322 Dr. Frederick A. Dixey on 
tropical has ever been fully recognised. The mimetic 
groups here referred to are no doubt mainly of the 
“Miillerian ” kind; that is to say, they are associations 
between inedible species of various affinities ; each asso- 
ciation possessing a conspicuous and distinctive pattern 
of its own, more or less perfectly reproduced by all its 
members. In the paper already cited and elsewhere* I 
have given reasons for considering the principle of Miil- 
lerian mimicry to be far more widely operative than has 
generally been supposed; and I have also endeavoured 
to supply a test by which, even in the absence of 
information as to the edibility and relative abundance of 
the members of a mimetic group, a conclusion may some- 
times be arrived at as to whether the assemblage is 
Batesian or Miillerian. As there are grounds for suppos- 
ing that the arguments just referred to have sometimes 
been misunderstood, it will be attempted in the following 
section to re-state, in as simple language as possible, what 
appears to be the best interpretation of the facts at present 
known. 
Mimetic Attraction. When a species of butterfly has 
become established in such a region as the neotropical, 
where life of all kinds is very abundant and competition 
extremely keen, it may be taken for granted that the 
species possesses some efficient means of defence, failing 
which it would be unable to maintain its position. In 
very many instances, as is well known, the required 
protection is essentially afforded by the possession of a 
nauseous flavour, which causes the butterfly in question 
to be avoided, when recognised, by some at least of its 
insect-eating enemies. ‘lhe possibility of easy recogni- 
tion in such a case constitutes, of course, an important 
factor in the safety of the species ; since there would be 
no advantage in being inedible, if the fact only became 
known in each individual case as the result of an 
experiment fatal toits subject. It is in consequence of this 
necessity for ‘advertisement ” that, as is also well known, 
inedible species tend to assume gaudy and conspicuous 
colours, and to adopt habits calculated to display their 
warning signals with the utmost publicity. In this 
manner the members of a distasteful and conspicuous 
species are enabled to profit by the experieuce gained at 
* Trans, Ent. Soc. Lond. 1894, pp. 297, 298 ; ibid., 1896, p. 75. 
