On the Amazonian waters is found the carapus, called by the Brazilians
sarapo, belonging to the genus Gymnotus; though far smaller than the
electric gymnotus. They are very numerous, and the most lively of the
whole group. Their motions are winding and rapid, like those of the
eel; but yet different, inasmuch as they do not glide quickly forward,
but turn frequent somersaults, and constantly change their direction.