174 ALGM MELANOSPERME.E. [Chorda. 



constricted, truncate ; fruit " terminal, elliptical, solitary." 

 (Turn.) Ag. Syst. p. 260. Fucus Cabrera. Turn. Hist, 

 t. 140. 



At Youghal, among rejectamenta, very rare ; Miss Ball. Hoot a 

 shapeless tuber. Stems 68 inches high, much branched in an irregu- 

 larly dichotomous manner, flat, nerveless, except near the base, where 

 there is a faint trace of a central midrib, coriaceo-cartilaginous. 

 Branches erect, with acute axillaB, distichous, alternate, narrow below, 

 rather broader upwards, here and there constricted, the apices truncate 

 and often discoloured. Fructification, " placed upon the ends of the 

 branches, which then expand into a small flat disk, supporting a single 

 cylindrical tubercle scarcely a line long, of a pale flesh colour, slightly 

 tinged with brown, destitute of any epidermis, and wholly consisting of 

 very thin parallel whitish fibres, of a clavate shape, with a rounded 

 tip, mixed with which lie oblong reddish seeds." Turn. Hist. vol. iii. 

 p. 14. Miss Ball's specimens are unfortunately without perfect fruit, 

 though many of the apices present imperfect indications of fructifica- 

 tion. 



TRIBE V. DICTYOTE.E. 



Plants marine, of an olive-green colour, and membranaceous 

 flexible substance, rarely cartilaginous, and scarcely at all juicy, with 

 a highly reticulated structure. Frond cylindrical or flat, simple or 

 branched, nerveless ( except in HaliserisJ, often divided in a flabd- 

 liform manner. Fructification, dark-coloured ovate or pear-shaped 

 seeds, with pellucid cases, which are variously arranged in, lines, 

 sori, or covering the whole frond ; very rarely enclosed in capsules. 

 A beautiful family, easily distinguished by the highly reticulated 

 structure. Under the microscope, the frond appears like a delicate 

 network. 



11. CHORDA. Stackh. Sea Whip-lash. 



Frond simple, filiform, cylindrical, with an interrupted cavity. 

 Root naked, scutate. Fruct.: external continuous masses of 

 pear-shaped seeds, fixed by their base. Grev. Name ; chorda, 

 a cord. 



1. C. Filum, Lamour. Common Sea Whip-lash. Frond 

 cartilaginous, very long, slimy, cylindrical, internally jointed. 

 Hook. Hr. Fl. v. ii. p. 276. E. Bot. t. 2487. 



Sea-shores, common. 120 or even 80 feet long, according to the 

 depth of water ; composed, as Captain Carmichael well expresses it, 

 "of a simple fillet, one or two lines in breadth, spirally twisted into a 

 filiform tube, formed by the cohesion of its edges." 



2. C. lomentaria, Grev. Jointed Whip-lash. Frond short, 

 membranaceous, jointed at irregular intervals, the joints exter- 

 nally much constricted. Hook. Br. Fl. v. ii. p. 276. Lyngb. 



