TELEOSTEI 



CHAP. 



The best known member of this family is the so-called 

 Electric Eel (Gymnotus electricus), of the Orinoco, Amazons, and 



D 



FIG. 351. Outlines of heads, showing shape of snoxit and position of vent (v). A, 

 Sternarchus albifrons ; B, Sternarchus macrostona ; C, Rhamphosternarchtm 

 curvirostria ; D, Rhamphosternarchus tamandua. 



intermediate river-systems. It grows to a length of 8 feet 

 and the thickness of a man's thigh, and is much feared for the 

 electric shocks it is able to discharge. The " Tremblador," as 

 it is called by the Spanish-speaking inhabitants of the Orinoco 

 district, is found only in marshes and in comparatively shallow 

 parts of rivers, to the great annoyance of travellers who have 

 to ford at such points, beasts of burden being frequently knocked 

 down by the electric shock. Specimens have often been ex- 

 hibited alive in this country ; two brought to London in the 

 year 1842, neither of them weighing more than one pound, had 

 by 1848 reached the weights of 40 and 50 pounds respectively. 

 About four-fifths of the length of the fish is occupied by the 

 tail, which contains the electric organ ; this is formed by modified 

 muscular tissue, and consists of two huge masses, longitudinal 

 bands or columns, of cells filled with a jelly-like substance, 

 occupying the whole of the caudal region below the vertebral 

 column and separated by a narrow median septum ; a smaller 

 body, of similar structure, extends along each side at the base 

 of the anal fin. The whole apparatus is supplied with a great 

 number of nerves branching from the spinal nerves. The 

 electrical apparatus is exercised by the will of the fish, even to 



