IV. 
F U CACE2E. — H IM ANTE ALIA. 
71 
7. Fucus vesiculosus, Linn., frond flat, leathery, thick, linear, dichotomous, quite 
entire at the margin, midribbed ; air-vessels globose or elliptical, mostly in pairs, 
(often absent) ; receptacles terminal, turgid, ellipsoid, ovoid, or spindle-shaped. 
J. Ag. Sp. Alg ., vol. 1, p. 210. Kutz . Sp. Alg. p. 589- Turn. Hist. t. 88. E. 
Bot. t. 1066. Harv. Pliyc. Brit. t. 204. Fucus divaricatus, F. inflatus, F. spiralis, 
F. volubilis , F. Sherardi, Auct. F. bicornis , and F. microphyllus , l)e la Pylaie, eye. 
Hab. On rocks and stones between tide-marks. Very common on all rocky 
shores from Greenland to New York. Also on the N. W. coast ; in California, and 
northward. (The southern limit on the east coast not ascertained.) (v. v.) 
Fronds from two inches to two feet long, or more ; varying from a line to nearly 
an inch in breadth, flat, midribbed, many times forked ; often spirally twisted. 
Air-vessels generally in pairs, one at each side of the midrib, spherical or oval, 
their size varying with the breadth of the frond. Peceptacles very turgid, and 
filled with a lax, watery jelly, through which a network of delicate filaments 
extends. Colour olive or brown. Substance coarse and thick. 
Very variable in size and degree of ramification, according to the locality in 
which it grows. When destitute of air-vessels, it may be mistaken by the student 
for F. ceranoides , but the frond is much thicker and more opaque than in that species, 
and contains a far greater proportion of alkaline matter. The earlier writers on 
marine plants made a great number of species out of this ; but its varieties only 
appear different when isolated specimens are examined in the cabinet. On the sea 
shore all the various forms may be seen passing into one another at different tidal 
levels. F. vesiculosus is distributed in the northern Atlantic from the Arctic coasts 
to the Canary Islands ; and in the Pacific, from Kamtschatka to California. It is 
reported to have been brought from the Cape of Good Hope and from Australia, 
but these localities want confirmation. On the east coast of America it and F. 
nodosus constitute at least three fourths of the covering of tidal rocks. 
YI. — PIIMANTHALIA. Lyngb. 
Root a disc. Frond at first top-shaped, then cup-shaped, vesicular, unbranched. 
Receptacles very long, strap-shaped, repeatedly forked, springing from the centre of 
the cup-shaped frond, filled with mucus, traversed by jointed fibres, and pierced by 
numerous pores, beneath which are placed the spherical conceptacles (or spore- 
cavities). Spore cavities diclinous. Spores four within the same hyaline perispore, 
several perispores attached to the walls of the cavity. Antheridia on branching 
filaments, racemose. Paranemata simple, lining the cavity. 
