414 
these soundings have been carried out on behalf of the navigation, 
consequently with the object to discover and to map the shallow 
parts rather than the deeper portions of the seas concerned. 
Now when consulting the published charts *) and the original sheets 
one can, indeed, gather from them something (though not much) 
about the course of the larger rivers in the pleistocene Sunda-peneplain. 
First of all it appears that in this peneplain the chief watershed 
ran between the Bali Sea and the China Sea from Sumatra across 
the present islands of Banea, Billiton, through Karimata-strait, and 
further on across the Karimata-islands towards Borneo. It may 
be called the Karimata-divide. Again, from the trace of the 
isobath of 40 fathoms we conclude that from the China Sea a bay 
(see Fig. 1) eut deep into the land between the islands of Great- 
Natuna and Subi. At its entrance this bay is wide, but it narrows 
towards the south and passes into a large stream, which, coming 
from the south, empties itself into it. That main river flowed west 
of the Tambelan-islands and closely past the Badas-island and can 
be traced towards the south almost as far as Pedjantan-island. 
This large river, which drained the whole. Sunda-peneplain 
north of the Karimata-divide, presumably received on the right 
the Kapuwas and the Sambas as principal tributaries and on the 
left the Musi and the Djambi, which, however, may have united 
before they had reached the main stream. The submarine course of 
the Kapuwas is feebly indicated by a gully which is the direct 
prolongation of the Pungur-branch, while the ancient bed of the 
Musi is represented straight along the north-west coast of Banca by a 
gully with depths of 20—25 fathoms. On the existing charts the 
Kapuwas gully cannot be traced beyond Datu-island, the Musi-gully 
no farther than the meridian of the northern extremity of Banca, 
so the data, borrowed from the charts, render it just probable that 
the Kapuwas and the Musi did empty themselves into the main 
stream in the way indicated on map N°. 1. They do not afford 
conclusive evidence ”). 
1) The charts which have been published, give only some of the soundings; their 
whole number is to be found on the original sheets which are kept in the depart- 
ment of hydrography of the Navy. 
1 take this opportunity of acknowledging my indebtedness to the Director of 
that Department, Captain Puarr, for his kindness in granting me perusal of these 
original sheets. 
2) After this paper has been read Mr. H. M. van Weer, then commander of the 
surveying-vessel Brak, has been able to compile another chart with lines of equal 
depths from fresh data then available. From that map the powerful riversystem which 
