OF THE AMAZON VALLEY. 
505 
Itkomia of the locality being thus changed, how stands it with the Lcptalides ? They 
are changed also, and again with close reference to the Ithomia?. I found a number of 
different varieties, which I could not doubt were local forms of the same species as that 
found on the Cupari and at Ega. Thus, there was one (PI. LV. fig. 2) closely resembling 
L. Theonoe (fig. 1), but modified to produce a nearer imitation of the Itkomia Onega 
(PI. LV. fig. 2 a), which I believe to be a local form of I. Flora. Another (PI. LVI. fig. 3) 
resembled Ithomia Chrysodonia (PI. LVI. fig. 3 a) ; but the imitation is not fixed or exact 
in all the specimens taken, as may be seen by comparing figs. 1, 2, 3, of the same Plate. 
We here detect nature, as it were, striving after a correct imitation : the explanation of 
this will be attempted further on. A third form of Leptalis found at St. Paulo is the 
one figured PI. LVI. fig. 6, which mimics the Ithomia Virginia (PL LVI. fig. 6a). 
Besides these, a few varieties occurred which did not closely counterfeit any Ithomia ; 
they were very much rarer than the others. I figure two of these (PI. LV. figs. 7, 9), to 
show how they connect the other more strongly modified varieties with the Ega forms. 
(r 
The Ithomia? concerned in these imitations have the character of true speci 
distinct and constant, with the exception of I Chrysodonia, whose varieties are detailed 
under the head of the species, which is variable, and throws light on the origin of the 
rest. They are all excessively numerous in individuals, swarms of each kind being found 
in the localities they inhabit. The Leptalidcs are exceedingly rare; they cannot be 
more than as 1 to 1000 with regard to the Ithomia?. It may be asked, how can we knon 
they are all varieties (using the term as meaning forms descended from others) of one 
species ? I must refer to the figures given, which, although they do not include all the 
connecting varieties that were collected, show how nearly all the forms are linked to- 
gether. The most distinct amongst them are those figured PL LVI. figs. 4 and 6. The 
feature which distinguishes fig. 4 is the white colour of the disk of the hind wings, and 
the veins which traverse it. This character is shown to be due to variation, from the 
facts that Ithomia Oncidia, an undoubted variety of I. Chrysodonia (or Orolina), exhibits 
a commencement of this milky shade of the wings, and that many individuals of I. Iter- 
dina (PL LVI. fig. 4 a) display steps of modification in the colours of the vems. The 
variety figured PL LVI. fig. 6, appears distinct, from the single pale spot near the tips of 
the wings ; an approximation to this is seen in the variety figured PL LV. fig. 9, which 
is an undoubted modification of L. Lysinoe (PL LV. fig. 3). The remarkable variety 
figured PI LV fi°*. 4 has been described by the only author who has treated on these 
insects (Mr. Hewltson) as a variety of L. Lysinoe. In a polymorphic form, like this 
Leptalis, none of the varieties can be taken from the rest and denominated species, 
(using the term as meaning forms which cannot have descended from other closely allied 
ones), without exercising the art of species-making in the most arbitrary manner. Eor if 
we allow so great a latitude to variation as that from figs. 3 to 4, o, 6, 7, 8, and 9, PL L V ., 
how can we venture to say that natural modification, having gone so far, was incompetent 
to go further, so as to produce figs. 4 and 6, PL LVI., and that those forms must have 
arisen by some unknown agency ? It is true, they have not arisen by simple variation 
or 
jporfe, in one generation, bnt, as we shall presently see, by an external 
umulating the modifications of many generations in two diverging directions 
o Y Z 
As 
