MOORLAND IDYLLS. 



into lateral halves, and approaching in struc- 

 ture those of an air-breathing reptile. 



This interesting series of living evolu- 

 tionary fossils links that are not missing 

 is completed for us in some ways by the 

 frogs and toads, which recapitulate, as it 

 were, in their own lifetime just such an 

 ancestral developmental history. Each ot 

 them begins life as essentially a fish that 

 is to say, as a tadpole breathing oxygen 

 dissolved in water, by means of gills, and 

 possessed of no limbs for terrestrial loco- 

 motion ; he ends it as essentially a full- 

 grown land-reptile, breathing atmospheric 

 air by means of lungs, having discarded his 

 now needless fin-fringed tail, and possessed 

 of jumping legs of great muscular power. 

 And the metamorphosis he thus undergoes 

 answers exactly to just such a drying-up of 

 the ponds that bore him. In early spring, 

 when the temporary puddles are full of 

 water, the parent frogs lay their spawn by 

 hundreds in the ancestral element ; and soon 

 228 



