218 FISHES. 



B. Acyprinoid Division. — Characterised by absence of 

 Cyprinidse and Labyrinthici. 



1. Tropical American Region. — Characterised by 



presence of Dipnoi. Chromides and Chara- 

 cinidse numerous. Gymnotidse. 



2. Tropical Pacific Region. — Characterised by 



presence of Dij)noi. Chromides and Chara- 

 cinidse absent. 



III. The Southern Zone. — Characterised by absence of 

 Cyprinidse, and scarcity of Siluridge. Haplochitonidse 

 and GaLaxiidse rejDresent the Salmonoids and Esoces of 

 the Northern zone. One region only. 



1. Antarctic Region. — Characterised by the small number 

 of species ; the fishes of — 



a. The Tasmanian sub-region ; 

 h. The New Zealand subreuion ; 

 c. The Patagonian sub-region ; 

 being almost identical.^ 



In the following detailed account we begin with a descrip- 

 tion of the equatorial zone, this being the one from which the 

 two principal famiHes of freshwater fishes seem to have 

 spread. 



I. Equatoeial Zone. 



Eoughly speaking, the borders of this zoological zone 

 coincide with the geographical limits of the tropical zone, 

 the tropics of the Cancer and Capricorn ; its characteristic 

 forms, however, extend in undulating lines several degrees 

 north and southwards. Commencing from the west coast of 



^ We distinguish these sub-regions, because their distinction is justified by 

 other classes of animals ; as regards freshwater fishes their distinctness is even 

 less than that between Europe and Northern Asia. 



