There is not the slightest reason for regarding the catfishes as direct descendants of the sturgeon or other Ganoid type. They should rather be looked upon as a degenerate and highly modified offshoot from the primitive Characins. =Order Gymnonoti.=—At the end of the series of _Ostariophysans_ we may place the _Gymnonoti_ (γυμνός, bare; νῶτος, 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 excessively 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 _Electrophoridæ_ constitutes by itself Cope's order of _Glanencheli_ (γλανίς, catfish; ἔγχελυς, eel). This group he regards as intermediate between the eel-like catfishes (_Chlarias_) 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 _Gymnotidæ_ 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. _Eigenmannia humboldti_ of the Panama region is a characteristic species. No fossil _Gymnonoti_ are recorded. CHAPTER X THE SCYPHOPHORI, HAPLOMI, AND XENOMI