110 FOSSIL INSECTS OF THE BRITISH COAL MEASURES. 



subacute apex. Costal area narrow and strap-shaped. Subcosta extending just 

 beyond the middle of the wing. Radius large, much divided, and occupying the 

 distal portion of the outer margin, and the outer half of the apical margin and 

 apex. Median a small vein with few divisions ending on the inner apical margin. 

 Cubitus occupying the whole of the inner margin beyond the anal veins. Surface 

 covered with a close series of oblique wrinkles. 



Description. — When I first described this specimen in 1911, I was of opinion 

 that the length of the complete wing was not more than 25 mm. With a larger 

 knowledge of the structure and form of the Blattoid tegmen I should now 

 estimate the length at nearer 35 mm., the complete structure being a little over 

 two-and-a-half times as long as broad. 



The costal border is broadly convex, more so in the distal than in the proximal 

 half. 



The subcostal area is narrow, the subcosta being a delicate vein, sending a 

 number of forked and simple branches obliquely to the costal margin. Probably 

 half of the subcosta is missing, though three branches of it are present. One 



Fig. 35. — Arehimylacris (Schizoblcttto) obovata, Bolton ; diagram of venation of left fore wing, three 

 times natural size. — Upper Coal Measures (Gwernau Level of the Mynyddislwyn Vein) ; Maes-y- 

 cwmmer, Monmouthshire. Mus. Pract. G-eol. (nos. 24506, 24507). Numbering of veins as in 

 Text-figure 33, p. 104. 



remains single, the next gives off a simple basal twig, and forks just before 

 reaching the margin, while the outer branch is undivided. 



The radius is much the largest of the principal veins, and is widely separated 

 from the subcosta over the middle portion of its length. Before reaching the 

 middle of the wing it divides into two diverging branches, each of which forks, 

 and afterwards gives off a series of smaller veins, eleven in number, which occupy 

 the distal outer margin, and the outer half of the wing-apex. 



The median vein is not complete, and seems to consist of a main stem, giving 

 off a long branch in the basal third of the wing, a second branch in the middle, 

 and a final branch in the outer third. The first branch only divides, so that the 

 median ends on the inner apical margin in five divisions. 



The remaining marginal veins are probably wholly cubital. They are five in 

 number, one only forking. 



