6. THE COELOM AND ITS DERIVATIVES - THE EXCRETORY SYSTEM 



61 



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Fig. 41. Diagram of the arrangement of the protocoele of Spirobrachia grandis, in ventral view. 

 сое I - protocoele; lof- lophophore; tc - tentacular crown, with the ventral tentacles cut away; 

 vad- right afferent vessel of the tentacular crown; val-Ml afferent vessel of the tentacular crown; 

 ved- right efferent vessel of the crown; vel-\dt efferent vessel of the crown. (After Ivanov, 1960a.) 



