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Mimicry ix the Butterflies of Mauritius and Bourbon. — 

 Professor E. B. Poulton, F.B.S., exhibited a series of species 

 A of the rapilio nireus group from many parts of Afi-ica, from 



Madagascar, Mauritius and Bourbon, together with other 

 Rhopalocera from the two latter islands bearing on the subject 

 of mimicry. He said that his attention had been directed to 

 the difficult and fascinating problems presented by these small 

 outlying islands by the recent interesting observations and 

 experiments of Colonel N. Manders, to whose kindness he 

 owed the opportunity of exhibiting some of the specimens. 



The black blue-marked upper-surface of the wings in the 

 numei'ous species and sub-species of the PajyUio nireus group 

 presented a singularly uniform and characteristic appearance 

 throughout Africa and Madagascar. It appeared probable to 

 the speaker that these forms constituted a definite Ethiopian 

 synaposematic group. One of the species {epiphorbas, Boisd.) 

 in Madagascar had, however, spread into Mauritius as Pcqnlio 

 manlius, F., and into Bourbon as F. phorbanta, L. (disparilis, 

 Boisd.). These two island-forms wei'e entirely separated 

 geographically from other members of their abundant and 

 dominant group, while they at the same time came into 

 contact with Euploeas of a characteristic Oriental type of colour- 

 ing, with E. euphone^ F., in Mauritius, with E. youdoti, Boisd., 

 in Bourbon. Under these circumstances the dark ground- 

 colour of the female Pcqnlio in Mauritius has faded to a 

 brown shade not unlike that of the Eupluia, while the blue 

 markings have lost their sharp outlines and have become 

 slightly reduced in size as compared with those of the male. 

 The mimicry is, of course, in a very incipient stage — so 

 incipient, indeed, as to be probably unrecognisable were it 

 not for the far more complete resemblance attained by the 

 female of phorbanta in Bourbon. "With this latter female 



[V 

 before us it is impossible to doubt the significance of the 

 differences which separate the female of vianlius from its 

 male. In the female of 2^horhant(i the central blue patches 

 have entirely disappeared, while the blue submarginal spots 

 of the hind-wing have become increased in size and trans- 

 formed into white. Furthermore, the ancestral submarginal 



