BATRACHIA 



129 



surface when it floats or swims in a tub of water ? Why? 

 Do frogs croak in the water or on the bank ? Why do 

 they croak after a rain ? Do toads croak ? 



Are the eggs laid in still or in flowing water? In a clear 

 place or among sticks and stems ? Singly, or in strings or 

 in masses? (Fig. 248.) Describe an egg. Why do frogs 

 dig into the mud in autumn in cold climates ? Why do 

 they not dig in mud at the bottom of a pond ? 



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Fig. 250. — Painted Frog ( Chorophllus omatus) , of Mexico. 



Describe the position of the frog when still (Fig. 250). 

 Of what advantage in this position? Does the frog use 

 its fore legs in swimming or jumping? Its hind legs? 

 How is the frog fitted for jumping ? Compare it in this 

 respect with a jumping insect; a jumping mammal. How 

 is it fitted for swimming ? Is the general build of its body 

 better fitted for swimming or for jumping? How far can a 

 frog jump ? 



External Features. — The frog may be said to have two 

 regions in its body, the head and the trunk. A neck hardly 



