The whole of the outer margin bears a dense series 

 of minute, conical, sharply pointed spinules of a black colour. These are arranged 

 in two rows on the proximal half, with the points of the spinules directed towards 

 the wing-apex. The bases of the spinules are expanded, and give a doubly corded 

 or monilated appearance to the wing-margin. Tillyard regards these spinules as 

 modifications of large hairs which lie has termed " macrotrichia," and I see no 

 reason to dissent from his view. 



The subcosta at its origin is widely spaced from the outer margin, and passes 

 out beyond the middle of the wing, gradually approaching, but failing to reach it. 

 The subcosta is a strong, straight vein, the greater part elevated above the level 

 of the wing-membrane, and distally flattening into it and disappearing. 



The radius is a strong vein, more convex than the outer or costal margin, and 

 therefore more widely separated from it at either end than in the middle. The 

 basal portion is parallel with the subcosta for the whole length of the latter; it 

 then becomes parallel with the outer margin for a short- distance, and afterwards 

 curves into the wing-apex. A single row of spinules can be distinguished along 

 the whole vein in some specimens, and gives a slight monilation to the vein-surface. 

 The radial sector is well marked, and comes off from the radius about the point of 

 origin of the first forward branch of the median. The two veins are close together 

 for some distance, but in the distal half of the wing they become parallel, the 

 interspace being equal in width to that between the radius and the outer margin. 

 The radial sector gives off four inward branches, which end on the inner side of 

 the wing-apex. The first branch arises just beyond the middle of the wing, at 

 an acute angle, and is separated from the second by an interval which is double 

 the length of that separating the second and third. The fourth branch is verv 

 short, and so close to the margin as to be absent in some specimens. 



The median vein for the first quarter of its course lies in the middle line of the 

 wing, and then bends inwards in a wide curve to the distal third of the inner 

 margin. It gives off two outward brunches, both of which are larger and stronger 

 than those of the radial sector. Itotli brunches have the' same sweeping curve 

 possessed by the branches of the radial sector, and are parallel \\itli the latter, 

 while the main stem becomes almost straight. 



The ciibitus is a single vein, not united at the base to the median, and passing 

 obliquelv to the margin. Some wings have broken oil so lur out from llie base 

 that the ciibifus appears lo join the wing-margin at the junction of the middle and 

 distal thirds. A striking feature of (he cubitus is iis isolated position upon the 



