Cuap. VI. NATURAL SELECTION. 137 
to its former shape when brought by natural redistribution into contact 
with it.* 
* If this explanation of the derivation of Heliconius Thelxiope be true, the origina- 
tion by natural process of a host of now distinct allied species of this genus, as well 
as, in fact, all other genera containing numerous closely related species, will have 
to be admitted. A species allied to H. Thelxiope, namely, H. Vesta, seems to have 
been derived also from H. Melpomene, for amongst the numerous varieties already 
mentioned are many examples intermediate between the two. There is this difference, 
however, between H. Thelxiope and H. Vesta: the former is confined in its range to 
the Amazons valley, whilst H. Vesta extends beyond this region over Guiana and the 
central valleys of the Andes; it seems, therefore, to have acquired a power of adapta- 
tion to a much wider diversity of local conditions. Insects seem to be well adapted 
to furnish data in illustration of this interesting but difficult subject. This arises 
chiefly from the ease with which ample suites of specimens can be obtained for com- 
parison from many points in the areas of distribution, both of species and varieties. 
It is scarcely necessary to add that the conclusions thus arrived at will apply to all 
organic beings. 
