518 MR. TRIMEN ON MIMETIC ANALOGIES AMONG AFRICAN BUTTERFLIES. 



Mr. M'Ken, and in tlie collection of the South- African Museum, is interesting from its 

 entirely wanting the ochreous subapical bar of the fore wings, all the apical region being 

 simply semitransparent fuscous grey (as in the tropical form), thougli the basal and 

 inner-marginal region has the red ground and black spotting as conspicuous as usual in 

 South-African specimens. This example thoroughly links the southern BoisduvaUi 

 with the West-African type-form, and seems to indicate that the process of assimilation 

 to the southern form of the Acraa has not been fully completed. 



Both sexes of the southern A. Zetes, but especially the male, exhibit a tendency to 

 whitish suffusion about the discoidal cell and median nervules of the hind wings. Even 

 this slight variation is imitated by the JPanopea ; for the only example, a male, brought 

 from the Zambesi by the Rev. H. Rowley* has some faint whitish clouding in the same 

 part of the hind wings ; and a female from Natal, in the South- African Museum, is 

 marked in the same manner. 



It is not only on the upper surface that BoisduvaUi successfully copies Zetes ; the 

 underside is very effectually imitated, as well as such Acrseoid characters as the yellow 

 palpi and the spotting of the thorax and abdomen. Even in outline (the female Acrcea 

 having less produced and blunter fore wings than the male) BoisduvaUi is in both 

 sexes a faithful imitator. 



11. AcR.EA Egina, Cram. 



Acraa Eyina, Cram. Pap. Exot. pi. 39. f. F, Gf. 

 A. Zidora, Godt. Enc. Meth. ix. p. 237. 



The principal characters distinguishing this species from its near ally, Zetes, Linn., are 

 as follows, viz. : in the fore toings the rufous marking near the posterior angle is much 

 enlarged and conspicuous ; the innermost of the three black spots in the discoidal cell, 

 the customary ochreous marks along the hind margin, and the whitish-ochreous clouding 

 beyond the costal black bar (all marked characters of Zetes) are wanting, and the costal 

 ])ar itself is much narrower ; while, in the hind loings, the black spots are larger, more 

 numerous, and grouped nearer to the base, and there are no red spots in the hind- 

 marginal border. These differences prevail in both sexes ; but the ? is much duller and 

 obscurer than the S , and with faint markings. 



Like A. Zetes, Egina inhabits Sierra Leone and Cape Palmas; but it also occurs in 

 Congo. Prom the latter region only there has been received Papilio Bidley anus, 'White, 

 a very rare butterfly |, which, in pattern and coloration, stands alone in its great genus, 

 though apparently belonging to the Leonidas and Cyrnus group. The likeness which 

 this Papilio bears to A. Egina is very striking ; and on the wing it must with difficulty 



* This speoimea is in the Hope Museum at Oxford, where Professor Westwood kindly pointed it out to me. I have 

 not found Acrcea Zetes recorded as a native of the Zambesi country ; but the presence of P. BoisduvaUi (of the southern 

 form) renders it highly probable that Zetes inhabits that region. 



t The Egina of Stoll (Suppl. Cramer, t. 2.5. f. c, 3 c) is distinct, being a smaller insect, -n-ith only a narrow reddish 

 line along the inner margin of the fore wings and a very narrow black hind-marginal edging to the hind wings. 



t I know of but three examples, viz. a male and female in the British Museum, and a male in Mr. Hewitson's 

 collection. 



