INTRODUCTION. 
THE SUMATRAN PROVINCE.' 
Sumatra and the shallow water islands off its east coast with which 
the islands of the Rhio, and Lingga Archipelagos are intimately related . 
The large islands of Banka and Billiton. The whole of the chain 
of islands off the west coast of Sumatra, the most important of which 
from north to south are, Simalur, the Banjak Islands , Nias, the 
Batu Islands, the Mentawi Islands [Siberut, Sipora, and the Pagi 
Islands), and Engano. 
In spite of the much larger size of the island, the avifauna of 
Sumatra is less rich than that of the geographically more favourably 
situated Malay Peninsula, but the two faunas are very closely allied. 
That of Sumatra shows rather more specialization : it lacks some 
continental forms, but on the other hand there is present a Sunda Island 
element. Sumatra has a few peculiar species and numbers of well- 
differentiated subspecies, but as in the Malay Peninsula no genus, 
or highly peculiar form is found (Gymnocrotaphus and Chalcocomus 
are not here recognized}, although the occurrence of Rimator, other- 
wise only known from the Himalayas, is remarkable. In the extreme 
south of the island there is a minor infiltration of Javanese forms. 
Most subspecific differentiation within the island is north against 
south, but in a few cases races on the alluvial flats of the east coast 
are not the same as those occupying the older land in the west : In 
such cases the western race approximates to the Javan and the eastern 
to the Malayan subspecies. 
An interesting item is that a broadbill (Sm 7 {>/>/twsr) on the 
mountains of Acbeen in the north of Sumatra is inseparable from the 
Malay States subspecies, geographically near and opposite, whereas 
the bird occupying the remainder of Sumatra, that is to the south, 
is more like that found in the north of the Malay Peninsula. 
The faunal boundary which cleaves the island from north to south 
is the Barisan Range in which the only major depression, that in the 
neighbourhood of Padang Sidempuan, Rat, i ° 30' N,, forms a second 
barrier, a number of subspecies being confined to the island north 
of this place* , The low-lying islands on the east coast of Sumatra 
call for no special remark. 
The Rhio and Lingga Archipelagos contain a poor avifauna com- 
posed of species common to the lowlands of central-east Sumatra and 
the south of the Malay Peninsula. The only degree of specialization 
seems to be an almost imperceptible divergence in the direction of 
races found in the Anamba and Natuna Islands. The avifaunas of 
* The basic literature for this province is, or is summarized in, the 
following papers. — Sumatra: Rob. and Kloss, Journ. F.M.S. Mus., viii, 
pt. 2, iQifS, p. 81; Kloss, Treubia, xiii, U) 3 i, p. 29Q. Rhio Archipelago: 
Chasen, Bull, Raffles Mus., 5, iq 3 '. P- Lingga Archipelago: 
Dammerman, Treubia, viii, 1926, p. 325* Banka: Kloss, l.e.s. Billiton: 
Kloss, Treubia xiii, 1931, p. 293. West Sumatran Islands: Chas. and 
Kloss, Ibis, 1026, p. 306; Riley, Proe. U.S. Nat. Mus,, Ixxv, Art. 4* 
igzg. p. 1. 
3 See Kloss, Treubia, xiii, 1931, p, 301. 
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