THE STRUCTURE OF THE FERTEBRATES 333 



From Ritchie's "Human Physiology" 



FIG. 122. Vertebrate limbs. A is the human leg ; B, the human arm ; C, the fore 

 leg of a horse ; D, the wing of a bird ; E, the foot of a bird ; F, the hind leg of a frog ; 

 G, the wing of a bat ; H, the fore leg of a tortoise. 



