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 edibiHty 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. The 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 to its 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 

 warniog signals with the utmost publicity. In this 

 manner the members of a distasteful and conspicuous 

 species are enabled to profit by the experience gained at 



» Trans. Ent. Soc. Lond. 1894, pp. 297,298 ; ibkl, 1896, p. 75. 



