BRITISH ZOOPHYTES. 303 



immersed, tlie outer ones being erect, with free tubular 

 extremities. 



The disc measures about j in. across. 



2. D. OBELIA, Johnston. 



Tubulipora obeha {G.J., R. Q.O.), D. hyahna {Sniitt), 

 D. latomarginata {Smitt). 



Hab. : Generally distributed. 



This species forms closely adherent crusts spreading 

 irregularly, but with a tendency towards cii'cular ex- 

 pansions. The zooecia are alternate, distinct, partially 

 free and erect, divided by pale lines, with the orifices 

 rounded and oblique. " A small adventitious tubule 

 rises from the back o£ some of the ceils. ■'^ 



It is a semitransparent species, and the centre of the 

 colony is usually slightly raised. 



3. D. Sarniensis, Norman. 



Hab. : Guernsey {A. M. N.), Cornwall (T. //.), 

 Hastings {Miss Jelly) . 



This species is distinguished from the preceding by 

 the absence of the boundary-lines between the cells, 

 which are regularly disposed in radial lines from the 

 centre, and by the orifice of the zooecium being occa- 

 sionally operculate. A small tubule, of doubtful purpose, 

 projects from the upper part cf the operculum. 



It forms thick, milk-white incrustations on shells, 

 &c., usually in deep water. 



4. D. suBORBicuLARis, HincJcs. 

 D. simplex {Bush, Smitt). 



Hab. : South Devon, Isle of Man {T. H.). 



This forms '^ thin papyraceous orbicular colonies of 

 i in. diameter, with the zooecia deeply immersed." 

 The orifice of the zooecium is elliptical, and projects 

 just above the surface. The zooecia are densely punc- 



