( Ixxi ) 



think that it may now be taken as a well-established law 

 (Trans. Ent. Soc. Lond. 1902, pp. 296, 489, 490; ibid. 1906, 

 pp. 216-218, 292-3). It will be seen from what follows 

 that the present exhibit probably furnishes a fresh instance 

 of its operation. 



"The resemblance of L. p^aris to the ordinary African 

 forms of Nychitona, though striking, is not exact. The 

 Leuceronia has no dark discal spot, the outline of the dark 

 apical border of the fore-wing is more regular, and the texture 

 of the wings is more solid-looking and opaque than in the 

 prevailing forms of the model. But among the specimens of 

 Nychitona collected by Mr. Wiggins in the neighbourhood of 

 the Victoria Nyanza and worked out by Mr. Neave in ' Novit. 

 Zool.j'Vol. XI, 1904, p. 324, there occur some forms which in 

 all these respects correspond with the mimic rather than with 

 the usual type of the model. The inference seems clear that 

 although the part played by the Leuceronia has been chiefly 

 that of a boiTower, it has in return bestowed certain features 

 of its own upon this particular race of its model. The form 

 of Nychitona in question, a specimen of which is included in the 

 exhibit, may possibly deserve to rank as a distinct sub-species. 



'•'Whether the aspect of the purely white specimens of 

 Nychitona from West Africa here shown in connection with 

 Pseudopontia affords another instance of reciprocal change, I 

 am not prepared to say, especially as similar forms occur in 

 districts where Pseudopontia is not met with. But on looking 

 at the genus as a whole, it would appear to be significant that 

 whereas in India, where, so far as we know, Nychitona is not 

 mimicked, its forms present a very uniform appearance with 

 the characteristic discal spot and irregular apical border con- 

 spicuously present, in Africa we find variations of Nychitona 

 each of which tends to bring it into more or less close corre- 

 spondence with a probable mimic. On these grounds it seems 

 not unreasonable to seek for an explanation of the facts in the 

 direction of diaposematic change." 



Mr. H. St. J. Donisthorpe exhibited examples of Dinarda 

 pygmsea, Wasm., with our other three species, B. hagensi, 

 Wasm., D. dentata, Gr,, and D. niiirkeli, Kies., with their 

 respective hosts, and read the following note : — 



