FIG. 30. Sections of orthognathous (light contour) and prog- 

 nathous (dark contour) skulls, one-third of the natural size, a b, 

 Basicranial axis ; b c t b f c', plane of the occipital foramen ; d d\ 

 hinder end of the palatine bone ; e e' t front end of the upper 

 jaw ; T T' t insertion of the tentorium. 



