XXIII ACANTHOPTERYGII 681 
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 (Aiphias gladius), of nearly 
world-wide distribution, occurring occasionally on the coasts of 
Great Britain and Ireland. 
Fam. 7. Luvaridae.—Mouth small, praemaxillaries not pro- 
tractile, 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 pro- 
tractile. 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, 
