Fig. 416.—Tetrapturus belone, from the Mediterranean. (After Cuvier and Valenciennes.) × ⅒.
The imperfectly known extinct family Palaeorhynchidae, from the seas of the Eocene, Oligocene, and Miocene periods, with the genera Palaeorhynchus and Hemirhynchus, is probably closely related to the Histiophoridae. The vertebrae number 50 to 60, and the ribs completely encircle the body. In Palaeorhynchus both jaws are equally produced into an ensiform weapon. Blochius, from the Eocene, with diamond-shaped, slightly overlapping bony scutes on the body, is perhaps also to be placed near this family.
Fam. 6. Xiphiidae.—Differs from the preceding in the absence of praedentary bone, and in the vertebrae (26 in number), which in the praecaudal region are provided with short but well-developed transverse processes, to which the short ribs are attached. Ventral fins absent, the pectorals being inserted in the place usually occupied by them. Adult without teeth or scales.
A single species, the Sword-Fish (Xiphias gladius), of nearly world-wide distribution, occurring occasionally on the coasts of Great Britain and Ireland.
Fam. 7. Luvaridae.—Mouth small, praemaxillaries not protractile, with very feeble dentition. Gill-membranes attached to the isthmus. Vertebrae 23, without transverse processes; ribs blade-like, inserted on the centra; no epipleurals. Body rough, with minute scales. Dorsal and anal fins elongate, formed of unarticulated, widely set rays. Pectoral fins inserted rather low down; ventrals much reduced, the two halves of the pelvis fused into a single bone. Supraclavicle fused with the forked post-temporal. Hypural bones completely embraced by the forked bases of the caudal rays. Pseudobranchiae present.
Luvarus imperialis, a rare pelagic fish from the Atlantic, Mediterranean, and Pacific, growing to a length of 6 feet, and occasionally captured on our coasts, is the only representative of this family. Very little is known of the habits of this strange fish. The excessive length of the intestines and the feeble dentition point to its feeding partly on vegetable matter, partly on minute animals; the circumstances under which certain specimens were captured tend to indicate that they follow up streams of pelagic life such as engage the attention of the Basking Shark, of similar distribution.
Fam. 8. Coryphaenidae.—Praemaxillaries small, not protractile. Vertebrae 30 to 33, without transverse processes; ribs and epipleurals attached close together on the centra. Body elongate; scales small, cycloid or elongate lanceolate. Dorsal and anal fins much elongate, without distinct spines. Pectoral fins inserted rather low down the side. Pseudobranchiae absent.
The "Dolphins" (Coryphaena), of which only two species can be distinguished, are large pelagic fishes, of carnivorous habits, pursuing the Flying-Fish. They grow to a length of 6 feet, and their flesh is much valued. Their deep head, with short snout, and their long posteriorly attenuate body ending in a large forked caudal fin, give them a peculiar appearance.
Fam. 9. Bramidae.—Praemaxillaries small, not or but feebly protractile; maxillaries large, scaly. Vertebrae 42 to 47, the praecaudal without transverse processes, but mostly with hæmal arches to which the ribs are attached, the epipleurals being inserted on the centra. Body deep; scales moderate or large, strongly imbricate, with processes which, in certain parts at least, serve to connect the rows of scales. Dorsal and anal elongate, some or all of the rays simple, but not forming true spines. Pectoral inserted rather low down the side, freely movable upwards and downwards. Pseudobranchiae present.