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ON THE INCUBATION —PLIGHT OF BIRDS. 63 



communication of many interesting particulars concerning 

 birds. Some of these will be found in his papers in the 

 second volume of the ZoologicalJournal, The fact to which 

 I allude is, that there is attached to the upper mandible of all 

 young birds about to be hatched a horny appendage, by 

 which they are enabled more effectually to make perfora- 

 tions in the shell, and contribute to their own liberation. 

 This sharp prominence, to use the words of Mr. Yarrel, 

 becomes opposed to the shell at various points, in a line 

 extending throughout its whole circumference, about one 

 third below the larger end of the egg; and a series of per- 

 forations more or less numerous are thus effected by the in- 

 creasing strength of the chick, weakening the shell in a 

 direction opposed to the muscular power of the bird: it is 

 thus ultimately enabled, by its own efforts, to break the walls 

 of its prison. In the common fowl, this horny appendage falls / 

 off in a day or two after the chick is hatched ; in the Pigeon 

 it sometimes remains on the beak ten or twelve days; this 

 arises, doubtless, from the young Pigeons being fed by the 

 parent bird for some time after their being hatched ; and 

 thus there is no occasion for the young using the beak for 

 picking up its food. 



The rapidity of the flight of Birds constitutes one of their 

 peculiarities; some of the more swift have been known to 

 travel many hundred leagues in a few hours. The Pigeon, 

 it is well known, is a bird of very swift flight j many of the 

 Falcon tribe are also very swift in their aerial motions , 

 some of them, it is said, will fly 150 miles in an hour. The 

 Swallows are also very swift on the wing. 



Hence, from the rapidity and power of their flight, many 

 birds are occasionally seen in most regions of the globe ; 

 and, from the powers of flight and of swimming which 

 many aquatic birds possess, they are also enabled to visit 

 the various parts of the earth. These last, indeed, are en- 



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