300 Professor E. B. Poulton on Mimetie Forms of 
striking example of Miillerian mimicry which it was to 
supply. 
I. Mimetic forms of Acrzea johnstoni, Godman. 
It is now proposed to consider the various often widely- 
separated forms of johnston in the probable order of their 
evolution in time, and to point out the models in each 
case. 
(1) Acraa johnstoni, Godm., form proteine, Oberth. 
Oberthiir (Etudes D’Entomologie: Dix-septieme Livr. : 
Avril 1893: Pl. II, Fig. 14) considers the variety with 
white spots in the fore-wing and a squarish pale buff 
discal patch in the hind-wing as the typical form of the 
species; and it is probably more ancestral than any other. 
It appears to be much more abundant than the buff-spotted 
form jlavescens, and also to have a wider range. The most 
southern examples in the Hope Collection, viz. three 
specimens sent to me by my kind friend Mr, Guy A. 
K. Marshall from Chirinda Forest, Gazaland, in S.E. 
Rhodesia (4000 feet), are all of this form, and it is also far 
more numerous than any other in the Rey. K. St. Aubyn 
Rogers’ series from the Kilimanjaro district, as also in the 
series from the Tiriki Hills on the N.E. shores of the 
Victoria Nyanza (5100 feet) kindly given me by Mr. C. A. 
Wiggins. 
The proteina form is an obvious and beautiful mimic of 
Amauris albimaculata and the white-spotted forms of 
Amauris echeria. Its synaposematic sensitiveness is well 
seen in Mr. Marshall’s specimens from Chirinda in which 
the squarish discal patch of the hind-wing is unusually 
large, clearly as an approach to Amauwris lobengula 
(Plate XXII, Fig. 1), one of the dominant Danaines of 
this locality. The discal expansion is more pronounced in 
the female Acrwa (Fig. 1b) than in the two males, one of 
which is represented in Fig. la. The more perfect mimetic 
likeness of the female is an example of the well-known and 
widely applicable principle explained by A. R. Wallace.* 
The resemblance of proteina to the Danaine model is far 
less perfect on the under-side, although the spots of the 
fore-wing and the patch of the hind-wing are still the 
prominent features. The ground colour in the marginal 
* Trans. Linn. Soc., vol. xxv, 1866, Pt. I, 1865, p. 22. See also 
Poulton in Linn. Soc. Journ. Zool., vol. xxvi, pp. 580-582, 
