Ser. MELANOSPERME.E. (25) ' Fam. FUCACEiE. 



FUCUS MACKAIL— Turn. 



Gen. Char. — Frond coriaceous, internally composed of densely - packed interlacing and 

 anastomosing filaments, the periphery of radiating filaments, short, simple, and 

 closely placed; air-vessels innate; receptacles terminal, or lateral and stalked, 

 containing within the periphery spherical receptacles communicating with the 

 surface by a minute pore, and containing attached to their inner surface obovate 

 spores or stalked antheridia, "or both." Name from ^wos, "a sea-weed." 



Fucus Mackaii. — " Frond cylindrical or subcompressed, slender, much 

 branched ; branches dichotomous ; air-vessels elliptical, solitary ; recep- 

 tacles lateral, lanceolate-ovate or forked, stalked, pendulous, scattered 

 near the base of the branches." — Phyc. Brit. 



Fucus Mackaii. — Turn. Hist. i. 52 ; Sm. E. Bot. t. 1927 ; Lamour. Ess. p, 20 ; 

 Aff. Sp. Alg. vol. i. p. 87 ; Hook. Fl. Scot, part 2, p. 95 ; Grev. Alg. 

 Brit. p. 17 ; Hook. Br. Fl. vol ii. p. 268 ; Grev. in Phyc. vol. i. 

 p. 465 ; Harv. in Mack. Fl. Hih. part 3, p. 169 ; Harv. P. B. 

 plate 52; Harv. Man. p. 19; Harv. Syn. p. 19; Atlas, plate 4, 

 fig. 14. 



Fucus nodosus, y Mackaii. — Ag. Syst. p. 275; /. G. Agarclh, Sp. Gen, Alg. 

 vol. i. p. 206. 



Physocaulon Mackaii. — Kv,tz. Phyc. Gen. p. 352. 



Hab. — Muddy shores, and among boulders. Perennial. April till June. North and 

 west of Scotland ; west of Ireland. Not uncommon. 



Geogr. Dist. — North of Europe ; Baltic. 



Description. — " Fronds growing in globular tufts, the size of a human 

 head or larger, six to twelve inches long," one to two lines in diameter, 

 linear, cylindi-ical or subcompressed, very much branched from near the 

 base in an irregularly dichotomous manner, here and there pinnated 

 with short, simple, or forked spreading branches. The branches are 

 nearly cylindrical, scarcely tapering, erect, erecto-patent or patent, often 

 trichotomous ; the axils obtuse, but not much rounded, apices obtuse- 

 Vesicles rather small, innate, elliptical, scattered through the frond at 

 irregular distances. Receptacles elliptical lanceolate, single, in pairs or 

 forked, pendulous, on slender cylindrical stalks, produced near the base 

 of the main branches. Substance subcoriaceous, somewhat brittle, more 

 or less adhering to paper. Colour, a dull yellowish olive. 



We have not seen this species in the growing state, but judging from 

 such characters as the dried plants afford, we must acknowledge that, to 

 say the least of it, it is a very puzzling species. 



VOL. in. s 



