1887.] VALUE OF COLOUR AND MARKINGS IN INSECTS. 229 



L. Distant (' Nature,' vol. xxvi. p. 105 ; and ' Rhopalocera Malayana,' 

 pt. ii. p. 33) ; but all his objections were very completely answered 

 by Prof. Meldola (' Ann. & Mag. Nat. Hist.' Dec. 1882), who, in his 

 concluding sentences, largely anticipates tliat further extension of 

 Fritz Midler's theory which is here brought forward, the suggestion 

 that all the conspicuous and dangerous or distasteful species in any 

 country will be found to share between them a few strongly contrasted 

 colours, arranged in few and simple patterns again and again repeated. 

 He says : — " I am persuaded that the extension of the tiieory of 

 mimicry proposed by Fritz Miiller marks a great advance in our 

 views on this subject, which is so interesting as having been the first 

 to which the Darwinian Theory of Evolution was applied with such 

 success by Mr. Bates. Not only are we now in possession of a 

 consistent theory which enables us to dispense with mysterious and 

 'unknown local causes,' but other groups of facts hitherto incompre- 

 hensible are capable of explanation. Thus 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 

 Ileliconias, the blue-black Euploeas, and the fulvous A'-rceas, is 

 perfectly intelligible in the light of the new hypothesis. While the 

 unknown factors of species-transformation have in these cases caused 

 divergence in certain characters, other characters, viz. superficial 

 colouring and marking, have been approximated or prevented from 

 diverging by the action of natural selection, every facility having been 

 afforded for the action of this agency by virtue of the near blood- 

 relationship of the species concerned. When discussing the origin of 

 mimicry, Mr. Darwin long ago suggested that it might have 

 commenced at a time when the species were nearly related in marking 

 and colouring." The suggestion here brought forward and depending 

 upon the results which aie tabulated below, is a further extension of 

 the same principles, so that certain resemblances between insects 

 belonging to very different groups are accounted for on the 

 supposition that natural selection has not only prevented divergence 

 in nearly related forms which were originally similar, but has in 

 other cases actually determined the convergence of widely separated 

 forms which were originally unlike. This latter explanation of the 

 resemblances was intended by Fritz Miiller in his paper on " Ituna 

 and Thyridia" for he looked upon these genera as widely separated, 

 and their similarity as due to convergence. There appears, however, 

 to be some dispute as to their true affinities. It is obvious that under 

 Prof. xMeldola's suggestion we shall expect to find a far greater 

 similarity between the species of a large group of closely allied 

 nauseous insects in any country than between those of other large 

 groups protected in other ways ; while, on the other hand, there is 

 no necessity for the expectation of equal uniformity among the 

 isolated nauseous species or even among those belonging to small 

 mmseous groups. We should rather expect the constant appearance 

 of a few simple but very different patterns, made up of a few strongly 

 contrasted colours ; and this is precisely the arrangement which is 

 proved to obtain by the tabulation of the appearances of all such 



