nostril 



grooire 

 '^'^0 mouth 



brain 



A. 



B. 



D. 



ujjperh'p 

 nostra 



Jarobsonlt 

 '■\carhiaoe 

 palate 

 r vomer 



"■fustac/iidn 

 roof of pharynx tube 



c • 



Jacohson's 

 or^an 



palate 



Fig. 66. Comparative Anatomy of the Human Palate. 



Recent shark, showing groove from nose to front of mouth. (After 

 Keith.) 



Lizard, in which internal opening (choana) from the nose opens in 

 the forepart of the mouth cavity. (After Plate.) 



Lion pup with cleft palate, recalling in form the palate of reptiles; 

 showing internal opening of the nose (indicated by the arrow- 

 point) in the forepart of the mouth cavity. In this abnormal 

 specimen the secondary palate has failed to grow over to the 

 midline. (After Keith.) 



Human embryo at the end of the sixth week, showing the secondary 

 palatal plates beginning to grow in toward the midline and the 

 "primitive choanse" (arrow-point) still exposed in the forepart 

 of the roof of the pharynx. (Afier Keith.) 

 (B, from AUgem. Zool., Gustav Fischer.) 



121 



