EMBRYOLOGY OF THALASSEMA MELLITA 



215 



elongated muscles runs from the apical plate and the anterior 

 part of the umbrella region to the body-wall beside the mouth, 

 and is continued by muscles which extend along the mid-ven- 



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Fig. 8. 



tral line. In Echiurus and Eiipomattis the ventral longitudinal 

 muscle is, in like manner, divided into a praeoral and postoral 



