The Nematognathi, or Catfishes 187 



Order Gymnonoti. At the end of the series of Ostariophysans 

 we may place the Gymnonoti (yv^vo?, bare; rcoros, back). This 

 group contains about thirty species of fishes from the rivers 

 of South America and Central America. All are eel-like in 

 form, though the skeleton with the shoulder-girdle suspended 

 from the cranium is quite unlike that of a true eel. There is 

 no dorsal fin. The vent is at the throat and the anal is ex- 

 cessively long. The gill-opening is small as in the eel, and as 

 in most elongate fishes, the ventral fins are undeveloped. The 

 body is naked or covered with small scales. 



Two families are recognized, differing widely in appearance. 

 The Electro <phorid<z constitutes by itself Cope's order of Glanen- 

 cheli (yXavis, catfish; eyx ^ rs > ee l)- This group he regards 

 as intermediate between the eel-like catfishes (Chlartas) and 

 the true eels. It is naked and eel-shaped, with a short 

 head and projecting lower jaw like that of the true eel. The 

 single species, Electrophorus electricus, inhabits the rivers of 

 Brazil, reaching a length of six feet, and is the most powerful of 

 all electric fishes. Its electric organs on the tail are derived 

 from modified muscular tissue. They are described on -p. 170, 

 Vol. I. 



The Gymnotidcz are much smaller in size, with compressed 

 scaly bodies and the mouth at the end of a long snout. The 

 numerous species are all fishes without electric organs. Eigen- 

 mannia humboldti of the Panama region is a characteristic 

 species. No fossil Gymnonoti are recorded. 



