ARCHIMYLACRIS INCISA. 107 



branches which it gives off. The first two branches of the radius are forked, 

 the rest undivided. The radius with its divisions occupies the distal third of the 

 wing-margin. At the junction of the basal and middle thirds of the wing, 

 the radius gives off a strong radial sector which diverges from it, giving off two 

 outer branches, the first forking twice into four twigs. The radial sector occupies 

 the outer half of the wing-apex. 



The median curves regularly inwards along its whole course, reaching the inner 

 end of the wing-apex, and giving off three outer branches, of which the first is 

 forked. With its subdivisions it occupies a much less area than any other main 

 vein. 



The cubitus follows a course nearly parallel with the median, and gives off nine 

 inward branches. "With its subdivisions, it occupies almost the whole of the distal 

 two-thirds of the inner margin. 



The anal area is strongly convex, and crossed by at least five anal veins, the 

 third being forked. 



The interstitial neuration is well developed in the neighbourhood of the 

 subcosta, and consists of a close-set series of straight cross-nervures. These are 

 in relief, and in places seem to unite laterally, and to cross the main veins. 



Affinities. — The wing is typically Archimylacrid. At the time of its discovery 

 in 1910 I was unable to show that it possessed a close relation to any known 

 species, but more recently Dr. Pruvost has recorded a very similar example, A. 

 atrebatica, Pruv., from the Coal Measures of Bruay, Northern France. 



The presence of a well-defined radial sector is a Palaeodictyopteroid feature 

 which most Blattoids have lost, and stamps the species as primitive. It is 

 therefore interesting to find that Pruvost draws special attention to the fact that 

 A. atrebatica, Pruv., is the oldest Archimylacrid of the Northern French Coal 

 Measures, being found in the lower portion of the Formation of Bruay, over the 

 vein Ernestine at Lens, in a shale containing seeds and drifted plant-remains. 



Archimylacris incisa, sp. nov. Plate VII, fig. 3. 



Type. — Pronotum, mesonotum, and the basal portions of the tegmina in an 

 ironstone nodule; British Museum (Johnson Collection, no. I. 15900). 



Horizon and Locality. — Middle Coal Measures (binds between the " Brooch " 

 and " Thick " coals) ; Coseley, near Dudley, Staffs. 



Specific Characters. — Wing robust. Principal veins widely spaced. Interstitial 

 neuration of stout cross-nervures, which unite in a meshwork in the wide areas. 



Description. — These Blattoid remains are 21 mm. long. The pronotum lies 

 with its underside uppermost on that portion of the nodule which also bears the 

 impressions of the under surfaces of the tegmina, while the impression of the 

 underside of the pronotum and the fragments of the tegmina upside down occur 



