AV£S. 



283 



Ostrich, tliey do not unite below, but remain sejiarate. As in the 

 higher Vertebrates, the lower limb consists of a thigh-boire {femur), 

 a shank, composed of two bones {tibia and fibula), a tarsus, a meta- 

 tarsus, and phalanges, but some of these parts are obscured by 

 coalescence. The thigh-bone or femur (fig, 204, /), is generally 

 very short, comparatively speaking ; and the chief bone of the leg 

 is the tibia {t), to which a thin and tapering jihiila (?■) is attached. 



Fig. 20r. — A, Pelvis and bones of tlie leg ortlie Loon ta- Diver (after Owen): i Innonii- 

 nate Ijone ; /Tlligli-bone (/emw?'); i Til)ia; *■ Fibula, togetliei' forming tlie slianlc ; 

 tn Tarso-nietatar.sus ; p Phalanges of the taes, B, Tail of the Golden Eagle: s 

 Plonghshare-shaped bune, carrying the great tail-feathers. 



In the regular typical limb of a Vertebrate animal the tibia and 

 fibula would be followed by a series of small bones, called the 

 tarsuit, constituting the ankle-joint (fig. 161); and the tarsus would 

 in turn be followed by a series of bones constituting the root of the 

 foot, or metatarsus. In Birds, however, the tibia and fibula are 

 followed by a single cylindrical bone, which is called the " tarso- 

 metatarsus " (m), and which is formed by the amalgamation of the 

 three principal metatarsal bones with the lower row of tarsal bones, 



