248 The Geographical Distribution of Fishes 



parallel series. Yet the fauna of Polynesia is strictly East 

 Indian, modified by the omission or alteration of species, and 

 that of Australia is Indian at the north, and changes to the 

 southward much as that of Africa does. In its marine fishes, 

 it does not constitute a distinct "realm." The East Atlantic 

 (Europe-African) series follows the same general lines of change 

 as that of the West Atlantic. It extends, -however, only to the 

 South Temperate Zone, developing no Antarctic elements. The 

 relative shortness of Africa explains in large degree, as already 

 shown, the similarity between the tropical elements in the two 

 Old-World series, as the similarity in tropical elements in the 

 two American series must be due to a former depression of the 

 connecting Isthmus. The practical unity of the Arctic marine 

 fauna needs no explanation in view of the present shore lines 

 of the Arctic Ocean. 



Minor Faunal Areas. — The minor faunal areas of shore fishes 

 may be grouped as follows ; 



East Atlantic. 



Icelandic, 



British, 



Mediterranean, 



Guinean, 



Cape. 



West Atlantic. 



Greenlandic, 



New England, 



Virginian, 



Austroriparian , 



Floridian, 



Antilkean, 



Caribbean, 



Brazilian, 



Argentinan, 



Patagonian. 



East Pacific. 



Arctic, 



Aleutian, 



Sitkan, 



Califomian, 



San Diegan, 



Sinaloan, 



Panamanian, 



Peruvian, 



Revillagigedan, 



Galapagan, 



Chilian, 



Patagonian. 



West Pacific. 



Arctic, 



Aleutian, 



Kurile, 



Hokkaido, 



Nippon, 



Chinese, 



East Indian, 



Polynesian, 



Hawaiian, 



Indian, 



Arabian, 



Madagascarian, 



Cape, 



North Australian, 



Tasmanian, 



New Zealand, 



Antarctic. 



Equatorial Fishes Most Specialized. — In general, the dif- 

 ferent types are most highly specialized in equatorial waters. 

 The processes of specific change, through natural selection or 



