hindwing has the same extent as in that sex. The rarity of the 
Q-form represented bv figure 6 may be judged from the fact that 
the broken specimen figured is the only one which the Tring 
Museum has received. Each form of the Planema is unisexual. On 
the other hand, every form of the £/ymzzas appears in both sexes; 
the five specimens figured are males, each of which could be 
matched by a corresponding female. | | 
If the similarity of the two species is to be explained by the 
assumption that there is an inherent tendency in them to develop 
along definite lines, which happen to be parallel or convergent, 
there is still the fact to deal with that the result in one Insect is 
polymorphism in doth sexes, the male and female forms being 
identical, whereas in the other species polymorphism is confined 
to the female sex. It may be argued that the P/anema with its 
monomorphic male is some steps in advance of the Zlymnias, 
having lost all the male forms which were similar to the females. 
That is a quite plausible proposition in the case of the Planema, 
however much we may differ as to the causes which have brought 
about the result. But if the argument is applied to the Zlymnias, 
it breaks down before the array of systematic facts. The propor- 
tional numbers of specimens of the various individual forms of 
E. phegea are opposed to the assumption that there is in this 
Butterfly a tendency of development which will result in the male 
becoming monomorphic and the female remaining polymorphic 
as in Planema epwa. The frequency, in the Gaboon, of the orange 
and the buffish forms in both sexes and the comparative scarcity 
of the others can only be interpreted as meaning that there is a 
tendency in E. phegea towards breaking up into two forms, of 
which each would still consist of both sexes. In Planema epwa, 
on the other hand, the disappearance of forms 6, 7 and 9 would 
result in the tawny colour being confined to the male and the 
buffish colour to the female, which means that the lines of deve- 
lopment in the Planema and Elymnias are different. Hence the 
above assumption that the two Insects follow the same line of 
development, Planema epwa being some steps in advance of 
Elymnias phegea, cannot stand scrutiny. That this is not mere 
speculation is proved by the systematics of the two species, if the 
whole range of these Butterflies is taken into account. The result 
of evolution in Planema epwa just alluded to hypothetically is an 
actuality in the northern faunistic district of tropical West Africa, 
