PLATE XXIV. 



Fig. I. Sertularella saccata Nutting. Part of colony, showing hjdrothecae and 

 gonangia with acrocysts (enlarged). 



2. Three hjdrothecae (still more enlarged). 



3. Single hydrotheca, showing operculum (drawn to same scale as Fig. 2). 



4. T/iutaria fabrtcii {'Levinsen). Part of branch showing hydrothecse and 

 gonangia (enlarged). 



5. Front view of part of branch (enlarged). 



(212) 



