THE PHARYNX. 



401 



day (Fig. 161) the maxillary, MX, mandibular, MX. hyoid, HY, 

 and first branchial arches form conspicuous ridge-like projections 



in the side walls of the pharyngeal region. Of the branchial 

 grooves, or external depressions separating the successive arches, 



D D 



