98 FOSSIL INSECT'S OF THE BRITISH COAL MEASURES. 



The pronotum lias a diameter of 13 mm., and 8 mm. of its length is exposed. 

 The sides curve evenly backwards, and show no sign of flattening, so that its 

 general shape is semicircular. The hinder border is hidden, and disposed at 

 an angle to the surface-plane of the wings. The presence of a sunken, central. 

 pyriform area on the inner surface of the pronotum probably marks the position 

 occupied by the head of the insect. The downward inclination of the front 

 margin of the pronotum, and the elevation of the hinder border, is a frequent 

 feature in the Coal Measure Blattoids. 



During life a small gap interposed between the pro- and mesonotum, and 

 this became filled up by sediment on burial in sufficient quantity to cause the 

 pronotum to be lifted from the body of the insect by that half of the nodule 

 which carries the wing-impressions. This inclined position of the pronotum is so 

 common that it appears to have been normal. 



The mesonotal area is covered by the anal areas of the tegmina, and its 

 character cannot be determined. 



The venation of the right tegmen differs considerably from that of the left. 

 The under surface of the latter is the more nearly perfect, and the venation is more 

 distinct. The costal margins of the tegmina form two broad arcs, sharply bent 

 inwards at the base, and distally merging into the wing-apex. The left subcosta 

 is widely separated from the margin, giving off three oblique branches which 

 fork, the first twice, before reaching the margin. Bej^ond these branches, 

 the left costa curves inwards and unites with the main stem of the radius at the 

 distal third of the wing. The right costa is more normal, and does not unite with 

 the radius. It gives off six outward branches, of which only the first is forked. 



The left radius, after a slight basal curve, passes straight out to the apex, 

 giving off four forward branches, the first forketl. This first forked branch 

 appears to be the continuation of the subcosta. The radius of the right tegmen 

 gives off two simple outer branches only. 



There is a wide difference between the radial sectors of the two teg-mina. 

 That of the left divides in the middle of its length into two equal branches, which 

 in turn fork, the outermost twig forking again, so that the radial sector ends on 

 the margin in five divisions. The right radial sector forks once only beyond the 

 middle of its length, and ends on the margin in only two divisions. 



The median in each tegmen is a comparatively simple vein, that of the left 

 being united with the cubitus in the basal fourth, and separating from it at an 

 acute angle. Beyond the middle of tin' wing it gives off a single forked branch 

 on its outer side. These divisions of the median, with the first branch of the 

 radial sector, occupy the inner half of the apex. The median of the right tegmen 

 is well separated from the cubitus along its whole length, and passes in a bold 

 curve to the inner half of the apex, giving off four simple outer branches. 



Apart from its union with the stem of the median, the cubitus of the left 



