110 ANIMAL BIOLOGY 



(flattened laterally) ? Do both forms occur among fishes ? 

 (See figures on pages 123, 124.) 



How is the shape of the body advantageous for move- 

 ment ? Can a fish turn more readily from side to side, or 

 up and down ? Why ? Is the head wedge-shaped or coni- 

 cal ? Are the jaws flattened laterally or vertically ? The 

 fish swims in the water, the bird swims in the air. Account 

 for the differences in the shape of their bodies. 



Is the covering of the body like the covering of any ani- 

 mal yet studied ? The scales are attached in little pockets, 



FIG. 209. WHITE PERCH (Morone Americana). 



or folds, in the skin. Observe the shape and size of scales 

 on different parts of the body. What parts of the fish are 

 without scales ? Examine a single scale ; what is its 

 shape ? Do you see concentric lines of growth on a scale ? 

 Sketch a few of the scales to show their arrangement. 

 What is the use of scales ? Why are no scales needed on 

 the head ? How much of each scale is hidden ? Is there 

 a film over the scale ? Are the colors in the scale or 

 on it ? 



The Fins. Are the movements of the fish active or 

 sluggish ? Can it remain stationary without using its fins ? 



