ala 
several directions which the male never possessed. The black 
female of Papilio hectorides ESP. (1794), the dark females of 
Papilio macareus GODART (1819), the females of Papilio andro- 
geos CRAM. (1775) and 2. lycophron HuùBN. (18187), etc., may 
also be mentioned as examples. 
However, it remains nevertheless true that in many instances 
the male of mimetic females is much more advanced than these on 
the road towards monochromatism, and that it has followed its 
own road unarrested. Considering that mimetic resemblance can 
never be a disadvantage, natural selection by means of predaceous 
enemies cannot give a satisfactory answer to the question, why and 
how the coloration of males like those of Papilio polytes and @geus, 
which are non-mimetic and represent a late phvletic stage, has 
been evolved. The theory of evolution by constitutional forces 
appears to step naturally into the breach : the male, as the less 
important sex for the maintenance of the species, being left alone 
by natural selection, followed its line of evolution, whose course 
depended on internal factors aided and guided by the physical 
environment. On the other hand, the systematics of the polymorphic 
females of these same species offer unsurmountable obstacles for a 
similar explanation of their coloration. As the same point comes 
up again, we propose to deal with it later, and now proceed to 
consider some illustrations of heterotrope resemblance which 
obtains in doth sexes. 
The Oriental Papilio clytia L. (1756) is a well-known instance of 
that kind of similarity. The species is strongly dimorphic, one form 
being spotted with white (f. clytia, pl. XXIII, fig. 11a) and the 
other streaked with white (f. dissimilis, pl. XXIII, fig. 100). The 
sexes are practically alike in each form. 
The two forms are very sharply separated in markings in most 
districts, although each form varies considerably in many places. 
The specimens figured are from South India. In North India, 
however, specimens of the c/y&a-form occur which bear grey 
streaks extending down to the base of the wings, and are clearly a 
connecting link between f. clytia and f. dissimilis. The sharply cut 
dimorphism breaks down. The fact is instructive. In order to 
understand a species and its bearing on general questions, it is 
necessary for the philosopher as well as the systematist to study 
the Insect from all districts of its range. Our species illustrates admi- 
rably how different the variation may be in the geographical races 
, 
