561 MR. H. W 
8. Eueides Aliphera, Godart. 
Papilio Aliphera, Godt. Encyclopedic Methodique, t. ix. p. 246. 
A widely distributed species, being found over nearly the whole of tropical America 
It seems to be constant throughout. I met with it at St. Paulo. 
Subfamily ACR^INjE. 
Genus Acr^ea, Fabricius 
1. Acr^a Thalia, Linnaeus. 
Papilio Thalia, Linn. Syst. Nat. ii. 75 7> n. 67- 
, Cramer, Pap. Exot. t. 246. f. A. 
I took (at Para) only one individual of this sole species of Acr&a found in the Amazon 
region 
EXPLANATION OE THE PLATES. 
The Plates are designed to show a few examples out of a great number of mimetic analogies between 
various Lepidopterous insects and the Heliconidae. The insects figured belong to four families, very 
widely dissimilar in structure and metamorphosis : Leptalis (fam. Pieridae), Dioptis (Bombycidae, Moths), 
Stalachtis (fam. Erycinidae), Ithomia, Mechanitis, Metkona (fam. Heliconidae). The figures also illustrate 
the process of the origination of a mimetic species through variation and natural selection. Reasons have 
been given (p. 504 et seq.) for considering the species of Leptalis and Dioptis, amongst others, as having 
been adapted by this process to the species of Stalachtis and the genera of Heliconidae — the colours being 
brought into exact resemblance by the successive preservation of such naturally arising variations as 
tended more and more to resemble. One species only, Leptalis Theono'e, furnishes a good example of the 
process, it being one which, by a rare chance, shows in its existing varieties the process in different stages 
of completion. The figures indicated by a simple numeral represent the adapted forms ; those marked a, 
the species to which they are adapted. 
Plate LV. 
Fig. 1*. Leptalis Theono'e (Hewitson).— Inhabits Cupari, 55° W. long. 
Fig. la. Ithomia Flora (Cramer). — Inhabits Cupari, 55° W. long. ; also the mouth of the Amazons ai 
Surinam. 
Neither of these forms is found further westward on the Tinner Amazons. w r here the followi 
occur 
Leptalis Theono'e, var. Melano 
W 
Fig. 2 a. Ithomia Onega (Hewitson).— Upper Amazons, from 58° to 70° W 
species, is very much larger than the one figured in this Plate. 
Hewitson 
very 
much 
m size. 
