104 FOSSIL INSECTS OF THE BRITISH f'OAL A 



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

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

 aliiinst straight. 



[)excription. A portion ot the base of the wing and a considerable part of the 

 apical and inner margin are missing, lint the length preserved is :'>:'>) nnn. and its 

 breadth is 1 <K> nun. 



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

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



and radial areas, causing the anterior margin tc 



reflexed dorsallv. 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. 



ffl 



FIG. 3M. ArcMmylacris hmstntn. I!<.lt<>n; diagram of venation of left fore-wing, tlirfe times natural 

 size. --Upper Coal Measures (Grellideg Level of the M\iiy<l<lislwyn Vein); near Maes'-y-cwmmer, 

 Monmouthshire. Mus. Praet. Gool. (nos. 2-J.50], 24502). Lettering of veins. I. costa ; II. sub- 

 eosta ; 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. Tt gives off 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 

 distal ly. 



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

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

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

 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 subeosta and radius toget her occupv a little less than hall I he \\ hole wing- 

 area. Dr. I'rnvost supposes that a comnussiiral branch unites the radial sector 

 and the median in this species (l'.H'.>. 'Alcmoires pour servir a 1'Bxplication de la 

 Carle (ieologique Detaillee de la I'Yance.' p. 1-M), but I cannot perceive this. 



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



