ACANTHROPTERYGIJ. 201 



THYNNUS, Cuvier. 



A soft corslet round the thorax, formed by scales larger and smoother than 

 those on the rest of the body ; a cartilaginous carina between the two little 

 crests on the sides of the tail ; the first dorsal extends close to the second. 



Sc. thynnw, Lin. (The Tunny.) This fish has been taken in the Mediter- 

 ranean, from a very ancient date, and by its abundance constitutes a great 

 source of wealth to Provence, Sardinia, Sicily, &c. It is said to attain the 

 length of fifteen and eighteen feet, and has nine spurious fins above, and as 

 many beneath ; the pectorals are one-fifth of its whole length. There are 

 some other subgenera. 



XIPHIAS, Linnceus. 



These fishes belong to the family of the Scomberoides, and approach the 

 tunnies, particularly in their excessively small scales, in the carinae on the sides 

 of their tail, in the power of their caudal fin, and in their whole internal 

 organisation. Their distinguishing character consists in the beak, (whence 

 their name of sword-fish,) or ensiform point or tusk, which terminates their 

 upper jaw ; a powerful weapon, with which they attack the largest sea animals. 

 This beak is chiefly composed of the vomer and intermaxillaries, being 

 strengthened at its base by the aethmoid, frontals, and maxillaries. Their 

 branchiae are not pectinated ; each of them being formed of two large parallel 

 laminae, the surface of which is reticulated. They swim with astonishing 

 swiftness, and their flesh is excellent. 



Xiphias gladius, Lin. (The Sword- Fish.) The point horizontally flattened 

 and trenchant like the broad blade of a sword ; sides of the tail strongly cari- 

 nated. It has but one dorsal, which rises from before and from behind; the 

 middle of it becoming worn with age gives it the appearance of being double. 

 It is one of the largest and best fishes of the European seas, frequently attain- 

 ing the length of fifteen feet. It is more common in the Mediterranean 

 than" in the Atlantic Ocean. A parasitic crustaceous animal penetrates into 

 its flesh, and sometimes renders it so furious that it dashes itself on shore. 



CENTRONOTUS, Lacepede. 



A genus of Scomberoides, characterised by the spines, which, in the Acan- 

 thopterygii in general, form the anterior portion of the dorsal, or a first 

 separate dorsal, but in them are free and unconnected by a common mem- 

 brane ; they all have ventrals. They are subdivided into four subgenera. In 



NAUCRATES, Rafinesque, 



The dorsal spines are free; body fusiform ; a carina in the sides of the tail as 

 in the tunny, and two free spines before the anal fin. 



The common species is blue with broad vertical bands of a much deeper 

 blue. The vulgar name of Pilot-fish owes its origin to the fact, that it follows 

 vessels to seize upon what may fall from them ; and as a similar habit is 



