Vol. 68.] THE MIDLAND AND SOrTH-EASTEEN COAL MEASUEES. 313 



other member of the Palseodictyoptera that we know of, by reason 

 of its branching and the area which it serves. 



The radial sector sends its branches outwards and not inwards, 

 in this respect showing a marked contrast to what obtains in the 

 Dictyoneuridse. Similar distinctive features mark the median vein, 

 which either divides very low down into two branches, or possesses 

 two points of origin. The commissure uniting the two is also an 

 unusual feature. The anal area is elongate-elliptical in outline, 

 crossed by one, possibly two, veins which pass obliquely forwards 

 towards the apex of the area. The undoubted and clearly dis- 

 tinguishable anal vein gives off branches alternately on either 

 side, which also run towards the inner margin, but die out in large 

 polygonal cells before reaching it. 



These large polygonal cells are more suggestive of the family 

 Hypermegethidee than of the Dictyoneuridse. The general form of 

 the wing somewhat resembles that which obtains in the Heolidae, 

 and the divergence of the cubitus is somewhat similar. Here, 

 however, the resemblance ends. The wing seems clearly to belong 

 to a new family related to the family Dictyoneuridae, and with 

 some suggestion of the family Heloidae. 



To this new family I propose to assign the name ofOrthocostidse. 



Family Orthocostidse. 



Characters. — Costal border almost straight, subcostal approach- 

 ing the costal border; radius straight, parallel, and close to the 

 subcosta ; radial sector diverging, not more than twice furcate ; 

 median divided into two branches united by a basal commissure ; 

 cubitus stout, forked near the base, the outer branch forking twice 

 and the inner branch once before reaching the inner margin ; anal 

 area oblong-elliptical ; areas between veins filled by widely-open 

 polygonal subsidiary venation. 



Genotype : OrtJiocosta. Characters as above. 



I propose the name of splendens for the species. 



The diagnostic description is as follows : — Wing two and a half 

 to three times as long as wide ; costa, subcosta, and radius closely 

 approximated and parallel. Eadial sector divergent, reaching the 

 inner half of the tip of the wing. Median dividing near the base ; 

 outer branch four or five times divided, inner branch simpler and 

 forked. Cubitus dividing low down into two main stems, the outer- 

 most being the strongest, each branch doubly forked. Anal veins 

 one or two in number, alternately branched. Venation an open 

 polygonal network. 



Horizon and locality. — 30 or 40 feet below the Top Hard 

 Coal, Middle Coal Measures, Shipley Clay-pit, Hkeston (Derbyshire). 



Pteeonidia plicatula, gen. et sp. nov. (PI. XXXII, figs. 1-3.) 



This is a long, delicate left wing, of which the inner half only 

 has been preserved. The hinder margin is straight or nearly so, and 



2a2 



