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Sumatra. The distribution of fens in the low regions along the 
north-east coast is very extensive. To these belong in the first place 
the paja-soils of Langkat, Deli, Serdang etc. (residency Sumatra’s 
East coast) which a comparatively short time ago were still swamps, 
but have now been reclaimed for tobacco-growing. 
The swampy region drained by the Little Siak river which has 
not yet been examined, probably contains fens, because one of the 
lakes bears the name Tasik Ajer Itam, and therefore must be counted 
among the black waters. 
The Great Siak river also belong to the black waters. Peat strata 
have been found along its banks above and below Siak Sri Indrapura. 
A fen region of about 80.000 hectares lies between the Siak and 
Kampar rivers. Although known before, it was more closely examined 
in 1891, at the time of the expedition under J. W. IJzerman, by 
S. H. Koorders, especially as regards its flora. There are also exten¬ 
sive fen regions south of the Kampar. The Batang Nila is a black 
river and one of its affluents is called Ajer Itam. 
In Djambi peat strata were found by S. C. Crookk as early as 
1820. In the low countries of Djambi there is an Ajer Itam Latit 
and in the subdivision Lower Tambesi an Ajer Itam is known. 
The residency Palembang is very rich in swamps. In lat. 3°29' S. 
and long. 104°55' E. there is a lake Danau Ajer Itam which is 
drained by the Ajer Itam. An Ajer Itam Laut has its mouth in lat. 
l^O' S., an Ajer Itam Dalam in lat. I°13'S. An Ajer Itam is further 
found in the subdivision Ogan Ulu and Enim, and another one in 
the subdivision Ranau districts. 
Most fens in Sumatra owe their existence to the fact, that in 
consequence of the deposit of sludge etc. the beds are constantly 
raised, so that the banks are also higher than the surrounding 
country. In the lowest portions of the depressions thus formed 
between the rivers, lakes and swamps were formed which gave rise 
to peat formation. 
Fens are known in the island Bengkalis , and probably it will also 
be possible to show their presence in the neighbouring islands of 
Kupat, Padang , Rantau etc. which are also marshy. 
In the island of Bangka there is an Ajer Itam with a village of 
the same name, in the district Pangkal Pinang, north of the place 
of that name. 
Borneo. C. A. L. M. Schwaner was the first to draw attention to 
the extensive fen formations in the South and East Division. He has 
urther pointed out that the lakes along the Barito and the Kapuwas 
Murung represent river branches (Danau Kalabin, D. Masura, D. 
