Origin of the Fauna of Celebes. 129 



Sunda Islands. That they are, perhaps, less numerous in the 

 latter locality I have already tried to explain by the fact that 

 a given amount of water can only harbour a certain number of 

 fishes. The western islands possess fishes peculiar to their 

 rivers, and these are wanting in the eastern islands, where a 

 more abundant immigration is rendered possible. 



2. True freshwater fishes, which also belong to the Oriental 

 region. We may cite Dules, JJapIochiton, and, if we go 

 further, Toxotes, Gobi'us, Eleotris, Agonostoma, Anguilla. 



3. True freshwater fishes, which are absent from the Indian 

 Archipelago, east of the " Wallace line." These are Gera- 

 todus, Osteoglossum, Oh'gorus, G ataxias. 



With the exception of Osteoglossum, which occurs in Borneo 

 and Sumatra, it is just these fish characteristic of Australia 

 that are absent both east and west of the " Wallace line." 

 The similarity of the freshwater fishes of Australia and 

 Celebes rests therefore on the following points : — 



1. The Cyprinidae, Mastacembelidae, Nandoidse, belonging 

 to the Oriental region, are absent. 



2. Siluridaj are represented only by marine immigrants. 



3. Numerous marine forms inhabit the fresh water. 

 There are, however, considerable differences : — 



1. Ceratodus, Osteoglossum, Oligorus, Oalaxias, forms 

 characteristic of Australia, are absent. 



2. On the other hand, Celebes has certain genera belonging 

 to the Indian region which are wanting in Australia — Anabas, 

 Ophiocephalus, ISymbranchus, Monopterus. 



Opposed to these positive differences there remains a simi- 

 larity in negative characters, which rests on an absence of a 

 number of Indian forms in Celebes as well as in Australia. 

 It may be expressed thus : — Australia and Celebes agree in 

 poverty of freshwater fishes ; Australia has some forms 

 peculiar to itself which do not occur in Celebes ; on the other 

 hand, Celebes possesses some forms which belong to the 

 Indian region and do not occur in Australia. Thus the 

 character of the fish-fauna of Celebes is not Australian, but 

 Indian, and that in a high degree impoverished. 



4. How CAN THE Fish-fauna of Celebes be explained? 



From the foregoing statements it may be seen that the 

 freshwater fauna of Celebes is principally recruited by immi- 

 gration from the sea, and that only isolated representatives 

 of true freshwater fishes [Ophiocephalus striatus, Bl., Anabas 

 scondens, Laid., Haplcchilus celebensis, M. V\ eb., Monopterus 

 javanensis, Lac, i^^i/inbranchus bengalensis, M'Clell.) are 



