DUTCH NIGHTINGALES. 63 



perfectly adapted to a terrestrial existence. The toad has 

 advanced a stage further ; water is not such an urgent 

 necessity to him as to the frog. Thousands of years hence 

 a race of frogs may be evolved which can live out of water 

 for indefinite periods. If such be the case we must hope, 

 for the sake of our descendants, that such frogs will have 

 lost their power of croaking and no longer merit the name 

 of " Dutch Nightingale." 



