16 FRINGILLIM. 



shutting within the edges of the upper, nor was there the 

 slightest indication to which side either mandible would 

 heareafter be inclined. I may here add, that an opinion 

 prevails that the sexes in the Crossbill may be known by 

 the direction of the curves of the mandibles, those of the 

 males turning outward in the contrary direction to those of 

 the females ; but the examination of a great many speci- 

 mens, in reference to this point, has convinced me that this 

 is not a rule to be depended upon, the upper mandible in 

 both sexes turning sometimes to the right and sometimes 

 to the left. I observed a record in the Essex Literary 

 Journal for January, 1839, that the Crossbill bred in Or- 

 well Park, near Ipswich, in the year 1822. 



The peculiar formation and direction of the parts of the 

 beak in the Crossbill, its anomalous appearance, as well as 

 the particular and powerful manner in which it is exercised, 

 had long excited in me a desire to examine the structure of 

 an organ so curious, and the kindness of a friend supplied 

 me with the means. To those who have not made the 

 habits and economy of birds an object of investigation, it 

 may be necessary to premise that our species of Crossbills 

 are the only British Birds that exhibit, or seem to require, 

 any lateral motion of the mandibles, and it is my object 

 here to describe the bony structure and muscles by which 

 this peculiar and powerful action is obtained. 



The beak of the Crossbills is altogether unique in its 

 form ; the mandibles do not lie upon each other with their 

 lateral edges in opposition, as in other birds, but curve to 

 the right and left, and always in opposite directions to each 

 other. In some specimens the upper mandible is turned to 

 the right, the lower mandible curved to the left ; in others 

 the position of the mandibles is reversed as to their direc- 

 tion. In the specimen I examined, the upper mandible 

 curved downwards, and to the left ; the under portion 



; 



