HOOPER. 



193 



spicuous than those which have been referred to as external, 

 and of the former, the organ of voice furnishes the most 

 valuable and decisive characters. This peculiarity was 

 known to Willughby, but it was previously noticed by Sir 

 Thomas Browne, who mentions " that strange recurvation 

 of the windpipe through the sternum." 



The cylindrical tube of the trachea or windpipe passes 

 down the whole length of the long neck of the bird, in the 

 usual manner, but descends between the two branches 

 of the forked bone, called the merrythought, to a level 

 with the keel of the breast-bone or sternum. The keel of 

 the breast-bone is double, and receives between its two 

 plates or sides, the tube of the trachea, which, after 

 traversing nearly the whole length of the keel, turns sud- 

 denly upon itself, passing forwards, upwards, and again 

 backwards, till it ends in the vertical bone of divarication, 

 from whence the two long bronchial tubes go off, one 

 to each lobe of the lungs. This singular structure will be 

 further understood by a reference to the vignette below, 

 where a portion of one side of the keel is removed to show 

 the convoluted tube within. 



The depth of the insertion is not, however, so consi- 

 derable in females or young males. 



VOL. III. 



