470 PISCES SUB- CLASS III. TELEOSTOMI. 



that, according to Mr. Wood, a sword-fish, in striking a whaling vessel, drove 

 its weapon " through the copper sheathing, an inch-board sheathing, a three- 

 inch plank of hard wood, the solid white oak timber of the ship twelve 

 inches thick, through another two-and-a-half-inch hard oak ceiling plank, and 

 lastly, perforated the head of an oil-cask, where it remained immovably 

 fixed, so that not a drop of oil escaped." 



The so-called scabbard-fish (Lepidopus) and the hair-tails (Trichiurus), 



together with the barracudas (Thyrsitis), may be cited as well-known 



examples of a family and section presenting the following 



Section Trichi- leading characteristics. All have very long and compressed 

 uriformes. bodies, which sometimes assume a band-like form ; and the 

 Family skin is either naked or with rudimental scales. Both the 

 Trichiuridce dorsal and anal fins are elongated, with their spinous and 

 soft portions of nearly equal extent ; and when the pel vies 

 and caudal are present, the former are thoracic in position, and the latter is 

 distinctly forked. In some forms a portion of the median fins is split up into 

 finlets. The mouth is wide, and there are some large and powerful teeth 

 either in the jaws or on the palate. In all the forms there is an air-bladder. 

 These fishes are carnivorous and predatory in their habits. They have a wide 

 range in space ; but whereas some are surface-dwellers, others are found at 

 considerable depths. None afford a very high-class food, although the flesh 

 of several is eaten. In the scabbard-fish, which grows to a couple of yards 

 in length, the body is riband-like, the pelvic fins are wanting, as are scales ; 

 but there is a small caudal fin. The flesh is largely consumed in New 

 Zealand, where the species is known as the frost-fish. On the other hand, 

 the hair-tails take their name from the circumstance that the tail terminates 

 in a tapering whip-like extremity, without trace of a caudal fin, the pelvics 

 being wanting, or reduced to a pair of scales, and the anal rudimental, with 

 its spinous portion represented by a number of very short isolated spines. 

 From three to four feet is a common length for these fishes. Barracudas 

 also locally known as " snoek " are still larger, and are extensively caught 

 for food in New Zealand and at the Cape. They are characterised by the 

 presence of minute scales in the skin, and of from two to six finlets behind 

 the dorsal and anal, while the palatine bones are toothed. Although essenti- 

 ally coast-fishes, they are occasionally found far out at sea. 



For some time we have been dealing with sectional groups represented 



only by a single family each ; but we now come to one including several 



families. In the present group the dorsal fin is either single, 



Section Cotto- or, if divided, has its two portions closely approximated. 



Scombriformes. When normal, the spinous portion is short ; but it may be 



Family modified either into separate spines, tentacles, or a sucker. 



Acanthuridce. The anal resembles the soft dorsal, the hinder part of both 

 these fins being sometimes split up into finlets. When 

 present, the pelvics may be either jugular or thoracic in position, and the 

 region of the vent is never furnished with papillae. Most of the members of 

 the section are marine fishes. The popular name of surgeons is given to the 

 representatives of the family Acanthuridce x on account of the circumstance 

 that in the typical genus Acanthurus each side of the tail of the adult is 

 furnished with a spine somewhat resembling a surgeon's lancet, and capable 

 of inflicting a severe wound. In other kinds the spines may be two or three 



1 The family is commonly known as Acronuridce, but Acronurus is now ascertained to be a 

 synonym of the type genus. 



