PLATE I. 



Cceuoecium of Cephalodiscus dodecalophas, about the natural size ; a few of the liraiiches 

 terminate in somewhat flattened tips. At ((, one of the pillars, which like aerial 

 roots pass downwards to the stones and sponges on which it grows, is represented, 

 its tip being expanded into a broad surface. Numerous inosculations take place 

 between the various branches. 



I have to th;iuk Mr. E. E. Prince for most kindly aiding nic in drawing certain 



figures, as indicated on the Plates. 



