104 FOSSIL INSECTS OF THE BRITISH COAL MEASURES. 



apex of wing. Median branching further out than the radius. Cubitus 

 reaching margin in distal third of wing. Anal veins numerous. Inner margin 

 almost straight. 



Description. — A portion of the base of the wing and a considerable part of the* 

 apical and inner margin are missing, but the length preserved is 33"4 mm. and its 

 breadth is 16*5 mm. 



The wing is strongly outlined, especially along the outer margin, partly owing 

 to a broad concave depression which runs almost the whole length of the subcostal 

 and radial areas, causing the anterior margin to be reflexed dorsally. The inner 

 margin is preserved only along a portion of the anal border, and the inner two- 

 thirds of the wing-apex are also missing. Sufficient is left of the apex to show 

 that it must have been bluntly rounded. 



n 



I?\-' 



Fig. 33. — Archimylacris hastata, Bolton; diagram of venation of left fore-wing-, three times natural 

 size.— Upper Coal Measures (Gellideg Level of the Mynyddislwyn Vein) ; near Maes-y-cwmmer, 

 Monmouthshire. Mus. Pract. Geol. (nos. 24501, 24502). Lettering of veins. — I. costa : II. sub- 

 costa; III. radius; IV. median; V. cubitus: VI. anal. 



The subcostal vein passes out obliquely from the point of attachment and 

 reaches into the distal third of the wing. It gives off 9 — 10 very oblique branches, 

 the basal three forking twice, the next two undivided, and the last branch but one 

 forked. The subcostal area is broad basally, and terminates in an acute angle 

 distally. 



The actual origin of the principal veins is lost, and the radius appears at its 

 origin therefore to be widely removed from the subcosta. It follows a parallel 

 course to the origin of the first anterior branch, and afterwards diverges, so that 

 it finally ends on the apex of the wing near the middle line. The first branch is 

 important, forking three times in its course and ending in six divisions. The 

 second branch forks only once. 



The subcosta and radius together occupy a little less than half the whole wing- 

 area. Dr. Pruvost supposes that a commissural branch unites the radial sector 

 and the median in this species (1919, ' Memoires pour servir a l'Explication de la 

 Carte Geologique Detaillee cle la France,' p. 151), but I cannot perceive this. 



The median vein arises in actual contact with the stem of the radius, or is 



