Sept. 1S96 ] Skinner: Study of N. American Butterflies. Ill 



on low moss lands, on which water is charged with iodine, in Cumber- 

 land, Westmoreland and Lancashire, it is a rich fulvous brown insect, 

 larger and stronger built ; and when these are acted upon by hydro- 

 chloric acid gas they assume the exact color of the hill specimens. The 

 dark Annulet moth (^Gnophos obsciiraria) on chalk lands is a light 

 colored grey or drab insect. In carboniferous limestone districts it is 

 a lead-colored insect, whilst on the New Red Sandstone formation it 

 varies from a rich ochreous color where oxide of iron is present in the 

 soil to a dark, almost black insect on the white sandstone parts of the 

 New Red formation, thus clearly pointing to geologically caused changes 

 of color. Any of these latter forms acted upon by chlorine appear as 

 highly colored grays. The same remarks apply to Dianthoecia car- 

 pophaga. On chalk it is light buff; on "New Red" here, darker; 

 but all buff in Cambrian at Llangollen ; and at Penmaenbach darker 

 still, buff or ochreous brown ; and on quartoise early rock, rich dark 

 cold grey-brown, as in the Isle of Man, and at the Howth, in Ireland, 

 ochrey shades being rarely observable upon them ; but, acted upon by 

 hydrochloric acid gas they all turn to a beautiful bright light fawn buff, 

 veritable carpophaga of the chalk. 



It is to be observed, however, that some varieties we might be in- 

 clined to attribute to certain formations may be the result of a food 

 proper to the soil. Thus in the cases of the Welsh Wave Moth 

 {^Acidalia contiguaria), bred continuously on heather from moss lands, 

 all specimens become varieties, fumose specimens, whilst fed on succu- 

 lent plants they are large light colored specimens, rarely darkish, but 

 never so dark as when fed on heather from the moss. "We find sea- 

 sonal varieties not alone alternating in ordinary years, but witness their 

 production by fluctuations in annual temperatures. Thus while many 

 butterflies produce one or two annual broods, in certain years, those or- 

 dinarily single brooded become double brooded ; or those which are 

 double brooded produce three annual generations."* 



I now wish to apply some of these facts to our own Lepidoptera and 

 wish to say in the beginning that want of exact localities and exact data 

 on our specimens has been most pernicious and detrimental to all such 

 studies. In many cases specimens are without localities or dates of cap- 

 ture or only have a State locality. Studies of variation produced by 

 geographical variation in the broad sense indicated, or the effect pro- 

 duced by seasonal broods, are impossible without such data. I also wish 



* I am indebted to Insect Variety, by A. H. Swinton, for these facts in relation 

 to European Diurnals. 



