XX] MAIN DIVISIONS 495 



they are eaten just after being caught, this fugitive substance dis- 

 appears and the flesh becomes comparatively tasteless. But in the 

 Sole the characteristic flavour is only developed two or three days 

 after death in consequence of the formation of some characteristic 

 substance by incipient decomposition. Hence the Sole is a tasty 

 fish even when it is brought long distances. 



The GADIFORMES or Cod-like fish are fish with a peculiar mixture 

 of primitive and secondary characters. Thus the pelvic fins are 

 moved into a jugular position ; the original tail fin supported by 

 the hypural bones has disappeared and is replaced by a new tail fin 

 formed by the separation of portions from the dorsal and anal fins, 

 and supported by the neural and haemal spines. There are no spines 

 developed in any of the fins, and the pelvic fins may have 10 or 

 12 rays. These features all imply specialisation, but on the other 

 hand there is an extension of the cranial cavity forwards above 

 the interorbital septum, and this contains the long stalks of the 

 olfactory lobes of the brain. 



This group includes the food-fish known as the Cod (Gadus 

 morrhua), the Saithe (sometimes called the Coal-fish) (G. virens), 

 the Pollack (termed the Lithe in Ireland) (G. pollachius), the 

 Haddock (G. aeglefinus) and the Whiting (G. merlangus), the Hake 

 (Merlucius vulgaris) and the Ling (Molva vulgaris). 



The Cod, which is captured by line and bait is perhaps the 

 most sought after food-fish in the world. This is due to (1) the 

 ease with which it can be preserved in the dried condition and so 

 carried long distances, (2) the stable and satisfying character of its 

 flesh ; it is said to be the only fish which can be eaten daily year in 

 and year out as a staple of diet without provoking nausea. 



In their pursuit after Cod the French fishermen were led further 

 and further into the Atlantic, and this led to the discovery of Canada, 

 and even yet the Cod-fishery attracts a population of between 20,000 

 and 30,000 to the desolate ice-bound shores of Labrador. British 

 fishermen who formerly found the Hake in their own territorial 

 waters now pursue it further and further South till they go to the 

 Atlantic off the coast of Morocco to find it. 



It is obvious that if a fishery is to be an economic success, the 

 fish must be taken in enormous numbers at a time, and this is only 

 possible if they are caught when they congregate in shoals. That 

 branch of Zoology known as Fishery Science has for its object the 

 determination of the whole course of the life history of fish of 

 economic value, and of the causes which determine their migrations. 



