SKELETON 



7 



Birds, and certain Petrels, but dwindles almost to disappearance 

 in some flightless forms such as the Dodo, the Kakapo {S'tringcrp^C), 

 the extinct New Zealand Goose (Cnemiornis), and a good many 

 Rails. The absence of a keel is characteristic of the other and 

 smaller group of Birds, made up of the Ostrich, Ehea, Emeu and 



Fig. 2. — Skeleton of the tnmk of a Falcon. C«, coracoid, ■which articulates with the 

 sternum {St) at f ; CV, keel of sternum ; Fii (67), furcula (clavicles) ; G, glenoid 

 cavity for humerus ; .S', scai)ula ; Un, uncinate iirocess ; V, vertebral, and Sp, sternal, 

 jiortion of rib. (PYom Wiedersheim.) 



Cassowary, Moa and Kiwi, which from the resemblance the 

 sternum thus bears to a flat-bottomed boat (ratis) are known as 

 Ratitae. Whether keeled or not, the breast - bone affords a 

 surface of attachment to the principal muscles of the fore-limbs, 

 and its anterior end supports the coracoids, as in Fig. 2. Various 

 processes are in most cases developed on the sides of the sternum 

 itself, behind its junction with tlic ri1)s, especially towards the 



