138 Z. HYDROIDA. Thuiaua. 



of Scotland, and in the noi'tb of England, ])articularly 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 ci'ust 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 Fabricius 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-Spleenwort or Polypody, £ffis, C'orall. 11, no. 10, pi. 6, fig. a, A 



Sertularia articulata, Pall. Elench. 137 S. Lonchitis, jBffis and A'o- 



land. Zooph. 42 S. Liclienastrum, J5erA. Syn. i. 219. Turt. Gmel. 



iv. 683. Turt. Brit. Faun. 216. Stew. Elem. ii. 447. Bosc, Vers,iii. 



119. Cellaria Lonchitis, Lam. Anim. s. Vert. ii. 1.39. Thuiaria 



articulata, Flem. 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, 3Ir Bean. 



Polypidom about 4 inches high, pinnate, lanceolate, corneous, sub- 



3 



