group of Butterfiies, Potaro District, British Guiana. 417 



a collection of these brown and black insects is found on 

 thu EupatoTiuiii flowers, it is not so invariably. On May 

 14th, 1901, I remember being disappointed (from the 

 collector's point of view), in coming upon a bush where 

 there were only Mechanitis polymnia and Ceratinia euclea 

 {G. philidas and C. hendis) present. Such a case as this 

 clearly shows the value it is to these members to have 

 been brought into harmony with the colours of the 

 dominant Melin^ea mneme. As although these species are 

 only commencing to conform to the main colouring of the 

 model they are able even among themselves to alight on 

 these flowers and be comparatively immune from danger. 

 It would have been interesting had every specimen of 

 Meliniea mneme been retained to see the accurate propor- 

 tions of the difierent forms. I have actually kept 70 set 

 specimens, and these are divided up as follows : — 



Melina^a mneme. 



Hind-wing distinctly banded 40 = 57 % 



Hind-wing obscurely banded 22 = 31 2% 



Hind-wing with band obliterated 8 = 11|% 



Thus only 1 in 9 is heavily black, and this I have more 

 than once verified to be the approximate percentage. 



A further interesting phase of variation is the presence 

 or absence of the red marks just before the yellow apical 

 band on fore-wing. The specimens give these figures : — 



Upper-side and 

 Under-side 



These comparative figures are of great interest, as 

 although this species is so dominant in point of numbers, 

 the influence it exerts with its dark forms is very small 

 indeed compared with that of its banded forms. It there- 

 fore becomes tolerably clear that the allied Melinaia, — 

 crameri — which, although, not nearly such a common 

 species, but has a very constant black pattern, must 

 have acted very strongly to create the powerful darkening 

 tendency in the hind- wing. 



