116 FOSSIL INSECTS OF THE BRITISH COAL MEASURES. 



portion of the tegmen itself, and has the dorsal surface uppermost. Traces of 

 hind-wings are present, lying on a slightly lower plane than the tegmina, and 

 showing only the underside. 



As the two tegmina are specifically identical, the more nearly complete example 

 has been taken as the type and is here described in detail. 



The tegmen has a length of 32 mm., and, as a small part of the apex is missing, 

 its total length must have been about 35 mm. The width is uniform over the 

 basal half of the wing, and averages 11*5 mm. 



The costal margin forms a strong convex curve, in this respect contrasting with 

 the inner margin, which is nearly straight. The wing-apex is directed backwards 

 owing to the great convexity of the costal margin. The whole wing has a broad 

 semilunate appearance. 



The subcosta is a feeble vein, not easily discernible; its outwardly -directed 

 twigs pass out obliquely, and are twice or thrice forked. Like the main stem, they 

 are faintly impressed, and cannot be traced up to the costal margin. Eight twigs 

 can be determined. The subcostal area is strap-shaped, and extends beyond the 

 middle of the wing. 



Fig. 37. — Phyloblatta transversalis, Bolton; diagram of venation of left fore-wing of type-specimen, 

 twice natural size.— Middle Coal Measures ; Staffordshire. Geol. Mus. Univ. Birmingham. 



The radius is a strong vein, and shows an inner sub-division which has all the 

 characters of a radial sector. Basally, it seems joined to the median, but it is an 

 apparent junction only, the wing-base being pressed in upon itself, and bringing 

 the two close to one another. After giving off the inner (radial sector) branch, 

 the radius <;ives off five outer branches which reach the distal third of the outer 

 margin. The first of these branches seems to break up into three twigs, but the 

 structure of the Aving is not clear at this point. The radial sector, which arises m 

 the basal half of the wing, forks at the distal third into two equal branches, the 

 outer forking twice into four divisions, and the inner forking once. The radius 

 and radial sector occupy the whole of the outer half of the wing-apex. 



The median vein diverges from the radius along its whole course, and reaches 

 the distal end of the inner margin, giving off three outer branches in the distal 

 half of the wing. These pass straight to the apex, the first forking twice, and 

 the second once, the third remaining undivided to the broken edge of the wing. 

 The branches of the median occupy the whole of the inner half of the wing- 

 apex. 



