4 
INTRODUCTION. By Dr. A. Seitz. 
As what is known of the biology of most of the species has been outlined in the main volumes, and as 
what has been said there concerning the classification and groups should be sufficient for the purpose of “The 
Macrolepidoptera”, the whole space in the supplement has been used for information regarding the differences 
between the various genera, species and their varieties. But even then it looked as if the enormously accumu¬ 
lating material would cause the text of the supplement to outgrow the size of the main Work. Space could 
not be found for details of all the chief differences of thousands of forms, however superficially dealt with, and 
as a rule only the most important and most apparent distinctions have been mentioned in the supplement. 
There is no room for critical discussion. As regards contents, the supplements follow closely the original volumes 
of the original work. Recognising that it is not yet possible to show a perfect genealogical sequence of species, 
no alteration has been made that might conflict with the order of the main Work. The classification already 
applied by classical authors has scarcely been altered so as to avoid any conflict which would be detrimental 
to progress. 
The geographical delineation is exactly the same as that given in the original Work. There was no 
work in existence in 1905 dealing with this difficult subject which might have given the necessary guidance 
when the program for the Work was drawn up, so that the author had to decide for himself. A joiuney of 
exploration was undertaken by him of the palaearctic southern frontier in Asia and Africa with a view to 
studying this subject and after having crossed the boundary line in China some 18 times, making observations 
and notes both by day and night, he formed the opinions as set forth briefly in the ,,Verhandlung der Deutschen 
Zoolog. Gesellschaft” (minutes of the German Zoological Society P. 16). The results ascertained are due to 
statistical observations. All species met with in one country have not been assembled as forming a separate 
fauna as formerly was done. On the contrary allowance has been made for the different characteristics observed 
on entering a territory. 
Naturalists of earlier days who had not the advantage of making personal observations were forced 
to group together all species known to occur in a certain territory and it was impossible for them to judge what 
part each species played in their surroundings. No consideration was given to the question of natural conditions 
and the possibilities of migration of the various species. This caused vast territories to be described as inter¬ 
mediate or transitory districts between the clearly defined frontiers of distinct Fauna. As a matter of fact the 
characteristics of the Fauna often seem to change quite suddenly. Species that appeared in great numbers 
suddenly become rare and others that we had hardly noticed become more plentiful with every step we take. 
This state of affairs cannot be shown of course in statistics of the names of insects occurring in any given frontier 
and this has often led to the importance of such boundaries being underestimated. 
For instance the Southern Island of Japan, Kiushiu, with its genuine Indian Lepidoptera was declared 
to be a transitory district (that is to say belonging to the Indo-Australian Fauna) because Danais Chrysippus, 
Plexippus, Vulgaris and Papilio Memnon, Mikado and other undoubtedly Indian Species occur there. However, 
over a period of 7 months in the neigbourhood of Nagasaki, during which over 30 collecting excursions were 
made I found myself surrounded by Pieris Napi, Colias Hyale, Satyrus Dryas, Limentis Sibylla, Chrysophamis 
Phlaeas, Lycaena Argia etc. I also found forms of Apatura Ilia, Vanessa Xanthomelas and Glauconia so that 
the general impression made on me was one of a genuine Palaearctic Landscape. On the other hand in consequence 
of the appearance of a few cosmopolitan insects or northern insects invading Indo-Australian territory some 
authors ascribe the Island of Formosa (whose main features are undoubtedly Indo-Australian) to the Palaearctic 
region. This would be incorrect even for the Riukiu Islands which lie to the North of Formosa. From a 
thorough examination of the collections of Dr. Fritze at Okinawa which I was able to make at Tokyo I 
ascertained that the Fauna of the Lutchu Islands is undoubtedly Indian. Nor was I able to discover palaearctic 
characteristics in the insects of the southern slope of the Himalayas which clearly belong to the Indian Fauna. 
Assam and Burma with their mountain districts of Khasia and Naga have nothing in common with palaearctic 
Fauna and even the extreme south-eastern districts of Thibet and the entire southern part of the Chinese Western 
provinces are purely Indian in character: Ta-tsien-lu and Siao-lu are borderland districts in which palaearctic 
forms are being displaced by Indian fauna. The boundary line becomes more complicated in those districts 
that are intersected by tropical deep-cut valleys lying between high mountain ranges running from north to 
south, in which tropical insects invade palaearctic zones and where palaearctic species which naturally prefer 
more temperate climes appear far to the south on the high and cold mountain ridges: in such districts both 
Fauna are interspersed. 
Precisely the same conclusions as I reached in 1890—92 in my studies of the Macrolepidoptera of Eastern 
Asia were also drawn by Caradja in his researches among the Microlepidoptera of Asia. He also states that 
the line of demarcation between palaearctic and tropical Fauna is exactly and well defined. It begins in the 
Bay of Hangchow, proceeds via Nanking, following approximately the 30th degree of latitude. In the Punjab 
it recedes far to the north so that in Cashmir the whole of the southern slopes of the Himalayas and the hot 
