XXIII ACANTHOPTERYGII 68 1 



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 pro- 

 tractile, with very feeble dentition. G-ill-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 " {Coryphaenci), 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. 



