SEETULARIA. 159 



None of the corpuscula proved to be spherical or of regtdar shape, 

 under the microscope. But when viewed within the vesicle, the contents 

 then appearing a single irregular corpusculura, may present that charac- 

 ter, from the compression of several together. 



Exact uniformity did not prevail in the vesicles of fig. 7. One had 

 a kind of short spinous prolongation, fig. 12. In other specimens there 

 was no sensible distinction, fig. 13. 



This product usually occurs on old empty shells. I do not recollect 

 to have found it on other substances. 



Certain desiderata yet remain to render its history explicit. 



Plate XXV. Fig. 6. Sertularia aUetinula. 



7. Group on a shell. 



8. Branch of fig. 7, enlarged. 



9. Vesicle on a branch of fig. 6, enlarged. 



10. Prolific vesicle. 



11. Vesicles discharging yellow corpuscula amidst albuminous 



matter, enlarged. 



12. Vesicle of fig. 7, enlarged. • 



13. Vesicle of fig. 7. 



§ 4. Sertularia rosacea — Lilt/ Coralline. — Plate XXVI. Figs. 1-13. 



^This is a delicate product, generally pure white, or of the faintest grey 



colour : it rises two inches, or somewhat more, in height, by a stem per- 

 pendicular, or slightly recurved, from which boughs diverge, either in the 

 same plane, or from around the circumference. Sometimes these are at 

 right angles to the stem. Subordinate parts are few. — Plate XXVI. 

 Figs. 1, 2. Articulations are seen at irregular and distant intervals, but 

 only in decaying specimens ; for they are inconspicuous in those which are 

 vigorous, and the parts occupied by the pith. 



The whole stem, together with all the subordinate parts, are clothed 

 with long wide cells, disposed in pairs ; and all the extremities terminate 

 in a similar pair, mature or elementary, fig. 3. The cells incline outwards. 



