akk oa hats 
dele E Ange |. Z 
Sheen re Se ae 
kee eles eee Pels 
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an | s 
Gyrinocheilus pustulosus Vaill. + + 
Paracrossochilus vittatus (Blgr.) — — 
Discognathus borneensis Vaill. 5 +0 
Epalzeorhynchus kallopterus Blkr. | -+ ; + + 
Crossochilus oblongus (C.V.) a. + 3 + + + M 
Crossochilus cobitis (Blkr.) + + ; ; + + | 
| 
to the Mahakkam or other neighbouring rivers flowing into Macassar 
Strait. Of the 6 remaining species only 3 (13 °/,) occur also in East 
Sumatran rivers, while 3 other species are distributed over a wider 
range 
When studying the well-defined genera it appears that of the 53 
genera inhabiting the Kapuwas 20 (38°/,) are lacking in the Mahak- 
kam. It strikes us, however, that of these 20 genera as many as 
18 are represented in the East Sumatran rivers. On the other hand, 
the Mahakkam possesses only 36 genera, 33 of which are also found 
in the Kapuwas, only 3 are wanting there, but they are not known 
to exist elsewhere, and are for the present to be considered as 
autochtonous. 
We conclude, therefore, that the Kapuwas does not owe its far 
greater abundance of fish to autochtonous forms, but to such as 
occur also in Kast Sumatra. They point to a former connection with 
Kast Sumatran rivers, which, as alluded to above, finds an explanation 
in the Crorr-PrNcK theory. This constitutes the great difference 
between the Kapuwas and the Mahakkam, though their sources are 
lying only at a few hours’ distance from each other. 
If my reasoning is correct, it must be so also for other groups of 
animals whose distribution underwent some change, anyhow in the 
pleistocene, not only for freshwater-, but also for land-animals. 
For the latter, the land of the Java- and the South China Sea, when 
laid bare, procured apparently the bridges required by zoogeography 
for emigration and immigration of animals. 
Fundamentally this is quite correct; still even such evidence as 
