INTRODUCTION. 
fauna is also found on the Nicobar Islands;' and on the deep-water 
islands of the West Sumatran Chain. It has been thought expedient 
however, to exclude Tenasserim and the Nicobars. They are fully 
covered by regional publications dealing with British India and the 
Philippine Islands; their inclusion would be undesirable bibliographi- 
cally; and furthermore, I have no collections or detaited knowledge 
of these areas. It can be noted that their omission is not important for 
they would only add to the list a few geographical races of species 
already included and, in the case of Tenasserim, one or two continental 
species. 
On the other hand the Sunda Shelf includes the Palawan 
groups of islands and Sibutn, of which the avifauna though 
strongly Bornean has a conspicuous Philippine element. As these 
islands are also politically Philippine and fully covered by other 
publications they are excluded from the present work. 
Lastly, purely on grounds of geographical proximity, the Cocos- 
Keeling Islands and Christmas Island in the Indian Ocean are 
included although the natural avifauna of the former is, in the main, 
Oceanic, and of the latter, Austro-Oriental. 
GENERAL FEATURES OF THE MALAYSIAN AVIFAUNA . 
Excluding migratory species (the great majority from the north 
and a small minority from the south-east) many of which in their 
non-breeding season are found everywhere in the subregion from its 
coasts to the tops of its highest mountains, we find that the avifauna 
is more or less sharply divided at an altitude of about 3,000 feet 
although such broad division excludes a small, but not unimportant, 
group of sub-montane forms. The montane forms may, or may not 
be represented in the lowlands by allied sub-species : usually they 
are not. 
On the mountains of Sumatra, Java and Borneo, Sondaic species 
occur together with a geographically more widely spread Himalayo- 
Sondaic element. A third element, more purely Continental (as 
distinct from Himalayo-Sondaic) reaches the Malayan and Sumatra 
mountains. An outstanding feature of the mountain orais is an 
isolated and imperfectly identified element on the Bornean mountains : 
it is either Philippine or Austro-OrientaL 1 * 3 
In the lowlands the Himalayo-Sondaic association which is perhaps 
the palteomalaysian fauna, is lost in the Malaysian, or taking a rather 
broader view, the Indo-Malayan fauna. The Malaysian fauna is 
comparatively even, pointing to land connections geologically not 
1 The Andamans and Nicobars form a part of the mountain range that 
once extended from Cape Negrais in Lower Burma, a continuation of the 
Arakan Yoma. to Achin Head in Sumatra. The Andamans contain an 
impoverished Burmese fauna; that of the Nicobars approximates to the 
Sumatran type- Malcolm Smith, 1931. 
* See Robinson and Kloss, Journ. F.M.S. Mus, viii, 1918, p. g?. 
vi 
