138 
Z. HYDROIDA. 
Thuiara. 
of Scotland, and in the north of England, particularly about Scar- 
borough, where the fishermen have given them the name of Bottle- 
brushes,” Ellis. “ Very frequently found on the coast of Durham,” 
J. Hogg. Common on N. Durham and Berwickshire, G. J. Leith 
shore, Jameson. 
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 produced 
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 by the greater inter- 
vals between the origin of the pinnae, and by the shape of the cells. 
The Fig. 1 , 2 of Plate XV. represents a specimen of this kind, which has 
been the more readily introduced, since it exhibits the living polypes 
in an active state, and proves that the coralline has no relationship 
to Cellaria. — The Sertularia thuia of Fcibricius in his Fauna Groen- 
landica, p. 444, I am inclined to refer to Sert. pumila. 
2. Th. articulata, cells ovate , obtuse or truncate ; ovarian 
vesicles elliptical. Ellis. 
Plate XV. Fig. 3, 4. 
Sea- Spleen wort or Polypody, Ellis, Corail. 11, no. 10, pi. 6, fig. a, A.—— 
Sertularia articulata, Pall. Elench. 137 S. Lonchitis, Ellis and So- 
land. Zooph. 42 S. Lichenastrum, Berk. Syn. i. 219. Turt. Gmel. 
iv. 683. Turt. Brit. Faun. 216. Stew. Elem. ii. 447. Bose, Vers, iii. 
119 Cellaria Lonchitis, Lam. Anim. s. Vert. ii. 139. Thuiaria 
articulata, Elem. Brit. Anim. 545. La B. articulee, Blainv. Actinol. 
482. 
Hab. On shells and stones in deep water, very rare. In the har- 
bour of Dublin, Ellis. At Scarborough, Mr Bean. 
Polypidom about 4 inches high, pinnate, lanceolate, corneous, sub- 
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