There is a very small fish[2495] that is in the habit of living among the rocks, and is known as the echeneis.[2496] It is believed that when this has attached itself to the keel of a ship its progress is impeded, and that it is from this circumstance that it takes its name.[2497] For this reason, also, it has a disgraceful repute, as being employed in love philtres,[2498] and for the purpose of retarding judgments and legal proceedings—evil properties, which are only compensated by a single merit that it possesses—it is good for staying fluxes of the womb in pregnant women, and preserves the fœtus up to birth: it is never used, however, for food.[2499] Aristotle[2500] is of opinion that this fish has feet, so strong is the resemblance, by reason of the form and position of the fins. Mucianus speaks of a murex[2501] of larger size than the purple, with a head that is neither rough nor round; and the shell of which is single, and falls in folds on either side.[2502] He tells us, also, that some of these creatures once attached themselves to a ship freighted with children[2503] of noble birth, who were being sent by Periander for the purpose of being castrated, and that they stopped its course in full sail; and he further says, that the shell-fish which did this service are duly honoured in the temple of Venus,[2504] at Cnidos. 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.[2505] CHAP. 42. (26.)—FISHES WHICH CHANGE THEIR COLOUR. The mæna changes[2506] its white colour, and in summer becomes swarthy. The phycis[2507] also changes its colour, and while at other times it is white, in spring it is parti-coloured. This last is the only fish that builds itself a nest; it makes it of sea-weed, and there deposits its eggs. CHAP. 43.—FISHES WHICH FLY ABOVE THE WATER.—THE SEA-SWALLOW.—THE FISH THAT SHINES IN THE NIGHT.—THE HORNED FISH.—THE SEA-DRAGON. The sea-swallow,[2508] being able to fly, bears a strong resemblance to the bird of that name; the sea-kite[2509] too, flies as well. (27.) There is a fish that comes up to the surface of the sea, known, from the following circumstance, as the lantern-fish:[2510] 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,[2511] raises them nearly a foot and a half above the surface of the water. The sea-dragon,[2512] again, if caught and thrown on the sand, works out a hole for itself with its muzzle, with the most wonderful celerity. CHAP. 44. (28.)—FISHES WHICH HAVE NO BLOOD.—FISHES KNOWN AS SOFT FISH.