studies M.L.Vol.IY, PI. XI. 



endoderm. 





'm 



• 











-nerve cord. 



1 V -^/WA-'iSIp * 





external opening of 

 nephridium. 



cr\ir ^1. 



*^e 



muscles of le^ 



'H 



F Huth.Lith' Elin' 



