The Eels belong to the family of bony Fishes, although the Lampreys
which they resemble in general appearance, belong to the family of
Fishes whose framework is made up of cartilage, or gristle. The Eels
form a very large family if we would include the different kinds of bony
Fishes that have the same snake-like form of the common Eel. We find
these smaller families classed under the name of Apoda; this word means
without feet when applied to animals, but when used to describe Fishes,
means without the ventral fins which serve in the place of feet.
As the different kinds of Eels found under this family of Apoda are
described by their Greek or Latin names, it will be well for us to
understand the meaning of each of the four divisions. We would hardly
recognize the plain Sand Eel, when we find him classed with “Osseous
Fishes” under the name of “Ammodytes,” yet this is where the Naturalists
place him, because this word in Latin means a sand-burrower, a kind of
serpent, and is also derived from two Greek words meaning sand, and
diver. The Electrical Eel is classed under fresh water Fishes under the
name of Gymnotus, which comes from two Greek words meaning naked and
back, showing that the back of the Electrical Eel is without fins. The
Sea Eel is classed under the name of Muraenas, while Anguilla, which
means snaky, serpent-like, is used to describe the plain Eels with
smooth bodies and very few of the characteristics which distinguish the
other Eels.
We will simply give all these different kinds of Eels their plain common
name, but when we read of wonderful fresh water Fishes called Gymnotus
Electricus, who have strange electrical powers, we will know the word is
used to describe the Electrical Eel.