THE ELECTRICAL EEL. 
161 
name of the order (from vr/^ay vrffxaro^y thread, and 
yvado^y jaw) is in alhision to the filaments or barbels 
growing out from the jaws, and which are characteristic of 
the members of the group. 
The horned pout (Amiiirus 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 Arms (Fig. 
204), the eggs 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 these eggs are half an inch in diameter. 
Fig. 204.— Young Arius with its yolk-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 b. Teleocephali (cod, percli, 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 {Gymnotus electricus 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 
