102 LOWER VERTEBRATES. 



are A. vulgaris (arctogsean), A. marmorata and A. mona (Indian Ocean), and A. 

 megalostoma (Oceanica). 



Eel is the name by which the species of Anguilla are known to all English-speaking 

 peoples, and only where peculiar marine forms of the order are very abundant are the 

 representatives of the genus designated by any qualifying term, such as the fresh-water 

 eel. Local synonyms are unusually few, at least outside of England. 



Fig. 1i. — Anguilla vulgaris, eel. 



Species of the genus are very widely but not universally distributed. In the 

 United States they are found in almost all streams of the eastern slope of the conti- 

 nent having uninterrupted communication with the ocean, but were originally wanting 

 in the great lakes above Niagara, as well as along the Pacific coast. The significance 

 of some of these facts will soon appear. While occurring in fresh water, the same 

 species are also found in salt water. Furthermore, in certain seasons of the year very 

 young eels may be seen ascending the streams, and evidently having come from the 

 salt water, where they must have been bom. In some streams such young eels are 



