THE SMELT AND ITS ALLIES 



239 



zontal cavity of which the fish can lie while it deposits its 

 eggs. The male is polygamous, and guards the single 

 nest, which receives the eggs from various females (Figs. 

 219, 220). 



The codfishes, among the most important of food fishes, 

 are characterized by having ventral fins without spines, 

 and articulated fin-rays, well-developed caudal fin, isocercal 

 tail, and barbel 011 chin. Our common codfish (Fig. 221) 



FIG. 221. Gadus morrhua, the codfish. About one-seventh nat. size. 

 After Storer. 



occurs over the whole of the North Atlantic ; but the 

 most important fishing localities are the banks near New- 

 foundland, especially Grand Bank. 



The flatfishes are peculiar among fishes in that they 

 have the habit in the adult stage of lying on one side. In 

 consequence the under eye migrates to the upper side, so 

 that both eyes come to lie on the same side of the body. 

 The mouth also tends to become unsymmetrical. The 

 flatfish, .consequently, illustrates well the principles of self- 

 adaptation to a peculiar environment. 



The catfishes are distinguished by the possession of 

 four to eight long barbels around the mouth, and by the 



