VII 



FLIGHT 197 



inwards, the scapula being useful mainly for hingeing 

 the back and breast together. A bird with a broken 

 clavicle is said to be incapable of flight. 1 But the 

 coracoid is much the stronger bone of the two. Its 

 broad base is fixed in a long groove in the sternum, to 

 which it is tied by powerful ligaments, and, besides 

 this, a strong membrane, covering all the space between 

 it and the clavicle, binds the two together. If skeletons 

 representing a number of species arc examined, I 

 believe it will be found that in birds of powerful flight 

 the coracoids project outwards more than in inferior 

 flyers. I have no accurate measurements of my own 

 to give. But I once looked carefully through the 

 collection of breastbones at South Kensington and 

 noted clown that in the Albatross, the Adjutant, the 

 Golden Eagle, and other birds that fly well, the two 

 coracoids made a large angle with each other and 

 were, at the same time, strong and short : whereas in the 

 Crowned Pigeon, Game-fowl, Goose, Parrot, Pheasant, 

 they formed a small angle and were at the same time 

 in proportion to the size of the bird longer and weaker. 

 I ought to mention however, that Furbringer, a very 

 great authority, holds that the size of the angle made 

 by the coracoids varies according to the size of the 

 bird : the greater the bird the greater the angle.' 2 

 He recognises exceptions to the rule, and these 

 exceptions will, I think, be accounted for by the 

 power of flight of the particular species. His rule has, 

 no doubt, considerable foundation : a big bird takes 



1 Yet some Parrots, whose clavicles are rudimentary, fly well. 

 - SeeMaxFurbringer's Untersuchungen zur Morphologie und 

 Systcmatik der I "ogel, p. 740. 



