Plate XIII 



Figs. 6 to ig. Transverse frontal sections of a 20 millimeter embryo. Columbia 

 Collection, No. 325, X 80, reduced 5. For levels of sections see Fig. 20. 

 Fig. 6. Series No. 325, slide 17, row, 3, section 8. 

 Fig. 7. Series No. 325, slide 17, row 2, section 2. 



I. Buccal sulcus. 



6. Proparotid ridge. 



8. Lingual sulcus. 



g. Submaxillary anlage. 



10. Greater sublingual anlage. 



14. Alveolar sulcus. 



16. Intermediate sulcus. 



ij. Tongue. 



iS. Sublingua. 



iQ. Plica fimbriata. 



21. Meckel's cartilage. 



2S. Superior dental anlage. 



2Q. Inferior dental anlage. 



40. Epithelial thickening between the intermediate and Ungual sulci. 



