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P late G U I.
DICTYOTA DICHOTOMA, Lamour.
Gen. C h a r . .Sao/ coated, with woolly fibres. flat, membranaceous,
ribless, reticulate, dichotomous or irregrdarly cleft. Fructification,
scattered clusters of spores formed beneath the cuticle, through which
they finaUy b u rst; or, on distinct plants, solitary spores irregularly
dispersed over the surface. D ic ty o ta {Lamx.)—from SiktCok, a n e t;
because the surface is reticulated.
D ic ty o ta dieJwtoma ; frond regularly dichotomous, linear ; segments cuneate
at the base, erect or erecto-patent, gradually narrower towards
tbe apices, axUs rounded.
D io ty o ta dichotoma, Lamour. Fss. p . .58. Orev. Alg. Brit. p . 5 7 . 1 . 1 0 . Ilooh.
Br. M. vol. ii. p . 3 8 0 . Harv. in Mach. M. Hib. part 3. p . 1 7 7 . Wyatt. Alg.
Banm. No. 1 0 . Harv. Man. p . 3 3 . Buby. Bot. Gall. p . 9 5 4 . Menegh. Alg.
Ital. and Balm. p . 2 2 4 . Endl. 3rd. Suppl. p . 2 4 . Mont. El. Alg. p . 3 0 .
Z o n a r ia d ic h o tom a , Ag. Sp. Alg. vol. i. p . 1 3 3 . Ag. Syst. p . 2 6 6 . Hoolc. FI.
Scot. v ol. ii. p . 9 0 . Grev. I I . Edin. p . 2 9 7 .
Diohophyllium vulgare, Kiitz. Phyc. Gen. p. 337. t. 2 2 . I I. f. 1 - 4 .
Dichophyllium dichotomum, Kütz. I. c. p. 388.
H aliseris dichotoma, Spreng. Syst. Veg. vol. 4. p. 338.
U lva d ic h o tom a , Huds. M. Ang. Ed. vol. ii. p . 5 6 8 . (ed . vol. i. p . 4 7 6 .) ,
Ughtf. El. Scot. p . 9 7 5 . t. 3 4 . With. v ol. iv . p . 1 2 4 . Eng. Bot. t. 7 7 4 .
lyngb. Hyd. Ban. p . 3 1 . t. 6. G.
Yar. ß. intricata; frond very narrow, much branched, twisted aud entangled,
Orev.
Dictyota dichotoma, ß. intricata, Grev. Alg. Brit. p. 58. Menegh. Alg. Ital.
and Balm. p. 327.
Dictyota implexa, Lamx. I. c. J. Ag. Alg. Medit. p. 37. Mont. El. Alg. p. 30.
Dichophyllium implexum, Kütz. Phyc. Gen. p. 338,
H a b . Parasitical on various Algæ ; also growing on rocks and stones in
tide-pools near low-water mark, and at a greater depth. Annual.
Summer. Both varieties common on the British Coasts.
Geogb. Dist e. Abundant throughout the Atlantic Ocean, extending from the
shores of Norway to the tropic. Southem Ocean, Western Shores of South
America ; Cape of good Hope ; New Zealand.
D esor. Root smaU, coated with fibres. Eronds several from the same base, from
three to twelve inches in length, from | to | an inch in breadth, cuneate at
base, afterwards nearly linear, very many times divided in a regularly
dichotomous manner ; segments generaUy very erect, with narrow interstices,
occasionally more or less spreading. Substance delicately membranaceous.
Colour olivaceous towards the tips. Eructification ; oval clusters of spores,
2 c