256 TROPICAL NATURE, AND OTHER ESSAYS. 



green colour not found in any other continent/ Again, 

 we have a group of African Pieridae which are white 

 or pale yellow with a marginal row of bead-like black 

 spots ; and in the same country one of the Lycaenidse 

 {Leptena erastus) is coloured so exactly like these that 

 it was at first described as a species of Pieris. None of 

 these four groups are known to be in any way specially 

 protected, so that the resemblance cannot be due to 

 protective mimicry. 



In South America we have far more striking cases ; 

 for in the three subfamilies Danainae, Acraeinae, and 

 Heliconiinae, all of which are specially protected, we 

 find identical tints and patterns reproduced, often in the 

 greatest detail, each peculiar type of coloration being 

 characteristic of separate geographical subdivisions of 

 the continent. Nine very distinct genera are implicated 

 in these parallel changes — Lycorea, Ceratinia, Mecha- 

 nitis, Ithomia, Melinaea, Tithorea, Acraea, Heliconius, 

 and Eueides, groups of three or four (or even five) of 

 them appearing together in the same livery in one 

 district, while in an adjoining district most or all of 

 them undergo a simultaneous change of coloration or of 

 marking. Thus in the genera Ithomia, Mechanitis, 

 and Heliconius we have species with yellow apical spots 

 in Guiana, all represented by allied species with white 

 apical spots in South Brazil. In Mechanitis, Melinaea, 

 and Heliconius, and sometimes in Tithorea, the species 

 of the Southern Andes (Bolivia and Peru) are charac- 

 terized by an orange and black livery, while those of 

 the Northern Andes (New Granada) are almost always 



^ Romaleosoma and Euryphene (Nymphalidse), Fapilio zalmo'xis and 

 several species of the Nireus-group (Papilionidse). 



A. 



