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. 



