SERTULARIAD^E I SERTULARIA. 77 



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 Serputoe ; 

 but it is a much more delicate species, and, notwithstanding the 

 similarity of their specific characters, perfectly distinct. " The sin- 

 gularity of its waved stem, with its erect single denticle at the in- 

 sertion 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 

 species from any of this genus." Ellis. 



15. 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 XIV. FIG. 2, 2. 



Muscus marinus denticulatus, procumbens, caule tenuissimo, denticulis bijugis, Rail 

 Hist. i. 79. Morrison Plant. Hist. Oxon. iii. 650, tab. 9, fig. 3. Plukenet 

 Phytogr. tab. 47, fig. 11. Corallina muscosa, denticulata procumbens, Rail Syn. 

 36, No. 18. Sea-hair, Ettis CoralL 8, No. 6. tab. 3, fig. b. B. Serttilaria oper- 

 culata, Lin. Syst. 1307. Ellis and Soland. Zooph. 39. Berk. Syn. i. 216. Esper 

 Pflanz. Sert. tab. 4, fig. 1, 2. Lam. Anim. s. Vert. ii. 118. Johnston in Trans. 

 Newc. Soc. ii. 258, pi. 11, fig. 2. Templeton ut supra cit. 468. Hassall in Ann. 

 Nat. Hist. vi. 168. Couch Zooph. Cornw. 9. Maegittivray in Ann. and Mag. 

 Nat Hist. ix. 464. Couch Corn. Faun. iii. 23. S. usneoides, Poll. Blench. 132. 

 Dynamena operculata, Lamour. Cor. Flex. 176. Flem. Brit. Anim. 544. 

 Blainv. Actinolog. 483, pi. 83, fig. 5. Krauss Condi, and Zoophyt. der Sudsee, 

 27. Dynamena pulchella, D'OrUgny. 



Hob. Near low-water mark on Fuci, particularly on the stalks 

 of Laminaria digitata. Common on all parts of the British coast. 



Grows in tufts from two to four, or even twelve inches high. The 

 shoots are slender and neat, filiform, flexuose or widely zig-zag, 

 always erect, alternately branched, the branches erect, and, like the 

 first shoot, serrulated with the polype-cells, which are exactly oppo- 

 site, and less everted than is usual to the genus. The outer angle 

 of the aperture of the cell is produced into an acute point, and there 

 is a sharp tooth on each side, which is omitted in the otherwise 

 admirable figure of Ellis, although it could not escape his lyncean 

 ?ye.* Often there is only a tooth on one side of the margin of the 

 iperture, and this is sometimes so far advanced that the apex may 

 De said to be bicuspidate. The latter formation is particularly 



* " Zoophytorum lynceus Ellisius." Lin. Syst. 1071. 



