TEE ELECTRICAL EEL. 



161 



name of the order (from VTJf.ta, vrji-iaTo?, thread, and 

 yvado'^, jaw) is in allusion to the filaments or barbels 

 growing out from the jaws, and which are characteristic of 

 the members of the group. 



The horned pout {Amiurus atrarius) lays its eggs in 

 holes in gravel during midsummer. The Great Lake cat» 

 fish is sometimes a metre in length. 



In certain Siluroid fish in tropical seas, as Ariiis (Fig. 

 204), the eggs ai-e carried by the males in their mouth, from 

 five to twenty being thus borne about until the young hatch. 

 They are probably caught up after exclusion and fertiliza- 

 tion. Some of these eggs are half an inch in diameter. 



Fig. 204. — Young Arius with its xollc-sac, probably taken from the mouth of its 

 male parent. 



In Aspredo (Fig. 205) the eggs are attached to the out- 

 side of the body by slender stalks. 



Order 5. Teleocephali (cod, perch, trout, etc.). — This 

 group comprises most of the bony fishes; and they are the 

 most specially developed of all fishes. 



Beginning with the lower kinds, we have the electrical 

 eel [Oymnotus eUdricus Linn.) of South America, which 

 is two metres in length, and is characterized by its greatly 

 developed electrical batteries. These are four in number, 

 situated two on each side of the body, and together form 

 nearly the whole lower half of the trunk. The plates of 

 the cells are vertical instead of horizontal, as in the tor- 

 pedo, while the entire batteries or cells are horizontal, in- 

 stead of vertical, as in the electrical ray. The nerves sent 



