Three species; small pelagic fishes from the Mediterranean and Atlantic.—Sudis, from the Mediterranean, has a dentition slightly different from that of Paralepis.
Plagyodus.—Body elongate, compressed, scaleless; snout much produced, with very wide cleft of the mouth. Intermaxillary very long and slender; maxillary thin, immovable. Teeth in the jaws and of the palate very unequal in size, the majority pointed and sharp, some very large and lanceolate. Eye large. Pectoral and ventral fins well developed; the rayed dorsal fin occupies the whole length of the back from the occiput to opposite the anal fin; adipose and anal fins of moderate size. Caudal forked. Branchiostegals six or seven.
Fig. 270.—Plagyodus ferox.
This is one of the largest and most formidable deep-sea fishes. One species only is well known, P. ferox, from Madeira and the sea off Tasmania; other species have been noticed from Cuba and the North Pacific, but it is not evident in what respects they differ specifically from P. ferox. This fish grows to a length of six feet, and from the stomach of one example have been taken several Octopods, Crustaceans, Ascidians, a young Brama, twelve young Boar-fishes, a Horse-mackerel, and one young of its own species. The stomach is coecal; the commencement of the intestine has extremely thick walls, its inner surface being cellular, like the lung of a reptile; a pyloric appendage is absent. All the bones are extremely thin, light, and flexible, containing very little earthy matter; singular is the development of a system of abdominal ribs, symmetrically arranged on both sides, and extending the whole length of the abdomen. Perfect specimens are rarely obtained on account of the want of coherence of the muscular and osseous parts, caused by the diminution of pressure when the fish reaches the surface of the water. The exact depth at which Plagyodus lives is not known; probably it never rises above a depth of 300 fathoms.
The other less important genera belonging to this family are Aulopus, Chlorophthalmus, Scopelosaurus, Odontostomus, and Nannobrachium.
Fig. 271.—Pharyngeal bones and teeth of the Bream, Abramis brama.
Third Family—Cyprinidæ.
Body generally covered with scales; head naked. Margin of the upper jaw formed by the intermaxillaries. Belly rounded, or, if trenchant, without ossifications. No adipose fin. Stomach without blind sac. Pyloric appendages none. Mouth toothless; lower pharyngeal bones well developed, falciform, sub-parallel to the branchial arches, provided with teeth, which are arranged in one, two, or three series. Air-bladder large, divided into an anterior and posterior portion by a constriction, or into a right or left portion, enclosed in an osseous capsule. Ovarian sacs closed.