SEASONAL VARIATION 
15 
in certain areas. For instance, well-marked specimens of the 
dry phase of the genus Teracolus (orange tips) are hardly ever 
to be found in the damp districts of the coast and are very preva- 
lent in the colder and dryer districts in the highlands ; in fact 
I have my doubts whether the full dry form in this genus is ever 
produced by drought alone apart from cold. The special sub- 
ject of this paper is however the seasonal forms in the genus 
Junonia or Precis. I have chosen this genus because it is 
specially suitable to illustrate the subject, and, moreover, it con- 
tains the most diverse seasonal forms at present known. In 
the first place, there are four species of the genus which exhibit 
the variation in its simplest form. All of these are ornamented 
with large blue spots in the hind wing. They are J. clelia, 
J . hierta, J. boopis and J. westermanni. All except the last are 
to be found all over the country, but J. westermanni is only 
to be found to the west of Nairobi, and I should add that its 
female has no blue and differs much from the male ; it is 
possibly minetic. In all these species the only difference 
between the two phases is to be found on the underside. In 
the dry form all the markings tend to become more or less 
obsolete, especially the eyespots which are easily to be dis- 
tinguished in the wet phase. Both forms are distinctly 
protective, the butterflies very frequently settle on the ground, 
but the wet phase is less protective than the dry. 
The next two species to be considered are J. elgiva and 
J. aurorina. Both these resemble those already mentioned 
in that the markings of the underside tend to become obsolete 
in the dry phase, but they differ in one respect — and that is 
the more perfect resemblance to a dead leaf of the dry phase. 
This is produced not only by the obsolescence of the eyespots 
but also by the development of a marking across all the wings 
from the tip of the fore wings to the anal angle of the hind wings 
which resembles the midrib of the leaf. The resemblance to 
the dead leaf is marked in both forms, especially in J. aurorina , 
but it is much more marked in the dry form. There is another 
difference, moreover, which is nearly always to be found in 
these ‘ dead-leaf ’ butterflies, i.e. the shape of the wings is 
different. In the dry form the projection below the tip of 
the fore wing and the * tail ’ at the anal angle of the hind wing 
