72 THE STORY OF BIRD-LIFE. 



and the bones of the skeleton which support 

 them. 



These comprise a breast-bone, a pair of long 

 bones which are fastened on to its front end, a 

 pair of shoulder-blades fastened on to the ends of 

 these, and a merry-thought. 



In birds that fly well there is a deep thin keel 

 running down the breast-bone. This keel is 

 familiar to us all in the fowl or duck as the bony 

 partition which divides the flesh of the left and 

 right sides of the breast. In birds that have 

 lost the power of flight, this keel, if the loss is 

 recent, is small, if of long standing it is absent 

 altogether. The merry-thought again is absent, 

 or feebly developed in birds which do not fly 

 much or well, or which are quite flightless. The 

 long bone which we referred to as being fastened 

 on to the end of the sternum, is called the 

 coracoid. AYe shall have occasion to refer to it 

 again later. This in flightless birds may become 

 immovably fixed to the blade-bone, and the angle 

 which the two form one with another is also a 

 point of some significance. 



Just as the bones supporting the breast-muscles 

 shrink away, so to speak, though lack of use, so 

 also do the bones of the hands and arm. 



As examples of birds that have but recently, 

 comparatively recently, lost the power of flight, 

 let us take, first of all, the New Zealand kakapo 

 or owl-parrot. 



This is a fairly large bird for a parrot, and one 

 of great and increasing rarity. There can be no 

 doubt that it once lived in trees, like other parrots, 

 and probably like them needed well developed 



