194 CHAPTERS ON THE NATURAL HISTORY 



a time, rising and falling alternately, and that as frequently as 

 it thought it necessary for securing its food when in sight of it; 

 for I am certain that these birds never immerse their lower man- 

 dible until they have observed the object of their pursuit, for 

 which reason their eyes are constantly directed downward, like 

 those of terns and gannets." 



The flight of the Skimmer is elegant in the extreme, being more 

 interesting and superior to that of any of the terns. Their cries, 

 however, when upon wing, are harsh and more or less discordant. 

 A slight excavation in 1 lie sand is the sole apology for a nest that 

 I his bird ever attempts to make. In this it lays, about the first 

 week in May, three eggs. These are pure white, heavily blotched 

 with black and various shades of dark brown, and often patches 

 of a light purple color. 



One of the earliest, and at the same time one of the best ac- 

 counts of the Black skimmer is given by Darwin in his famous 

 work entitled Journal of Researches into the Natural History and 

 Geology of tlic Countries visited during the voyage of U. M. >\'. 

 Beagle round the world, under the command of Captain Fits-Roy, 

 R. N. It is found in the first volume (p. 174), and a figure of the 

 head of the skimmer is given: one of the earliest drawings of the 

 species known to me (1S46). 



