P l a t e LXXX.
PTILOTA PLUMOSA, Ag.
Gen. Ciiar. Frond inarticulate, linear, compressed or flat, distichous, pectinato
pinnate ; the pinnules sometimes articulate. Fructification, of
two kinds, on distinct individuals; 1, tetraspores attached to, or
immersed in the ultimate pinnules; 2, roundish, clustered, receptacles
[favella] surrounded by an involucre of short ramuli. P t i l o t a [Ag.)
—from 7rrtXo)TÓs, pinnated.
P t i l o t a plumosa ; frond cartilaginous, decompound ; secondary branches
bi-tripinnate, elongate; pinnæ and pinnules exactly opposite,^ the
latter subulate, cellular, traversed by a narrow, immersed, jointed
filament ; tetraspores on short pedicels, fringing the margin of the
pinnules; flavellæ pedunculate, with an involucre of 6 -8 subulate
ramuli.
P t il o t a plumosa, Ag. Sp. Alg. vol. i. p. 385. [excl. m r. ß.) Ag. Syst. p. 195.
Lyngh. Hyd. Dan. p. 38. t. 9. Grev. M . Edin. p. 297. Spreng. Syst. Veg.
vol. iv. d. 344. Hook. El. Scot. part 2. p. 106. Grev. Alg. B n t. p. 155.
1 .16. Èook. Br. I I . vol. ii. p. 84. Harv. in Mack. El. Hib. part 3. p. 204.
Harv. Man. p. 84. Endl. 3rd Suppl. p. 36. Post, and Bupp. p. 16. Kütz.
Phyc. G e n .p .313. t .4 6 .î.& .
C e r a m iu m plumosum. Both. Cat. Bot. vol. iii. p. 133. Ag. Dist. p. 17.
P l o c am ium p lum o sum , Lamour. Ess. p . 5 0 .
F u ous plumosus, Linn. Mant. p. 134. Syst. Nat. vol.ii. p. 718. Huds. El.
Angl. p. 531. Gm. H ü t. Eue. p .l5 2 . El. Dan. i.3 5 3 . Ughtf. El. Scot.
vol. ii. p. 955. With. vol. iv. p. 120. Esper. Lc. Eue. vol. i. p. 92. t. 45.
El. Norv. vol. ii. p. 91. Linn. Trans, vol. iii. p. 188. Turn. Syn. Eue.
vol. ii. p. 296. Turn. Hist. Eue. i. 63 [excl. var. ß.). Eng. Bot. i.1 3 3 3 .
H a b . Parasitical oh the stems of Laminaria digitata. Perennial. Summer
and autumn. Frequent on the shores of Scotland, and of the
north and west of Ireland. Holyhead, Mr. Balfs. Scarborough, —— .
G b o g b . D i s t b . Distributed throughout the Arctic, the North Atlantic and
North Pacific Oceans. Davis’s Strait, Turner. Iceland, OEder. White
Sea, Greenland, Sitka, XJnalaska, Postéis and Bupprecht. Arctic America,
Bichardson. Kamtschatka, Bongard. Norway and Sweden.
D e s c b . Boot scutate. Eronds tufted, 4 -1 2 inches in length, compressed, hnear,
from the thickness of a hog’s bristle to neaiiy a line in diameter, irregularly
divided. Secondary branches distichous, 1 -3 inches in length, patent, linear-
oblong or obovate in circumscription, bi-tripinnate, the pinnæ and pinnules
very patent, scarcely a line asunder, gradually increasing in length toward
the middle of the branch, and dhninisliing to the apex. Ultimate pinnules
closely pectinate, awl-shaped, acute, cartilaginous, snb-opake, their outer
coat formed of numerous angular cellules, through which is visible a jointed
2 X
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