ARCHIMYLACRIS (SCHIZOBLATTA) OBOVATA. 109 



the base, and the remaining two at wide intervals further out. The course of the 

 main stem is such as to indicate that it reached the distal portion of the inner 

 margin, so that the wing-apex was wholly occupied by the divisions of the radius 

 and the median. 



The anal veins seen are five in number, the first forking twice and the rest 

 single. They probably occupied the proximal third of the inner wing-margin. 



The articulation of the tegmen to the mesonotum seems to have been strengthened 

 by the formation of three ridges, two formed by the deepening of the bases of the 

 subcosta and radius, and a third by a similar thickening just inside the anal furrow, 

 which in this specimen coincides with the line of the first branch of the cubitus. 



The basal part of the subcostal area shows a deep hollow ; this feature is seen 

 in several of the British Blattoids, and favours the assumption that while the point 

 of attachment lay immediately behind, the frontal part of the mesonotum developed 

 an area which served as a fulcrum for the tegmina. 



The right tegmen is represented only by the base of the costal border and sub- 

 costa, short portions of the radius, median, a part of the cubitus with two proximal 

 branches, and the inner anal vein dividing into three. 



The interstitial neuration consists of strong cross-nervures, frequently uniting 

 laterally, and on the broader areas forming a slight open meshwork. 



Affinities. Fragmentary though the wing is, it yet shows many of the features 

 of A. venusta, Scd., having the same Avide costal area, the same relation of subcosta, 

 radius and median so far as these can be traced, and the cubitus beginning to branch 

 low down before the radius and median show any trace of branching. The inter- 

 stitial neuration in both consists of straight cross-nervures occasionally uniting 

 laterally. 



This wing is more robust than that of A. venusta, Scd., and the anal veins are 

 more oblique in direction. The whole of the main veins and those of the anal area 

 are more widely spaced. In its robust character the wing approaches A. acadica, 

 Scd., but in that species the interstitial neuration does not unite laterally. 



Archimylacris (Schizoblatta) obovata, Bolton. Plate VII, fig. 4; Text-figure 35. 



1911. Archimylacris (Schizoblatta) obovata, Boltou, Quart. Jouru. G-eol. Soc., vol. Ixvii, p. 157, pi. vii, 

 figs. 4-6. 



Type. The distal two-thirds of a left tegmen, having a length of 23 mm. and a 

 greatest breadth of 10mm.; Museum of Practical Geology, Jermyn Street (nos. 

 24506 and 24507). 



Horizon and Locality. Base of the Upper Coal Measures (Grwernau Level of 

 the Mynyddislwyn Vein) ; Maes-y-cwmmer, Monmouthshire. 



Specific Characters. Costal border moderately convex, and passing into a 



