248 THE entomologist's kecord. 



of insects to Canada. For the purpose of packing, I went out and 

 collected some sphagnum moss. For some reason or other I delayed 

 my package until February and then sent it. When it reached Canada 

 and was opened, out flew a fine, perfect specimen of R. jMaeas. In 

 what condition had that specimen hybernated ? and where ? 



Nisoniacles tages in Durham. — I had no opportunity of taking A". 

 tacjes inland, in either Durham or Northumberland, although it occurs 

 sparingly in all suitable localities in northwest Durham and southwest 

 Northumberland, but I took it upon the Durham coast for the first 

 time on July 7th. 



Collective Inquiry as to Progressive Melanism in Lepidoptera. 



Summary of Evidence prepared by L. Doncaster, M.A. 

 {Concluded from p. 226.) 

 In the introduction to this paper attention has been called to some 

 of the more important points connected with melanism in moths. It 

 remains to indicate to what extent the evidence hitherto received helps 

 to elucidate the problems mentioned, and to point out in what directions 

 additional information is chiefly needed. 



The great interest of progressive melanism lies in the fact that it 

 is almost the only known instance of a secular varietal change which 

 has actually been observed in nature. Many instances are known of 

 change in distribution, but here we have a definite evolutionary process 

 taking place under our eyes, and quite apart from any conscious human 

 interference. It is, therefore, of the utmost scientific importance that 

 the process should be watched with the greatest care ; the progress of 

 the variation and its spread from one locality to another must be 

 recorded with accuracy, and all the possible causes must be considered 

 in order that we may find out, if possible, which are really effective. 

 For this purpose observations are especially needed on the borders of 

 the chief melanic areas, e.//., in the Midlands and around Birmingham, 

 and, unfortunately, these are the districts from which the information 

 is at present most incomplete. Breeding experiments are also needed 

 in order to determine how the melanic variation is inherited in different 

 species in order to throw light on the nature of the variation and its 

 manner of spreading. Something has already been done in this way, 

 and has shown that the results obtained are not always similar with 

 different species, but more is needed before any general rules can be 

 laid down. 



Although more evidence is still much wanted, the records sent in 

 make it possible to form a definite judgment on several points of 

 importance, and suggest fresh lines of valuable inquiry. We will 

 discuss, in order, the nature of melanic variation and its inheritance, 

 its geographical distribution and manner of spreading, and, finally, the 

 possible causes which may have led to its increase in many localities. 



It is evident at the outset that the phenomena spoken of collectively 

 as melanism represent more than one kind of variation. In the first 

 place, in most of the species considered, melanism consists of a general 

 suffusion of black scales, but in Hevicrophila abriq^taria and Polia chi 

 the colour is not black, and in the banded form of Acidalia aversata 

 the suffusion is strictly limited in area, although a diffusely melanic 

 form also occurs in London. Another obvious difference, and one, 



