(Co 0") [xliv, xlv 
strong mutual resemblance within a group of butterflies of 
different genera and sub-families, inhabiting a single locality, 
are due to the direct action of peculiar local physical or 
chemical influences ; but the suggestion loses all its attract- 
iveness when it is applied to the resemblance between a spider 
and an ant or a moth and a wasp, and yet few could bring 
themselves to believe that the resemblances which are here 
contrasted have been built up by two entirely different sets 
of forces.” In another part of the same paper, Professor 
Poulton points out the very different conditions under which 
the larval stages of mimetic insects undergo their develop- 
ment. Thus the larva of the drone fly lives on putrefying 
animal matter, “a food as different as possible from that pro- 
vided for the larval bee,” and we are reminded that ‘“ when 
the imago emerges from the pupa and its expanded wings 
have dried, nothing that it will eat or endure henceforward 
produces any further effect upon its colours or patterns. 
Hence identity of food and condition during the final stage 
cannot be of any assistance to the interpretation of mimicry.” 
Professor Packard further proceeds to point out that bright 
colours are not invariably associated with a nauseous taste or 
smell, but surely a negative fact of this kind does not in any 
way invalidate the theory of warning colours. The fact that 
certain nauseous insects have not developed warning colours 
does not appear to show that the bright colours of other 
nauseous insects are not of a warning nature, neither does the 
fact that certain inedible moths have no mimics materially 
affect the question. 
There is fairly conclusive evidence that inedible species of 
butterflies adopt for the most part a slow, negligent form of 
flight. This habit, which has probably arisen through im- 
munity from pursuit, also serves to display those colours 
which are supposed to be of a warning nature. It is a re- 
markable fact that mimetic species, though belonging to 
genera which ordinarily fly quickly, also exhibit the same 
carelessness of pursuit. This latter fact is referred to in 
Professor Packard’s paper, and it is even suggested that 
climatic or local causes may be sufficient to account for a 
change in the mode of flight. I cannot but think that such a 
