THE BONY FISHES. 



159 



They are probably caught up after exclusion and fertiliza- 

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



In Aspredo (Fig. 163) the eggs are attached to the out- 

 side of the body by slender stalks. 



The Order of Teleocephali (cod, perch, trout, etc.) 

 comprises most of the bony fishes; and they are, on the 

 whole, the most perfectly deyel- 

 oped of all fishes. 



Beginning with the lower 

 kinds, we have thie electrical eel 

 {Oymnotus elect rims Linn.) of 

 South America, which is two 

 metres in length, and is charac- 

 terized by its greatly-developed 

 electrical batteries. These are 

 four in number, situated two on 

 each side of the body, and to- 

 gether form nearly the whole 

 lower half of the trunk. The 

 plates of the cells are vertical 

 instead of horizontal, as in the 

 torpedo, while the entire batte- 

 ries or cells are horizontal, in- 

 stead of vertical, as in the elec- 

 trical ray. The nerves sent to 

 the batteries of the eel are sup- 

 plied by the ventral branches of 

 about two hundred pairs of spi- 

 nal nerves. 



Succeeding these fish are the 

 herrings, represented by the 

 common English herring, Clupea liarengus, which inhab- 

 its both sides of the North Atlantic, extending on the 

 American side from the Polar regions to Cape Cod; the 

 alewife (Pomolobus pseudoharengus), which ranges from 

 Newfoundland to Florida; the shad {Alosa sapidissima), 

 which has the same geographical distribution as the ale- 



Fio. 163.— Aspredo, a Siluroid flsh, 

 with little sacs filled with eggs at- 

 tached by slender stalks. 



