Song Birds and Water Fowl 
and contains but a single egg. Although so 
essentially aérial, they are web-footed, and in 
calm weather will often half fly and half spring 
over the surface of the water. Hardly any bird 
is less intimately known than the ever-roaming 
petrel ; and, as we look upon this vanishing and 
ever-distant living mystery, with its minute and 
dusky form, white spotted, dashing tirelessly 
above the sea, it is an exquisite symbol of the 
dark waves, crested with white, that are ever 
sweeping on, age after age, in restless flight. 
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