506 



SKELETON OF BIRDS. 



number, and are connected together very firmly, so as to form 

 a nearly inflexible column ; and this, again, is closely united 

 to the sacrum vs. The vertebrae of the tail v% are few in 



ta 



Fig. 249. SKELETON OF VULTURE. 



vc, cervical vertebrae; vs, sacral vertebrae; vq, caudal vertebrae; cl, clavicle; 

 h, humerus ; o, fore-arm; ca, carpus; ph, phalanges; st, sternum; /, femur; 

 t, tibia ; ta, tarsus. 



number, and possess little motion. The ribs are very strongly 

 connected to each other and to the vertebras, and are united 

 to the sternum st by bony instead of cartilaginous prolonga- 

 tions. Thus the whole bony apparatus of the trunk is very 

 strongly knit together ; and the purpose of this is evidently 

 to give as firm an attachment as possible to the muscles which 

 move the wings. The sternum is raised into a high keel or 

 ridge (as is better seen in fig. 250, 6), for the attachment of 

 the powerful pectoral muscles which draw down the wings ; 

 and the degree of this projection is proportioned to the power 

 of flight which the species possesses, the sternum being flat 

 (as in Mammals) in birds which, like the Ostrich, have the 

 wings undeveloped. The scapula (fig. 250, o), to which are 



