See. MELANOSPERME^. ( 33 ) Fam. SPOROCHNOIDE^. 



Plate CXLIII. 

 DESMAEESTIA ACVIjEAT A.— Lamour. 



Gen. Char. — Frond cartilaginous, cellular, composed of three strata of cells, surrounding 

 a single-tubed jointed axis ; cells of the inner sti-atum very minute, of the second 

 rather large, those of the periphery very small ; "producing, when young, mar- 

 ginal tufts of byssoid, branching fibres." Name in honour of A. G. Desmarest, 

 a celebrated French Naturalist. 



Desmarestia acideata. — Frond linear, flattened, not two-edged, irre- 

 gularly divided in a bi-tripinnated manner, very narrow and elongated ; 

 branches all attenuated at each end, ciliated when young with very 

 delicate byssoid filaments, when old by suberect spine-like teeth. 



Desmakestia aculeata. — Lamour. Ess. p. 25 ; Grev. Alg. Brit. p. 38, t. 5, f. 2, 3 ; 

 Hooh. Br. Fl. vol. ii. p. 273 ; Wyatt, Alg. Damn. No. 158 ; Endl. 

 Srd Suppl. p. 28 ; Kiitz. Phyc. Gen. p. 343, t. 2C, f, 1 ; Ilarv. in 

 MacJc. Fl. Hib. part 3, p. 172 ; Harv. P. B. plate 49 ; Barv. Man. 

 p. 23; Harv. Syn. p. 22; Atlas, plate 5, fig. 18; Harv. N. B. A. 

 part 1, p. 78 ; /. Q. Agardh, Sp. Gen. Alg. vol. i. p. 167. 



Dksmia acideata. — Lyngh. Hyd. Dan, p, 34, t. 44 B, 1. 



Spoeochnus aculeatus. — Ag. iSp. Alg. vol. i. p. 151 ; Ag. Syst. p. 259 ; Hook. 

 Fl. Scot, part 2, p. 96 ; Gi-ev. Fl. Edin. p. 287. 



Vvovs -aculeatus. — Linn. Sp. PI. p. 1632; Huds. Fl. Angl. p. 585; Light./ . Fl, 

 Scot. p. 924 ; Fl. Dan. t. 355 ; Stack. Ner. Brit. p. 24, t. 8 ; Turn. 

 Syn. vol. ii. p. 262 ; Turn. Hist. t. 187. 



Fucus muscoides. — Linn. Sp, PI. p. 1630 ; Huds. Fl. Angl. p. 590 



Hab.— On rocks and stones in the sea, and at low-water mark. Perennial. Common. 



Geogk. Dist. — Atlantic shores of Europe; shores of Piedmont. 



Description. — Root, a hard conical disc. Frond with a very short 

 cylindrical stem, linear, compressed, the edges rounded, much branched, 

 two to four feet or more in length, half a line to a line in breadth ; 

 branches bi-tripinnated, generally alternate, sometimes opposite, fre- 

 quently two, occasionally three, arising from the same point, with 

 which exception all are regularly distichous, long and slender, the lower 

 ones very gi'adually tapering to an acute point, the upper very much 

 attenuated to each end ; all the divisions when young are beautifully 

 fringed with very delicate jointed byssoid filaments, much branched in 

 a regularly bi-tripinnate manner; pinnae and pinnulse opposite, regu- 

 larly shorter upwards, foiming a conical outline ; when old fringed with 



VOL. III. V 



