INTRODUCTION. 
Banka and Billiton are closely allied but by no means exactly alike 
and include a few not very distinctive, subspecies. Fresh material 
on which a critical examination of races in the modern way can be 
based is needed from Banka, but in the meantime it can be stated that 
the avifaunas are largely what could be expected from the map posi- 
tions, Basically, Malay -Sumatran, there is a strong Bornean influence 
in Billiton which is less strongly marked in Banka. 
The islands of the West Sumatra Chain 1 * are of special interest 
for, collectively, they contain many well-marked bird-races, although 
taking the broad view followed in this handlist, no peculiar species 3 . 
In their fauna the islands vary much among themselves, and some- 
times from Sumatra. There is no proof that this island chain ever 
formed one land-mass, or that all the islands were ever joined to 
Sumatra and the whole archipelago cannot be treated as an entity. 
There is reason for regarding the deeper water islands, that is those 
outside the one-hundred fathom line (Simalur, the Mentawi Islands, 
and Engano) as forming a zoo-geographical province, small in area, 
but equal in value to the four other provinces here adopted. Those 
within the forty -fathom line, the Batu and Banjak Islands, have a few 
subspecies of their own, but these are not so distinct as some on the 
deeper water islands of Simalur and the Mentawi group where most 
of the land birds are peculiar to the islands. Nias also has a number 
of subspecies of its own, but these are not so well marked as the 
most distinctive of the Mentawi races and quite a number of the 
Nias birds seem inseparable from Sumatran forms. 
THE BORNEAN PROVINCE .3 
Borneo and its coastal islands, the most important of which are 
Labuan, and MamJanani off the north-west coast; Maratua, off the 
cast coast; and Pulau haul off the south-east corner; the North Bornean 
Islands of Banguey, Balambangan, and MallewalU; the North and 
South Natuna Islands; the Karimata Islands . 
The outstanding feature of the avifauna of Borneo is that although 
it has the general Malaysian facies it is more specialized than that of 
the Malayan and Sumatran, and if consideration is limited to the 
high-level fauna, even the Javan, Province. 
The avifauna is by no means even, either in the mountains, or in 
the lowlands, and there are several obvious faunal boundaries in the 
island. The most striking, if not the most efficacious of these is 
* See Kloss, Proc. Zool. Soc., 1027, p. 797. 
a The mammals include an isolated genus of Monkeys ( Sintias ), a 
very distinct langur ( Pygathrix poUnzxani), and other very peculiar forms. 
3 The basic literature from the systematic view-point can be obtained 
by reference to.— Moulton, Journ. Straits Br. Rov. Asian Soc. 67, JO 14. 
p, 125 (Borneo); Chasen and Kloss, Bull. Raffles Mus., 4, [930 (Borneo 
and the coastal islands); Oberholser, Bull. U.S. Nat, Mus. 159, 1932 
(Natuna Islands); Chasen and Kloss, Treubia, xiv, 1933, p. 155 (Karimata 
Islands). 
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