FAMILY SCOMBRID.E. Ill 



GENUS XIPHIAS. Linneus, Cuvier. 



TJie upper jaw elongated into a sword. Body fusiform, covered tvith minute scales. No 

 ventral fins. Mouth, luithout teeth. Sides of the tail ridged. 



THE COMMON SWORD-FISH. 



XiPHUS GLADIUS. 



PLATE XXVI. FIG. 79. One-sixteexth or the natur.il size. 



Xtphias gladius. Linneus, Syst. Nat. 12 Ed. p. 432. 



X id.. Sword-fish. Mitchill, Am. Month. Mag. Vol. 2, p. 242. 



Z'Espadon cpcc, X. gladius. Cnv. et V,4l. Hist, des Poiss. Vol. 8, p. 255, pi. 225 ; and 226, adult and young. 



The Sword-fish, X. id. Storer, Massachusetts Report, p. 51. 



Characteristics. Dorsal fin in the young, single ; becoming effaced in the middle, and forming 

 two distant fins in the adult. Length 10-15 feel. 



Description. Surface of the body and head very slightly roughened in the young, of a foot 

 or eighteen inches long. There are numerous series of tubercles on the body, which disap- 

 pear with age. Lateral line scarcely perceptible, except near the opercles, where it is 

 irregularly sinuous. A lateral carina on, each side of the tail, from 6-8 inches long; the 

 caudal portion with a transverse furrow. Eyes very large and rounded. Nasal orifices con- 

 tiguous ; the posterior largest ; the anterior rounded, with a raised margin. Upper jaw 

 produced into a flattened sword ; the edges bluntly trenchant, and approaching each other 

 and terminating in a blunt point. On the upper side, this is minutely striate, and elevated in 

 the centre ; this elevation becomes gradually effaced about the middle, where a groove extends 

 to the tip. Lower jaw short and pointed. The gape of the mouth extends behind the orbits. 

 No teeth, but slight asperities may be felt on the lower jaw, and velvet-like teeth in the throat. 

 A membrane within both jaws. Tongue rudimentary. Seven flat branchial rays. Gills, 

 instead of being pectinated, are retiform, and, as Mitcliill has observed, are of a spongy 

 texture. 



The dorsal fin, which in the young forms one long, high and nearly equal fin of forty-three 

 rays, extending nearly to the tail, becomes obliterated for the greater part of its length, and 

 in fact is divided into two distant fins. This curious fact, which is now well established, may 

 serve to explain why the descriptions of this fish agree so little with each other, and why 

 distinct species have been created out of but one. Li the adult, the dorsal is falciform, with 

 from 18 - 20 rays ; the posterior part is represented by a few rays. Pectorals falciform, 

 elongated, placed very low down, and composed of sixteen rays, of which the three first are 

 very long. Vcntrals none. The anal fin commences under the posterior third of the dorsal, 

 falciform in front, low behind ; but in the adult, this fin likewise becomes obliterated in the 

 middle, and divided into two. Caudal fin crescent-shaped, with 17 rays. 



