^22 THE entomologist's RECORt). 



wings frequently crossed by transverse lines. M. galiata, a 

 distinctly white species with a dark central band (frequently 

 pale transversely in the upper part), becomes dark grey in 

 ground colour, and has a very much blacker band in Lanca- 

 shire. M.fliicttiata, in its highest developed forms pure white 

 (var. inunaciilata) , then with a small costal spot, becomes as 

 we travel north and west almost uniformly grey in ground 

 colour, with the band becoming more or less complete, until, in 

 certain parts of Scotland, the ground colour becomes greyish- 

 black, and the central band in many specimens becomes more 

 or less merged into transverse lines crossing the whole of 

 the anterior wings. Camptograrnma bilineata, in its highest 

 developed forms, in both sexes, almost unicolorous golden 

 yellow, transversely lined with yellowish colour in both sexes, 

 becomes frequently faintly lined with black near costa, which 

 develops into a more or less complete band in some (generally 

 female) specimens, the black band becoming more typical in 

 Scotland and affecting males equally with females, until we find 

 that Hebridean specimens have the ground colour frequently 

 greyish yellow with a distinct black central band, the other 

 parts of the wing also finely lined transversely. These, I 

 think, will offer sufficient examples for my purpose. 



As I have previously stated, there seems to be but little 

 doubt that, when the country was covered with forests, 

 etc., the general condition of the atmosphere was more humid 

 than at the present time, and I have before pointed out 

 how, as Dr. Chapman has stated, in the northern and 

 western parts of the British Islands, rocks, tree-trunks, etc., 

 are made permanently darker by rain. Now, the species 

 of moths to which I have just referred, all sit with 

 their wings fully expanded, so that the whole surface of the 

 wing must be taken into account in studying the effect of 

 " natural selection " on the group. They rest on leaves, trunks, 

 fences, and similar situations in the south, and hence their 

 colour assimilates in some measure to their respective resting- 

 places ; but, in the more exposed localities in the north, they 

 .settle frequently on the bare rocks. In moist and exposed 

 situations under such conditions, then, we should look for an 

 approximation towards the original forms in the species, and in 

 such, we find but few banded specimens, the prevailing forms 

 being of a dark ground colour crossed with transverse wavy 

 lines. That we get a gradual increase of the banded form as 

 we come from the west and north of the British Islands, 



