9 
INTRODUCTION. By Dr. A. Seitz. 
rendered unsuitable for the Indian immigrants by the long, cold, and sometimes rainy winter, the type of 
the older Australian lepidopterous fauna is still preserved. The Australian Synemon, Hepialus and Xyleutes, 
Charagio, Oxycanus, Pielus and the remarkable Zelotypia stacyi are such original inhabitants of the land; 
primitive Bombycids, Microlepidoptera, and of the butterflies Satyrids of the genera Heteronympha, Hypocysta 
and Xenica. 
It is not only the seasonal changes that make the Indian Lepidoptera dimorphic. Just the part of 
the Indo-Australian Region that is best adapted for the development of a rich lepidopterous fauna, namely 
the region of the equatorial forests, is broken up into numerous large and small islands and peninsulas by 
Ihe formation of the Malay Sea. According to its position with regard to the trade-winds, in, at or beyond 
the limit of regular winds, almost every one of the Malayan islands has developed a character of 
its own, which can sometimes be sharply distinguished in islands lying close together. We find then that 
on almost every island or group of islands the Lepidoptera of the Indo-Australian Region have developed 
special forms diverging in a definite direction. These characteristics may be very slight and so little 
noticeable that the older authors never mentioned them at all; but they may also be so obvious as to be 
immediately noticed by everyone who works in one of these specialised districts. It was already mentioned 
by A. H. Wallace that most of the Lepidoptera from certain districts of Celebes have a similarly curved 
costal margin of the wings, differing from that of nearly allied species found elsewhere, and L. Kuhlmann, 
who compared the butterflies of Ceram with those of other islands, established the fact that of all the local 
forms of a species the largest almost always occurs on Ceram. 
As a third cause which favourably influences the development of polymorphism, we have specially 
mentioned Mimicry in the general introduction. As almost every one of the often widely separated islands 
has a different model, the mimic was compelled to choose a different garb in the various districts. For 
instance, Papilio polytes, which mimics an Aristolochia-Papilio, occurs everywhere from East China to the 
extreme west of East India. But there is no Aristolochia-Papilio of like distribution; in the Himalayas 
occurs P. aristolochiae, on Ceylon hector and ceylanicus, on Borneo cintiphus, etc. Consequently the mimetic ¥ 
of P. polytes could only wear its polytes-g arb, copied from P. aristolochiae, in the localities of the latter, and 
was obliged on Ceylon as romulus to wear the hector- garb, on Borneo as melanides the antiplms- garb, etc. 
There is no more conclusive evidence for proving that, mimetic imitation is intentional than an exact 
examination and geographical comparison of the various lepidopterous forms of the Indo-Australian fauna. 
It is in the Malay Archipelago that the Indian Region produces the greatest variety of tropical 
lepidopterous forms. From there the number of Lepidoptera decreases most rapidly towards the South. 
The interior Australian desert was impassable for most of Ihe Indian immigrants. Only the narrow strip 
of forest along the east coast of Australia offered to a limited number of the larger butterflies a way to 
advance further south. But on the whole the south of Australia is especially poor in buttertlies, and in 
my wanderings over the profuse carpet of vegetation which one finds in New South Wales, so rich in 
flowers but almost completely without animal life, it often seemed to me inexplicable that a vegetation so 
rich and everywhere so favourable to butterfly life, could be so strangely devoid of it, and even in glorious 
summer weather live and die untasted. 
Towards the East the ocean has permitted no wide distribution of the Malayan lepidopterous world. 
More and more dispersed, more irregular and smaller become (he groups of islands, always more furious 
the seething of the sea at high tide, and always more powerful the storms which lash the coasts of the 
islands. It is precisely these sweeping hurricanes which check the distribution of the delicate-winged 
Lepidoptera and endanger their existence. In my work on the Lepidoptera of the Marshall Islands I have 
expressed the conjecture that the lepidopterous fauna of these remote islands is sometimes partly or almost 
entirely annihilated and has to be formed anew by accidental immigrants. Thus it happens that in some 
parts of the extreme east of the Indian Region there exists no fixed fauna, i. e. composed } r ear in, year 
out of the same species of Lepidoptera, i. e. that a collector 40 } T ears ago must have met with a different 
set of species on certain remote islands from what he would find to-day in the same localities. 
Towards the West the southern limit of the region is in the Indian Ocean. The meagre fauna of 
the Laccadive Islands and the still more insignificant one of Ihe Maldives consist only of scanty forms 
immigrated from India; the Seychelles and Maskarenes have along with many specific forms which however 
are all allied to the Ethiopian type, a thoroughly African fauna, so that the broad strip of sea lying 
between the 60. and 70. degrees of longitude is to be regarded as the faunistic boundary. In its northern 
part the Indian Region touches in South Arabia on the Ethiopian, in North-West India on the Palaeai'ctic 
Region. Where the exact boundary lies in Inner Arabia, which has been as yet but little explored as 
regards Lepidoptera, we cannot at present determine. Maskat is entirely Indian, Aden thoroughly African 
in its lepidopterous fauna. Between these two districts extend deserts, which stretch from Nejd far towards 
the South-East, and reach the sea in the strip of coast, outwardly rocky and inwardly sandy, between 
Makalla and Mirbad. In this border-land there are probably only very few Lepidoptera, principally Noc- 
tuids of the genera Anonds, Eurrhipia, Ophiusa, and some butterflies common to both faunas, such as Junonia 
oenone, Hypolimnas misippus , Lycaena baetica and a few others. 
