PLATE X. 



FIG. 



1. SERTULARIA POLYZONIAS, var. a, p. 61, of the natural size. 



2. SERTULARIA POLYZONIAS, var. (3, p. 61, of the natural size. 



3. A portion of Sertularia polyzonias magnified. 



4. SERTULARIA RUGOSA, p. 63, of the natural size. 



5. SERTULARIA RUGOSA, considerably magnified, but without 



vesicles. 



6. A portion of the creeping variety of Sertularia rugosa 



magnified, shewing both the cells and vesicles. 



