MONTAGU'S HARRIER. 



113 



the natural size of the breast-bone of a young male Pere- 

 grine Falcon, which exhibits the depth of the keel, the 

 breadth of the sides, as well as the strength of the coracoid 

 bones ; and the power of flight peculiar to all the species 

 of Falcons is still further illustrated by the form and sub- 

 stance of the forked bone,* commonly called the merry- 

 thought, which is circular, broad, and strong, affording a 

 permanent support to the shoulders. 



By an extended examination of the different species of 

 Buzzards and Harriers, it will be found that the characters 

 described as necessary to produce rapid flight decline gra- 

 dually. The sternum decreases in size, the keel loses part 

 of its depth, the coracoid bones and furcula become more 

 slight ; while the form of the cranium, the loose ruffled fea- 

 thers of the neck, as well as the softer and more downy 

 texture of the plumage generally, indicate an approach to 

 the family next in succession. 



A representation of the sternum of an Owl will be in- 

 serted as a vignette to one of the species, to afford a com- 

 parative view of the size and structure of the same part in 

 the diurnal and nocturnal Birds of Prey. 



* Which, when the two sides are united, represents both clavicles. 



