ORTHOMYLACRIS LANCBOLATA. 133 



very small anal veins are also seen in the curve of the wing-margin. The anal 

 area is strongly convex between the anal furrow and the first anal vein. 



The interstitial neuration of the anal area appears to consist of straight cross- 

 nervures. Over the rest of the wing the interstitial neuration cannot be made out. 



Affinities. When first describing this species, I regarded it as closely allied to 

 forms which Handlirsch has placed in his genus Hemimylacris. There can be no 

 doubt, from what has been already said, that a close relationship exists. Pruvost 

 (op. cit., pp. 222 4) has recorded two species of Soomylacris from the Lens and 

 Lievin Coalfields of Northern France, 8. lievinensis, Pruv., and 8. aff. deanensis. 

 The occurrence of these British species may serve to indicate the Westphalian 

 affinities of the Kent and Forest of Dean Coalfields. 



Genus ORTHOMYLACRIS, Handlirsch. 

 1906. Orthomylacris, Handlirsch, Proc. U.S. Nat. Mus., vol. xxix, p. 768. 



Generic Characters. Tegmina two to two-and-a-half times as long as wide, 

 with a sub-cordate outline. Costal area extending from one-half to two-thirds the 

 length of the tegmen. Radius extending to the tegmen-apex, and giving off a 

 large number of outward branches. Median with few veins, directed towards the 

 apex and the inner margin. Cubitus never reaching the apical margin, and with 

 few branches. Anal area at least twice as long as high. Structure leathery, and 

 with cross-wrinkles. 



Orthomylacris lanceolata, Bolton. Plate IX, fig. 5 ; Text-figure 43. 



1911. Orthomylacris lanceolata, Bolton, Quart. Journ. Geol. Soc., vol. Ixvii, p. 167, pi. x, figs. 1, 2. 



Type. Left tegmen; Museum of Practical Geology, Jermyn Street (no. 24511). 



Horizon and Locality. Coal Measures (shales associated with the Graigola Seam, 

 Pennant Series) ; Clydach Merthyr Colliery, Clydach Valley, Swansea Vale, Grlam. 



Specific Characters. Tegmen long, and uniformly tapering to the apex. 

 Upper surface regularly convex. Subcostal area broadly triangular, with oblique 

 branches. Radius much branched. Median unbranched in basal half, with three 

 outer branches. Cubitus divided into two main branches, the outer forking into 

 two equal twigs, and the inner giving off three inward twigs, the first only forking. 

 Outer and inner margins convex. 



Description. The tegmen, which measures 23 mm. long and 10 mm. wide, lies 

 with the dorsal surface uppermost, and is gently rounded along its length, a slight 

 flattening only being visible over the middle of the outer margin. The uniform 

 tapering of the two margins to the apex produces an elongate form of tegmen of 

 an unusual type among Blattoids. The base of the tegmen is lost, and the costal 

 area appears therefore to occupy nearly half the outer margin. 



