292 VERTEBRATA 



or scapula, the arm bone or humerus, the ulna and radius 

 in the forearm, several small bones in two rows forming 

 the carpus or wrist, and five metacarpal bones in the hand, 

 each bearing three phalanges, except the first, which has 

 only two. In the hind limb the femur occupies the thigh 

 region, while the tibia and fibula in the lower part of the 

 leg join the several small bones of the ankle to which are 

 united the five bones of the foot, called metatarsals, each 

 bearing three phalanges, except the first, which has only two. 

 In many forms some of the digits are wanting and others 

 are more or less rudimentary, as in the cattle, horses, and 

 pigs. In some cases the ulna and radius are grown to- 

 gether, as are also the tibia and fibula, and in these species 

 the ulna and fibula are usually rudimentary. 



