152 



ANIMAL BIOLOGY 



toes, the 

 - joints ; 



The pigeon has - 

 hind toe having 

 of the three front toes, the 



inner has joints (count 



the claw as one joint), the 



Fig. 286. — Skeleton of Bird. 



Rh, vertebrae; CI, clavicle; Co, coracoid; Sc, scap- 

 ula; St, sternum; H, humerus; R, radius; U, 

 ulna; P, thumb; Fe, femur; T, tibia. See Fig. 394. 

 Questions : Which is the stiflfest portion of the 

 vertebral column ? How are the ribs braced against 

 each other ? Which is longer, thigh bone or shin ? 

 Compare shoulder blade with man's (Fig. 399). Which 

 is the extra shoulder bone ? Compare tail vertebras 

 with those of extinct bird, Fig. 290. 



Fig. 285. — Leg Bones 

 of Bird. 



middle has 



joints, and the 



outer toe has 



joints (Fig. 285). 

 Is the thigh of a bird bare or 

 feathered ? The shin ? The 

 ankle ? Where is the ankle 

 joint of a bird ? Do 

 you see the remains 

 of another bone (the 

 splint bone, or fibula) 

 on the shin bone of 

 the shank? (Fig. 285 

 or 286.) Why would 

 several joints in the 

 ankle be a disadvan- 

 tage to a bird ? 



