Papilio dardanus (merope) and Acrxa johnstoni. 299 
B. MIMETIC FORMS OF Acrea johnstoni, Godman. 
Introductory.—In the following section the attempt will 
be made to show that the whole series of diverse forms 
which have given to this species its long synonymic list 
has arisen through the development of mimetic likeness to 
several distinct models, both Danaine and Acreine. ‘The 
form-names suggested by Oberthiir * have been followed 
throughout, Acrea toruna, Grose-Smith, being regarded 
as a form of semifulvescens, Oberth. In a later part of the 
section facts will be brought forward which appear to 
prove that this protean butterfly is not only conspecific 
with fallax, Rogenh. (= hilimandjara, Oberth.), as 
Aurivillius suggests, but also with Godart’s species, lycoa. 
I owe the opportunity of writing this part of the present 
memoir to my kind friend, the Rev. K. St. Aubyn Rogers, 
M.A., of Wadham College, Oxford, who has presented to 
the University Collection the deeply interesting series of 
models and mimics represented on Plate XX. The 
whole of the butterflies there represented together with 
other examples of the same mimetic forms were captured 
on the slopes of Kilimanjaro in 1905. In addition to this 
extensive material Mr. St. Aubyn Rogers has presented 
many examples of A. johnstoni from Taita and Taveta in 
British East Africa, including the fine and remarkable 
variety from the last-named locality, represented on Plate 
XXII, Fig. 2a. The series of models and mimics would 
however have lacked completeness if other kind friends 
had not also afforded valuable help:—Mr. Guy A. K. 
Marshall sending me an extreme south-eastern form 
(Plate XXII, Figs. la, 1b) with its model (Fig. 1); and 
Mr. C. A. Wiggins the extreme western mimetic form 
(Plate XXII, Fig. 3a) with the model (Fig. 3) from the 
same district. 
The mimetic resemblance of the commonest forms of 
A. johnstont (proteina and flavescens) to Danaine butterflies 
of the genus Amawris was suggested by the present writer 
in 1897.t Although greatly impressed by the likeness of 
Acreine to Danaine, I was then quite unaware of the 
existence of this wonderful range of forms and of the 
* Etudes d’Entomologie: Dix-septi¢me Livr.: Avril 1893. 
7 “Theories of Mimicry, as illustrated by African Butterflies,” 
read before Section D of the British Association at Toronto, Aug. 20, 
1897. Abstract in Report of the Toronto Meeting, pp. 688-691. 
TRANS. ENT. SOC. LOND. 1906.—PART Il. (SEPT.) 20 
