Ixxi, Ixxvii] G nore) 
(Trans. Ent. Soc. Lond. 1902, pp. 296, 489, 490; zbed. 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 Z. pharis to the ordinary African 
forms of iVychitona, 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.,’ 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 Zeuceronia has been chiefly 
that of a borrower, it has in return bestowed certain features 
of its own upon this particular race of its model. The form 
of Vychitona 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, Vychitona 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 Vychitona 
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. W. J. Kaye read “Some Notes on the Dominant 
Miillerian Group of Butterflies from the Potaro River 
District of British Guiana.” 
