FEET OF BIRDS. 585 



extent of this base is so considerable that a bird 

 can, in general, support itself with ease upon a 

 single foot, without danger of being overset by 

 the unavoidable vacillations of its body. 



The femur is short compared with the tibia, 

 which is generally large, especially in the order 

 of Gralla;, or wading birds : the fibula is ex- 

 ceedingly slender and always united, at its 

 lower part, with the tibia ; and there is a total 

 deficiency of tarsal bones, except in the Ostrich, 

 where rudiments of them may be traced. Already 

 we have seen, in ruminant quadrupeds, that 

 these bones have dwindled to a very small size : 

 but here they have wholly disappeared. The 

 long bone which succeeds to the tibia, though 

 considered by some anatomists as the tarsus, 

 is properly the metatarsal bone, and in the 

 Grallse is of great length. At its lower end it 

 has three articulations, shaped like puUies, for 

 the attachment of the three toes : there is besides, 

 in almost all birds, a small rudiment of another 

 metatarsal bone, on which is situated the fourth 

 toe. The number of bones which compose each 

 respective toe appears to be regulatedby a uniform 

 law. The innermost toe, which may be com- 

 pared to a thumb, consists invariably of two 

 bones: that which is next to it in the order 

 of sequence has always three ; that which follows 

 has four ; and the outermost toe has five bones : 

 the claws in every case being affixed to the last 



