Seb. MELANOSPEKME^. (35) Fam. SPOROCHNOIDEvE- 



DESMARESTIA \miDlS. —Lamour. 



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

 a single-tubed jointed axis ; cells of tlie inner stratum 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 viridis. — Frond filiform, cylindrical, decomposito-pinnate ; 

 pinnae and pinnulee all opposite ; young branches confervoid. 



Desmarestia viridis. — Lamour. Ess. p. 25 ; Endl. 3rd Suppl. p. 28 ; Kiltz. Phijc. 

 Gen. p. 344 ; KiUz. Sp. Afj. p. 570 ; Harv. P. B. plate 312 ; Harv. 

 Man. p. 24; Harv. Syn. p. 22 ; Atlas, plate 5, fig. 19 ; Harv. N. B. A. 

 part 1, p. 77. 



DiCHLORiA viridis. — Grev. Ah;. Brit. p. 39, t. 6 ; Hoot:. Br. Fl. vol. ii. p. 274 ; 

 Harv. in Mack. Fl. Hib. part 3, p. 173 ; Wyatt, Alg. Hanm. No. 56 ; 

 /. G. Agardh, Sp. Gen. Alg. vol. i. p. 164. 



Sporoohnus viridis. — Ag. Sp. Alg. vol. i. p. 154 ; Ag. Syst. p. 259 ; Grev. Fl. Edin. 

 p. 287. 



Chordaria viridis. — Ag. Syn. p. 14 ; Hook. Fl. Scot, part 2, p. 98. 



GiGARTiNA viridis. — Lyngh. Hyd. Dan, p. 44. 



FuctJS viridis. — Fl. Han. t, 886 ; Esper, Ic. Fuc. t. 114 ; StacTc. Ner. Brit. t. 17; 

 Turn. Syn. vol. ii. p. 397 ; Turn. Hist. t. 97 ; E. Bot. t. 1669. 



Hab. — On stones in the sea. Also on the larger Algje, and extending to between tide- 

 marks. Annual. Spring and summer. Common. 



Geogr. Dist. — Atlantic shores of Europe and America ; Northern Pacific ; Southern 

 and Antarctic Oceans. 



Description. — Root, a minute disc. Frond filiform, cylindrical, one 

 to two feet or more in length, and less than half a line in diameter, 

 repeatedly branched in a regularly pinnated manner, all the parts 

 opposite, gradually tapering upwards, and shorter, giving the frond an 

 ovate outline ; at first composed of a simple confervoid axial filament, 

 which gradually becomes coated with successive layers of simple cellules, 

 interspersed with several series of veiy large empty ones ; those near 

 the surface somewhat smaller. Substance rather soft and flaccid, closely 

 adhering to paper. Colour, a fine brownish olive when fresh, passing 

 into brownish orange when suffered to decay in salt water ; but when 

 removed from the water, and especially if left in contact with other 

 Algee, the colour soon changes to a deep verdigris gi'een, often com- 

 municating the tint to the others. 



