128 INTRODUCTION TO THE CLASS OF AMPHIBIANS 



permanently inhabit some very cold and inhospitable por- 

 tions of the temperate zone. With but very few exceptions 

 the amphibians are quite useless to man. The legs of certain 

 large species of frogs are prized by epicures, but, with this 

 exception, civilized man regards amphibians generally as in- 

 edible. Scientifically, the Class is highly interesting, chiefly 

 by reason of the striking changes which so many of its mem- 

 bers undergo. As subjects for the classroom and laboratory, 

 frogs and toads are of well-nigh universal availability. Un- 

 fortunately, however, too many courses in elementary zoology 

 do not forge beyond the frog. 



As usual in seeking an acquaintance with Nature, a very 

 simj^le diagram places this Class of animals on a clear and 

 comprehensible basis. 



