84 ANTHOZOA HYDROIDA. 



This remarkable coralline is sometimes a foot in height, generally 

 less, affixed by a tubular fibre, which is sometimes agglutinated to 

 others from other shoots, so as to form a lichen-like crust concentri- 

 cally wrinkled. Stem percurrent, erect, filiform, rigid, zig-zag, 

 knotted, naked underneath, bearing on the upper part a cylindrical 

 tuft of dichotomous short equal branches, coming off alternately and 

 so disposed that four complete a whorl. The knots on the lower 

 part are the remains of former branches, which seem to drop off as 

 the portion of the stem immediately beneath them successively loses 

 its vitality. The stem has no cells, and neither it nor the branches 

 are jointed. Cells close-pressed, arranged in two rows, sub- alternate, 

 smooth, tapered from the base to a contracted orifice. Vesicles sub- 

 pedicellate, pear-shaped, smooth, placed in clusters or solitary on the 

 upper side and towards the base of the branches. They are pro- 

 duced mostly in the winter season, and are filled with a milk-white 

 grumous fluid previous to the discharge of the ova. 



Young specimens of this polypidom are simply pinnate, but these 

 may be always distinguished from the following species by the 

 greater intervals between the origin of the pinnse, and by the shape 

 of the cells. The Figures 1, 2 of Plate XVIII. represent a specimen 

 of this kind ; which have been the more readily introduced, since they 

 exhibit the living polypes in an active state, and prove that the 

 coralline has no relationship to Cellaria.. 



The SERTULAEIA THUIA of Fdbricius, in his Fauna Groenlandica, 

 p. 444, I am inclined to refer to Sertularia pumila. 



2. TH. ARTICULATA, cells ovate, obtuse or truncate ; ovarian 

 vesicles elliptical. Ellis. 



PLATE XVIII. Fig. 3, 4. 



Sea-spleen wort or Polypody, Ellis Corall. 11, no. 10, pi. 6, fig, a, A. Sertularia 

 articulata, Pall. Elench. 137. Esper Pflanz. Sert. tab. 8, fig. 1, 2. S. Lonchitis, 

 Ellis and Soland. Zooph. 42. S. Lichenastrum, Berk. Syn. i. 219. Turt. Brit. 

 Faun. 216. Stew. Elem. ii. 447. Cellaria Lonchitis, Lam. Anim. s. Vert. ii. 

 139 : 2de dit. ii. 186. Thuiaria articulata, Flem. Brit. Anim. 545. Hassall in 

 Ann. Nat. Hist. vii. 284, pi. vii. fig. 1, 2. Couch Zooph. Cornw. 12 : Corn. Faun, 

 iii. 28, pi. 4. 



Rab. On shells and stones in deep water, rare. In the harbour 

 of Dublin, Ellis. " I have remarked this species adherent to the 

 Pecten maximus dredged at Donaghadee, co. Down ; and Mr. E. 

 Forbes finds it on Pecten opercularis at the Isle of Man. Mr. 



