WARNING COLOURS 193 



Miiller.* This eminent naturalist suggested that both 

 species were benefited by the resemblance, because 

 the number of individuals which must be sacrificed to 

 the inexperience of young birds and other enemies 

 would be made up by both of them instead of by each 

 independently. This fruitful suggestion was at once 

 accepted by Wallace.^ The mathematical aspects of 

 the subject were accurately worked out by Mr. Blakis- 

 ton and Mr. Alexander, of Tokio, Japan.^ 



The next step was taken by Professor Meldola,^ 

 who extended Fritz Miiller's explanation of these 

 comparatively rare cases of close resemblance, to the 

 general similarity which obtains throughout whole 

 groups of unpalatable and conspicuous species. * The 

 prevalence of one type of marking and colouring 

 throughout immense numbers of species in protected 

 groups, such as the tawny species of Danais, the 

 barred Heliconias, the blue-black Euploeas, and the 

 fibrous Acrceas, is perfectly intelligible in the light of 

 the new hypothesis.' 



This list comprises the whole of the large groups 

 of butterflies alluded to in the last few pages. The 

 species belonging to them are very familiar in every 

 collection of tropical butterflies, while some of them 

 are even abundant in temperate climates. Until re- 



' Ituna and Thyridia, Eosmos, May 1879, p. 100, translated by 

 Meldola, Proc. Ent. Soc. Lond. 1879, p. xx. 

 2 Nature, vol. xxvi. p. 86. 

 ' Ibid., vol. xxix. p. 405. 

 * Ann, and Mag. Nat. Hist. December 1882. 



