Till-: ELECTRICAL EEL. 



161 



name of the order (from nnur, vtjptaroi, thread, 

 yvadoSf jaw) ia in allusion to the filaments <>r barbels 

 growing oul from the jaws, and which are chara ic ul 



Hi.' members of the group. 



The horned pout (Amiurus atrarius) lavs i - in 



holes in gravel during midsummer. The Great Luke 

 fish is sometimes a metre in length. 



In certain Siluroid fish in tropical as A i 



204), i: are 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 I are half an inch in diameter. 



Fig. 204. — Young Arius with its yolk-sac, probably tak--n from the mouth of its 



male parent. 



In Aepredo (Fig. 205) thi ire attached to the out- 



of the body by slender Btal 



der 5. /' ephali (cod perch, trout, —This 



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

 5J specially developed of all fisl 



Beginning with the lower kinds, we have the ■ ical 

 eel (Gymnotus electri s Linn.) of South America, which 

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

 loped 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 plat 

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

 pedo, while the entire batteries or eel's are horizontal, in- 

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



