WINGS OF BIRDS. 499 



purpose is evidently the same as in the bird. Not- 

 withstanding the great modification which the 

 sternum has received in the bird, when compared 

 with its form in the tortoise and the quadruped, we 

 may still trace the same nine elements entering into 

 its composition, though delevoped in very different 

 proportions. 



The scapula is generally a small and slender 

 bone. The coracoid bone (k) is largely developed, 

 and assumes much of the appearance of a clavicle.* 

 But the real clavicles (c) are united below, where 

 they join the fore part of the sternum, forming a 

 single bone, which, from its forked shape, has been 

 denominated the fur cular hone. In the fowl, it is 

 commonly known by the name of the merry- 

 thought. This bone, placed at the origin of the 

 wings, and stretching from the one to the other, is of 

 great importance as constituting a firm basis for 

 their support, and for securing their steadiness of 

 action ; and being, at the same time, very elastic, 

 it tends to restore them to their proper situations, 

 after they have been disturbed by any violent 

 impulse. 



The wing of a bird does not, at first view, present 

 much analogy with the fore extremity of a quadru- 

 ped ; but on a closer examination we find it to 

 contain all the principal bones of the latter, though 

 somewhat altered in shape, and still more changed 

 in their functions. Yet still the same unity of plan, 

 and perfect harmony of execution may be discerned 



* Many have considered this bone as being- the clavicle, and have 

 regarded the furcular bone as a new bone, or supplementary clavicle; 

 but all the analogies of position and of developement are in favour 

 of the views stated in the text. 



