S. II. Scu elder — European Fossil Cockroaches. 11 



i 2 . Tegmina relatively slender, rarely less than two and a half times as long as 

 broad ; the mediastinal area usually rather slender and ribbon- 

 shaped, not or scarcely broader at base than in the middle, and 

 rarely occupying more than a fourth of the basal width of the 

 tegmina. 

 b x . Tegmina distinctly less than three times as long as broad. 



c 1 . Internomedian area long, but far from attaining the apex of the tegmina, 

 rarely prolonged by distinct sinuosity of the main vein. 1 

 d l . Mediastinal area extending well beyond the middle of the tegmina. 



e x . Externomedian vein first branching beyond the middle of the tegmina. 



9. E. carbonaria. 

 e 2 . Externomedian vein first branching far before the middle of the tegmina. 

 /'. Tegmina of large or medium size, well rounded at apex ; externo- 

 median area expanded, and on the margin as important as the 

 scapular. 

 g x . First scapular branch arising far before the succeeding, near the 

 middle of the basal half of the tegmina ; internomedian vein 



scarcely sinuate 10. E. russoma. 



g 2 . First scapular branch arising but little before the middle of the 

 tegmina and at ordinary distance before the succeeding ; interno- 

 median vein strongly sinuate 1 1 . E. dyadica. 



f 2 . Tegmina of small size, subacuminate at apex ; externomedian area 

 compressed and on margin of much less importance than the 



scapular 12. E. parvula. 



d 2 . Mediastinal area scarcely, if at all, surpassing the middle of the tegmina. 2 

 e 1 . Scapular and externomedian veins first branching at nearly the same 

 point. 3 

 f 1 . Primary offshoots of the externomedian vein numerous. 



g l . Course of the externo -internomedian interspace gently oblique, 



arcuate 13. E. Manebachcnsis. 



g 2 . Course of the externo-internornedian interspace strongly oblique, 



sinuous 14. E. ornatissima. 



f 2 . Primary offshoots of the externomedian vein only two or three in 



number 15. E. anthracophila. 



e 2 . First branching of the externomedian vein far beyond that of the 



scapular 16. E. mantidioides. 



c 2 . Internomedian area very long, nearly reaching the apex, or reaching the 

 apical margin, often prolonged by distinct sinuosity of the 

 main vein. 

 d x . Mediastinal area extending well beyond the middle of the tegmina. 

 e 1 . Scapular vein first branching far beyond the middle of the tegmina. 



17. E. Johnsoni. 

 e 2 . Scapular vein first branching before, often far before, the middle of the 

 tegmina. 

 f l . All the intern oniedian branches simple or simply forked. 



g 1 . Scapular vein first branching at some distance before the externo- 

 median 18. E. Dohrnii. 



g 2 . Scapular vein first branching but little before the externomedian. 

 A 1 . Mediastinal and scapular branches with normal obliquity ; 

 internomedian branches frequent, with normal obliquity. 



19. E. didyma. 



h 2 . Mediastinal and scapular branches very longitudinally oblique ; 



internomedian branches exceedingly few and longitudinally oblique. 



20. E. bituminosa. 

 f 2 . Some apical branches of the internomedian vein compound. 



21. E. anaglyptica. 

 d 2 . Mediastinal area hardly reaching the middle of the tegmina. 



1 This is only conjectural in E. mantidioides, but indicated by the parts preserved. 



2 This is conjectural, but probable, in E. ornatissima by the brief extent of the 

 scapular area. 



3 Conjectural again, but probable, with E. ornatissima. 



