PLATE XII. 



[Proc. Wash. Acad. Sci., Vol. Ill, PI. XXIII.] 



Fig. I. Halecium reversum Nutting. Part of colony, showing internodes and 

 hjdrophores (enlarged). 



2. Single hydranth with hydrophore (enlarged). 



3. Halecium robustum Nutting. Tip of branch, showing expanded hy- 

 drant hs (enlarged). 



4. Part of branch with soft parts removed to show the hydrophores (en- 

 larged). 



5. Single hydranth with its hydrophore (greatly enlarged). 



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