

MR. TRIMEN ON MIMETIC ANALOGIES AMONG AFRICAN BUTTERFLIES. 



the insular race constant to one pattern, and not differing greatly from the male ; 1 

 the African female presents four distinct forms (besides certain intermediate Yaric 

 not one of which resembles the male. It would appear reasonable to amue from 



11 



nil. 



ies), 



that Madagascar was the original starting-point of this type of PapUUf, and thai the 

 harder and more complex conditions of African life, causing a severer persecution, had 

 occasioned a necessity for the less active, and perhaps, as now, scarcer ? to assume the 

 protective, colouring and outline of the surrounding Danaidce. Yet the verv widi 



cry 



dispersion of this butterfly over the continent seems rather to indicate that the original 



form of Merope was of African derivation, and at one time had extended to Madagascar, 

 possibly before that region became insulated, but that since that period, during slou ly- 

 changing conditions of life, natural selection has induced the elimination in Africa of 

 all the pale, conspicuous females of the male coloration, only preserving these that 

 more or less resembled the -protected Danaidce— while in Madagascar the female, in 



the absence of any keenly persecuting agency, has retained the form and colour possessed 

 by the first immigrants from the continent. In the broad black costal bar of the for- 



j which distinguishes the female in Madagascar, regarded in relation to the hind- 



o""~~ JL » *~o 



marginal black border, it is not difficult to recognize the material upon which natural 

 selection might gradually work, to the ultimate production of a Danaidiform butterfly 

 like Rippocoon or even Cenea ; and it is remarkable that, in all the African forms of th< 

 female, an oblique, narrow, whitish marking remains near the extremity of the discoidal 

 cell of the fore wings, in a position exactly corresponding to the outer border of the costal 

 bar, as if to record, with the other pale spots and markings, how the black of the margins 

 had gained upon the ground-colour as the process of increasing resemblance to Dana is 

 was slowly wrought out. 



Returning to the subject, from which this has been so lengthy a digression, it is worthy 

 of note that the mimicking Diadema above described seems only to occur at Natal, and 

 correctly copies the variety of Danais Echeria which is there prevalent, viz. that which 

 has all the spots of the fore wings white. 



4. Danais Niavitjs, Linn. (Tab. XLII. fig. 6.) 



danais Niavius, Syst. Nat. ii. p. 766. no. 109 (1767) ; Cram. Pap. Exot. t. 2. figg. E, G. 



This is an abundant butterfly in Tropical Western Africa ; but the only special localities 

 that I have found recorded for it are Sierra Leone, Ashanti, and Angola. In the two 

 former of these districts occur two very accurate imitators of Niavius, viz. Diadema 

 Anthedon, DoubL, and the prevalent West-African form of the ? Papilio Merope (P. 



Fab.). The Papilio has also been received from Calabar. 



It is to this striking case of mimicry that Boisduval refers in the passage which I hav, 

 quoted at the head of this paper. He mentions, it is true, Diadema dubia ; but this is 

 °wing to the confusion that has prevailed regarding the closely allied mimetic Diadema, 

 & Anthedon being the species concerned, and being easily distinguished by the very 

 krge inner-marginal white patch, and broad subapical bar of the fore wings. Cramer, 

 " IW. Westwood has pointed out (Arc. Ent. i. p. 152), figured the Papilio as the ? 



Mmus, in his Plate 234. fig. A; and Palisot de BeauYois subsequently did the same 



