i6o LEPIDOPTERA. 



lovely white form is reached, haviug none of the usual dust- 

 ing of dark colour, but with the transverse markings clear 

 and well defined in the most exquisite lace-like pattern. 

 Taking another direction of variation, specimens from the far 

 west, especially from the Welsh coast, are uniformly of a far 

 more smooth uniform slate-grey or even slate-brown, the 

 markings less distinct and hardly blackened, the black dusting 

 merged in the uniform ground colour ; this form is larger in 

 expanse, and has very ample wings, which also are more 

 shining. These seem to be the principal forms of local 

 occurrence. The names oijndlata, serotinaria, and dilucidaria, 

 have been rather freely applied to them, but these are the 

 names of species well known on the Continent, not existing 

 in these Islands, and since these were variously applied, and 

 always erroneously, they should be totally disregarded here — 

 except to point out that even so recently as the date of pub- 

 lication of the Manual (1859) the whiter forms were looked 

 upon as a distinct species, and called G. jndlata. All the 

 varieties are united b}^ intermediates — usually from other 

 localities ; among the grey-white forms some of those from 

 Folkestone have the central area of the fore wings most 

 exquisitely irrorated with black scales, much intensifying its 

 colour ; others take somewhat similar ranges of coloiiring, 

 paler or darker; occasionally also these are nearly devoid of 

 markings. Specimens from Penmaenmaur, North Wales, 

 are sometimes beautifully dusted with olive-brown, or olive- 

 grey, so much so as to obscure the markings. From the 

 Cheshire coast are occasionally oDtained specimens of a 

 reddish-grey. Although the range of regular variation is so 

 large, casual aberrations are very rarely met with, but in the 

 collection of the late Mr. F. Bond is one wholly shining 

 greyish-white with scarcely a trace of dark scales or 

 markings. 



It is interesting to observe the suitability of the varying 

 tints on this species to the soil or rocks upon which the 

 different varieties exist — the whitest upon chalky ground, 



