VIL 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! 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 are 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 down 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 Fiirbringer, 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.” 
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. 
2 See Max Fiirbringer’s Untersuchungen zur Morphologie und 
Systematik der Vogel, p. 740. 
