The Structure of Game Fishes 3 



The large bone (28) is the cover, or door, to the 

 gill chamber, which opens and closes convulsively 

 when a fish is landed. The fish smells but does 

 not breathe by its nostrils, the nasal aperture 

 being shown at (15). 



In the skeleton the arrangement and use of the 

 limbs, or fins, is readily seen. The top or dorsal 

 fins (75) are balancers, upper centre-boards, 

 capable in some fishes of a decided screwlike 

 movement, enabling them to move. It also is an 

 expressive organ, erect when the fish is excited, 

 low or folded at other times, and incapable of 

 movement in certain forms. In the tuna it fits 

 into a scabbard, or notch. The tail, caudal fin 

 (71), is the most useful locomotive organ, con- 

 trolled by powerful muscles and lashed about by 

 the entire sweep of the body; it is readily seen 

 that by it the salmon makes its tremendous leaps 

 and the tuna literally whirls itself into the air, 

 nearly all fishes using it as a screw. The peculiar 

 motions are readily observed in a soft-tailed fish, 

 like the perch, in confinement. 



Directly below the second dorsal fin, near the 

 tail, is the anal fin (86) and its bones, held in 

 place by spines (79), which are placed firmly in 

 the muscular tissue. It is these interspinous and 



