EELS. 
273 
soft and leathery. The intestines are not fur- 
nished with caeca ; but the air-bladder is generally 
well- develop e d . 
About one hundred and fifty species are recog- 
nised as constituting this Family, some of which 
are exclusively marine, others exclusively fiuvia- 
tile ; while others, as our own common Eels, are 
found in both salt and fresh waters. They are 
widely scattered over most parts of the globe. 
One of the most curious forms of the Family is 
that of the Gymnotus or Electric Eel, containing 
a few species peculiar to the rivers of tropical 
South America. The species best known, which 
has been exhibited alive in England, attains a 
length of five or six feet, with a diameter of eight 
inches. It has the power of communicating elec- 
tric shocks of such violence, that the largest ani- 
mals are stunned, and even destroyed by them. 
The organ which possesses this truly formidable 
power, consists of two large bundles of tendinous 
fibres on each side, occupying the hinder regions 
of the animal’s body ; these are crossed at right 
angles by other plates of the same kind, and thus 
a wide and deep network of cells is formed, each 
filled with a tremulous jelly; the whole organ 
may be likened to a powerful voltaic battery. 
Contact is not necessary for the exercise of its 
powers ; it is said that shocks sufficient to kill 
other fishes are communicated through water to a 
distance of five or six yards. 
Genus Anguilla. (Cuv.) 
The pectoral fins are well developed, though 
small, in this genus ; the dorsal and anal are con- 
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