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P l a t e CLXXXIV.
GRIFFITHSIA SETACEA, Ag.
G en . Oh a r . Frond rosy-red, filamentous; filaments jomted throughout,
mostly dichotomous; ramuli single-tubed; dissepiments hyaline.
Fructifioation of two kinds on distinct individuals; 1, tetraspores
affixed to whorled involucral ramuli; 2, gelatinous receptacles [favellce)
smrouiided by an involucre, and containing a mass of minute, angular
spores. G r ip e it h s ia [Ag.),—in honour of Mrs. Oriffiths, the most
distinguished of British Algologists.
G r ip e it h s ia setacea ; filaments setaceous, straight, rigid, dichotomous, or
subdichotomous; axils very acute; lesser branches sometimes opposite,
attenuated to a point, erect ; articulations cylindrical, five or six
times longer than broad; involucres (of both kinds) pedunculate,
lateral.
Gr ip p it h s ia setacea, J g . Syn. p. xxviii. Ag. Syst. p. 144. Ag. Sp. Alg.
vol ii. p. 129. Grev. M. Edin. p. 312. Hook. Br. El. vol. ii. p. 838.
Harv. in Mack. El. Hib. part 3. p. 212. Wyatt, Alg. Banm. no. 187.
Harv. Man. p. 103. Endl. 3rd Suppl. p. 35. Kiitz. Phyc. Gen. p. 373.
Hook. fil. El. Ant. vol. i. p. 191.
Conferva setacea, EUis, Phil. Trans, vol. 57- t. 18. f. e. Turn. Linn. Tr.
vol. vii. p. 107. Huds. El. Ang.-p. 699. With. Yol.vi. p. 131. E .B o t.
t. 1689. Billw. Conf. t. 82. Bolh, Cat. Bot. vol. iii. p. 278.
H ab . On the perpendicular sides of deep rock pools, near low-water mark,
under the shade of larger Algæ. Perennial. Fruiting in spring and
summer. Frequent on the British shores, from Orkney to Cornwall.
Channel Islands.
Geogr. D is t r . Atlantic shores of Europe and America. Southern Ocean,
especially Tasmania.
D esc r . Tufts three to eight inches long, or more, dense, frequently interwoven
in the lower part with tangled fibres. Eilaments as thick as hog’s bristle,
sometimes not quite so thick, gradually attenuated from the base upwards,
many times dichotomous at short intervals ; the lesser divisions more in-e-
gular, alternate, or secund, frequently opposite ; itll the branches straight,
and generally erect, with acute axils. Frequently small, root-like, irregular,
horizontal ramuli issue from the sides of the main branches, and
catching on a neighbouring branch, connect the filaments in a tangled
web. Lesser branches gradually attenuated to the point. Arliculations
cylindrical ; the lower ones five or six times as long as broad, or sometimes
more ; the upper gradually shorter, all containing bags of endochrome surrounded
by a narrow border. Involucres of both kinds raised on short,
lateral peduncles, about a line in length, scattered on the sides of the
branches, those containing tetraspores most frequently found. Tetraspores
spherical, attached to the inner faces of the dicliotomous, involucral ramuli,
with wide borders. Eaveüæ generally binate, oval, likewise attached to
involucral ramuli, on distinct plants. Antheridia, or minute oval bodies,
l l i 'c \ r l íe r R i i i i A- i - ‘ •