PRUVOSTIA SPEOTABILIS. 49 



by a film of ironstone winch cannot be removed. Fortunately the slight film of 



ironstone does not hide the outline of the wing, and it is evident that the outer and 



inner wing-margins are almost parallel, while the apex is well rounded. The outer 



margin merges by a well-rounded contour into the wing-apex. The subcosta is 



well-marked, widely removed from the outer border proximally, and lies in a shallow 



groove formed of the intercostal and radial subcostal areas. These two areas are 



reduced distally to less than half their proximal diameter owing to the backward 



inclination of the outer margin. The subcosta seems to die out near the radius, 



about 7 mm. from the wing-apex, and gives off a numerous series of irregularly 



spaced and forwardly directed nervures, which are at first straight and then curved 



towards the wing-apex. At their point of origin the cross-nervures are very 



distinct, but they thin, and occasionally die out, before reaching the outer margin. 



The radius is a strong vein, passing perfectly straight out from the wing-base to 



the outer part of the wing-apex. The radial sector arises near the base of the 



radius, gradually diverging from it up to the junction of the middle and outer 



thirds, where a single branch is given off, the latter taking a position parallel with 



the main stem of the radial sector, and entering the middle of the wing-apex. 



Eleven mm. further out and within 7 mm. of the apex a second branch is 



given off, which lies evenly between the main stem and the first branch. The 



median vein arises so close to the radius as to appear united with it. Like the 



radial sector, it does not divide until it reaches the junction of the middle and outer 



thirds of the wing. Here the first inward branch arises, and at equal distances 



further out are given off two more ; the first two each fork in the middle of their 



length, the third remaining undivided ; the median ends therefore on the inner 



wing-margin in six divisions. The cubitus consists of two, and possibly three, 



main stems. Owing to the base of the wing being broken away these stems are 



not seen to be in actual union. Little doubt can exist as to the union of the first 



two, but if the third vein is a branch of the cubitus, it can only join the other two 



by a strong outward curvature. This third vein may be the first anal, although its 



manner of division is similar to that of the cubitus, in this respect agreeing with 



what is seen in the first anal of Lithosialis brongniarti. The next vein is parallel 



with the one succeeding, which is undoubtedly anal, while it shows an increasing 



basal divergence from the second cubital. For this reason I have regarded the 



third vein as the first anal. The first branch of the cubitus diverges widely from 



the median, passing obliquely to the inner margin of the wing, which is reached 



just beyond the middle third. Owing to the great divergence of the first cubital 



branch from the median, the area between the two, at the point where they first 



branch, is very wide — almost twice the width of any other area. 



The first cubital vein gives off three outward twigs. The second is parallel 

 to the first as far as its division into two equal twigs. The next vein is that to 

 which I have already alluded as a possible third branch. It is widely separated 

 7 



