72. XIPHIID.E XIPHIAS. 419 



the longer. Lateral line wavy and irregular, descending posteriorly. . 

 Head 4^ in length; depth 5. D. VIII-I, 26; A. II, 25. L. 5 feet. 

 In all warm seas, occasional on our Atlantic coast in summer. 



( GasteroHteiw canadus Linn. Syst. Nat. : Elacate atlanticus Cuv. & Val. viii, 334 : Elacate 

 nigra Giinther, ii, 375 ; Holbrook, Iclath. S. Car. 97.) 



FAMILY LXXIL XIPHIID2E. 



(The Sword-fishes.) 



Scombroid fishes of great size, with the body elongated, naked or 

 covered with rough rudimentary scales, and the upper jaw very much 

 prolonged, forming a "sword," which is composed of the consolidated 

 vorner, ethmoid and preinaxillaries. Teeth small and rudimentary, or 

 wanting. Dorsal fin long, usually divided in the adult, continuous in 

 the young, without differentiated spinous part, the posterior portion 

 much smaller than the anterior. Anal fin similarly divided in the 

 adult. Caudal peduncle slender, keeled. Ventral fins thoracic, incom- 

 plete or entirely wanting. Caudal fin widely forked in the adult. Gills 

 of peculiar structure, the laminee of each arch joined into one plate 

 by reticulations. Gills 4, a slit behind fourth ; gill-membranes separate, 

 free from isthmus. Pseudobranchiie present. Branchiostegals 7. Air- 

 bladder present. Pyloric co3ca very numerous. Very young individuals 

 differing much from the adults; the fins high, both jaws prolonged into 

 a beak, and the head armed with long spines. Genera 3; species about 

 5; powerful fishes, inhabiting the open seas, most of them valued as 

 food. (Xipliiidce Giinther, ii, 511-514.) 



a. Ventral fins entirely wanting ; teeth none. (Xipldince') XIPHIAS, 209. 



aa. Ventral fins present ; teeth small. (Histiophorince.) 



6. Ventral rays united into one ; dorsal fin low TETRAPTURUS, 210. 



66. Ventral rays three ; dorsal very high HISTIOPHORUS, 211. 



2O9. XIPHIAS Linnaeus. 

 Sword-fishes. 



(Linn. Syst. Nat. : type Xiphias gladius L.) 



Sword-fishes without teeth and without ventral fins. Body somewhat 

 compressed. Dorsal fins 2, the anterior beginning opposite the gill- 

 openings, falcate and elevated, its height rather less than that of the 

 body ; second dorsal very small, on the tail, opposite the small second 

 anal. In the young, teeth are present and the two dorsal fins are con- 

 nected, the fin being elevated as in the species of Histiophorus. First 

 anal similar to first dorsal, but smaller, less falcate, and far behind it; 



