LINNKAN SOCIETY OF LOXDON. 4I 



iridescence — and oninge bhick-spottetl black-margined bind wings, 

 similar forms with varying amounts ot' white and of orange in the 

 fore wing and of white in the hind ; finally, forms in which this 

 white invasion is so extreme as to form a broad continuous bar 

 crossing both wings. Furthermore there are immense differences 

 in the breadth and the pattern of the dark margin of both wings. 

 Here is a butterfly which seems to present ready-made, in tiie 

 material afforded by female variability, the foundation of half a 

 dozen different mimetic patterns. 



A much less striking but still convincing example of the 

 importance of female variability in tlie origin of mimicry is 

 offered by Pieris na^n described on pp. 27-29. Here the possi- 

 bility for tlie development of new patterns is obviously nuicli 

 greater in the varial)le female than in the constant male. 



A good example of an undoubted but very imperfect mimic — 

 such a mimic as might easily arise from almost any of the female 

 forms of Precis ivestennanni — is afforded by a form of Pseudacrcva 

 aUiostriata common, alrliough not so abundant as the typical non- 

 mimetic form, in the Entebbe disti'ict of Uganda. This local form 

 with its white-barred hintl wing and orange-red marked fore wing 

 is clearly an outlying member of the great assemblage of mimics 

 clustered round the powerful Acrajine models PJanema i>o(jriei and 

 the male of P. macarista. I have only recently realised that it 

 is an evident secondary mimic of another outlying mimic of the 

 Planemas, the male of Acnea altlwffi. In Pseudaorcea alhostriata 

 both sexes are highly dyslegnic, but the female more so than 

 the male ; both have produced the local mimetic form, but the 

 female's is more perfect than the male's. This too was only 

 recently determined when all the best mimics were selected from 

 the series collected by Mr. Neave, and it was found that they 

 were all females and that those left behind were ail males. The 

 sex-linking here is confined to the degree of variiition and does 

 not involve its kind. The male and female are on the same path 

 but the female keeps a little ahead. 



F. PoLYMOKPHic Mimics and the Oiiigin of Mimicuy. 



One of the most interesting and indeed exciting developments 

 of butterfly mimicry in recent years is the immense increase in 

 our knowledge of single species with many polymorphic forms 

 resembling a number of models belonging to different species. 

 The firm and solid foundation of this development lies far back 

 in the three great monographs by Bates, Wallace, and Trimen, 

 published in our Transactions in 1862, 1865, and 1869 *. But 

 wonderful as was the discovery of the polymorphic mimetic 

 females of Oriental Papilios by Wallace and of the African 

 Papilio dcirdamis {merope) by Trimen, naturalists were certainly 



* The two latter papers are often quoted as piibHshed in 1866 and 1870, 

 the dates of the volumes i)i wjjicli tliey appear, but the parts were issued 111 

 each case in the previous year. 



