BONES OF LEG AND FOOT. 



41 



lowest birds can scarcely walk; for perching on trees, etc., in the vast 

 majority, most of which hop about there, and many of which climb or 

 scramble in every imaginable way, with or without the aid of the tail ; for 

 swimming on the water, or diving, in a great many ; for grasping and hold- 

 ing detached objects in some, as the parrots, birds of prey, and a few 

 others. The modifications of the leg and foot are more numerous, more 

 diverse, and more important, in their bearing upon taxonomy, than those 

 of either bill, wing or tail. 



§ 72. (a.) The bony framework. (Fig. 8, somewhat diagrammatic il- 

 lustration, taken from a loon's right leg. ) This ordinarily consists of twenty 

 bones, of wlaich fourteen are toe-bones, one is a little bone connecting the 

 hind toe with the rest of the foot, one a little bone in front of the knee- 

 joint, and four are the princii^al bones from the hip-joint down to the roots 

 of the toes. The first is the femur or thigh-bone, a, reaching from hip a, to 

 knee b; a large terete bone, corresponding to the humerus of the wing. 

 Then come two bones, b, the (ibia, or principal (and inner) leg-bone, and c, 

 the Jibula, or lesser (and outer )^ leg-bone ; both these joint M'ith the femur 

 above, and in front of this, the knee-joint, there is in many or most birds a 



Fig. 8. Bones of leg-and foot. 



little knee-pan, or knee-cap : the patella, p. The tibia runs to the heel, c, 

 and there has an enlarged extremity to joint with the next bone : but the 

 fibula is only a slender spicula not reaching the heel, but ending in a sharp 

 point part waj' down the leg, and partly soldered with the tibia. It is only 

 in a few of the lowest birds, that the tibia runs up to a point above the knee- 

 joint, as shown in this figure : ordinarily, it ends at the knee itself. The 

 portion of the leg represented by the femur, or from a to b, is the thigh • 

 that represented by tibia and fibula is the leg or CRUS ; leg proper, there- 

 fore, is from knee to heel, or b to c only. 



KEY TO N. A. BIRDS. 



