SYNOPSIS OF THE BRITISH EPHEMERID.E. 15 



the middle of the posterior wings is generally a minute 

 dark spot. 

 Female similar, but of paler colours ) the middle of the 

 head and the middle and sides of the prothorax rusty" 

 yellow ; abdomen paler ; the black streaks remain 

 straight, and do not expand into triangular spots ; the 

 colouring of the wings is essentially paler than in the 

 male, and the spots more indistinct. 

 Length of the body ^ 7, $ 9^ hues; expansion of the 



wings $ 15, $ 20 lines ; setae $ 15^, 2 12 lines. 

 Sub-imago similar to the imago throughout, only the 

 genei'al colouring has a dull grey tinge, the caudal 

 filaments are black. Stephens rightly observes that 

 the colouring of E. vidyata is very variable, the costa 

 and wings especially are more or less dark. Pictet's 

 E. Danica should be referred to E. vulgata. 

 This description is made from Prussian specimens 

 which have been compared with the Stephensian 

 types. 

 Habitat near London, common (" the May Fly"). 

 In comparison with the abundance of the males, one rarely 

 meets with the female ; she does not share the mazy dance of 

 the males, but sits solitarily on the grass. 



I know also one female English sub-imago of the pale 

 variety which Pictet figures, pi. 7, f. 2, but I am not yet 

 certain whether it should not form a distinct species. 



2. E. Daxica, Miiller; E. cognata, Stephens, 56, 2; 

 Curtis, Brit. Entom. fol. 708, $ imago ; Colhnson, 

 Philosoph. Transactions, 1746, pi. 44, p. 363 — 366, 



%• 



Imago. Head and antennas black; mouth beneath 

 yellow ; prothorax ferruginous, on each side with a 



