( xlii ) 



have varied a good deal during the time that Mr. Fenn's in- 

 sects were in the pupa state. 



Mr. Jenner Weir, who said that he had been to Mr. 

 Merrifield's house and exarained his arrangements for forcing 

 and retarding the emergence of moths from the pupae, bore 

 testimony to the careful way in which Mr. Merrifield's ex- 

 periments were conducted. 



Colonel Swinhoe said he considered that the amount of 

 light at the time of the emergence of the moth influenced the 

 colouring, and suggested that attention should be directed to 

 to this in any further experiments. 



Mr. Elwes expressed the opinion that many other causes 

 besides temperature had their influences. 



Mr. C. G. Barrett thought that in a hilly country moths 

 were darker than in the plains. The black betidaria were 

 spreading in districts far removed from any smoky atmo- 

 sphere. Mr. M'Lachlan, Mr. G. T. Porritt, and others, 

 continued the discussion. 



Mr. Merrifield, in reply, said that with regard to Mr. Fenn's 

 autumnaria, it was probable that during the three summers in 

 question some of the pupae had been subjected to very 

 different temperatures ; he had found a variation of 15 

 degrees F., or less, applied at the right time, sufficient to 

 make all the difference between a very light and a very dark 

 autumnaria. He thought it was proved beyond doubt that, 

 in the two species experimented on by him, temperature 

 had been the chief cause of difference in colouring, though 

 the hereditary tendencies of the particular brood, and the 

 variability of the individuals, had their share in the pro- 

 duction of the variations. He quite believed, also, that in 

 many cases other and different causes operated; for example, 

 in the case of the dark Gnophos obscurata he was disposed to 

 think that it was a fixed variety, the colour being a protective 

 one, caused by the gradual assimilation of the colour of the 

 moth to the colour of the soil on which it reposed. 



Mr. G. T. Baker read a paper entitled •' Notes on the 

 Lepidoptera collected in Madeira by the late T. Vernon 

 WoUaston." The paper was illustrated by a number of 

 figures drawn and coloured some years ago by Professor 

 Westwood. 



