250 DARWINISM chap. 



triplets that resemble each other is usually a species of the large 

 and handsome genus Heliconius, the others being species of 

 the genera Mechanitis, Melinaea, or Tithorea, though several 

 species of other Danaoid genera also imitate each other. The 

 following lists will give some idea of the number of these 

 curious imitative forms, and of their presence in every part of 

 the Neotropical area. The bracketed species are those that 

 resemble each other so closely that the difference is not per- 

 ceptible when they are on the wing. 



In the Lower Amazon region are found— 



f Heliconius sylvana. 

 \ Melinsea egina. 



C Heliconius numata. 

 -! Melinsea mneme. 

 ^ Tithorea harmonia. 



i Methona psidii. 

 ( Thyridia ino. 



{ Ceratina ninonia. 

 \ Melinsea mnasias. 



In Central America are found — 



(Heliconius zuleika. 

 Melinsea hezia. 

 Mechanitis sp. 



[ Heliconius formosus. 

 | Tithorea penthias. 



n , -, { Heliconius telchina. 

 Guatemala j Melin[ea ^.^ 



In the Upper Amazon region — 



Heliconius pardalinus. 

 Melinsea pardalis. 



Heliconius aurora. 

 Melinsea lucifer. 



In New Grenada — 



/Heliconius ismenius. 

 \ Melinsea messatis. 

 ( Heliconius messene. 

 -J Melinsea mesenina. 

 ((?) Mechanitis sp. 



Heliconius hecalesia. 



Tithorea hecalesina. 



Heliconius hecuba. 



Tithorea bonplandi. 



