134 MIMICRY AND VARIATION [ch. 



test of breeding, through which alone we can hope to 

 arrive at a satisfactory verdict upon any given case. 



The particular geographical variation which has 

 just been considered happens to be a small one. But it 

 may happen that a geographical variety is much more 

 distinct. Indeed it is not impossible that butterflies 

 which are at present ranked as distinct species may 

 prove eventually to be different forms of the same 

 species. Especially is this hkely to be true of many 

 forms in South America, of which Bates long ago 

 remarked "that the suspicion of many of the species 

 being nothing more than local modifications of other 

 forms has proved to be well founded." Since Bates' 

 day more material has been forthcomifng^ and it has 

 been shewn that certain colour schemes are character- 

 istic of distinct geographical regions in South America 

 where they may occur in species belonging to very 

 diferent genera and families. In Central America, for 

 example, the pattern common to many species is deter- 

 mined by horizontal and oblique black bands on a bright 

 fulvous brown ground, with two broken yellow bars 

 towards the tip of the fore wing. The general type is 

 well shewn by Mechanitis satwata and the female of 

 Dismorphia praxinoe (PL X, figs. 7 and 3). Belongiag 

 to this pattern group are a number of different speeieS 

 belonging to various families, including several Heli- 

 conines and Ithomiines, Pierids such as Dismorphia 

 and Perrhybris, Nymphalines of the genera Eresia and 



1 See Moulton, J. C, Trans. Ent. Soe. London, 1909. 



