SERTUL ARIADNE : PLUMULARIA. 97 



5. P. SETACEA, pinnate, the pinnae, alternate, one originating 

 at each ringed joint of the rachis , cells very remote, campanu- 

 late, with an even margin ; vesicles elliptical, smooth. Ellis. 



PLATE XXII. Fig. 35. 



Sea Bristles, Ellis Corall. 19, no. 16, pi. 11, fig. a, A. CoraUina setacea, Ellis Corall. 

 38, fig. 4. Sertularia pinnata 0, Lin. Syst. 1312. D. Chiaie Anim. s. Vert. Nap. 

 iv. 144. S. setacea, Pall. Elench. 148. Ellis and Soland. Zooph. 47. Lister in 

 Phil. Trans, an, 1834, 371, pi. 8, fig. 4. Aglaophenia setacea, Lamour. Cor. Flex. 

 272. Plumularia setacea, Lam. Anim. s. Vert. ii. 129 : 2de edit. ii. 165. Flem. 

 Brit. Anim. 547. Tempkton in Mag. Nat. Hist. ix. 467. Stark Elem. ii. 440. 

 Risso L'Europ. Merid. v. 313. Hassatt in Ann. and Mag. N. Hist. vii. 285. 

 Couch Zooph. Cornw. 16 : Corn. Faun. iii. 33. 



Hob. Parasitical on other corallines, common. 



In favourable sites this coralline will sometimes attain a height of 

 six inches ; but in general it is smaller, more delicate, and less plum- 

 ous than PL pinnata, with which it has been confounded, although its 

 habit and minuter characters prove it to be quite distinct. The stem 

 is somewhat waved and regularly jointed, the joints consisting of two 

 or three rings, and immediately under each joint the internode is 

 somewhat enlarged in consequence of the pinna originating there, a 

 single pinna only springing from under each joint ; whereas in P. 

 pinnata, as already remarked, three pinnae proceed from each inter- 

 space, the joints of which, moreover, consist of a single fracture. 

 The pinnae are jointed like the stem, celliferous, the cells small and 

 distant. At the base of each there is a minute tubular process 

 (abortive cell ?), visible only with a high magnifier. The vesicles 

 are elliptical, smooth, with a narrow plain orifice, and originate in 

 the axils of the pinnae. " The ova within were opake and yellow. 

 Its polypi had from sixteen to nineteen arms, and when they were 

 full blown it was an object of remarkable beauty." Lister. " The 

 upper part of the vesicles of this species is prolonged into a short 

 tube, affording an additional distinctive character between it and 

 PI. pinnata, which it so closely resembles." Hassall. 



6. P. CATHARINA, stem plumous, the pinnae opposite, bent 

 inwards ; cells distant, campanulate, with an even margin ; 

 vesicles scattered, pearshaped, smooth. Gr. J. 



VIGNETTE, No. 1, page 3. 



Plumularia Catharina, Johnston in Mag. Nat. Hist. vi. 498, fig. 61, 62. Hassatt in 

 Ann. and Mag. Nat. Hist. vii. 285. Macgillivray in Ibid. ix. 465. Couch 

 Zooph. Cornw. 18 : Corn. Faun. iii. 35. 



H 



