DISTEIBUTION OF FEESHWATER FISHES. 217 



although more numerous, showing no great variety of struc- 

 ture, aU belonging to the same group {Amiurina). Towards 

 the south their progress was still slower, Tasmania, New 

 Zealand, and Patagonia being without representatives, whilst 

 the streams of the Andes of Chili are inhabited by a few 

 dwarfed forms identical with such as are characteristic of 

 similar localities in the more northern and warmer parts of 

 the South American continent. 



After these preliminary remarks we propose the following 

 division of the fauna of Freshwater fishes : — 



I. The Northern Zone. — Characterised by Acipenseridse. 



Few Siluridffi. Numerous Cyprinidse. Salmonidee, 

 Esocidse. 



1. Eur opo- Asiatic or Palcearctic Region. — Characterised 



by absence of osseous Ganoidei ; Cobitidoe and 

 Barbus numerous. 



2. North American Eegion. — Characterised by osseous 



Ganoidei, Amiurina, and Catostomina ; but no Cobi- 

 tid£e or Barbus. 



II. The Equatorial Zone. — Characterised by the develop- 



ment of Siluridse. 



A. Cyprinoid Division. — Characterised by presence of 

 Cyprinidse and Labyrinthici. 



1. Indian Region. — Characterised by [absence of 



Dipnoi ^] Ophiocephalidce, Mastacembelidae. 

 Cobitidse numerous. 



2. African Region. — Characterised by presence 



of Dipnoi and Polypteridse. Chromides and 

 Characinidse numerous. Mormyridce. Cobi- 

 tidse absent. 



1 Will probably be found. 



