LITHOSIALIS BRONGNIARTI. 47 



Description. The left fore-wing measures 61 mm. long and 18 mm. wide 

 across the distal third. The apex, the inner margin and a very small portion 

 of the base are missing. The wing appears to have been strap-shaped, with a 

 blunt apex, the inner margin curving most into the apex. 



The outer margin is feeble, almost straight over the greater part of its length, 

 and slightly sloped backwards. B.isally it dips abruptly inwards to the point 

 of attachment. The subcosta is widely spaced from the outer or costal margin 

 proximally. the two gradually approaching each other until they meet at the 

 wing-apex. The radius passes straight out to the apex, giving off the radial sector 

 before the middle of the wing is reached ; the radial sector remains undivided up 

 to the distal third of the wing, beyond which it forks twice. The median vein 

 divides a little further out than the radial sector, forming two strongly divergent 

 branches, an outer large branch with two large forward twigs, and a small inner 

 branch which forks, the inner twig forking again. The median, therefore, ends 

 on the inner margin of the wing in six twigs. 



Fia. 10. Lithosialis brongniarti (Mantell) ; diagram of neuration of left fore-wing, natural size. 

 Coal Measures; near ' Coal brookdale, Shropshire. Mantell Collection, olim Parkinson Collection, 

 Brit. Mus. (no. 11,619). 



The cubitus divides into three branches, the first arising low down, and passing 

 in a bold sweep beyond the middle of the inner margin. The anal veins are five 

 in number, all but the first being undivided. The first anal forks near the base, 

 the outer branch forking again. 



The whole wing is covered by a numerous series of strong transverse nervures, 

 rarely branching, and usually crossing at right-angles to the main veins. A few 

 are oblique or curved. 



The "file" or "serrated vein," described at length by Swinton, and by him 

 correlated with that present in recent forms of Gryllacris, appears to be nothing 

 more than an irregular torn edge of the basal part of the wing, which is also lifted 

 up a little above the general level. The torn edge extends along the line of the 

 median vein for a short distance, and wholly lacks the symmetry and detail given 

 to it by Swinton. 



Affinities. Although, closely allied to Lithomantis carbonarius, Woodw., this 

 wing differs in the great width basally of the intercostal area, and in the straighter 

 course of the cubitus and anal veins, due to the greater length of the wing. The 

 interstitial neuration is much the same. 



