144 FOSSIL INSECTS OF THE BRITISH COAL MEASURES. 



robust character and sweeping curve, and gives off, on its inner side, a series of 

 twigs, which divide and separate so widely that first a double and then a treble 

 series of cellules are enclosed between them. On its distal side it intercepts five 

 branches arising from the inner border of the main stem of the anal, the enclosed 

 quadrangular areas being increasingly elongated antero-posteriorly up to the 

 eighteenth branch, the course of that branch to the margin being uninterrupted. 

 The integument in many of the quadrangular areas or cellules is marked by a 

 slight central elevation, which, under high magnification, presents the appearance 

 of a circular thickened lip, with a central depression or perforation. These 

 structures have no regularity of arrangement, but are most numerous on each side 

 of the twelfth branch of the anal. The integument within the cellules is, in some 

 instances, obliquely wrinkled. These structures appear to resemble aborted 

 spiracles. 



The inner margin of the wing is sharply sloped forwards from the broken edge 

 onwards to the point of attachment, and is well-defined and spinous along the 

 whole or the greater part of its length. The spines are low, directed distally, and 

 in character somewhat like those on the outer margin of the wing. They are not 

 so clearly shown, however, and they may not be truly marginal, as it is a matter 

 of doubt whether the integument stretches a little outside them. I incline to the 

 latter view. The ventral surface of the wing seems to be uppermost, in which 

 case the wing-fragment is the proximal portion of a right wing. 



Affinities. The general characters of the wing-fragment are those typical of 

 the genus Mi'i/mifiii'ii, and it cannot be confused with the genus I'/i r/dinjnu. It is, 

 however, unlike M. 'inmuji, in which the development of marginal spines has not 

 been recorded, and the tuberculation so characteristic of the Radstock wing is not 

 shown in that species. M. moiii/i is a wider and longer wing, and does not possess 

 the areolse seen in the quadrangular cellules of this species. 



Considered as a Meganeurid wing, the Radstock specimen is no primitive 

 structure, but highly specialised, an anal cubitns connection is present, the costal 

 border has become thickened and tuberculated, and a secondary development of 

 spinules and tuberculations has arisen. 



IXCERT^E SEDIS. 



Genus TILLYARDIA, 



Generic < 'A/owr/iT*. Wings elongated, five times as long as wide. Subcosta 

 short ; radius simple, radial sector forming an accessory vein with several divisions. 

 Median vein with 1'ew branches. Culiitus with two main branches, the inner much 



