Chap. 49.] THE BW ALLOW. 513 



and its note ; the smaller ones are heard singing in the reed- 

 beds. It is a thing of very rare occurrence to see a halcyon, 

 and then it is only about the time of the setting of the Vergilise, 

 and the summer and winter solstices ; when one is sometimes 

 to be seen to hover about a ship, and then immediately dis- 

 appear. They hatch their young at the time of the winter 

 solstice, from which circumstance those days are known as the 

 " halcyon days :" during this period the sea is calm and navi- 

 gable, the Sicilian sea in particular. They make their nest 

 during the seven days before the winter solstice, and sit the 

 same number of days after. Their nests 41 are vtruly wonderful ; 

 they are of the shape of a ball slightly elongated, have a very 

 narrow mouth, and bear a strong resemblance to a large sponge. 

 It is impossible to cut them asunder with iron, and they are 

 only to be broken with a strong blow, upon which they sepa- 

 rate, just like foam of the sea when dried up. It has never 

 yet been discovered of what material they are made ; some 

 persons think that they are formed of sharp fish-bones, as it 

 is on fish that these birds live. They enter rivers also ; their 

 eggs are five in number. 



CTTAP. 48. OTHER KINDS OF AQUATIC BIRDS. 



The sea-mew also builds its nest in rocks, and the diver 42 in 

 trees as well. These birds produce three at the very most ; the 

 sea-mew in summer, the diver at the beginning of spring. 



CHAP. 49. (33.) THE INSTINCTIVE CLEVERNESS DISPLAYED BY 

 BIRDS IN THE CONSTRUCTION OF THEIR NESTS. THE WONDER- 

 FUL WORKS OF THE SWALLOW. THE BANK-SWALLOW. 



The form of the nest built by the halcyon reminds me also 

 of the instinctive cleverness displayed by other birds ; and, in- 

 deed, in no respect is the ingenuity of birds more deserving of 

 our admiration. The swallow builds its nest of mud, and 

 strengthens it with straws. If mud happens to fail, it soaks 

 itself with a quantity of water, which it then shakes from off 

 its feathers into the dust. It lines the inside of the nest with 



41 This bird in reality builds no nest, but lays its eggs in holes on the 

 water side. The objects taken for its nest are a zoophyte called halcyonium 

 by Linnaeus, as Cuvier informs us, and similar in shape to a nest. 



42 Or didapper. 



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