250 Z. ASCIDIOIDA. Vesicularia. 



expanded, in which state it is of the same diameter as the rest of the cell ; but 

 when the animal retracts is folded up and drawn in after it, and completely closes 

 the mouth of the cell. 



" The flexible part consists of two portions, the lower half being a simple 

 continuation of the rest of the cell ; the upper consisting of a row of delicate 

 bristle-shaped processes or setae, which are arranged parallel with each other round 

 the top of the cell, and are prevented separating beyond a certain distance by a 

 membrane of excessive tenuity, which surrounds and connects the whole. This 

 mode of termination of the ceU is one of constant occurrence, as will be describ- 

 ed in other species, and is evidently a provision for allowing of the freest possible 

 motion of the upper part of the body in its expanded state, to which it affords 

 at the same time support and protection." Phil. Trans, an. 1837, p. 393. 



22. Vesicularia, * Thompson. 

 Charactek. Polypidoms rooted^ confervoid, Jistular.^ horny, 

 dichotomoiisly branched, jointed at the divisions : cells ovate, dis- 

 junct, iiniserial and unilater'al. Polypes ascidian. 



1. V. spiNOSA. Dillenius. 



Plate xxix. Fig. 1-4. 

 Conferva marina cancellata. Rait, Syn. i. 59, no. 1 1 . Dill. Hist. Muse. '24, 

 no. 22, pi. 4, fig. 22, — fide D. Turner in Lin. Trans, vii. 106 Con- 

 ferva cancellata, Lin. Syst. ii. 720. With. Bot. Arrang. iv. 131 



Silk Coralline, Ellis, Corall. 20, no. 17, pi. 11, fig. b, B, c, D Ser- 



tularia spinosa, Lin. Syst. 1312. JEllis and Soland. Zooph. 48. Turt. 

 Gmel. iv. 682. Jameson, in Wern. Mem. i. 364. Bosc, Vers, iii. 118. 

 Stew. Elem. ii. 446. Berk. Syn. i. 219. Turt. Brit. Faun. 215. La- 

 marck, Anim. s. Vert. ii. 120. 2de edit. ii. 148. Hogg, Stock. 33 



Sert. sericea. Pall. Elench. 114 Laomedea spinosa, Corall. 91. 



Templeton in Mag. Nat. Hist. ix. 466 Valkeria spinosa, Flem. Br. 



Anim. 551 Vesicularia spinosa, Thomp. Zool. 111. 98, pi. 3. fig. 1-8. 



Farre in Phil. Trans, an. 1837, 401, pi. 22 La Laomedee epineuse, 



Blainv. Actinolog. 474. 



Hab. In deep water, not uncommon. " Junio et Julio mensibus 

 pone Sheerness in insula Shepey copiose observavi," Dillenius. " At 

 the Nore, near the entrance of the Thames," Ellis. Leith shore, 

 Jameson. " Rarely found near Hartlepool," J. Hogg. " Found 

 on the shore of Belfast Lough : common/' Templeton. Liverpool, 

 Hev. D. Landsborough. 



Polypidom affixed by a fibrous base, very slender, confervoid, of <i 

 thin membi'anous pellucid texture, much branched, erect, sometimes 

 as much as 8 inches in height, usually about 4 ; main branches com- 

 posed of intertwined capillary tubes, tapered, zigzag ; branchlets arising 

 from the bends, eitlier solitary or in pairs, short, much divided dicho- 

 toniously, the apices pointed and closed ; all the branches are joint- 



* From vesicula, diminutive of vesica, a bladder 



