#^ 





JOURNAL OF VARIATION. 



No. 3. Vol. I. June 15th, 1890 



MELANISM AND MELANOCHROISM IN BRITISH 

 LEPIDOPTERA. 



By J. W. TUTT, F'.E.S. 

 {Continued frovi paoe 7.) 

 |efore dealing with the pecuharities of the meteorology 

 and ph3'sical geography of the British Islands, I should 

 like to quote a remark made by Dr. White {Eiit. Mo. 

 Mag. iv., p. 248), where he speaks of the peculiarity 

 of the fauna and flora of Western Scotland, although not then 

 referring to variation. He writes : — " No one who has studied 

 the ^ MmiuaV can have failed to have noticed a great similarity 

 between the fauna in the Lake District of England and that of 

 Rannoch in Scotland. In the Lake District we have a similar 

 elevated region of lakes and mountains, with a like western 



situation Another fact worth noticing about Rannoch 



is, that while it seems to appropriate to itself most of the 

 Alpine and boreal insects, yet it possesses but few (and these 

 the commonest) Alpine plants ; while the neighbouring district 

 of Breadalbane, lying immediately to the south, has more 

 Alpine and boreal plants than any other place in Britain, and 

 }et but few Alpine and boreal insects. Breadalbane, however, 

 has higher mountains and less wood, which may perhaps 

 account for the difference." I would point out how conclu- 

 sively in this extract Dr. White proves that food has nothing 

 to do with the peculiarity of the Rannoch, or, in a wider sense, 

 the Alpine fauna. Generalising, we find Dr. White again 

 writing : — " Botanists are aware that the plants of the w^est 

 coast are less brilliantly coloured than those of the east ; and 

 I think that it is in the west rather than the north that 

 melanochroism in British insects may best be studied." 



The excellence of these observers is beyond question, and 



