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. 
( Heliconius numata. 
-J Melinsea mneme. 
t Tithorea liarnionia. 
i Methona psidii. 
( Thyridia ino. 
i Ceratina ninonia. 
( Melinsea mnasias. 
In Central America are found — 
Nicaragua 
Guatemala 
Heliconius zuleika. 
Melinsea hezia. 
Mechanitis sp. 
Heliconius formosus. 
Tithorea penthias. 
Heliconius telchina. 
Melinsea imitata. 
In the Upper Amazon region— 
\ Heliconius pardalinus. 
\ Melinsea pardalis. 
( Heliconius aurora. 
( Melinsea lucifer. 
In New Grenada— 
f Heliconius ismenius. 
\ Melinsea messatis. 
f Heliconius messene. 
4 Melinsea mesenina. 
((?) Mechanitis sp. 
i Heliconius hecalesia. 
\ Tithorea hecalesina. 
\ Heliconius hecuba. 
| Tithorea bonplandi. 
