72 



BRITISH ORTHOPTERA. 



9 mm. E. perspicillaris.^ 



25 mm. B. orientalis. 



ARTIFICIAL KEY TO BRITISH BLATTODEA. 



A. Indigenous; living under 



natural conditions; small. about 

 (a). Pronotum dark, with pale 



margins . . . *10 mm. E. lapponicus. 

 (b). Pronotum pale, with a few 



darker dots 

 (c). Pronotum pale, with dark 



markings on disc; very 



small . . . . 8 mm. E. panzeri. 



B. Naturalised; living under arti- 



ficial conditions ; larger. 



(a). Dark; wings rudimentary 



in female, truncated in 



male .... 



(b). Wings developed in both 



sexes. 



i. Femora with spines. 

 (1). Ochreous-brown; two 

 dark lines on prono- 

 tum; rather small . 13 mm. B. germanica. 

 (2). Sienna-brown; pro- 

 notum nearly con- 



coloroug; large . 35 mm. P. americana. 

 (3). Sienna -brown; pro- 

 notum with yellow 

 margin; mediastinal 

 area of elytra 



yellow; large. . 27mm. P. australasise, 

 ii. Femora without spines. 

 (1). Very dark; pronotum 

 chiefly black; size 

 moderate 20 mm. L. surinamensis. 



Approximate length from front of head in resting- position to tip of 

 abdomen. As cabinet specimens naturally dry in this position, such 

 measurements are most convenient for purposes of comparison. 



f Although, as is usually done, E. perspicillaris is here treated as distinct 

 from E. lapponicus, it may ultimately be necessary to place them together 

 as two forms of the same species. The males are certainly unlike in appear- 

 ance ; but in the females of E. lapponicus the dark centre to the pronotum 

 often tends to disappear, while the organs of flight vary in development. 

 Consequently the suspicion arises that we may not really be dealing with 

 two distinct species. Further examination of the two forms, especially in 

 the way of intermediates, is called for. 



