282 VERTEBRATE ANIMALS. 
the tarsus is fused with the lower end of the tibia. In this case 
the ankle-joint is placed in the middle of the tarsus. In most 
of the long-legged birds it is by the great elongation of the 
tarso-metatarsus that the enormous length of the legs is pro- 
duced. The tarso-metatarsus is followed below by the foot, 
which consists in most birds of four toes, of which three are 
directed forwards and one backwards. if no wild birds are 
Fig. 152.—A, Pelvisand bones of the Leg of the Loon or Diver (after Owen): z 
Innominate bone ;_f Thigh-bone (femur) ; ¢ Tibia, x Fibula, together forming the 
shank ; #z ‘Tarso-metatarsus ; # Phalanges of the toes. B, Tail of the Golden 
Eagle: s Ploughshare-shaped bone, carrying the great tail-feathers, 
there more than four toes; but some domesticated varieties 
possess a fifth. In all birds with four toes, the toe which is 
directed backwards consists of two phalanges ; the innermost of 
the three forward toes has three phalanges, the next has four, 
and the outermost or little toe is composed of five. In many 
birds, such as the Parrots, the little toe is turned backwards, so 
