Ser. MelanospermejE. Earn. Fucea>. 



Plate ML 

 FUCUS MACKAII, Turn. 



Gen. Char. Frond linear, either flat, compressed, or cylindrical, dichotomous 

 (rarely pinnated), coriaceous. Air vessels, when present, innate, 

 simple. Receptacles either terminal, or lateral, filled with mucus tra- 

 versed by a net-work of jointed fibres, pierced by numerous pores, 

 which communicate with immersed spherical conceptacles, containing 

 parietal spores, or antheridia, or both. Fucus (L), fyvicos, a seaweed. 



Eucus MacJcaii; frond cylindrical or subcompressed, slender, much 

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

 ceptacles lateral, lanceolate, ovate, or forked, stalked, pendulous, scat- 

 tered, near the base of the branches. 



Fucus Mackaii, Turn. Hist. t. 52. 8m. E. Bot. t. 1927. Lam. Ess. p. 20. 

 Ag. Sp. Alg. vol. i. p. 87. Hook. Fl. Scot, part 2. p. 95. Grev. Alg. Br. 

 p. 17. Hook. Br. Fl. vol. ii. p. 268. Harv. in Mack. Fl. Hid. part 3. 

 p. 169. Harv. Man. p. 21. Grev. in Phyc. vol. i. p. 465. 



Fucus nodosus, y. Mackaii, Ag. Syst. p. 275. 



Physocaulon Mackaii, Kiitz. Phyc. Gen. p. 352. 



Hab. Muddy sea shores, usually in land-locked bays, and among boulders. 

 Perennial. April and May. Birterbui Bay, Cunnemara, Mr. J. T. 

 Mackay. (1805). Loch Seaforth, Lord SeqfortA. Arasaig, Mr. 

 Borrer. Loch Coul and Kyle Scough, Sutherland, Messrs. Borrer 

 and Hooker. East coast of Skye, and head of Loch Duich Messrs. 

 Hooker and Greville. 



Geogr. Distr. North of Europe. Baltic sea, Areschoug. 



Descr. Fronds growing in globular tufts the size of a human head or larger, 

 many fronds radiating from a subcentral point, but without obvious root or at- 

 tachment. Fronds 6-] 2 inches long, from half a line to two lines in diameter, 

 cylindrical or subcompressed, cartilagineo-coriaceous, rather brittle, ribless, 

 with a short, simple or forked main stem, from which issue, without much 

 regularity, numerous long, repeatedly dichotomous or occasionally trichoto- 

 mous branches, which gradually taper to the apices, where they are often 

 less than a quarter of a line in diameter, and are beset throughout their 

 length with more or less frequent, lateral, simple, or forked, patent ramuli. 

 Axils patent, rounded; apices blunt. Vesicles from a quarter to half ;m 

 inch in length, two lines wide, few, occurring generally below the forking 

 of the longer branches ; sometimes wanting. Receptacles lateral, borne by 

 slender peduncles issuing irregularly from the sides of the branches near 

 their base, pendulous, lanceolate, or bilobed, or somewhat ovate, yellow, 

 containing numerous spherical conceptacles, full of roundish Bpores, each of 

 which separates at maturity into four sporules. Colour a dull olive. Sub- 

 stance when dry somewhat horny and translucent. 



