THE FROG, A TYPICAL VERTEBRATE 



255 



the pectoral girdle. The principal ones are the breastbone or 

 sternum, the shoulder blades or scapula, and the collar bones or 

 clavicles. 



The bones of the fore limbs are very similar to those of man 

 and other vertebrates. They are the arm bone or humerus, 



FIG. 145. Skeleton of the frog. 



the forearm or radio-ulna, the wrist containing six small bones, 

 and the hand with a row of bones in each of the five digits. 



The hind limbs are attached to the vertebral column by the 

 pelvic girdle consisting of three bones on each side closely fused 



