DISTRIBUTION OF FEESHWATEK FISHES. 211 



10. Galaxias is equally represented in Southern Australia, 

 New Zealand, and the southern parts of South America. 



G. Families identical in distant continents — 



1. The Lahyrinthici, represented in Africa by 5, and in 

 India by 25 species. 



2. The Ghromides, represented in Africa by 25, and in 

 South America by 80 species. 



3. The Characinidce, represented in Africa by 35, and in 

 South America by 226 species. 



4. The Maplochitonidce, represented in Southern Australia 

 by one, in New Zealand by one, and in Patagonia by a third 

 species. 



This list could be much increased from the families 

 of Siluridce and Gyprinidce, but as these have a greater 

 range than the other Freshwater fishes, they do not illus- 

 trate with equal force the object for which the list has been 

 composed. 



The ways in which the dispersal of Freshwater fishes has 

 been effected were various ; they are probably all still in opera- 

 tion, but most work so slowly and imperceptibly as to escape 

 direct observation ; perhaps, they wiU. be more conspicuous, 

 after science and scientific inquiry shall have reached to a 

 somewhat greater age. From the great number of fresh- 

 water forms which we see at this present day acclimatised 

 in, gradually acclimatising themselves in, or periodically or 

 sporadically migrating into,' the sea, we must conclude that, 

 under certain circumstances, salt water may cease to be an 

 impassable barrier at some period of the existence of fresh- 

 water species, and that many of them have passed from one 

 river through salt water into another. Secondly, the head- 

 waters of some of the grandest rivers, the mouths of which 

 are at opposite ends of the continents which they drain, are 



