Papilio dardanus (merope) and Acrea johnston. 301 
part of the hind-wing and the apical part of the fore-wing 
is marked by alternating dark and light stripes,—dark 
veins, paler ground colour and again darker internervular 
radi. This is certainly the conspicuous feature of the 
insect during prolonged rest with closed wings hanging 
downwards, and it is an appearance characteristic of 
many Acrwine.* Hence in complete rest the prominent 
characters are synaposematic with other Acrvinw ; during 
flight and in brief rests with wings open the characters 
are synaposematic with the genus Amauwris. 
Oberthiir’s form semialbescens (l.c., Plate III, Fig. 29) 
with white spots on the fore-wings and reddish-brown 
hind-wings bearing a paler discal patch of the same colour, 
may be looked upon as an exceptional variety of proteina. 
It is of much interest as an example of the variational 
material out of which natural selection has probably 
produced such mimetic forms as /fulvescens (Plate XXI 
Fig. 4a), and torwna (Plate XXII, Fig. 3a.) 
(2) Acrea johnston, form flavescens, Oberthiir (J. c., Pl. I, 
f. 4). This form differs in the spots of the fore-wing being 
buff instead of white. It is an obvious mimic of the buff- 
spotted forms of Amauris echeria. Every gradational 
shade between pronounced buff and the pure white of 
proteina is to be found. A good intermediate example is 
figured on Plate XXI, Fig. 1b, but the methods of photo- 
eraphy do not at present enable us to distinguish between 
these pale tints. The remarks upon the under-side 
colouring of proteina apply equally to flavescens. 
(3) Acrea johnstont, form semifulvescens, Oberthiir (1. c., 
Pl. II, f£. 19). This is the form of the species described 
by Godman from Kilimanjaro, and therefore from the 
systematist’s point of view the type of the species. From 
every other point of view it is evidently highly specialized 
—a comparatively modern offshoot from the ancestral 
Amauris-mimicking forms proteina or flavescens. The 
change has been brought about by selection in the direc- 
tion of other models, Acreeine in place of Danaine. There 
are at least three different sub-forms included under seimi- 
* It is also reproduced in the mimicry of Acrwinx, e.g. in the 
males of certain species of Pseudacrea. In the magnificent W. 
African Lycenid, Kpitola honorius, F., the portions of the under-side 
_ exposed in prolonged rest are beautifully mimetic of this Acrewine 
appearance, not only as regards the radiate markings but also in the 
characteristic group of black spots at the base of the hind-wing. 
