Animals. 83 



We call the fin on the back the dorsal fin, and the one 

 below near the tail the anal fin. Point out the dorsal fin 

 on the dead fish. Point out the anal fin. Notice the parts 

 of the fins. See the fine spines which form their framework. 

 How many spines in the dorsal fin ? 



We call the tail fin the caudal fin. Compare the caudal 

 fins of these fishes. Sketch them. 



Measure the fish from the tip of the head to the base of 

 the tail. What part of this length is head ? 



Open the mouth of the dead fish several times. See how 

 the bones and gill-covers move. Is his mouth large or 

 small when compared with the size of his body ? Open the 



FIG. 19. PERCH. 



mouth wide and feel the teeth. Are there many or few ? 

 How do they point ? Where are they placed ? 



Now see the eyes. Can the fish wink ? Has he eyelids ? 

 Why not ? Can he move the eyes around and look upward, 

 right, left, and downward as we can ? Why, then, do fishes 

 swim in a zigzag manner ? Try to move the dead fish's eye. 

 Can you push it so as to make it turn as our eyes turn ? 



Can a big fish catch a smaller one easily when the smaller 

 one goes swimming in this way from side to side ? 



Lift up the gill-covers. See the dark-red fringes of the 

 gills. Put your pencil into the fish's mouth and out at the 

 gills,. That is the way water goes as. the fish breathes, 



