In Northern Gaul the fish called murÆna has on the right jaw seven spots, which bear a resemblance to the constellation of the Great Dipper, and are of a gold color, shining as long as the animal is alive, but disappearing as soon as it is dead. Vedius Pollio, a Roman of equestrian rank, and one of the friends of the late Emperor Augustus, found a method of exercising his cruelty by means of this animal, for he caused such slaves as had been condemned by him, to be thrown into preserves filled with murÆnÆ; not that the land animals would not have fully sufficed for this purpose, but because he could not see a man so aptly torn to pieces all at once by any other kind of animal. It is said that these fish are driven to madness by the taste of vinegar. Their skin is exceedingly thin; while that of the eel, on the other hand, is much thicker. Verrius informs us that formerly the children of the Roman citizens, while wearing the prÆtexta, were flogged with eel-skins.

There is a very small fish that is in the habit of living among the rocks, and is known as the echeneis.[138] It is believed that when this has attached itself to the keel of a ship its progress is impeded, and from this circumstance it takes its name.

Mucianus speaks of a murex of larger size than the purple murex with a head that is neither rough nor round; and the shell of which is single, and falls in folds on either side. He tells us, also, that some of these creatures once attached themselves to a ship freighted with children of noble birth, and that they stopped its course in full sail. Trebius Niger says that this fish is a foot in length, and that it can retard the course of vessels, five fingers in thickness; besides which, it has another peculiar property—when preserved in salt, and applied, it is able to draw up gold which has fallen into a well, however deep it may happen to be.

The only fish that builds itself a nest is the phycis: it makes it of sea-weed, and there deposits its eggs, which it defends from the attacks of enemies.

The sea-swallow, being able to fly, bears a strong resemblance to the bird of that name; the sea-kite, too, flies as well.

There is a fish that comes up to the surface of the sea, known, from the following circumstance, as the lantern-fish: thrusting from its mouth a tongue that shines like fire, it emits a most brilliant light on calm nights. Another fish, which, from its horns, has received its name, raises them nearly a foot and a-half above the surface of the water. The sea-dragon, again, if caught and thrown on the sand, works out a hole for itself with its muzzle, with the most wonderful celerity.