BOMB YCID^. 39 



Much variation exists in tlie males, in the degree of dark 

 clouding of the fore wings, and some difference also in size, 

 those from the fen districts of Norfolk being particularly 

 large, and also very coarsely scaled. In the fens and adjoin- 

 ing districts of Cambridgeshire, where the insect is extremely 

 abundant, a form of this sex is occasionally found which is 

 wholly of the pale yellowish buff of the female, or even of a 

 still whiter buff, and in some instances these have the 

 nervures tinged with steely grey. Mr. H. Goss has also 

 obtained this form at Brighton. In specimens in which the 

 dark chocolate colouring is much extended over the wings 

 there is often a straight narrow streak or patch of the paler 

 colour from the white central spot toward the second line ; 

 this, with the white spot, shows a curious resemblance to a 

 bull's-eye lamp and the stream of light proceeding from it. 

 In still darker specimens this disappears, and in the extreme 

 west of South Wales examples are occasionally obtained in 

 which the whole of the fore and hind wings are of a deep 

 rich glossy pui-plish-chocolate, except the white spots, and 

 even these are apt to be diminished, one of my specimens 

 having no trace of the upper, and only one-half — forming a 

 crescent — of the lower. Some of these specimens, moreover, 

 have the nervures of the fore wings very conspicuously 

 blackish. Similar forms have been obtained from the coast 

 of Sussex, but not commonly, and Mr. W. H. B. Fletcher has 

 some from Sutherlandshire. In Lancashire is a variety of a 

 peculiar reddish chestnut colour with no tinge of purj)lish. 

 Variation in the female hardly follows that in the male, being 

 mainly confined to increase of the darker shading outside the 

 long second line, with occasionally some brownish colouring- 

 near the costa ; the hind wings also become darkened outside 

 the transverse shade. These forms occur more particularly 

 in the western districts, and on the south coast, near the sea. 

 In Mr. S. Webb's collection are two females of a very curious 

 dull umbreous drab ; and Mr. S. Stevens has one of a dull 

 dark chocolate-brown, almost as dark as any male, also 



