MARINE BIOLOGICAL STATION AT POUT ERIN. 131 



degree, of assimilating their colour to that of the ground 

 upon which they live, and are thus able to conceal 

 themselves from their enemies. Their food consists of 

 small crustaceans, worms, molluscs, sand eels and other 

 small fry. It is the plaice that has, so far, been chiefly 

 dealt with in the Hatchery at Port Erin, and a short 

 account of the stages to be seen in the development of the 

 young plaice will be found at p. 126. 



The Cod Family (Fig. XXX., A). 



This family, like that of the flat-fishes, is of great 

 economic importance. In addition to the cod, which is 

 probably the most useful of all fishes to man, it includes 

 such valuable food fishes as the haddock, whiting, hake 

 and ling, besides the coal-fish and pollack, which, though 

 edible, are much less esteemed. The two last named are 

 abundant around the shores of the Isle of Man, and may 

 always be seen in our tanks. The pollack is the 

 " callagh " of the local fishermen, and is a handsome fish. 

 It is easily recognised by its projecting lower jaw and 

 the silvery sheen upon its sides. The coal-fish is the 

 " blockan " of the Manx fishermen. It is of much darker 

 colour than the pollack, and the lower jaw does not 

 project. A silvery-white line, the " lateral " line, runs 

 along each side of the body from head to tail. Few 

 fishes have had so many names bestowed upon them as 

 the coal-fish. The young appear in Port Erin Bay in 

 late autumn, when only a few inches long, and are then 

 known as " gilpins." The pollack soon accustoms itself 

 to confinement in a tank, and will take food from the 

 hand, but the coal-fish is timid and retiring, and seldom 

 approaches the front of the tank when visitors are near. 

 The common cod is too well known to need description. 



