Page:First course in biology (IA firstcourseinbio00bailrich).pdf/346

 (flattened laterally)? Do both forms occur among fishes? (See figures on pages 123, 124.)

How is the shape of the body advantageous for movement? Can a fish turn more readily from side to side, or up and down? Why? Is the head wedge-shaped or conical? 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.

(Morone Americana).

Is the covering of the body like the covering of any animal yet studied? The scales are attached in little pockets, 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?