INTRODUCTION. By Dr. A. Seitz. 
5 
plains adjoining thereto present a purely Indian Fauna. On the high ridges and plateaux, and in part also in 
the lower and cooler valleys the insects on the other hand show palaearctic characteristics. 
Near Peshawar and beyond over the 24th degree of latitude the Indian Fauna retreats again to the 
south in Afghanistan leaving the cooler northern districts to the palaearctic animal world. The high plateau 
of Persia is decidedly palaearctic except for the narrow southern slope extending down to the Persian Gulf. 
Stoney Arabic Petraea is separated by a broad zone almost bare of animal life around the Tropic of Cancer 
from the more Ethiopian Arabia Felix, especially the Yemen, which again is bordered by the entirely lifeless 
Hadramaut. To the East of this near Muskat Indian Fauna again reappear. 
The southern boundary of the palaearctic region forms itself very naturally in Africa. Egypt being 
almost devoid of insects reaches to the south in the deserts of Assouan, a sandy waste with scarcely any insect 
life. In Abyssinia and the Soudan we then find an entirely different animal world which has changed its 
character and is now purely Ethiopian. Scarcely any insect has been able to cross the endless waste of the 
Sahara Desert, large stretches of which are bare of vegetation. There is no possibility of a migration or inter¬ 
mixing of the Ethiopian and the palaearctic Fauna. Rio de Oro being almost bare of insect life also separates 
the Fauna and as to the Islands which may be called outposts to this district, the Canary Islands, are purely 
palaearctic, whilst the Cape Verde Islands are unquestionably Ethiopian. 
It is clear therefore that perhaps with the exception of the more or less unexplored mountain districts 
in the Interior of China and South-Eastern Thibet there are no difficulties in the demarcation of the Palaearctic 
Region. The entire first part of “The Macrolepidoptera” has been drafted in accordance with the principles 
enunciated above and the supplementary volumes will deal with the subject in precisely the same way. It will 
always be possible that certain species inhabiting the frontier-districts will cross these boundaries. Only where 
this occasional invasion appears highly probable the species are mentioned in both regions. All Asiatic Insects 
found missing in the palaearctic zone will be found in the Indo-Australian Volumes and the Africans (with 
the adjoining Arabians) among the Ethiopian Fauna. 
