AcAMARCHis. Z. ASCIDIOIDA. 293 



moved \ip wards and downwards with the regularity of a pendulum. 

 The polypes have apparently twelve tentacula. 



The cells have the characters of Acamarchis or Flustra rather than 

 of Cellularia. IMany naturahsts make the zoophyte a vari ety of Flustra 

 avicularia, but Mr Bean and Milne Edwards dissent from this associa- 

 tion. The principal distinction between them lies in the dissimi- 

 larity of their habit : in the shape of the cells I do not perceive any 

 noticeable difference, but in this I have never seen more than two 

 spines at the top of each cell, while in the Flustra I have seen four 

 on some cells, though certainly many of them are armed with two 

 only. 



5. C. HOOKERi, ^^ cells rounded, diverging, projecting." — Sir 



W. J. Hooker. 



Cellularia Hookeri, Flem. Brit. Anim. 339 La Bicellaire de Hooker, 



Blainv. Aclinol. 460. 



Hab. " Found by Dr Hooker at Torquay, 1812," Fleming. 



" H eighth upwards of an inch, dichotomously branched, branches 

 straight, stiff, brittle, divaricate ; the cells are protuberant dorsally, 

 and their rounded top is nearly free, projecting laterally, giving the 

 edge a remarkably jagged outline, and the pearly ovaria are rounded." 

 Fleming. — This is probably syonymous with Cellaria denticulata 

 of Lamarck, Anim. s. vert. ii. J 37. 



37. Acamarchis,* Lamouroux. 

 Character. Polypidom plant-like, subcalcareous, attached 

 hy fibrous radicles, bushy, dichotomously branched, the branches 

 composed of a double series of semialternate oblong cells whose 

 apertures occupy nearly one side and face one way, usually pro- 

 tected by an operculum. — Polypes ascidian. 



1. A. neritina, " cells quadrangular, lengthened, with a 



truncated summit, the outer angle projecting." — Miss Blackburne. 



Remarkable Coralline, Ellis in Phil. Trans, abridg. x. 345, pi. 8, fig. a, A. 



G. Ellis, Corall. 33, pi. 19 Sertularia neritina, Lin. Syst. 1313. 



Turt. Gmel. iv- 683. Stew. Elem. ii. 448 Cellularia neritina, 



Pall. Elencb. 67. Flem. Brit. Anim. 339 Cellaria neritina, £ffis and 



Soland. Zooph. 22. Bosc, Vers, iii. 131. Lam. Anim. s. vert ii. 



140. 2de edit, ii- 190 Acamarchis neritina, Corall. 38, pi. 3, fig. 2. 



Risso, I'Europ. Merid. v. 318. Blainv. Actinolog. 439, pi. 77, fig. 3. Tem- 

 pleton in Mag. Nat. Hist. ix. 469- 

 Hab. On the English coast, very rare. " I possess a specimen 



" The name of one of the daughters of Oceanus, 



