RTitr'] of some of the Lejoido^tera. 317 
questioned, but there can be no doubt about the two in the plate. 
When the plates containing all the figures are ready, their simi- 
larities and difierences will be apparent. It is to my friend Mr. 
Labrey's industry and information that I owe a knowledge of these 
plumules. I had often examined the insects unsuccessfully : and it 
well might be so ; for these scales are not found in the ordinary 
places, but, as I believe, only in the upper part of the secondary 
wings, where overlapped by the primary and fringing the light- 
coloured patch on the inferior wings ; here they exist in Euploea 
Midamus in large and compact masses, presenting an appearance 
similar to a bed of bulrushes at the edge of a marshy lake. I can- 
not doubt that further search in this genus will be rewarded with 
valuable evidence as to the identity or difference of many species. 
Family V. HELicoNiDiE. — Here I have been able to find plu- 
mules in the genus Heliconia only, but in twenty-six species. They 
are of singular interest in our view of their use for classification and for 
the determination of species. 
Mr. Bates, in his ' Naturahst on the Amazons,' vol. i., p. 256, 
&c. (1863), devotes some pages to show that many species of this 
genus have had a common origin, proving the "manufacture 
of new species in nature." He takes "Melpomene, abundant in 
Guiana, Venezuela, and some parts of New Granada," as the original 
species, and argues that Thelxiope, " ranging 2000 miles from east 
to west, from the mouth of the^ Amazons to the eastern slopes of 
the Andes," is merely a local modification ; and yet he says that 
" if local conditions, acting directly on individuals, had originally 
produced this race or species, they certainly would have caused 
much modification of it in difierent parts of this region; for the 
Upper Amazons country difiers greatly from the district near the 
Atlantic in climate, sequence of seasons, soil, forest-clothing, pe- 
riodical inundations, and so forth." He then proceeds to contend 
" that there is some more subtle agency at work in the segregation 
of a race than the direct operation of external conditions," and that 
the principle of natural selection, as lately propounded by Darwin, 
" seems to offer an intelligible explanation of the facts." 
The plumules, however, enable an observer to detect without 
doubt the species : if those taken from any number of specimens of 
the species Melpomene, Thelxiope, Aoede, and Vesta are examined, 
each can be named ; but mere varieties of each species will exhibit 
the same plumule, as in the case of Thelxiope and Aglaope. Surely, 
if the Darwinian theory were true, that a change is constantly in 
progress, we ought to find plumules of an undecided form in some 
specimens, partaking of and hovering between the characteristics of 
their supposed ancestors. With all deference to Mr. Bates, whose 
opportunities of observation have been great, I cannot but regard 
his theory as improbable and far-fetched. Why should Thelxiope 
have descended from Melpomene rather than the latter from the 
