Plate XI 



Fig. 2. Transverse frontal section of the buccal sulcus in a 7.5 millimeter human 



embryo near the angulus oris. Columbia Collection, No. 22g, slide 4, 



row 4, section 8, X 187, reduced 5. 

 Fig. 3. Same embryo, slide 4, row 4, section 2. More caudal section of buccal 



sulcus. 

 Fig. 4. Reconstruction of the oral epithelium of a 20 millimeter human embryo, 



Columbia Collection, No. 325, X 60, reduced |. Ventral view. 



1. Buccal sulcus. 



2. Parotid anlage. 

 J. Orbital inclusion. 



4. Orbiloparotid interval. 



6. Proparotid ridge. 



7. Thickening of the epithelium of the buccal sulcus near the angulus oris. 



8. Lingual sulcus. 



9. Subma.xillary anlage. 



10. Greater sublingual anlage. 



11. Anlage of apical gland. 

 14. Alveolar sulcus. 



j6. Intermediate sulcus. 



22. Frenulum. 



24. Angulus oris. 



20. Inferior dental anlage. 



