CHARACTERISTICS OF VALUABLE MARINE FISHES 



49 



often occur off our coast in abundance in summer and autumn, 

 and are taken in the mackerel nets : the gar-fish is much the 

 commoner. The flying-fishes of the tropical parts of the ocean 

 are placed in the same family, but in them the body is shorter 

 and the jaws are not elongated. Their pectoral fins are greatly 

 enlarged. 



The next division of bony fishes is distinguished by the fact 

 that the air-bladder is closed, the second pair of side fins is 

 placed either just below or in front of the breast fins, and that 

 all the fin-rays are jointed and flexible, or soft. They are pre- 

 eminently the spineless fishes. The absence of spiny fin-rays 

 is also associated with the almost entire absence of large spines 

 on the body or head. The scales, however, are often well 

 developed and furnished with a spiny border. This order is 

 formed principally by the two great families of the cod-like 

 fishes and the flat-fishes, by far the most important ground 

 fishes, from a commercial point of view, in existence. 



In the cod family (Fig. 13), there are in some cases three 



Fig. 13.— The Cod. 



fins on the back and two behind the vent, in other species two on 

 the back, the front one being short and the hinder long, and a long 

 ventral, in other species again a single long dorsal and a single 

 long ventral. The scales are small, without spines, and easily 

 detached. There is in many kinds a barbel on the chin. These 

 fishes belong chiefly to arctic and temperate coasts, a few species 

 living in the ocean abysses. The more valuable British species 

 are the cod, haddock, whiting, coalfish, pollack, bib or whiting 

 pout, ling, hake, and tusk or torsk. The family of sand-eels is 

 not very different in characters, but the fishes are much smaller : 



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