HEMTMYLACRIS CONVEXA. 123 



The cnbitus is convex in its basal half, and straightens out distally, giving off 

 four inward branches, the second dividing into three, and the fourth forking. 

 The divisions of the cubitus occupy the distal half of the inner margin. 



The anal area is large, and marked off from the rest of the wing by a deep 

 anal furrow. The first anal vein breaks up into five divisions, by a triple forking, 

 and the second forks twice. The third anal vein forks near its base, and the 

 remaining 3 4 veins appear simple. The anal veins end on the margin in at least 

 fourteen twigs. 



The interstitial neuration cannot be determined. 



Affinities. The mode of branching of the subcostal vein, the presence of a 

 decided radial sector and the character of the first anal vein, are features which 

 would justify the inclusion of this species in the genus Soomylacris, were it not for 

 the fact that the median is not divided into two equal branches. There is a close 

 correspondence between this species and H. ramificata, Handl., and I therefore 

 retain it in the genus Hemimylacris^ although, as I have stated elsewhere, I am 

 inclined to merge the two genera into one, as marking a transitional group between 

 the Archimylacridae and the Mylacridas. 



Hemimylacris convexa, Bolton. Plate VIII, fig. 8. 



1911. Hemimylacris convexa, Boltoii, Quart. Journ. Geol. Soc., vol. Ixvii, p. 156, pi. vii, fig. 3. 



Type. Proximal half of a tegmen lying on an irregular surface of black shale; 

 Museum of Practical Geology, Jermyn Street (no. 24512). 



Horizon and Locality. Pennant Series (Shales associated with the Graigola 

 Seam) ; Clydach Merthyr Colliery, Clydach Valley (Swansea Vale), Glam. 



Specific Characters. Costal area triangular. Radius with a well-defined radial 

 sector, the two occupying most of the outer margin and the outer half of the 

 wing-apex. Median small. Cubitus arcuated and ending on the middle of the 

 inner margin, and outer third of the apex. Anal veins few. 



Description. Only the proximal half of the tegmen is shown, and this does not 

 exceed 10 mm. in length. The subcostal area is much crushed and broken, and 

 but two branches of the subcostal vein can be seen on it. 



The radius arises in the middle of the base, and at once divides, evidently 

 giving off a radial sector. The radius shows two marginal veins, while the radial 

 sector sends off a long branch towards the wing-apex, the branch forking near the 

 broken edge of the wing. 



The median vein is represented by a portion of the main stem, which f, 



twice. 



The cubitus has an arcuated stem bifurcating twice into four branches. 



anal veins can be distinguished. 



