SERTULARIA. 123 



Hab. On old shells, from deep water. Aberdeen, Skene ; 

 Angusshire,Don ; Seaton, J. Hogg ; Scarborough, Mr. Bean ; 

 Dundee, W. Jackson, jun. ; Firth of Forth, Dr. Jameson, 

 Dr. Fleming, Dr. Coldstream ; Cornwall, Mr. Couch ; 

 Giant's Causeway, Mr. Hassall ; on oyster-shells from Loch- 

 ryan, D. L. 



Height two or three inches; stems erect, the stem and 

 branches composed of closely agglutinated tubes; cells 

 short and narrow; vesicles large, numerous, rough with 

 spinous ridges. See the figure of it in Dr. Johnston's work, 

 plate ix. fig. 3, 4. 



Genus IX. SERTULARIA, Linnaeus. 



Gen. Char. Polypidom growing in the shape of a plant, and 

 faxed by its base, variously branched, the divisions or branches 

 formed of a single tube denticulated or serrated with the cells, 

 and jointed at regular intervals : cells alternate or paired, bi- 

 serial, sessile, urceolate, short, with everted apertures : ovarian 

 vesicles scattered. Polypes hydraform. Dr. Johnston. 



* Cells alternate, one to each internode. 

 1. SERTULARIA POLYZONIAS, Great Tooth Coralline, James 

 Newton. (Plate IV. fig. 10.) 



