Ser. RnoposPERMEZ. Fam. Ceramiec. 
Prate LXXX. 
PTILOTA PLUMOSA, “%. 
| Guy. Car. Frond inarticulate, linear, compressed or flat, distichous, pec- 
. tinato-pinnate ; the pinnules sometimes articulate. Fructification, of 
. two kinds, on distinct individuals; 1, f¢efraspores attached to, or 
immersed in the ultimate pinnules; 2, roundish, clustered, receptacles 
(favellz) surrounded by an involucre of short ramuli. Prrtora (4y-) 
| —from srideris, pinnated. 
Pritota plumosa ; frond cartilaginous, decompound; secondary branches 
bi-tripinnate, elongate; pimne and pinnules exactly opposite, the 
| latter subulate, cellular, traversed by a narrow, immersed, jointed 
| filament ; tetraspores on short pedicels, frmging the margin of the 
pinnules ; flavellze pedunculate, with an involucre of 6-8 subulate 
| 
| 
: 
: 
+ 
ramuli. 
Pritota plumosa, 4g. Sp. Alg. vol.i. p. 385. (exel. var. 8.) dg. Syst. p. 195. 
Iyngb. Hyd. Dan. p. 38.+.9. Grev. Fl. Edin. p.297. Spreng. Syst. Veg. 
vol. iv. p. 344. Hook. Fl. Scot. part 2. p.106. Grev. Alg. Brit. p. 155. 
t. 16. Hook. Br. Fl. vol. ii. p. 84. Harv. in Mack. Fl. Hib. part 3. p. 204. 
Harv. Man. p. 84. Endl. 3rd Suppl. p. 36. Post. and Rupp. p.16. Kiitz. 
Phyc. Gen. p. 378. t. 46. f. 6. 
CERamivm plumosum, Roth. Cat. Bot. vol. iii. p. 133. 4g. Dist. p. 17. 
PLocamiumM plumosum, Lamour. Ess. p. 50. 
Fucus plumosus, Linn. Mant. p. 134. Syst. Nat. vol.ii. p.718. Huds. FI. 
Angl. p.587. Gm. Hist. Fuc. p.152. Fl. Dan. t. 350. Lightf. F7. Scot. 
vol. ii. p. 955. With. vol.iv. p.120. Esper. Ic. Fue. vol.i. p. 92. t. 45. 
Fl. Norv. vol. ii. p. 91. Linn. Trans. vol. ii. p. 188. Turn. Syn. Fue. 
vol. ii. p.296. Turn. Hist. Fuc. t. 60 (erel. var. 8.). Eng. Bot. t. 1308. 
Has. Parasitical on the stems of Laminaria digitata. Perennial. Sum- 
mer and autumn. Frequent on the shores of Scotland, and of the 
north and west of Ireland. Holyhead, Mr. Ralfs. Scarborough, . 
Grocer. Distr. Distributed throughout the Arctic, the North Atlantic and 
North Pacific Oceans. -Davis’s Strait, Turner. Iceland, Gder. White 
Sea, Greenland, Sitka, Unalaska, Postels and Rupprecht. Arctic America, 
Richardson. Kamtschatka, Bongard. Norway and Sweden. 
Descr. Root scutate. Fronds tufted, 4-12 inches in length, compressed, linear, 
from the thickness of a hog’s bristle to nearly a line in diameter, irregularly 
divided. Secondary branches distichous, 1-3 inches in length, patent, linear- 
oblong or obovate in circumscription, bi-tripinnate, the pinnz and pinnules 
very patent, scarcely a le asunder, gradually increasing in length toward 
the middle of the branch, and diminishing to the apex. Ultimate-pinnwles 
closely pectinate, awl-shaped, acute, cartilaginous, sub-opake, their outer 
coat formed of numerous angular cellules, through which is visible a jointed 
pat § 
