879 
apparent diversion from the original pattern is attributed to the 
influence of natural selection, leading gradually to a perfect though 
wholly superficial and spurious similarity with the model. 
In order to be able to accept this hypothesis, it is obvious 
that we are obliged first to prove the assumed deviation from the 
primitive common type of the genus or family. We ougbt to abstain 
from accepting it a priori as a fixed truth, but should try to recon- 
struct the original common genus- or family-type of colour- 
design by a perfectly impartial comparative investigation of all the 
existing members of the group, mimetic as well as non-mimetic, 
judging them exclusively after the features of their markings, without 
the least regard to any biological profit these markings might possibly 
procure them. 
The value of these considerations can best be appreciated by their 
application to a few concrete examples. 
In the famous paper of Barres on the resemblance between members 
of the Pierid genus Dismorphia (Leptalis) and certain South-A merican 
Ithomiids and Heliconids, the author figures a perfectly white species 
of the said genus, side by side with the mimetic forms, and expressly 
states that this represents the original type of that family. It neces- 
sarily follows that he considers the mimetics as widely deviated 
from this type. Punnett, in the chapter on “Mimicry Batesian and 
Müllerian” of his valuable critical review ‘“Mimicry in Butterflies”, 
expressly puts forward that this is the current view among the 
supporters of the mimicry-theory, where he says: “We come back 
to our Pierine, which must be assumed to show the general charac- 
ters and coloration of the family of whites to which they belong”... 
and “If however they could exchange their normal dress for one 
resembling that of the Ithomiines”. (The italics are mine). 
Doubtless Barns did not for a moment presume that the case 
might as well be exactly the reverse: the mimetics representing the 
more original, least altered forms, while the whites, under the pre- 
vailing influence of albinism, have considerably departed from the 
primitive condition. 
To make a choice between these two opposite views, we must in 
the first place undertake a careful and complete investigation of the 
various colour-patterns of all the members of the genus Dismorphia 
and different other genera of Pierids, and after that come to a clear 
understanding about the real nature of the differences between the 
mimetic and non-mimetic forms. 
These differences can be summarized under three heads: those of 
pattern, of hue and of shape. 
