Ser. Melanospeeme^e. Fam. Sporoehnoidece. 



Plate XLIX. 



DESMARESTIA ACULEATA, Lamm. 



Gen. Char. Frond linear, either filiform, compressed, or flat, distichously 

 branched, cellular, traversed by an internal, single-tubed, jointed fila- 

 ment ; producing, when young, marginal tufts of byssoid, branching 

 fibres. Fructification unknown. Desmarestia (Lamour.) — in honour 

 of A. G. Desmarest, a celebrated French naturalist. 



Desmarestia aculeata ; stem short, cylindrical, bearing numerous slender, 

 elongate, flattish, irregularly bi-tri-pinnate branches ; pinnae and pin- 

 nulse alternate, tapering at the base, filiform, either fringed with oppo- 

 site tufts of bright green fibres, or margined with erect, awl-shaped, 

 alternate, distichous spines. 



Desmarestia aculeata, Lam. Ess. p. 25. Oreo. Alg. Brit. p. 38. t. 5. f. 2, 3. 

 Hook. Br. II. vol. ii. p. 273. Harv. in Mack. II. Hib. part 3. p. 1 72. Wyatt, 

 Alg. Damn. no. 158. Harv. Man. p. 26. Endl. 3rd Suppl. p. 28. Kiitz. 

 Phyc.Gen. p. 343. t. 26. f. 1. 



Desmia aculeata, Lyngb. Hyd. Dan. p. 34. t. 44. B. 1. 



Sporochnus aculeatus, Ag. Sp. Alg. vol. i. p. 151. Ag. Syst. p. 259. Hook. 

 II. Scot, part 2. p. 96. Grev. II. Edin. p. 287. 



Fucus aculeatus, Linn. Sp. PL p. 1632. Huds. II. Ang. p. 585. Light. II. 

 Scot. p. 924. M. Dan. t. 355. Stack. Ner. Brit. p. 24. t. 8. Turn. Syn. 

 vol. ii. p. 262. Turn. Hist. 1. 187. 



Eucus muscoides, Linn. Sp. PL p. 1630. Huds. II. Ang. p. 590. 



Hab. On rocks and stones in the sea, near low- water mark, and at a greater 

 depth. Perennial. Common on the shores of the British Islands. 



Geogr. Distr. Atlantic shores of Europe, from North Cape to Spain. Shores 

 of Piedmont, Allioni (but omitted by </. Agardh in his Alg. Medit.). 



Descr. Root a hard disc. Ironds 1-3, to 6 feet in length, undivided, or 

 branching from a short distance above the base, preserving throughout a 

 nearly equal breadth of half a line, compressed, more or less angularly 

 tlexuous, bearing along their whole length alternate lateral branches, the 

 lower of which are longest, the rest gradually shorter upwards. Lower 

 /'ranches repeatedly compound, bearing one, two, or three sets of distichous, 

 alternate, erect or erecto-patent lateral branches ; upper ones gradually less 

 and less compound, and those near the apex quite simple. Occasionally 

 two branches spring from the same point, at the same side of the stem; 

 and more rarely, two of the lesser branches are found opposite to each other. 

 In an early stage of growth all the branches are clothed, at intervals of 

 about a line, with opposite pencils of finely divided, repeatedly pinnate, 

 byssoid, articulated fibres of a beautiful yellow-green colour, which appa- 

 rently originate in the jointed thread which runs through (he centre of the 

 frond. These fibres soon fall away. Leaving the steins and branches naked, 

 and then alternate, subulate spines are developed at intervals of two t<> foul 



