132 Z. HYDROIDA. Sertularia. 



ftbietina, /3, Pall. Elench. 134 DjTiamena filicula, Flem. Brit. Anim. 



544. La D. fUicule, JSlainv. Actinolog. 48-3. 



Ilab. 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, ^bs. ^/rfer. Diinstanhorongh, H. Embleton. Common on the 

 shores of N. Durham and Berwickshire, Go J. Frith of Forth, 

 Ja77ieson. 



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 tulnilous aperture. 



This, like its ally the S. abietina, is often infested with Serpulae, 

 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 denticulatiis, procumbens, caule tenuissimo, denticulis bi- 

 jugis, Rail, Hist. i. 79. Morrison, Plant. Hist. Oxon. iii. 650, tab. 9, 



fig. 3. Pluhenet, 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. h- B. Sertularia operculata, Lin. Syst. 1307- El- 

 lis and Soland. Zooph. 39. Berk. Syn. i. 216. Turt. Gmel. iv. 676. 

 Jarneson'irv Wern. Mem. i. 564. Turt.Wit. Faun. 212. Steiv. Elem. 

 u. 441. Base, Vers, iu. 106. Lam. Anim. s. Vert. u. 118. Hogg's 

 Stockton, 32. Johnston in Trans. Newc. See. fi. 258, plate 11, fig. 2. 



Templeton, ut supra cit, 468. S. usneoides. Pall. Elench. 132 



Dynamena operculata, Lamour. Cor. Flex. 176. Corall. 78. Flem. Brit. 

 Anim. 544 — La Dynamene operculte, Blainv. Actinolog. 483, pi. 83, 

 fig- 5. 



