Fig. 252.—Aphyonus gelatinosus.
One specimen only of this most remarkable form is known; it is 5½ inches long, and was obtained at a depth of 1400 fathoms south of New Guinea.
Of the remaining genera belonging to this group, Brotulophis, Halidesmus, Dinematichthys, and Bythites are surface forms; Sirembo and Pteridium inhabit moderate depths; Rhinonus is a deep-sea fish.
II. Ventral fins replaced by a pair of bifid filaments (barbels) inserted below the glossohyal: Ophidiinæ.
Ophidium.—Body elongate, compressed, covered with very small scales. Eye of moderate size. All the teeth small.
Small fishes from the Atlantic and Pacific. Seven species are known, differing from one another in the structure of the air-bladder (see p. 145).
Genypterus is a larger form of Ophidium, in which the outer series of teeth in the jaws and the single palatine series contains strong teeth.
Three species from the Cape of Good Hope, South Australia, New Zealand, and Chili are known. They grow to a length of five feet, and have an excellent flesh, like cod, well adapted for curing. At the Cape they are known by the name of “Klipvisch,” and in New Zealand as “Ling” or “Cloudy Bay Cod.”
III. No ventral fins whatever; vent at the throat: Fierasferina.
These fishes (Fierasfer and Encheliophis) are of very small size and eel-like in shape; the ten species known are found in the Mediterranean, Atlantic, and Indo-Pacific. As far as is known they live parasitically in cavities of other marine animals, accompany Medusæ, and more especially penetrate into the respiratory cavities of Star-fishes and Holothurians. Not rarely they attempt other animals less suited for their habits, as, for instance, Bivalves; and cases are known in which they have been found imprisoned below the mantle of the Mollusk, or covered over with a layer of the pearly substance secreted by it. They are perfectly harmless to their host, and merely seek for themselves a safe habitation, feeding on the animalcules which enter with the water the cavity inhabited by them.