PTERONIDIID^E. 29 



straight to the wing-tip, parallel with the outer margin, and not far removed from 

 it. Basally it appears to be united to the radius. 



The radius gives off the radial sector at about 10 mm. from its base, and then 

 passes out to the wing-tip, at no point being more than 10 mm. from the subcosta. 

 The radial sector diverges widely from the radius, the two enclosing along, narrow 

 triangular area. At 50 mm. beyond its origin it divides into. two equal branches, 

 which diverge to a distance of 3 mm. and then become parallel. The direction of 

 the branches of the radial sector is such that they must have ended on the inner 

 half of the wing-apex, the outer branch probably forking again before the wing- 

 apex was reached. The median vein consists of two branches, the common origin 

 of which is not shown, owing to the absence of the base of the wing. To the 

 middle of the wing the two branches are parallel, and both pass beyond this 

 point before branching. The outer branch attains a length of 66 mm. before 

 branching, and then gives off four branches on its outer side, the last arising close 

 to the margin. 



The second of the four branches bifurcates. The inner branch of the median 

 gives off one forward branch only, which forks into a feeble twig dying out in the 

 polygonal meshwork, and into a stronger division which reaches the margin. The 

 two branches of the median are united at the base of the wing by an oblique 

 commissural vein which comes off at an acute angle from the outer branch, and 

 passes obliquely to the inner branch. 



The basal portion of the cubitus has been lost, so that its branching is not 

 readily determinable. The main vein seems to have divided near the base into 

 two equal branches, which curve down to the inner wing-margin, bifurcating 

 twice in each case before the margin is reached. The eight marginal twigs of the 

 cubitus thus produced enclose the middle third of the inner margin. The anal 

 area is wholly destroyed on the wing, and only a trace of one vein can be distin- 

 guished on the counterpart. This is a narrow deeply-sunk vein which gives off 

 feeble off-shoots on both sides. It diminishes in strength, so that the last portion 

 of its course can only be determined with difficulty. The anal area is comparatively 

 narrow and small, and exhibits few veins. 



Family PTERONIDIID.E, Bolton (emend. Cockerell). 

 1912. Bolton, Quart, Journ. G-eol. Soc., vol. Ixviii, p. 314. 



Wings long and narrow. Outer margin arcuate. Median and cubitus with 

 divergent branches. 



The attempt to classify these wings is difficult. That they possess affinities 

 with the genus Polycreagra is certain, but they are more simple and more 

 Dictyoneurid in type. As Dr. Handlirsch observes, it is not possible to refer them 

 to the family Polycreagridge, and they must be taken as the type of a new family. 



