LIXXEAX SOCIETY OF LOXDOX. 45 



ill the locality." The origin of the Uganda mimic was suggested 

 in these words * : — " It is probable that by spontaneous variation 

 a white band .... appeared in the ancestral form .... and that 

 this was from the very first sufficient to confer some advantage 



by suggesting the appearance of a dominant Model Prom 



tliis point Natural Selection acting on further variations produced 

 the detailed likeness which we see in the white band itself and 

 in ttie other mimetic features." After these words were written 

 tlie oppoi-tunity was afforded me of studying Mr. S. A. Neave's 

 ci)llecti()n of butterflies from the Semliki Valley the W. boundary 

 of Uganda, and the forest patches near it. " In his whole collec- 

 tion from this part of Uganda there is not a single mimetic female 

 alciope of the eastern [viz. E. Uganda] type : there are many 

 females of the western type, and of these a considerable proportion 

 bear the incipient bar developed to a very variable extent, and 

 sometimes appenring on the under surface alone. Here, then, 

 in the very zone of country where, on the theory of mimicry, 

 we should exj^ect them to be, we meet with the earliest stage of 

 the eastern mimic, but, so far as we know, never the fiuished 

 product" t. 



The results cannot be explained by cliuiate or any other of the 

 physico-chemical influences of a locality, for the ancestral stage 

 persists into E. Uganda although it is very rare as compared 

 with the fully-developed mimic J. 



I conclude this set-tion with the following general statement 

 made nearly three years ago § : — " I have always recognised that 

 the first variation must be something appreciable, something 

 which, at any rate, at a distance and on the wing would recall 

 the pattern of the model. Mimicry is far more characteristic of 

 forest species than of those living in the open, and Mr. C. F. M. 

 Swynnerton has made the reasonable suggestion that the origin 

 of mimicry is facilitated by the alternating light and shade of a 

 tropical forest, where it is easy to confuse patterns readily distin- 

 guishable imder ordinary conditions of illumination" ||. 



I wish to emphasise these earlier statements because, as will 

 ajipear in the next section, my position has recently been 

 misunderstood. 



a. The Beginning of Mimicry in the North American IVi/mphcdine 

 Bntterjl;i, Limenitis archippus. — One of the most beautiful and 

 elaborate examples of butterfly mimicry in the world is found in a 

 North American " White x'^dnn'ral " (Limenitis) whose pattern has 

 been profoundly modified in mimicry of invading Danaines. The 



* Bedrock, Apr. 19f2, p 63. 

 t Bedrock, Oct. 1913, p. 303. 

 + Bedrock, A])!-. 1914, pp. 35, 36. 

 § Bedrock, Oct. 1913, p. 301. 



II For the special development of mitnicry in forest areas, see Proc. Ent, 

 S:ic. Lund., 1911*. pp. l^Iiii. 



