114 



AMPHIBIANS 



Figure 114. — Common Frog. 



114. Frogs. — There are several kinds of frogs, one of 

 which, the leopard frog, is found generally distributed 



throughout the United 

 States. It can be recog- 

 nized by the presence, 

 on the dorsal surface, of 

 many brownish or green- 

 ish spots, edged with 

 white, which help the 

 frog to escape the notice 

 of his enemies as he 

 squats among the water 

 weeds. These colors 

 form rather definite bands on the hind legs, though there 

 is much variation. The general form of the body, the 

 shape of the head, and the long hind legs adapted for 

 jumping are much the same in all frogs. 



LABORATORY STUDY 



Compare the general shape of fish and frog. How do the colors 

 differ ? Show how the legs and feet are adapted to the way the frog 

 lives. Is the frog sensitive to touch in various parts of the body ? 

 Examine the eyes. Open the mouth and see that the frog can draw in 

 its eyes. The ear membrane is on the side of the head back of the eyes. 

 Pass a probe through the ear membrane of a dead frog and see where it 

 comes out in the mouth. This is the opening of the Eustachian tube. 

 How far can the living frog see ? Notice the method of breathing. See 

 the throat move up and down. Hold the frog under the water and 

 gently rub its sides. It will usually croak. Thus we can prove that the 

 frog is able to make the air travel from his lungs to his mouth and back 

 again while under water. 



115. Habitat. — Frogs are seldom found far from some 

 pond or stream and they are usually seen on the bank. 

 When disturbed, they jump into the water, swim to the 

 bottom, stir up the mud, and quietly come to rest a 

 short distance from the place where they entered. As 



