One genus only is known, Pegasus. Its pectoral fins are broad, horizontal, long, composed of simple rays, some of which are sometimes spinous. Ventral fins one- or two-rayed. Upper part of the snout produced into a shorter or longer process. Mouth inferior, toothless. Suborbital ring well developed, forming a suture with the gill-cover. Vertebræ in small number, thin; no ribs. Four species are known, two of which are of a shorter, and the two others of a longer form. The former are P. draconis, common in the Indian Ocean, and P. volans, which is frequently stuck by the Chinese into the insect-boxes which they manufacture for sale. The two elongate species, P. natans and P. lancifer, are from the Chinese and Australian coasts. They are all very small fishes, probably living on sandy shoal places near the coast.
Fig. 217.—Pegasus natans.
Ninth Division—Acanthopterygii Gobiiformes.
The spinous dorsal, or spinous portion of the dorsal is always present, short, either composed of flexible spines, or much less developed than the soft; the soft dorsal and anal of equal extent. No bony stay for the angle of the præoperculum. Ventrals thoracic or jugular, if present, composed of one spine and five, rarely four, soft rays. A prominent anal papilla.
Shore-fishes, mostly exclusively marine, but some entering and living in fresh waters.
First Family—Discoboli.
Body thick or oblong, naked or tubercular. Teeth small. Ventral fins with one spine and five rays, all being rudimentary and forming the osseous support of a round disk, which is surrounded by a cutaneous fringe. Gill-openings narrow, the gill-membranes being attached to the isthmus.
Carnivorous fishes, living at the bottom of the shores of northern seas. By their ventral disk they are enabled to attach themselves very firmly to rocks.
Cyclopterus.—Body thick, short, covered with a viscous, tubercular skin. Head large, snout short. Villiform teeth in the jaws, none on the palate. Skeleton soft, with but little earthy matter.