288 
Z. ASCIDIOIDA. 
Flustra. 
Flustra membranacea, Lin. Syst. 1301. Fabric Faun. Groenl. 437, no. 
446. Mull. Zool. Dan. prod. 253. Ellis and Soland. Zooph. 18. 
Turt. Gmel. iv- 665. Wern. Mem. i. 563. Turt. Brit. Faun. 21 C. 
Stew. Elem. ii. 437. Bose, Vers, iii. 144. Corall. 47. Hogg's Stock. 
36. Flem. Brit. Anim. 536. Johnston in Trans. Newc. Soc. ii. 265. 
La F. membraneuse, Blainv. Actinol. 450. FI. telacea, Lam. Anim. 
s. vert. 2de edit. ii. 223. Grant in loc. s. cit. iii. Ill La mem- 
branipore membraneuse, Blainv. Actinol. 447. 
Flab. On the frond of Laminaria digitata ? common. 
Polypidom forming a gauze-like incrustation on the frond of the 
sea-weed, spreading irregularly to the extent of several square inches, 
in general, thin, and closely adherent, but sometimes becoming thick- 
ish, and then capable of being detached in considerable portions ; cells 
very obvious to the naked eye, oblong, quadrangular with a blunt hol- 
low spine at each angle. In many specimens there are some anoma- 
lous processes, a quarter of an inch in height, scattered over the sur- 
face : they arise from within the cells, are simple, horny and tubular, 
but closed at top. Ellis conjectured they were ovaries, but the con- 
jecture is certainly unfounded. — When the polypes are all protruded 
they form a beautiful object under the microscope, from their num- 
bers, their delicacy, the regularity of their disposition, and the viva- 
city of their motions, now expanding their tentacula into a beautiful 
campanulate figure, now contracting the circle, and ever and anon 
retreating within the shelter of their cells. The tentacula are nume- 
rous, filiform, white and in a single series. 
9. F. lineata, cells oval , separate , the margin armed with 
several short equal spinous denticles . Professor Jameson. 
Plate xxxvii. Fig. 4. 
Flustra lineata, Lin. Syst 1301. Mull. Zool. Dan. prod. 253. Fabric . 
Faun. Groenl. 437. Turt. Gmel. iv. 665. Corail. 46. Jameson in 
Wern. Mem. i. 563 La F. lineee, Blainv. Actinol. 450 F. spi- 
nifera, Johnston in Trans. Newc. Soc. ii. 266, pi. 9, fig. 6 F. hir- 
ta? Bose, Vers, iii. 144. Bisso, L’Europ. Merid. v. 334. Corall. 49. 
Hab. On stones at low- water mark in Berwick Bay, G. J. Ork- 
ney Islands, Jameson , 
Polypidom membranous, of a horny texture, yellowish-brown, 
rough, closely adnate, thin, spreading irregularly : cells scarcely visi- 
ble to the eye, separate by a space not equal to the cell in breadth, 
the marginal teeth stout and somewhat inclined inwards. 
10. F. ? carnosa, “ substance fleshy ; cells remote, aperture 
contracted , armed at the top with spinous processes Jameson. 
Plate xxxvii. Fig. 5. 
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