76 



FRANKLIN P. REAGAN 



Pcd. Myc- 



3-10 Explanation of abbreviations. Coel., coelom; Ed., ectoderm; Endc, 

 endocardium; Ent., entoderm; Mijc, myocardium; Par. mes., parietal mesoderm; 

 Pcd., pericardium; Ph., pharynx; Pv.m., prevascular mesoderm; Vis. mes., vis- 

 ceral mesoderm; x, point of fusion of ectoderm and entoderm. 



