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 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 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? Why is digging unnecessary in the Gulf states?

Describe the position of the frog when still (Fig. 250). 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 jumping? How far can a frog jump?

(Chorophilus ornatus), of Mexico.

External Features.—The frog may be said to have two regions in its body, the head and trunk. A neck hardly