236 THEORIES OE MIMICRY 



for these facts. Uniform local conditions, if they can 

 produce any effect at all. must be expected to produce 

 the closest likeness where there is the closest constitu- 

 tional similarity — in other words, in the more nearl) 

 related forms, in preference to the less nearly related, in 

 each locality. With the theory of Internal Causes we 

 should also expect the facts to be the reverse of those 

 which exist. At the best it is unable to account for the 

 observed j)henomena. 



Any theory of Selection (Natural, Artificial, or Sexual) 

 affords a logical exjjlanation of the facts, in the sense that 

 it is quite conceivable that the observed results might be 

 thus obtained. Hence the objection to Sexual Selection 

 as a suggested cause is not as strong as the objection 

 to the other causes which have been brought forward. 

 Nevertheless, I believe that very few will be found to 

 support the h)pothcsis that Sexual Selection supplies the 

 interpretation we are seeking. 



The conclusions here arrived at by a consideration 

 of the facts presented by the Lepidoptera are entirely 

 confirmed by those already known in the Coleoptera ; 

 although as yet but little attention has been paid to the 

 latter Order in this respect. C. J. Gahan, in an interest- 

 ing pajjer,^ clearly shows that the Phytophagous genus 

 Diabrotica is in the same position as the large protected 

 groups of butterflies alread)- mentioned [Dauainac, IlJio- 

 )uii)iat\ Hcliconinac, Acraeinac). The individuals of its 

 species sw^arm in the localities where they occur; they 

 are conspicuously coloured, and many of them arc known 

 to feign death when captured and to discharge a yellow 

 fluid from various parts. The facts at present ascertained 

 justify the conclusion that these Coleoptera form centres 

 of Miillerian Resemblance, in that ' some of the species 

 belonging to one section in this genus are, in colour and 

 marking, extremely like certain species of the other section 

 which come from the same localities '.- Mr. Jacoby has 

 also * recorded that many of the species of his genus Neo- 

 brotica exhibit most striking resemblances to species of the 



^ Trans. Ent. 6'('f., Lond ^ 1891. pp. 367-74. 

 I.e. p. 372. 



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