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 vertebre of the tail vg are few in 
Fig. 249.—SKELETON OF VULTURE. 
ve, cervical vertebre; vs, sacral vertebre; vq, caudal vertebre; el, clavicle; 
kh, humerus; o, fore-arm; ea, carpus; pk, phalanges; st, sternum; jf, femur; 
t, tibia; ta, tarsus. 
number, and possess little motion. The ribs are very strongly 
connected to each other and to the vertebrae, and are united 
to the sternum s¢ 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, 0), to which are 
