46 CHORDARIA. 



** Frond either tuber-shaped or crustaceans and spreading. 



III. Leathesia. Frond tuber-shaped. [Plate 10, C] 



IV. Ralfsia. Frond ciustaceous. [Plate 10, D.] 



*** Parasites, consisting of densely tufted filaments, connected at the 



base, free above. 



V. Elachistea. Filaments pencilled, rising from a tuber- 



cular base, composed of vertical fibres. [Plate 10, E.] 



VI. Myrionema. Filaments pulvinate, rising from a flat 

 base, composed of decumbent fibres. [Plate 10, F.] 



I. Chordaria. Ag. [Plate 10, A.] 



Frond filiform, much branched, cartilaginous ; the a.vis 

 composed of densely packed, longitudinal, interlaced, cylin- 

 drical filaments ; the periphery of simple, club-shaped, hori- 

 zontal, whorled filaments, and long, byssoid, gelatinous fibres. 

 Fructijication : obovate spores, seated among the filaments 

 of the periphery. — Name, from Chorda, a cord. 



1. C. Jlagelliformis,Mw\\.; frond filiform, equal through- 

 out • branches alternate, long and mostly simple ; filaments 

 of the periphery club-shaped. Grev. Alg. Brit. p. 44 ; Hook. 

 Br. Ft. ii. p. 275 ; E. Bot. t. 1?22 ; Wi/att, Alg. Damn. No. 

 57 ; Harv. Phyc. Brit. t. cxi. 



Between tide-marks, on rocks and stones, common. Annual. Summer. 

 — Root small, discoid. Fronds from three inches to three feet long, slen- 

 der, about half a line in diameter, with a central stem, which is either 

 simple or irregularly divided in its upper part, and bears numerous lateral, 

 irregularly inserted, long, generally simple branches, of equal thickness. 

 The colour is dark olivaceous green ; the substance firm and cartilaginous. 

 The whole frond, if viewed in the water, appears fringed with exceedingly 

 fine colourless fibres, which give to the surface a slimy feel. They have 

 some resemblance to the colourless fibres of Myriotrichia. 



2. C. divaricata, Ag. ; frond irregularly divided ; branches 

 divaricate, subdichotomous, flexuous, furnished towards the 

 apices with short, very patent, mostly forked ramuli ; filaments 

 of the periphery capitate. Harv. Phyc. Brit. t. xvii. 



Thrown up from deep water, at Carrickfergus, Mr. M'cCalta. Annual. 

 Autumn. — Fronds 1 — 3 feet long, not a line in diameter, forming globose 



