164 FIRST LESSONS IN ZOOLOGY. 



order. In these fishes the body is very unsymmetrical, the 

 fish virtually swimming on one side, the eyes being on the 

 upper side of the head. The upper side is colored dark, 

 due, as in other fishes, to pigment-cells ; the lower side is 

 colorless, the pigment-cells being undeTeloped. When first 

 hatched the body of the flounder is symmetrical, and in 

 form is somewhat cylindrical, like the young of other fishes, 

 swimming vertically as they do, and with pigment-ceUs on 

 the under side of the body. The flounder is not bom with 

 the eyes on the same side of the head, but one eye gradu- 

 ally passes from the blind to the colored side ; the transfer 

 of the eye from the blind side to the colored side occurs 



Fio. 168.— The Codfish, Gadus morrhua. 



very early in life, while all the facial bones of the skull are 

 still cartilaginous, long before they become hard and ossi- 

 fied, i.e., when the flounder {Plaqusia) is twenty-five milli- 

 metres (one inch) long. Young flounders, when less than 

 two inches in length, are remarkably active compared with 

 the adults, darting rapidly through the water after their 

 food, which consists principally of larval, surface-swim- 

 ming crustaceans, etc. The common flounder from Nova 

 Scotia to Cape Hatteras is Pseiidopleuro7iectes Americanus. 

 The Anglers. — The type of the order Pediculati is the 

 goose-flsh. The name was given to the group from the 

 long slender bones supporting the pectoral fins. The gill- 



