158 



CHORDATE ANATOMY 



The Skull. There are two chief parts to the skull, which have different 

 origins and a different history. One of these is the cranium or brain-case, 

 together with the bones of the face except the two jaws. The other is 

 the visceral skeleton, that is to say, the two jaws, the hyoid bone, the 

 ear bones, and the cartilages of the larynx. 



3ASISPHENOI0 

 ORBITOSPHENOID \ ALISPHE>JOID 

 PRESPHENOID \ \ \ PARIETAL 

 FRONTAL 

 VOMER 

 PREFRONTAL \ \ J^>Cpp@>W 

 NASAL ^ ^ \ ^<<!r*-fi\#.\r-.\( t vA 



SUPRAOCaPITAL 



EXOCCIPITAL 

 ,BASIOCCIPITAL 



A. MAMMAL 



ALISPHENOip 

 ORBITOSPHENOID 



PRESPHENOI 



FRONTAL. 

 PREFRONTAL 

 VOMER 

 NASAL' 



SUPRAOCaPITAL 



EXOCCIPITAL 



B. MAN 



Fig. 148. — Owen's figures illustrating the Goethe-Oken vertebral theory of the skull. 

 Owen believed that he could find in the mammalian skull four enlarged vertebrae, the 

 components of which he identified with the elements of a trunk vertebra. Not knowing 

 the embryology of the skull, he did not realize that vertebrae lack the membranous 

 bones which are so conspicuous in the skull. (Redrawn from Wilder.) 



The Evolution of the Cranium. In the early part of the nineteenth 

 century it was generally assumed by morphologists that the skull consists 

 of four or five enlarged vertebrae. Originally suggested by the poet 

 Goethe, this "vertebral theory" of the skull was developed by Oken in 

 Germany and by Owen in England. See Fig. 148. The basis of this theory 



