422 Tesh a N. Manders on a factor in the 
Butler, with A. psyttalea, f. damoclides, Staud.” Mr. Neave 
writes as follows: “On examining a large series of both 
Amauris echeria and A. albimaculata, which, as Messrs. 
Rothschild and Jordan have recently pointed out, are 
clearly distinct species, I was much struck with the 
difference between the Victoria Nyanza specimens and 
those from South Africa. The echeria specimens have 
long since been described by Miss Sharp as A. jacksoni, 
a distinct species, but are doubtless not more than a 
geographical race of A. echeria. The albimaculata speci- 
mens are extremely like if not identical with A. hanning- 
tont of Butler, which is also only a form of albimaculata. 
I shall endeavour to show that both these forms differ 
from typical South African ones in a commen direction, 
and that these differences are due to the presence of A. 
psyttalea, bringing all three species into a clearly marked 
synaposematic group.” His argument given as briefly 
as possible is as follows: This resemblance of E. echeria 
and A. albimaculata to their model, A. psyttalea, is mainly 
brought about by a gradual enlargement of a spot in the 
discoidal cell of the forewing, which is at its smallest in 
specimens south of the Limpopo and gradually increases 
northwards until in the neighbourhood of the Victoria 
Nyanza, where the two species come under the influence of 
the larger-spotted A. psyttalea it reaches 1ts maximum 
development, the three species thus forming a Miillerian 
combination or synaposematic group. He gives a table of 
measurements showing the average length and breadth of 
the discoidal spots in these two species in their various 
areas of distribution, but as they are so similar it is only 
necessary to refer to one. I find that in A. echeria south 
of the Limpopo the average length is 2:26 mm. and 
breadth 1:13 mm., east and north-east of the Victoria 
Nyanza, where it reaches its maximum, the length is 
4049 mm. and breadth 15525 mm. It would seem, 
therefore, that the struggle for existence among these 
three species, owing to the experimental attacks of young 
birds, has been so oreat as to necessitate for their mutual 
protection an increase in size in the discoidal spot in the 
forewing of two of these of 1°789 mm. in length and 
*395 mm. in breadth. If this should indeed be the case 
we can agree with Mr. Neave’s conclusion that * “this 
* This conclusion has been accepted by Professor Poulton, Essays 
on Evolution, p. 335. 
