352 ACTION OF THE WOODPECKER. 



the central part stiff and firm throughout its length, 

 so that it admits of flexure in the flank angles only. 



Upon examining the anterior part we find the 

 coracoid bones produced in the direction of the 

 sternum, and as long as that bone ; while the furcal 

 bone is nearly a continuation of the line of the keel, 

 and, though not wide in proportion, it is longer than in 

 any example which we have yet adduced. The lateral 

 processes are also very much produced, and two of 

 the five ribs on each side are articulated upon them. 

 The blade bones are of yery pecuhar shape, being 

 curved downwards at the terminations in the shape of 

 blunt hooks, as if the coracoids, which lie nearly 

 parallel to the axis of the body, instead of approaching 

 it obliquely, as in most birds, were hooked to the 

 muscles near the spine. 



And this is a highly typical sternum, and one 

 upon which, if space permitted, many observations 

 might be made. Though its peculiarities have much 

 less reference to the style and manner of flight than 

 to the action of the bird when upon the bark, v^nth 

 closed wings, yet they show, and perhaps on that 

 account show more clearly, that the sternum of a 

 bird, that organisation which supports the body, having 

 the spinal column in a great measure bare, is the 

 grand characteristic portion of its structure — the 

 essential part by which a bird is distinguished from 

 every other animal — and the basis, as it were, upon 

 which all the rest of its organisation is built, and in 

 accordance with which the whole of the minor parts 

 are formed. 



The main office for which the structure of a 

 woodpecker has to be adapted, is that of maintaining 

 with the under part of the body a vertical position 

 on the bark of a tree, in such a manner as to have 



