580 TELEOSTEI CHAP. 
The best known member of this family is the so-called 
Electric Eel (Gymnotus electricus), of the Orinoco, Amazons, and 
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Fic. 351.—Outlines of heads, showing shape of snout and position of vent (wv). A, 
Sternarchus albifrons; B, Sternarchus macrostoma,; C, Rhuimphosternarchus 
curvirostris ; 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-lke 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 
