WINGS AND FORE-LEGS. 311 



to each side of which there are muscles attached, 

 which move the bone backwards or forwards, accord- 

 ing as is necessary to the action of the other parts of 

 the limb. But in birds the scapula is never furnished 

 with a ridge or keel of this description ; and it is most 

 developed and enlarged at the end farthest from the 

 joint in those birds which make the nearest approach 

 to the quadruped action of the mammalia, as for 

 instance, in the penguins, which use the wings and the 

 feet, with nearly equal energy, as they make their 

 way under water. In those land-birds, such as the 

 ostrich, which cannot raise the wings, but use them 

 only for balancing the body as they run, the scapulae 

 are less developed ; but even in them, they are more 

 so than in the birds of the most powerful flight. These 

 birds have not the clavicles united in front into a 

 regular arch, as in powerfully-winged birds, or even 

 into a fork with the branches nearly straight, as in the 

 gallinidse and other bad fliers ; and in some of the 

 species they are little else than mere processes on the 

 anterior edges of the coracoid bones. 



In no case, however, of these short-winged birds 

 are the coracoid bones, which connect the scapulars 

 with the anterior part of the sternum, wanting : and 

 in no case, even of those of most vigorous flight, in 

 which the furcal bone is the most developed, are the 

 humeral bones of the wings articulated directly upon 

 that bone. 



It is here, that we find one of those strikingly dis- 

 tinctive characters from which we can at once pro- 

 nounce a bird to be a bird, whether it has or has not 

 the power of flight ; and here, that we are enabled 

 to see which is the characteristic bone in this part of 

 the skeleton which is possessed by birds and never by 

 mammalia. On this point it would be unjust not to 



