VEETEBRATA. 



105 



Vertebrates. The clavicles are often wanting, or rudimentary, 

 and they are the least essential elements of the scapular arch. 

 The fore-limb proper consists, firstly, of a single bone which 

 forms the upper arm, and which is known as the humerus (h). 

 This articulates above the shoulder-girdle, and is followed 

 below by the fore-arm, which consists of two bones, called 



Fig. 482.— Pectoral limb (arm) 

 of Chimpanzee (after Owen), c, 

 Clavicle ; s, Scapula or shoul- 

 der - blade ; h, Humerus ; r, 

 Radius ; it, Ulna ; d, Bones of 

 the wrist, or carpus ; m, Meta- 

 carpus ; p, Phalanges of the 

 fingers. 



Fig. 483.— Hind-limb of the 

 Chimpanzee. i, Innominate 

 bone ; /, Thigh-bone or femur ; 

 t, Tibia ; s, Fibula ; r, Bones of 

 the ankle, or tarsus ; m, Meta- 

 tarsus ; p. Phalanges. 



the radius and 2dna. Of these the radius is chiefly concerned 

 with carrying the hand. The radius and ulna are followed 

 by the bones of the wrist, which are usually composed of 

 several bones, and constitute what is called the carpus (d). 

 These support the bones of the root of the hand, which vary 

 in number, but are always more or less cylindrical in shape. 

 They constitute what is called the rnetacarims. The bones of 



