618 THE EMBRYOLOGY OF THE FROG 



The pterygoids form along the inner faces of the palato-quadrate 

 cartilages. 



The squamo&als form along the outer face of the palato-quadrate 

 cartilages, and ultimately reach back to the auditory capsules. The 

 quadrat ojugal is that portion which has developed at the posterior angle 

 of the palato-quadrate cartilage and then fused with the quadrate bone. 

 This is the only one of the membranous bones which cannot be distin- 

 guished from the cartilaginous bones of the skull. 



