PLATE XIII. 



Figs. 1, 2. Mycedium fragile Dana, natural size. 

 Fig. 3. Mycedium fragile Dana, simple calicle, magnified. 

 Fig. 4. Mycedium fragile Dana, calicle in process of division, magnified. 



Fig. 5. Mycedium fragile Dana, cross-section of corallum, showing septal ridges (upper surface) on the 

 left, costal ridges, lower surface on the right, magnified. 



