202 



COMPARATIVE ANATOMY 



and not even in the higher forms have become completely integrated. 

 These are the appendicular skeleton of the four limbs with their girdles; 

 and the axial skeleton, which includes the skull with the jaws, and the 



Fig. 154. — Diagrams illustrating two theories of the origin of chondrin in the 

 formation of cartilage. According to one opinion (A) chondrin is of intracellular origin. 

 According to the other view (B) chondrin is of intercellular origin. (Redrawn after 

 Bremer.) 



vertebral column, the sternum, and the ribs. The individual bones 

 number in man, sixty-four for the shoulder girdle and the arms, sixty-two 



_J . /SUPI 



SUPRAOCCIPITAU 

 EXOCCIPITAL 



METATARSALS 

 PHALANGES 



Pig. 155. — A diagram of the vertebrate skeleton, showing the division of the skeleton 

 into axial, visceral, and appendicular. Membrane bones are shown in black, cartilage 

 bones stippled. 



in the pelvic girdle and the legs, twenty-three in the skull, twenty-six 

 in the backbone, and twenty-five for ribs and sternum, with six ear bones 

 besides, over two hundred in all. 



