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XV. Notes oil Seasonal Dimorphism of R-hopalocera in 
Natal. By Cecil W. Barker. Communicated 
by George Francis Hampson^ B.A._, F.E.S. 
[Read April 3rd, 1895.] 
Some species of butterflies are on the wing throughout 
the year, whilst others appear at one season only. The 
seasonal variations of the double or many-brooded species 
are often of a very marked character, modifying the 
facies so considerably as to lead bo much confusion in 
the determination of species and varieties. The Pierinse 
exhibit this seasonal variation most markedly, but it is 
also observable among the double-brooded species of 
both the Nymphalid^ and Lycasnidae. 
The following rules generally hold good as character- 
istic of the changes and modifications which occur, and 
which serve to distinguish the dry season form from its 
summer or wet season representative : — 
1st. Smaller size and a disposition to greater acute- 
ness in the apices of the forewings. 
2nd. The dark markings of the upperside of wings 
become contracted or even obsolete. The 
markings of underside (especially of the apices 
of forewings and the whole of the hindwings) 
become suffused or merged in a generally 
duller and darker ground-colour. 
Those butterflies having spots or ocelli or both_, show a 
disposition to contraction or obliteration of those spots. 
As regards those species having recognized varietal 
forms, the correctness or otherwise of the above rules 
is easily verified by simply first determining whether 
the variety in question be a dry season form or not of 
the species. Should it prove to be so, it is then easy 
to apply the principles as given above to it. 
But practical field observation, during a course of 
years, has convinced me that many of the so- 
called species are simply seasonal varieties of one and 
TRANS. ENT. SOC. LOND. 1895.— PART ITT. (SEPT.) 27 
