132 
Z. HYDROIDA. 
Sertularia. 
abietina, /2, Pall. Elencb. 134 Dynamena filicula, Flem. Brit. Anim. 
544. La D. filicule, Blainv. Actinolog. 483. 
Hob. Parasitical on sea- weeds, particularly on the entangled roots 
of Laminaria digitata. Coast of Yorkshire, Hudson. Scarborough, 
Ellis. Frequent about Seaton, Hartlepool, Whitburn, and other 
places on the coast of Durham, Hogg. Cullercoats, Northumber- 
land, Jos. Alder. Dunstanborough, R. Embleton. Common on the 
shores of N. Durham and Berwickshire, G, J. Frith of Forth, 
Jameson . 
Polypidom arising from a creeping fibre, 1 to 4 inches in 
height, spreading bifariously, irregularly branched, slender and flex- 
ible, of a straw- yellow or brownish colour, homologous throughout ; 
the rachis zig-zag, or “ bent to and fro into alternate angles,” close- 
ly pinnated, the pinnae shooting from every bend alternately on op- 
posite sides, linear, patent, simple or composite. Cells closely set, 
minute, giving a serrulated appearance to the ramifications of the 
polypidom, shaped something like a Florence-flask, smooth, the aper- 
ture oblique, entire. The vesicles are rarely produced, nor have I 
seen a specimen with them : they are represented by Ellis as of a 
pear shape with a short tubulous aperture. 
This, like its ally the S. abietina, is often infested with Serpulse, 
but it is a much more delicate species, and, notwithstanding the si- 
milarity of their specific characters, perfectly distinct. “ The singu- 
larity of its waved stem, with its erect single denticle at the insertion 
of the branches, together with the single pair of denticles on each 
part of the stem, that form the angles, make it a very distinct spe- 
cies from any of this genus.” Ellis. 
14. S. operculata, cells opposite , inversely conical , the aper- 
ture patulous , obliquely truncate , pointed on the outer edge , with 
two small lateral teeth ; vesicles obovate. Mr Newton. 
Plate XL Fig. 2, 2. 
Muscus marinus denticulatus, procumbens, caule tenuissimo, denticulis bi- 
jugis, Raii , Hist. i. 79. Morrison , Plant. Hist. Oxon. iii. 650, tab. 9, 
fig. 3. Plukenet , Phytogr. tab. 47, fig. 11. Corallina muscosa denti- 
culata procumbens, Raii , Syn. 36, No. 18 Sea- Hair, Ellis, Corall. 8, 
No. 6, tab. 3, fig. b. B. Sertularia operculata, Lin. Syst. 1307. El~ 
lis and Soland. Zooph. 39. Berk. Syn. i. 216. Turt. Gmel. iv. 676. 
Jameson in Wern. Mem. i. 564. Turt. Brit. Faun. 212. Stew. Elem. 
ii. 441. Bose, Vers, iii. 106. Lam. Anim. s. Vert, ii- 118. Hogg's 
Stockton, 32. Johnston in Trans. Newc. Soc. ii. 258, plate 11, fig. 2. 
Templeton, ut supra cit, 468 S. usneoides, Pall. Elench. 132.— — 
Dynamena operculata, Lamour. Cor. Flex. 176. Corail. 78. Flem. Brit. 
Anim. 544. — La Dynamene operculee, Blainv. Actinolog. 483, pi. 83, 
fig. 5. 
