PLATPJ 1 



EXPLANATION OF FIGURE 



Fig. (j Ventral view of a wax reconstruction of the aortic arches and pharynx 

 of the same embryo. The body wall ectoderm is shown as partly removed 

 from the ventral surface of the visceral arches. (The asymmetry of the figure is 

 due to a twist in the embryo). 



508 



