2804 



THE BONY FISHES AND GANOIDS 



body is covered with small cycloid scales; there are either one, two, or three dorsal 

 fins, occupying nearly the entire length of the back, the rays of the hindmost being 

 well developed; the anal is either single or divided; and the jugular pelvic fins are 

 usually formed of several rays, but if reduced to filaments there is always a double 

 dorsal. The gill opening is wide, and the gill membrane in most instances not at- 



HADDOCK, WHITING, AND YOUNG AND ADULT COD. 

 (One-sixth natural size ) 



tached to the isthmus; while if false gills are present at all they are either glandular 

 or rudimental. As a rule, there is an air bladder. Mostly marine, the members of 

 the cod family are mainly characteristic of the Arctic and Temperate seas, where 

 they are comparatively shallow-water fishes. There are, however, a certain number 

 of deep-water types among the family, and these have a much more extensive dis- 

 tribution, some of them occurring in the tropical Indian seas. The fresh-water 



