ii6 VERTEBRATES: BIRDS. 



Fig. 86. 



II MLj^r - 



' ^~^ ^WG^^l^riTiiyf*' 4>s 



mt ....--^^> r ^^^ t i3 l ^5t 



Skeleton of a Bird. 



hd, head ; cv, cervical vertebrae ; p, pelvis ; sc, scapula : c /, clavicle ; cd, corocoid bone, 

 formerly regarded as the clavicle ; st, sternum ; /i, humerus ; u, ulna ; r, radius ; c, car- 

 pus ; me, metacarpus ; ph and tk, phalanges, th being the thumb ; fe, femur ; ft, fibula 

 and tibia, more or less united; t, tibia, where the fibula is no longer seen, or only faintly 

 indicated ; is, tarsus ; mt, metatarsus more or less consolidated with the tarsus ; PS, pha- 

 langes, or toes. 



ossified in order to give greater strength to the trunk ; 

 and a small bone is attached obliquely across each rib, 

 as a sort of cross-beam, which also contributes to the 

 same result. The shoulders, which would otherwise be 

 brought together by the effort of flying, are kept apart 

 by two bony braces. Regarding the wrist as part of the 

 hand, the wings are each made up of three sections, 

 the arm, forearm, and hand, thus corresponding to the 

 anterior extremities of man and other Mammals. The 

 wings are furnished throughout their whole length with a 

 range of quills, thus presenting a great surface to the air. 

 The quills attached to the hand are called primaries, and 

 are the largest and firmest; those attached to the fore- 



