PLAl'K 2 



EXPLANATION OF FIGURES 



15 Lateral view of a model of the pharj'ngeal entoderm from a 10 mm. human 

 embryo (No. 1000, Harvard Embryological Collection). X 50. The left half 

 of the anterior portion of the pharjTix only is shown in the model. Cut sur- 

 faces are indicated by lines, in this and figure 16. 



16 Ventral view of the same. X 50. 



17 View of the same model from the aspect that is toward the right in figure 

 15; that is, from the dorsal aspect as referred to the embryo's body. X 50. 



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