MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 



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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. 



E 



Fig. 8c. 

 Astrangia solitaria. — Three pairs of second-cycle metaenenies (III) have arisen toward the dorsal aspect of the polyp. 



Fig. Sd. 

 Astraiuiiu tnliturla. — Two additional pairs of second-cycle metacnemes haye appeared; as yet only a single pair of second-cycle metacnemes 



is contained within each primary exoccele. 



In tig-. Sd two additional pairs occur, one in the right middle system, and one in the left 

 ventral system. Two other polyps sectionized from another colony exactly correspond with 

 rig. 8d. 



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