MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 



461 



on each side of the dorsal directives and the pair of dorsal second-cycle mesenteries, and a similar 

 pair within the left middle system III. 



n 



Fig. 8e. 

 Aslrangia solUaria. — Three pairs of second-fyele metaonemes (III) have arisen toward the dorsal aspect of the polyp. 



Fig. 8d. 

 Astrangia salitarla. — Two additional pairs of second-cycle metacneme-s have appeared: as yet only a single i>nir of second-cycle metacncmes 



is contained within each primary exoctelc. 



In fig. 8d two additional pairs occur, one in the right middle system, and one in tlie left 

 ventral system. Two other polyps sectionized from another colon\- exactly correspond with 

 fig. 8^. 



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