KEY TO THE FAMILIES OF FRESH- WATER FISHES OF MAINE 



1. Mouth a sucker-like disc without jawsj gill openings seven j paired fins 

 absent 



Sea Lamprey 



^o . '^ * " ^ ^-^ Petromyzonidae 



p. 11 



Mouth with true jawsj gill slits four, covered by an operculum j 

 paired fins present 2 



2. Tail not symmetrical (heterocercal), caudal vertebrae extending into 

 the upper lobe of the tail 



Atlantic Sturgeon 

 Acipenseridae 

 p. 12 



Tail more or less symmetrical (homocercal) 3 



3. Body eel-shaped J ventral fins absent 



American Eel 

 Anguillidae 

 p. 40 



Body not eel-shaped j ventral fins present 4 



