ptera (butterflies and moths) that the
most numerous cases of variation have been observed, and every good
collection of these insects affords striking examples. I will first
adduce the testimony of Mr. Bates, who speaks of the butterflies of the
Amazon valley exhibiting innumerable local varieties or races, while
some species showed great individual variability. Of the beautiful
Mechanitis Polymnia he says, that at Ega on the Upper Amazons, "it
varies not only in general colour and pattern, but also very
considerably in the shape of the wings, especially in the male sex."
Again, at St. Paulo, Ithomia Orolina exhibits four distinct varieties,
all occurring together, and these differ not only in colour but in form,
one variety being described as having the fore wings much elongated in
the male, while another is much larger and has "the hind wings in the
male different in shape." Of Heliconius Numata Mr. Bates says: "This
species is so variable that it is difficult to find two examples exactly
alike," while "it varies in structure as well as in colours. The wings
are sometimes broader, sometimes narrower; and their edges are simple in
some examples and festooned in others." Of another species of the same
genus, H. melpomene, ten distinct varieties are described all more or
less connected by intermediate forms, and four of these varieties were
obtained at one locality, Serpa on the north bank of the Amazon.
Ceratina Ninonia is another of these very unstable species exhibiting
many local varieties which are, however, incomplete and connected by
intermediate forms; while the several species of the genus Lycorea all
vary to such an extent as almost to link them together, so that Mr.
Bates thinks they might all fairly be considered as varieties of one
species only.

Turning to the Eastern Hemisphere we have in Papilio Severus a species
which exhibits a large amount of simple variation, in the presence or
absence of a pale patch on the upper wings, in the brown submarginal
marks on the lower wings, in the form and extent of the yellow band, and
in the size of the specimens. The most extreme forms, as well as the
intermediate ones, are often found in one locality and in company with
each other. A small butterfly (Terias hecabe) ranges over the whole of
the Indian and Malayan regions to Australia, and everywhere exhibits
great variations, many of which have been described as distinct species;
but a gentleman in Australia bred two