SEASONAL VARIATION 
17 
that the salmon red of the wet phase is represented in the 
dry phase by a discal row of red spots across all the wings. 
It is, perhaps, needless to add that the two phases were looked 
upon for many years as quite distinct species and that sys- 
tematic naturalists were only convinced by the actual breeding 
of one form from the other. This was first accomplished 
by Mr. G. A. K. Marshall in 1898. The phases of J. antilope are 
hardly less remarkable. In this species the wet form resembles 
that of J. sesamus, except that the salmon red is replaced by 
fulvous, and it is of course a much smaller insect. The resem- 
blance in colour on the underside is much more marked and 
it is equally conspicuous. The upper side of the dry form 
resembles the wet form in colour, but the shape of the wings 
is quite different. The projection below the tip of the fore 
wings and the tail at the anal angle of the hind wings are 
much accentuated, though they can hardly be traced at all 
in the wet season phase, and the under side of the wings bears 
a very strong resemblance to a dead and withered leaf with 
a prominent mid-rib. It is by no means improbable that 
these last two species have made considerable progress towards 
splitting up into two species, and that under favourable con- 
ditions the development into distinct species might be rapidly 
effected. There can be little doubt that other forms, at present 
regarded by most naturalists as distinct species, will in the 
future have to be united, and the study of these forms which 
can only be undertaken by one living on the spot, since it 
involves breeding on an extensive scale, will amply repay 
the trouble and time expended. One such species is J. archesia. 
The wet form is a brown butterfly with a broad band of ochre- 
yellow across all the wings, both above and below. The 
dry form is very rare, if indeed it occurs at all in British East 
Africa. It is similar above, but the ochre-yellow band is much 
narrower, and the eyespots which exist beyond it are white. 
On the underside the broad band narrows into a midrib and 
other subsidiary paler markings are developed, increasing 
the resemblance to a dead leaf. We have, however, another 
form known as J. limnoria, which is probably only a form of 
this species and resembles it closely in the wet phase, but 
in the dry phase this last is banded on the underside with 
Vol. II. — No. 3. 
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