TRIFID.^. 225 



second line, rather far beyond the middle of the wing, is very 

 oblique, almost parallel with the hind margin, and composed 

 of a series of indistinct blackish curves, but near the anal 

 angle forms a broad black V-like marking ; in the middle of 

 the costa is a nearly perpendicular thick black streak, 

 continued down the anterior edge of the reniform stigma, 

 which otherwise is hardly perceptible ; beyond this streak is 

 a small black costal spot ; along the hind margin a row of 

 black spots or dots between the nervures ; cilia white. Hind 

 wings clear snowy- white ; nervures faintly tinged with brown ; 

 cilia white. Female slightly larger, with the body stouter ; 

 otherwise similar. 



Underside white, the nervures of all the wings faintly 

 brownish, and each wing with a more or less distinct central 

 black spot ; hind margin of the fore wings spotted with 

 black ; body and legs white. 



Variable, the variations being somewhat local or climatal. 

 The typical for?n described above is that usually found in the 

 southern counties of England, though accompanied occa- 

 sionally by specimens much dusted with dark grey or slate- 

 grey and with the aj)ical portions of the nervures grey, a 

 band outside the second transverse line being sometimes 

 especially dark ; along with this darkening of the ground 

 colour, the transverse lines are usually blacker, more distinct 

 and more complete ; the black central streak from the costa 

 is also thicker, and that portion of it at the back of the 

 reniform stigma often accompanied by a black mark at the 

 other side of the stigma. In the Eastern Counties these 

 darker forms appear almost to exclude the type, and assume 

 still stronger variations. Mr. F. J. Hanbury has a specimen 

 taken in Norfolk, in which the thorax and fore wings are 

 suffused with very coarse dark grey atoms, not of a slate 

 tinge, but singularly dark ; and specimens which I took in a 

 marsh near Norwich have the basal area much dusted with 

 black, and the whole hinder area beyond the second line 

 suffused with slate-grey. These grey forms were at one time 

 VOL. III. p 



