FISHES OF BKACKISH WATER. 253 



13. The Mugilidce : both families being most numerous 

 and abundant in brackish water, and almost cosmopolitan. 



14. Many Fleuronectidce prefer the mouths of rivers for 

 the same reason as the Eays; some ascend rivers, as the 

 Flounder, Gynoglossus, etc. 



15. Several Siluridce, as especially the genera Plotosus, 

 Cnidoglanis, Arius, which attain their greatest development 

 in brackish water. 



16. The Gyprinodontidce are frequently found in brackish 

 water. 



17. Species of Glupea, some of which ascend rivers, and 

 become acclimatized in fresh water, as Glupea finta, which 

 has established itself in the lakes of northern Italy. 



18. Ghatoessus, a genus of Clupeoid fishes of the Equatorial 

 Zone, of which some species have spread into the Northern 

 Zone. 



19. Megalops: Equatorial Zone. 



20. Anguilla. The distribution, no less than the mode 

 of propagation, and the habits generally, of the so-called 

 Freghwater-eels still present us with many dif&cult prob- 

 lems. As far as we know at present their birthplace seems 

 to be the coast in the immediate neighbourhood of the 

 mouths of rivers. They are much more frequently found 

 in fresh water than in brackish water, but the distribution of 

 some species proves that they at times migrate by sea as well 

 as by land and river. Thus Anguilla mauritiana is found 

 in almost all the fresh and brackish waters of the islands 

 of the Tropical Indian Ocean and Western Pacific, from 

 the Comoros to the South Sea; Anguilla vulgaris is spread 

 over temperate Europe (exclusive of the system of the 

 Danube, the Black and Caspian Seas), in the Mediterranean 

 district (including the ISTUe and rivers of Syria), and on the 

 Atlantic coast of North America ; Anguilla iostoniensis, in 

 Eastern North America, China, and Japan; Anguilla lati- 



