2 3 



Viji,. 30 .Sei'uil tivmsvci'sc section iif an embryo <)' twelves somites. ^, Cells 

 derived from visceral mesoderm in luncess of accretion to th(^ aorta; .f, cells of 

 selcrotoiae in syncytial continuity with en loth(4iam; 7, an^iocyst adiled tn aorta.; 

 a remnant of septum is still visibli^ 



SO 



