122 Prof. Dr. Max Weber on the 



1. What Differences are exhibited between the 

 Eastern and Western Portions of the Archipelago, 

 as regards the freshwater flshes ? 



The comparison of Sumatra, Borneo, and Java, on the one 

 hand, with Celebes, Flores, &c. (in short, those islands lying 

 to the east of the larger ones), on the other, shows at once a 

 marked falling off in the number of species of freshwater 

 fishes. 



One is, perhaps, at first inclined to explain this fact by the 

 smaller size of the individual islands in the eastern, as com- 

 pared with the western, portion of the Archipelago. The 

 area of fresh water, both rivers and lakes, must, of course, 

 from the nature of things, bear a certain proportion to the size 

 of the island. The smaller island will possess, on the whole, 

 a less developed and less extensive river-system, and thereby 

 be less adapted for the formation of a rich fish-fauna. 

 Further, the form of the island and the disposition of its 

 mountains have a proportionate influence. A glance at the 

 map shows, for instance, that Flores can possess only very 

 small insignificant rivers, and that also in Java, or on the 

 east [? west — Translator] coast of Sumatra, the rivers can 

 attain to only a small degree of development. 



The size and configuration of the island, with the con- 

 current formation of rivers and lakes, are factors which must 

 be taken into account in considering the peculiarities of the 

 interesting fish-fauna of fresh water. These present, how- 

 ever, no satisfactory explanation of the above-mentioned 

 decrease in the number of species of freshwater fishes in the 

 eastern portion of the Archipelago. This may be at once 

 seen in the case of Celebes as compared with Java. Celebes 

 has an area of 178,833 square kilom., while Java has 

 125,896 square kilom. ; and the opportunities for the forma- 

 tion of a freshwater fauna under present conditions are no 

 less favourable than in Java. As a proof of this I would 

 point out the river-system of the Tjenrana, in the south-west 

 peninsula of Celebes, concerning the extent of which there 

 exist careful estimates by A. Wichmann * ; and I myself 

 was able to collect here more or less extensively. According 

 to Wichmann, the river-system of the Tjenrana embraces an 



* A. Wichmann, " Die Binnenseen von Celebes,'' in Petermann's 

 Mittb. 1893, Heft, x., xi., and xii. Compare also A. Wichmnnn, " Be- 

 ricbt iib. eine Reise im Ind. Archipel," in Tijdschr. Koninklijk Neder- 

 landscb Aardrijksknndig Genootscbap, 1890, pp. 47-49, and idem, 1892, 

 pp. 299, 300. 



